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[Articles Home]  [Add Article]  

Antenna Tuners -- Do They Work?

William Caton (KL7VU) on January 28, 2014
View comments about this article!

The way I see it is KISS (keep it simple... stupid) OK, if my radio "see an SWR of over 2:1, it automatically decreases the output power to keep it's finals from overheating and thereby burning out. Simple enough.

Also, that SWR, which is a representation of the load mismatch "at the antenna" usually, means that whatever power my radio does decide to put out to the antenna, is being attenuated at the antenna too.

So -- for example, if a 3:1 SWR is eating half my power and the radio is only putting out 25 watts because of this condition, then using my tuner to "make the radio happy" is a good thing because now the radio is putting out the 100 watts it was design to.

If, and I say IF lightly, If the antennas' mismatch is still robbing me of 50% of my output power, then wouldn’t it be better to hit that mismatch with 100 watts -vs.- 25 watts?

So yes, I'd say that using an antenna tuner does a lot more than just 'Make the radio happy'.

Again, KISS.

KL7VU

Member Comments:
This article has expired. No more comments may be added.
 
Antenna Tuners -- Do They Work?  
by KB2DHG on January 28, 2014 Mail this to a friend!
Better to make the transmitter happy. Using an antenna tuner is the only way outside of using a 100% resonant antenna to keep that signal going in the right direction.
 
RE: Antenna Tuners -- Do They Work?  
by W5DXP on January 28, 2014 Mail this to a friend!
> kl7vu wrote: if a 3:1 SWR is eating half my power ...

The SWR at which 1/2 of the forward power is reflected by the load is 5.828:1. With a 3:1 SWR, the reflected power is 1/4 of the forward power, i.e. the power reflection coefficient is the square of rho, the voltage reflection coefficient, and since rho=0.5 when the SWR is 3:1 then Pref/Pfor=(0.5)^2=0.25

But you're right about the tuner. The purpose of an antenna tuner is obviously to radiate the maximum amount of available power from the antenna. It cannot accomplish that purpose without affecting voltage, current, and power conditions *at the antenna*.

A tuner in the shack doesn't change the SWR on the feedline but it does increase the power accepted by the antenna *at the antenna* to the maximum available amount.
--
73, Cecil, w5dxp.com

 
RE: Antenna Tuners -- Do They Work?  
by W5GNB on January 28, 2014 Mail this to a friend!
To answer your question "Do they Work"....Yes they do for what they are intended. Most of the "New" radios that we have today have a very narrow tolerance for anything Plus or Minus of a 50-OHM match. For this reason the manufacturers have included cutback features that will protect the finals.

The tuner will only provide a good match at the radio thus allowing full power output without danger of damaging the finals. The high SWR still exists from the back of the tuner out to the antenna but at least you are "Psudo-Matched" and things will work.

In the "OLD DAYS" of the Johnson Viking II type transmitters, we never were too concerned about SWR since the finals were Tubes (More Tolerant of Heating) and the output was a PI network capable of tuning a very wide range of impedances.

The new rigs have no tuning capability in the final, only filters. The power is delivered directly to the antenna so an EXTERNAL match is necessary if the antenna is not already resonate on the operating frequency.
 
Antenna Tuners -- Do They Work?  
by K1CJS on January 28, 2014 Mail this to a friend!
The plain and simple fact of the matter is they do work--to present a 50 ohm load to the radio. As far as getting maximum power to the antenna, you still will get about the same efficiency out of the antenna. You just move the 'fight' between the directed power and the reflected power from the finals of the radio to the matching circuits of the tuner.
 
RE: Antenna Tuners -- Do They Work?  
by K5DVW on January 28, 2014 Mail this to a friend!
Of course they work. That power that is reflected back from the antenna and then re-reflected back from the tuner will either be radiated or turned into heat in the transmission line. With low loss feedline like ladder line, for example, you could have a huge VSWR at the tuner and still have most of your energy radiated. The point is to get the maximum power out of your radio, and you do that by matching it to the transmission line/antenna system.
 
Antenna Tuners -- Do They Work?  
by KE6SLS on January 28, 2014 Mail this to a friend!

Oh this again.

All the new hams I mentor get the first lesson. It is a "matchbox". It is simply matching impedance between the rig and whatever antenna you are using. It ISN'T tuning the antenna, that is silly.

The second lesson is why we don't care what the SWR of any given antenna is since I always recommend balanced feeder. The matchbox will take care of it and the antenna will work well.

Good luck with your setup. Hope you have a lot of fun!

73
j
 
RE: Antenna Tuners -- Do They Work?  
by N4KC on January 28, 2014 Mail this to a friend!
Oh, boy! This topic usually results in miles and miles of comments and even a fist fight or two.

I don't think any aspect of our hobby--with the possible exception of code/no-code--generates as much controversy as "antenna tuners," SWR, and resonant (NOT "resonate") antennas.

That's why I wrote an article for eHam a while back titled "Resonance Schmesonance!" You can read it at:

http://www.eham.net/articles/25521

(There is an expanded version in a chapter in my book RIDING THE SHORTWAVES,)

73,

Don N4KC
www.n4kc.com
 
Antenna Tuners -- Do They Work?  
by N4DSP on January 28, 2014 Mail this to a friend!
There is no such thing as an Antenna Tuner.
 
RE: Antenna Tuners -- Do They Work?  
by N4KC on January 28, 2014 Mail this to a friend!
Sure there is, John! An Antenna Tuner is the guy you coerce to come to your house with a pair of wire cutters to trim each end of your dipole. :-)

73,

Don N4KC
www.n4kc.com
www.donkeith.com

 
RE: Antenna Tuners -- Do They Work?  
by WB2WIK on January 28, 2014 Mail this to a friend!
[quote]There is no such thing as an Antenna Tuner. [/quote]

Sure there is.

Part 7 of this rather famous article by Walt Maxwell W2DU entitled, "My Transmatch Really Does Tune My Antenna" explains how: http://www.k6mhe.com/files/Reflect_rev1.pdf

 
Antenna Tuners -- Do They Work?  
by K1DA on January 28, 2014 Mail this to a friend!
An antenna matching unit allows the use of low loss balanced feedline with 50 ohm transmitters. For multiband antennas it's a useful system. It may not be the onlly, or the best solution but it's aq whole lot better than NO solution.
 
RE: Antenna Tuners -- Do They Work?  
by AI4WC on January 28, 2014 Mail this to a friend!
I re-read my friend Don's article and I agree fully. I add to the general audience that they take Don's argument and incorporate the principles of the popular adjustable Steppir antenna and you can really talk about putting out a good signal! And, always remember: A good general rule is that a resonant antenna is truly resonant at only one frequency.

Thanks, Don

Jim
AI4WC
 
Antenna Tuners -- Do They Work?  
by KB4QAA on January 28, 2014 Mail this to a friend!
The Tuner allows the maximum transfer of power from the radio into the 'Antenna System (tuner+feedline+antenna).

The tuner does create a resonant circuit of the Antenna System (tuner+feeline+antenna).

It does not change the natural resonant frequency of the antenna.

It does not change the impedance match between the feedline and the antenna. If that is poor, you can still be losing lots of power there.
 
Antenna Tuners -- Do They Work?  
by K4PIH on January 28, 2014 Mail this to a friend!
Not having deep pockets, one of the ways I keep costs down and operations up is to build antennas that are as close to resonent as possible on the frequencies I use. I have a tuner (or matcher) but only use it when I don't have the room to put up the proper antenna or in an emergency situation. I know some hams think that a tuner is the end all to be all. You can transmitt off of a chain link fence if you have a big enough tuner, but I don;t know what the radiation pattern would be :>)
 
Antenna Tuners -- Do They Work?  
by KZ5A on January 28, 2014 Mail this to a friend!
OK, here's my take.

An "antenna tuner" does not match the transmitter to the antenna, it matches the TX to the complex impedance at the TX end of the feedline, which makes the TX happy.

If the antenna is mis-matched to the feedline, that condition still exists and there will be SWR on the feedline. The feedline SWR causes a degree of loss in the feedline.

So if your feedline exhibits a high SWR at the TX end, that condition is unaffected by an antenna tuner but the antenna/feedline does look to be matched from the perspective of the TX, so it will provide it's normal full power into the antenna tuner. The tuner itself has a degree of loss that is mostly related to circulating currents within the tuner elements, mostly IR loss in the coil, and is generally higher when the feedline SWR is higher.

Soooo, an antenna tuner is not a panacea for resolving a mis-tuned antenna situation but is better that nothing, especially with modern solid state transceivers that have a poor sense of humor about SWR.

Minimum loss and greatest radiated power will always occur when the antenna is resonant and has the same (50 ohm) characteristic impedance as the feedline. In the real world that "perfect" match almost never occurs so an antenna tuner is pretty much always needed to some degree.

73 Jack KZ5A

 
RE: Antenna Tuners -- Do They Work?  
by AA4PB on January 28, 2014 Mail this to a friend!
There are cases where an antenna tuner is not needed. For example, Yagis, trapped verticals, and most VHF/UHF beams are designed for 50 Ohms and don't require a tuner to operate. It's important to remember that using a tuner to match an antenna system to the radio's 50 Ohm output doesn't necessarily allow the antenna to work properly. For example, using a tuner to "force" a 10/15/20 yagi to take power on 40M doesn't mean that the antenna is going to have any forward gain or front to back ratio and it may very well cause the traps to fail. A tuner is not a magic black box that "fixes" all antennas. It's a "tool" that needs to be understood in order to use it effectively.


 
Do you want efficient RF power at you antenna?  
by AI2IA on January 28, 2014 Mail this to a friend!
Tattoo this on your brain:

A RESISTIVE LOAD CAN ONLY BE GOTTEN WITH A RESONANT ANTENNA.

If you fully comprehend that statement, then you know why multiple RESONANT antennas, while maybe costly and or difficult to fit on your property, remain the best way to go.

Of course you can live with a antenna "tuner," but why accept inefficiency so you can have as many bands as possible, when you can have several bands at best efficiency? It is up to you to answer that one.

de Ray, ai2ia

 
RE: Do you want efficient RF power at you antenna?  
by AA4PB on January 28, 2014 Mail this to a friend!
No, A RESISTIVE LOAD CAN ONLY BE GOTTEN WITH A RESONANT ANTENNA **SYSTEM** (tuner + feedline + antenna).

A tuner will add capacitance or inductance as needed to cancel the reactance and provide a resistive load to the transmitter.
 
RE: Resonant antennas do not need Tuners.  
by W4CNG on January 28, 2014 Mail this to a friend!
I have all resonant antennas in my Attic that work just fine. The only time the resonance changes is when I get a couple of inches of snow on the roof. Resonant frequency goes up. My definition of a Tuner is it is "A device that makes a bad antenna look good to a radio". My 800 watt Amp makes good bandwith of my Attic Antennas and has done the same for the antennas I used to have in our 5 Land second home.
 
RE: Resonant antennas do not need Tuners.  
by K6AER on January 28, 2014 Mail this to a friend!
"There is no such thing as an Antenna Tuner."

SteppIR comes to mind.

 
Antenna Tuners -- Do They Work?  
by N8NSN on January 28, 2014 Mail this to a friend!
If some type of restriction requires a radio antenna to be stealthy or perhaps there is just a desire to work a hand full of HF bands with one relatively small antenna a PROPERLY PLACED tuner is an acceptable practice.

In this case one good way to do this would be a remote tuner for an unbalanced feed system. This could be accomplished with minimal costs with: Three step motors, two inductors (roller types or tapped with a multi pos wafer on the motors' gearing), and one variable cap capable of the voltage and RF current products on the third motor. It would be educational and fun to build for anyone who likes that kind of thing. Hang a 30 foot vertical wire, two counterpoise wires 30 feet each. Connect the smaller 10 or so turn inductor as a shunt, the 30 or so turn inductor as a base load "L", and the variable cap in parallel with the base "L". This would work great from 80 through 15 meters and actually exhibit a bit of real gain on 30, through 15 meters, and a low t.o. Angle to boot. Minimal loss in the feeder, as well.

If parallel fed, a simple 30 foot per side vertical dipole for low overall height, or 30 foot per side as high as possible horizontally would be a great choice. Ditch the bal-un and use a link coupled tuner. This can be in the shack and that saves a ton of mechanics issues associated with home brewing a remote 2L1C ATU.

So, my 2 cents is that absolutely antenna tuners work if they're used properly and for their intended purpose.
 
RE: Antenna Tuners -- Do They Work?  
by K5TED on January 28, 2014 Mail this to a friend!
It can be done with an antenna coupler at the feedpoint, such as a SGC-230 or similar. It is what it is.

The concept posed here in the OP is that an antenna tuner has a useful aspect. That is true. Disregard those who choose to answer with tales of multiple band specific dipoles and such. That is simply strawman argument irrelevant to the context of the original topic.

The point is, in a restricted scenario, a tuner is the only way to deliver the maximum power to the antenna or feedline within the restrictions of the antenna resonance, etc.

The restrictions may be social, legal, territorial, practical or simply idiosyncratic.

Pretty simple.

If one were able or willing to put up multiple specific band dipoles or a Steppir, then the question wouldn't be posed here.

If one is not able or willing to erect such, then a tuner is the only answer to present a workable result.

Next?

 
RE: Antenna Tuners -- Do They Work?  
by KG6PHS on January 28, 2014 Mail this to a friend!
Yes they do. with reasonable expectations, and nice article Don, N4KC that you posted, and also good spelling of Schmesonance!
 
RE: Antenna Tuners -- Do They Work?  
by W5DXP on January 28, 2014 Mail this to a friend!
> KE6SLS wrote: It is a "matchbox". It is simply matching impedance between the rig and whatever antenna you are using. It ISN'T tuning the antenna, that is silly. <

One can prove for oneself that, in a low loss system, the antenna tuner is tuning for a near conjugate match *at the antenna feedpoint*. Here's how to do it.

XMTR---tuner----------feedline---------antenna

First tune the antenna tuner so the XMTR sees 50 ohms (SWR=1:1) looking into the tuner. Then disconnect the transmitter and connect a 50 ohm dummy load on the input of the antenna tuner. Then disconnect the antenna and use an antenna analyzer to measure the impedance looking back down the feedline from the antenna feedpoint. One will measure a value of impedance that is close to the conjugate of the antenna feedpoint impedance *at the antenna feedpoint*. It is not a perfect conjugate match because of losses in the feedline but, in a low loss system, it is close.

The antenna tuner doesn't change any ratios like SWR or dB of feedline losses but it does effect a near conjugate match at the antenna feedpoint in a low loss system. After measuring the impedance looking back down the feedline above, twist the knobs on the tuner and watch the impedance reading. It changes and that change is the effect a tuner has *at the antenna feedpoint*.

I have written an article on the subject, the latest revision being at:

http://w5dxp.com/OWT1.htm

Hint: It is obviously impossible for an antenna tuner to have no effect *at the antenna feedpoint* while at the same time increasing the forward and reflected voltage, current, and power *at the antenna feedpoint*. Think about it.
 
RE: Do you want efficient RF power at you antenna?  
by W5DXP on January 28, 2014 Mail this to a friend!
> AI2IA wrote: A RESISTIVE LOAD CAN ONLY BE GOTTEN WITH A RESONANT ANTENNA. <

You left out a word. A resistive load can only be gotten with a resonant antenna system. That's what an antenna tuner does - resonate the entire antenna system - at least in a low loss system. Hang an RF voltmeter at the antenna feedpoint and observe what happens when you adjust the tuner for a match. The voltage at the antenna feedpoint will increase to a maximum value and decrease on each side of a match. That's the IEEE definition of "resonance".
--
73, Cecil, w5dxp.com
 
RE: Do you want efficient RF power at you antenna?  
by G3RZP on January 29, 2014 Mail this to a friend!
The satisfactory definition of resonance that holds for both series and parallel circuits is that the applied voltage and current are in phase - i.e. the circuit looks purely resistive. But an antenna with a 'resistive' feedpoint i.e. is resonant, is not necessarily a good match to the transmitter. Consider a full wave dipole fed with a half wavelength open wire feeder leading to about a 5000 +j 0 ohm feed impedance. It's resonant OK, but the SWR is enormous.

Incidentally, a dipole .05 wavelengths long is only about 0.2 dB less efficient in theory that the usual half wave dipole. The problem is that the feed impedance is highly reactive and very low resistance, and so the power disappears in the matching network. Maybe if one had a matching network of superconductors.......
 
RE: Do you want efficient RF power at you antenna?  
by VK5CZ on January 29, 2014 Mail this to a friend!
While I have the attention of all you antenna gurus .
Can you answer me this I made a link dipole for SOTA trying to achieve 20/30/40m . I cut the wires the same length as my coax fed link dipole and fed it with 300 ohm tv ribbon but the resonate frequency for 14mhz is up in the 15 MHz band so my analyser tells me and the best impedance is 100 ohms. The tv ribbon is a weight saving exercise for my back pack 8m of ribbon is a lot lighter than the coax I take to a summit. Would you consider this antenna another flop !! or does it have potential if I increase the length of the dipole per side to lower the "Resonate" frequency .
de Ian vk5cz ..
 
RE: Do you want efficient RF power at you antenna?  
by W5DXP on January 29, 2014 Mail this to a friend!
> G3RZP wrote: Consider a full wave dipole fed with a half wavelength open wire feeder leading to about a 5000 +j 0 ohm feed impedance. It's resonant OK, but the SWR is enormous.<

IMO, it helps to identify that condition as "anti-resonant" to distinguish it from the low resistance series resonant condition.

http://en.wikipedia.org/wiki/Antiresonance
 
RE: Do you want efficient RF power at you antenna?  
by NA4IT on January 29, 2014 Mail this to a friend!
There is a very simple way to get around using an antenna "tuner / matcher/ SWR adjuster".

Put a high power 50 ohm resistor at the antenna feed point and you have a perfect match...

(;-0
 
RE: Do you want efficient RF power at you antenna?  
by W5DXP on January 29, 2014 Mail this to a friend!
> VK5CZ wrote: I made a link dipole for SOTA trying to achieve 20/30/40m . I cut the wires the same length as my coax fed link dipole and fed it with 300 ohm tv ribbon ... <

Let's look at a single 50 ohm resonant length dipole. When one switches from coax to 300 ohm twinlead, one causes a mismatch at the antenna feedpoint. The SWR on the twinlead is 300/50=6:1. Unless the length of the twinlead is an integer multiple of 1/2 wavelengths, one has created a non-resonant antenna system using a resonant antenna length. It is impossible to have a fixed length of twinlead that is Nx1/2 wavelength on 20m/30m/40m. So by replacing the coax with a fixed length of twinlead, you have gone from a flat, resonant antenna system to a non-resonant mismatched antenna system that requires a good wide-range antenna tuner, something you are probably trying to avoid.

If you are willing to chose a different length of twinlead for each band, then and only then can you make the twinlead length an integer multiple of 1/2WL on each band. It is similar to what I did for my all-HF-band no-tuner dipole.

http://www.w5dxp.com/notuner.com

For portable operation, different lengths of twinlead jumpers with banana plugs/sockets on the ends will allow one to quickly change bands, making the total length of twinlead equal to an integer multiple of 1/2WL. Since 1/2WL on 40m is equal to 2x1/2WL on 20m, you could probably get away with only one twinlead jumper wire. The length of VF=0.9 twinlead for 30m would be 43.7 feet. For 40m, it would be 61.5 feet and would probably work for 20m. So one 17.8 foot twinlead jumper might be all you need.

Since the feedpoint impedance of an antenna is rarely equal to the characteristic impedance of parallel feedline, virtually all wire antennas fed with parallel feedline are non-resonant antenna systems requiring a good wide-range antenna tuner. Sorry, a built-in autotuner will not usually get the job done.
--
73, Cecil, w5dxp.com
 
RE: Do you want efficient RF power at you antenna?  
by K3TIM on January 29, 2014 Mail this to a friend!
Hi Cecil,

Your link should read:
http://www.w5dxp.com/notuner.htm

Nice Website BTW

73's

_..--
Tim
K3TIM
 
Antenna Tuners -- Do They Work?  
by KC0FVN on January 29, 2014 Mail this to a friend!
Just because your antenna is reflecting 50% or even more of the power that gets to it does not mean that that power is not eventually transmitted. There is reflection at the antenna, yes, but there is also reflection at the tuner, which when tuned properly will reflect back 100% of the reflected signal from the antenna that gets to it. This re-reflected signal adds to your transmitted signal.

SWR really is a misunderstood beast. To many people attribute things to it that it has little or nothing to do with.


KC0FVN
 
RE: Do you want efficient RF power at you antenna?  
by W5DXP on January 29, 2014 Mail this to a friend!
> K3TIM wrote: Your link should read:
http://www.w5dxp.com/notuner.htm <

Sorry, senility strikes again. Thanks.
 
RE: Antenna Tuners -- Do They Work?  
by N4DSP on January 29, 2014 Mail this to a friend!
Exactly. Like I stated earlier there is no such thing as an antenna tuner. Lot of confusion comes to front for newcomers. KE6SLS stated it simply and correctly.

KE6SLS stated:

"Oh this again.

All the new hams I mentor get the first lesson. It is a "matchbox". It is simply matching impedance between the rig and whatever antenna you are using. It ISN'T tuning the antenna, that is silly.

The second lesson is why we don't care what the SWR of any given antenna is since I always recommend balanced feeder. The matchbox will take care of it and the antenna will work well.

Good luck with your setup. Hope you have a lot of fun!"

73
j
 
RE: Antenna Tuners -- Do They Work?  
by N6AJR on January 29, 2014 Mail this to a friend!
get your self a Steppir antenna, then they are always resonant on each spot in every band that they cover, no tuner needed. ever





good stuff, reliable, and the folks who run the place are nice too.



 
Antenna Tuners -- Do They Work?  
by K7TOM on January 29, 2014 Mail this to a friend!
WELL MY FELLOWS, I Have been a HAM for bout 4o plus yrs if u count my ARMY Days ? This really means nothing of course. BUT BEING WIFE POOR AND OR KID POOR ,OR BEING LAS FAIR ,( NOT ME ) I BECAME FAMILIAR WITH A LOT OF U KNOW ," CHEAP "Tuners over my life of
45 YRS OR SOOO, on The Ham bands. But, when i picked up this great
Alpha 78 From a Man in pennsylvania i needed something that would handle the Bigin. Well i looked high and low. I found the one that met
my criteria is the PALSTAR HF AUTO.This tuner is very good.
using the Auto Tune interfaced with Alpha 78 in the Alpha "by pass "
uses the factory pre tuning and driving it all with the kenwood makes it almost like being on the "BRIDGE OF THE ENTERPRIZE" .

And it is very fast and stores it all in memory! Any rate it is the neatest thing since my SOOO I would say with all my vast experience
it makes a very big difference for me.

K7TOM

 
RE: Antenna Tuners -- Do They Work?  
by KI6LZ on January 29, 2014 Mail this to a friend!
My mind is getting scrambled by the many meanings of meanings. An antenna is called resonant (at some frequency) when its impedance is only resistive,no reactance. If I were to add coax and use a tuner/matcher to maximize the transfer of energy from my transmitter to the non resonant antenna the antenna is non resonant, period. The whole system (ant+coax+tuner) could be called resonant, but that is not standard usage. And yes, one could terminate the transmitter end of the tuner with a 50 ohm resistor, haul up their transmitter to the antenna, connect it directly to the antenna and have a resonant antenna with whatever resistance it exhibits, surely not 50 ohms. Think that is called stub tuning.
 
RE: Antenna Tuners -- Do They Work?  
by VK5CZ on January 29, 2014 Mail this to a friend!
Thanks very much for the response to my off topic question. I will check out W5DXP web suggestion and probably keep carrying the coax instead of several lengths of ribbon for now. 73 de Ian vk5cz ..
 
RE: Antenna Tuners -- Do They Work?  
by W5DXP on January 29, 2014 Mail this to a friend!
> KI6LZ wrote: The whole system (ant+coax+tuner) could be called resonant, but that is not standard usage.<

Depends on what standard you adopt. A properly tuned low loss antenna system (including a properly adjusted tuner) meets the IEEE definition for "resonance" which is the one used by professional electrical engineers.

Here's something else one can do to detect resonance. Adjust the tuner such that the XMTR sees a 1:1 SWR. Disconnect the XMTR and couple the tuner input to a grid dip meter. Find the resonant dip frequency. Surprise, it is the same frequency that the XMTR was tuned to. One can couple that grid dip meter anywhere in the system including at the antenna, and the results will be a similar dip at the similar resonant frequency throughout the whole system. Using the grid dip meter, it can be proven that a tuner resonates an antenna system at the antenna. The conjugate matching theorem tells us why that is a technical fact.

When the tuner is properly adjusted for a match to the XMTR, all of the system components, including the antenna, have been tuned to resonance, i.e. the voltage has peaked everywhere in the system. That peaking of system-wide voltage is the IEEE definition of resonance, i.e. all voltages peak at the resonant frequency. The grid dip meter will indicate that it happens everywhere in the entire system, even at the antenna.

What some people need to do is learn the difference between an impedance match and a conjugate match. They are not the same thing. A system can be suffering a terrible impedance mismatch while at the same time being perfectly conjugately matched thus allowing maximum transfer of available energy from the source to the load.
--
73, Cecil, w5dxp.com
 
RE: Antenna Tuners -- Do They Work?  
by W6QW on January 29, 2014 Mail this to a friend!
Wow - lot's of misunderstndings about antenna tuners. W5DXP is correct about the conjugate impedance match. Antenna tuners are just part of an end-to-end antenna 'system' and can mitigate just a portion of a system's anomalies. Most hams incorrectly assume that their end-to-end antenna 'system' is good if they pacify the need for maximum transmitter power output.
 
RE: Antenna Tuners -- Do They Work?  
by W4PGM on January 29, 2014 Mail this to a friend!
Get a copy of Reflection III by Walter Maxwell, W2DU. It will give you a better understanding of what is happening on your feed line. If you send me your e-mail I'll send you and Excel sheet that calculates RHO and SWR for any forward and reverse power configuration. The formulas are in the clear so you can see how SWR is derived. I wrote it for those who buy old Bird meters where the chart is worn off. My e-mail is good on QRZ.

W5DXP calculation is correct. An easy thing to remember is that are 2:1 SWR your initial power is reduced by a little under 11%. If it takes double the power to get a 1 S-Unit increase what have you lost with a 2:1 SWR?

Now we can talk about what really happens to the reverse power but I suspect there will be countering opinions. Read Reflections and you will have a different opinion of feed-lines, tuners and antennas. Also, an antenna is only resonant at a single frequency or so. Also height about the ground has quite a bit to do with the impedance.
 
RE: Antenna Tuners -- Do They Work?  
by KI6LZ on January 29, 2014 Mail this to a friend!
It's easy to confuse others when we use words like resonant antenna when we actually mean resonant "system". Resonance to some means a 72 ohm dipole fed with 75 ohm coax, or a commercial beam fed with 50 ohm coax. Anyways, I do want to clarify someone's statement that 100% of power goes out the antenna. Using a 100 watt transmitter with a tuner to match RG-58 to a full wave resonant antenna will result in a SWR of about 95:1. A large portion of the output power gets reflected from the 50 ohm coax to 5000 ohm antenna impedance mismatch junction, this power then get re-reflected from the tuner conjugate match back to the antenna, and back and forth. Due to losses in coax the power delivered to the antenna is about 4 watts. Use some common ladder line and it goes up to 58 watts. Can't escape high SWR line loss due to antenna/line mismatch.
 
Antenna Tuners -- Do They Work?  
by AI2IA on January 29, 2014 Mail this to a friend!
I put my two cents in further up the thread, and I have been reading all the comments. I conclude that this topic is very much like religion. You can explain and explain with all the enthusiasm of dedicated believer, but only rarely are you going to make a convert.

P.S. After all my reading I am still inclined to thoroughly believe what I wrote in the first place. Isn't being a ham wonderful?
 
RE: Antenna Tuners -- Do They Work?  
by W5DXP on January 30, 2014 Mail this to a friend!
It can easily be proven with actual measurements, using a grid dip meter, antenna analyzer, or RF voltmeter that an antenna tuner resonates the entire antenna system including the antenna. If all an antenna tuner does is make the transmitter happy, the same thing can be done with a dummy load so we can throw away our antennas and use dummy loads to make the transmitter happy and all is well (or maybe not).

The transmitter is happy when there is no reflected energy incident upon the transmitter which the tuner can accomplish. But now one has to deal with the conservation of energy principle. If reflected energy is prohibited from being incident upon the transmitter then where does it go? In a low loss system, the answer to that question increases the the voltage *at the antenna* feedpoint which can easily be measured with an RF voltmeter.

People who deny that an antenna tuner in the shack has any effect at the antenna are simply engaging in a faith-based religion that denies reality because there are any number of scientific ways to actually measure the effects that an antenna tuner in the shack has at the antenna.
--
73, Cecil, w5dxp.com
 
RE: Antenna Tuners -- Do They Work?  
by N4KC on January 30, 2014 Mail this to a friend!
Cecil, your explanations are fantastic, as always. I'm happy when an "antenna tuner" article shows up here because I know it will generate vigorous discussion and I always end up learning from people like you...and, by the way, from those who have it all wrong, too.

I believe the biggest problem is some people's inability to visualize an antenna SYSTEM as a complete circuit, with each component in that circuit--"tuner," feedline, antenna, the atmosphere, etc.--having some effect on how it behaves electrically.

It becomes much clearer once that concept is grasped.

Don N4KC
www.n4kc.com
www.donkeith.com


 
RE: Antenna Tuners -- Do They Work?  
by K1BXI on January 30, 2014 Mail this to a friend!
Here is a little food for thought...........What does the antenna see for a load when it becomes the RF generator supplying a signal to the receiver input?

The same rule applies when the system is used for receiving. The tuner not only makes the transceiver "happy", it also makes the antenna "happy".

It may not be physically tuning the antenna, but it is tuning the antenna to the system load (transceiver and feed line) that it sees.

In this sense the tuner does indeed tune the antenna.

John





 
RE: Antenna Tuners -- Do They Work?  
by KI6LZ on January 30, 2014 Mail this to a friend!
Everything is happy except the transmission line and non resonant antenna. You can't escape the line loss caused by the impedance mismatch between the two. That is the unhappy part.
 
Antenna Tuners -- Do They Work?  
by W4ZFL on January 30, 2014 Mail this to a friend!
The internal antenna tuner on my Yaesu FT-990 is truly incredible. I can have an extremely high SWR and it will tune down very low. For example, I have a Mosley RV-4V trap vertical with a bad trap on 40 meters with an infinitely high SWR. With this tuner I was able to work I@VRN on 40 meters late at night an d get a good signal report. Also, with this tuner I can use my 4 element 15 meter beam in 10 meters, 17 meters and 12 meters.

73,
Cliff, W4ZFL
 
RE: Antenna Tuners -- Do They Work?  
by KI6LZ on January 30, 2014 Mail this to a friend!
Maybe we need an article on the safe usage of tuners, their limitations and self destruct capabilities. Can see it already: For Sale, FT-990, new but tuner not working.
 
RE: Antenna Tuners -- Do They Work?  
by W5DXP on January 30, 2014 Mail this to a friend!
> KI6LZ wrote: You can't escape the line loss caused by the impedance mismatch between the two. That is the unhappy part.<

A resonant 50 ohm 20m dipole fed with 100 ft. of RG-8x will have a matched line loss of 1.11 dB. That same resonant 50 ohm 20m dipole fed with 100 ft. of open-wire feedline creates a mismatch at the antenna feedpoint that causes an SWR of 12:1 on the 600 ohm feedline. Yet the mismatched loss in the open-wire feedline is only 0.44 dB. The loss in the matched RG-8x is 250% higher than the loss in the same length of mismatched open-wire feedline.

So which feedline causes the most unhappiness, the matched one or the mismatched one?:)
 
RE: Antenna Tuners -- Do They Work?  
by KI6LZ on January 30, 2014 Mail this to a friend!
Escape means to break free from. Mitigation is a different word. One has not escaped the line loss, only mitigated it. For the example, I would use the coax and not bother with open wire and tuner.
 
RE: Antenna Tuners -- Do They Work?  
by KI6LZ on January 30, 2014 Mail this to a friend!
Oops, change last to "escaped impedance mismatch"
 
Antenna Tuners -- Do They Work?  
by KI5WW on January 30, 2014 Mail this to a friend!
I read AGAIN the Resonance Schmezonance article. Very gud read. But yer making my Resonant on 7.2 inverted vee feel bad about itself. Sigh...
 
RE: Antenna Tuners -- Do They Work?  
by K1CJS on January 30, 2014 Mail this to a friend!
>>>Here is a little food for thought...........What does the antenna see for a load when it becomes the RF generator supplying a signal to the receiver input?<<<

That's a false premise. The antenna, being a passive device, is never a 'generator' as such. It supplies the signal, true, but is not generating anything, it is only gathering radio waves, which it would do best if cut close to the frequency being monitored--the definition of resonance.

If the antenna matching system actually 'tuned' the antenna, it would have to either actually lengthen or shorten the elements--for THAT is the ONLY way to tune an antenna to any wavelength.
 
RE: Antenna Tuners -- Do They Work?  
by KI6LZ on January 30, 2014 Mail this to a friend!
GQ GQ This is not a drill.
 
RE: Antenna Tuners -- Do They Work?  
by K1BXI on January 30, 2014 Mail this to a friend!
"That's a false premise. The antenna, being a passive device, is never a 'generator' as such. It supplies the signal, true, but is not generating anything, it is only gathering radio waves".

True, but Webster says to generate is.....": to produce (something) or cause (something) to be produced".....

Is it not causing an RF voltage to be produced at the receiver from the gathered radio waves?

I know.....I'm picky.

John
 
RE: Antenna Tuners -- Do They Work?  
by KI6LZ on January 30, 2014 Mail this to a friend!
>>The antenna, being a passive device, is never a 'generator' as such. It supplies the signal, true, but is not generating anything, it is only gathering radio waves, which it would do best if cut close to the frequency being monitored--the definition of resonance<<

In engineering we use the theory of reciprocity in describing and analyzing systems. For example, transmit and receive antenna patterns, gains are the same. Likewise, the antenna being a transducer (think tuner) which couples EM waves to the freespace impedance of 377 ohms can be considered a generator in the analysis.

Resonance of an antenna has no advantage over a non resonant antenna in gathering waves. An extended dipole, which is not resonant, would do better due to additional gain.
 
RE: Antenna Tuners -- Do They Work?  
by W5LZ on January 30, 2014 Mail this to a friend!
Per the original topic/title.
The only thing an 'antenna tuner' does is match impedances, it doesn't tune an antenna, it doesn't change the antenna at all. It does change the impedance seen by the transmitter from the whole -antenna system-. It's an impedance transformer, period.
Do they work, can they improve things? Absolutely, if they are used correctly. When they are used correctly there is not much loss associated with them as is commonly believed. After that, most of what you hear about 'tuners' should be spread on a garden to make things grow better. They don't 'do' miracles, but they can make a 'not so good' antenna system usable.
- Paul
 
RE: Antenna Tuners -- Do They Work?  
by W5DXP on January 30, 2014 Mail this to a friend!
Let's take an example:

XMTR---Tuner-------Low-loss Feedline-------Antenna

Let's say the antenna has a feedpoint impedance of 100-j100 ohms, i.e. non-resonant. Now adjust the tuner so the XMTR sees 50 ohms. What impedance would we measure at the antenna feedpoint looking back toward the tuner? It will be close to 100+j100 ohms, i.e. the conjugate of the antenna feedpoint impedance. That's the effect that a tuner has *at the antenna*. It changes conditions *at the antenna* from a conjugate mismatch to a conjugate match. That conjugate match maximizes the voltage, current, and power *at the antenna feedpoint* and that effect has been measured so it cannot be denied, at least not by a rational person.
--
73, Cecil, w5dxp.com
 
Antenna Tuners -- Do They Work?  
by W0FAA on January 30, 2014 Mail this to a friend!
Of course they work. What a troll of a topic.
 
RE: Antenna Tuners -- Do They Work?  
by AD7II on January 30, 2014 Mail this to a friend!
"Let's say the antenna has a feedpoint impedance of 100-j100 ohms, i.e. non-resonant. Now adjust the tuner so the XMTR sees 50 ohms. What impedance would we measure at the antenna feedpoint looking back toward the tuner? It will be close to 100+j100 ohms, i.e. the conjugate of the antenna feedpoint impedance."

Then where does the "50" come from?
 
RE: Antenna Tuners -- Do They Work?  
by W8IFI on January 30, 2014 Mail this to a friend!
I'm looking at an August 1976 QST. P.15 has an article by Maxwell W2DU/W8KHK....titled "My transmatch really does tune my antenna". It was one of a series of articles. Might be in the QST archives along with the whole series. If I recall correctly in summary if the Transmitter see's a 1:1 SWR then you are in great shape and your loss in the system is only a little over 3% due to resistance in the conductor.
He does emphasis that you have to treat the whole set up as a "system" which some posters here have pointed out.
He figured it out mathematically first and them verified it with actual tests.
Dunno if the QST archives have the whole series of articles.
 
RE: Antenna Tuners -- Do They Work?  
by W8IFI on January 30, 2014 Mail this to a friend!
Another article by Byron Goodman (W1DX) called "My feed line tunes my antenna" appeared in QST twice. March 1956 and April 1977. Very good article also.
 
RE: Antenna Tuners -- Do They Work?  
by W5DXP on January 30, 2014 Mail this to a friend!
> AD7II wrote: Then where does the "50" come from?<

The impedance that the tuner sees at its output is the antenna feedpoint impedance transformed by the transmission line but let's say the transmission line is 1/2WL long, about 61 ft on 40m, so the tuner sees the 100-j100 ohm antenna feedpoint impedance. The CLC tuner network transforms the 100-j100 ohms at the output of the tuner to 50 ohms at the input. That's easy to see on a Smith Chart.

But you have given me an idea how to illustrate a conjugate match without a transmission line getting in the way. Let's say we set our transmitter to 7 MHz and hang a 100-j100 ohm load on the output of the tuner. At 7 MHz, that would be a 100 ohm resistor in series with a 227 pF capacitor.

Adjust the tuner so the XMTR sees an SWR of 1:1, i.e. no reflected energy reaches the XMTR. Now disconnect the XMTR and install a 50 ohm dummy load on the tuner input. Disconnect the resistor and capacitor from the tuner output and use an antenna analyzer to measure the impedance looking back into the tuner output. It will be close to 100+j100 ohms, the conjugate of the previous load impedance.

That same experiment can be done anywhere in the system. The impedance looking in one direction will always be close to the conjugate of the impedance looking in the opposite direction (in low-loss systems).

Maximum transfer of available power from source to load cannot be achieved in an antenna system without a near-conjugate match existing at all points in the system - including at the antenna feedpoint. That's what an antenna tuner really does - achieve a near-conjugate match throughout the whole system including at the antenna feedpoint. If the system was lossless, the tuner would achieve a perfect conjugate match at all points in the entire system.

And one other point. 50+j0 ohms looking in one direction and 50-j0 ohms looking in the other direction is also a conjugate match albeit a trivial one. So an impedance matched 50 ohm system is also conjugately matched.
--
73, Cecil, w5dxp.com
 
RE: Antenna Tuners -- Do They Work?  
by KI6LZ on January 30, 2014 Mail this to a friend!
The 50 ohms comes from a tuner that tunes the tuner to the transistors.
 
RE: Antenna Tuners -- Do They Work?  
by KI6LZ on January 30, 2014 Mail this to a friend!
OMG!!!! My tuner tunes the transistor.
 
RE: Antenna Tuners -- Do They Work?  
by W8IFI on January 30, 2014 Mail this to a friend!
To W4ZFL.......

About your Tuner in the FT-990. Hang on to that one!!!
Nothing like being happy with a tuner and rig. I have two Dentrons, a Super Tuner and RT-3000 and also a Palstar. Will never part with the Dentrons.
 
RE: Antenna Tuners -- Do They Work?  
by KI6LZ on January 30, 2014 Mail this to a friend!
OMG!! And my amplifier pi output network tunes my tubes. Knew I had this all wrong, now I see the way.
 
RE: Antenna Tuners -- Do They Work?  
by AD7II on January 30, 2014 Mail this to a friend!
In keeping with KL7UV's KISS principle, would W5DXP simplify his example? Put just the 100 ohm resistor across the output of the tuner so the analyzer sees 100+j0. What values of CLC need to be tuned in at 7 MHZ so the analyzer shows 50+j0?

(KI6LZ, this one's for you.)
 
RE: Antenna Tuners -- Do They Work?  
by KI6LZ on January 30, 2014 Mail this to a friend!
I can calculate the network values but since the complex conjugate of 100+jo = 100-jo, one side of tuner will be 100+j0 and the other side will be 50-j0.
 
RE: Antenna Tuners -- Do They Work?  
by KI6LZ on January 30, 2014 Mail this to a friend!
Almost got me. Would not use a clc network.
 
Antenna Tuners -- Do They Work?  
by RSHIRE22 on January 31, 2014 Mail this to a friend!
If people can't agree on what antenna formulas are saying what good are antenna formulas?
If no two economists can agree on how to fix the ecomony what good is economics? Knowledge is mostly a waste of time.

I just build different antenna/tuner combinations and if it works I keep it. I don't need to know why or need to impress anybody. People like eham blow hards are fools. Who cares what other schmucks think about you? You learn that in grade school or never.
 
Antenna Tuners -- Do They Work?  
by QRPNEW on January 31, 2014 Mail this to a friend!
I would rather just ask the question what is my total antenna system radiation efficiency. Worrying about SWR does not address or answer the total antenna system radiation efficiency.

The next question I would be asking is what useful antenna gain do I have from the angles of 1 to 20 degrees.

The ham bands are of full endless discussion of G5RV versus balanced open wire line doublets and balanced versus unbalanced tuners. At the end of the day all these operators are talking down the road with 20 db of fading. Who cares if I lose 6db because I am using the worst antenna and antenna tuner if I am talking to a ham down the road or the next state. I regularly use one of the military broadband dummy load antennas with the worst efficiency imaginable and nobody every says, geez you signal is so crap you need to get a new antenna. However if I work a station in ZS or VU2 land they definitely struggle to hear me and regularly ask me if i am running QRP. If switch to my beam or doublet they automatically ask me if I turned on my amplifier.

Have design objectives in mind before being critical of one antenna system versus another. All antennas have their place. By not defining what your end game is for your antenna that is working or DX or talking down the road you cant really draw any conclusion. I suppose my dummy load has SWR of 1:1 and I can still work down the road that does not mean a dummy load is the best antenna for every communication need.

We need to be objective not subjective about how antennas perform. I am sick and tired of listening to and reading subjective antenna nonsense. At the end of the day best solution is the one with with best radiation efficiency and the most gain at the right takeoff angle. How you achieve these objectives does not really matter all that matters is the numbers. Can you tell us what you antenna system radiation efficiency is and what your gain is from 1 to 20 degrees. Blank stare? Thats normal with ham antenna and antenna tuner debates. All a lot of unsubstantiated hot air that cant be measured because guess what who has a calibrate S_meter that can produce the numbers. We all just a bunch of amateurs with amateurish equipment that cant be used for any meaningful scientific analysis. But did I tell you about my new Flusterbuster antenna thats works very well? It kills my G5RV that I had up last week. Did I tell you that I worked Mars and I beat my buddies FunkelFunk beam by a whopping 5 S_units. ZzzzZzZzZZZ
Just tune 40 meters and you will hear this same endless crap day after by the same people. These are the same people who cant hear the DX under them and will tell you when you switch from your dipole to the G5RV or your turned your amplifier your signal jumped by 20db. They might as well say it jumped a whopping 100db because its just a useless opinion that is not very scientific.

There are lot of good technical antenna gurus on here and many other forums. You wont hear 20Db G5RV experts mention these experts who understand how antenna systems really work. They just love spreading urban antenna myths, folklore and technobabble to their groupies and widely ignore science.

 
RE: Antenna Tuners -- Do They Work?  
by W5DXP on January 31, 2014 Mail this to a friend!
> AD7II wrote: In keeping with KL7UV's KISS principle, would W5DXP simplify his example? Put just the 100 ohm resistor across the output of the tuner so the analyzer sees 100+j0. What values of CLC need to be tuned in at 7 MHZ so the analyzer shows 50+j0? <

Easiest done with the tuner simulator at:

http://fermi.la.asu.edu/w9cf/tuner/tuner.html

Set the load to 100+j0 ohms, set the frequency, hit the tune button, and the simulator will display the CLC values that will achieve a match.

Please note that when the tuner achieves a match there will be a trivial conjugate match to 50+j0 ohms at the input and to 100+j0 ohms at the output. With a 100 ohm load on the tuner output an antenna analyzer will read 50 ohms at the input. With a 50 ohm dummy load on the input, the analyzer will read 100 ohms on the output.

In general, after the tuner is adjusted for a match, at any point in the system if the impedance looking in one direction is R+jX ohms, the impedance looking in the other direction is close to R-jX ohms. That is what an antenna tuner does and it is a system-wide effect.

For maximum available power transfer, there must be close to a conjugate match at all points in the system including at the tuner input, at the tuner output, halfway up the transmission line, and at the antenna feedpoint. That is a technical fact covered by the maximum power transfer theorem for distributed AC/RF networks.
--
73, Cecil, w5dxp.com
 
Antenna Tuners -- Do They Work?  
by KB2DHG on January 31, 2014 Mail this to a friend!
This is one of those post that can be pondered till days end...
BOTTOM LINE, YES they work!
What is the alternitave? Really what else can we do outside of installing multable resonant antennas and even at that they will ony be good at a certian frequencys with in that band. With most everything in life there will always be a trade off and in our wonderful world of Amateur Radio, loosing a Db here and there thru an trans match is not the end of the world. I use a home brew G5RV antenna with my trans match and have worked the world with no more that 100 watts...
Untill someone can invent a totally resonant multi band antenna the size of an HT rubber duck antenna, The use of a trans match is the only way to radiate your signal.

So, take this for what it is worth. Get on the air, tune that antenna to make your transmitter happy and QSO my friends...
 
RE: Antenna Tuners -- Do They Work?  
by W5DXP on January 31, 2014 Mail this to a friend!
> KB2DHG wrote: The use of a trans match is the only way to radiate your signal. <

But, but, but - how can you possibly radiate your signal from the antenna if the transmatch has zero effect at the antenna?:)
 
RE: Antenna Tuners -- Do They Work?  
by KI6LZ on January 31, 2014 Mail this to a friend!
I opine that using article titles like my "My transmatch tunes my antenna", which were created by either the author or technical editor (maybe in jest) to explain a matching idea, misleads and misinforms those that have a rudimentary understanding of the difficult subject matter involved. And no one can disagree that some of this subject matter is beyond the knowledge requirements of ham operators. Now we will have some that think they are only tuning their antennas when in fact they are also tuning their transistors/tubes. Why favor antenna over the active device producing the power in describing what is being tuned?
 
Antenna Tuners -- Do They Work?  
by AI2IA on January 31, 2014 Mail this to a friend!
Do they work? Sure they do.
How well do they work? Well, that is another matter.

Meatball's law: Any gadget you put between the transmitter and the antenna will cause loss.

Why add a gadget if you don't need it?

Well, in you arrangement you may need it

You could do things differently.

Lures catch more fishermen than fish.

Antenna tuners look important, they have knobs and meters, and such like, and ......well you get the idea.
 
RE: Antenna Tuners -- Do They Work?  
by W5DXP on January 31, 2014 Mail this to a friend!
> KI6LZ wrote: Why favor antenna over the active device producing the power in describing what is being tuned? <

Nobody is favoring the antenna. What we are objecting to is the following old wives tale: "An Antenna Tuner Does Absolutely Nothing Except Make The Transmitter Happy." Making the transmitter happy may be a very important function, but it is not the only function performed by an antenna tuner.

http://www.w5dxp.com/OWT1.htm
--
73, Cecil, w5dxp.com
 
Antenna Tuners -- Do They Work?  
by K1DA on January 31, 2014 Mail this to a friend!
There's a lot of talk here about "compromise" or marginal (sniff) antennas and the poor souls forced to use them with a tuner, but if you want to employ, for example, the directive properties of, perhaps, two half waves in phase on 80 meters, it is NOT a 50 ohm antenna, RESONANT or not.
 
Antenna Tuners -- Do They Work?  
by KD6SBN on January 31, 2014 Mail this to a friend!
just to see if this work , on hf , you always hear people tuning up , the signal goes from almost nothing to descent , so yes the antenna match / tuner helps .
 
RE: Antenna Tuners -- Do They Work?  
by KM3F on January 31, 2014 Mail this to a friend!
There a another important reason to make the impedance seen by the transmitter something near 50 ohms.
A mismatch at the transmitter output reflects an impedance change into the final stage of the transmitter.
Depending on the sign of the mismatch, the transmitter load resistance can change to cause it either draw more current (lower RL) causing it to run at higher dissipation levels or lower dissipation levels 'but' higher RF voltages (higher RL)that could wreck the device junctions or components in that circuit.
This is largely taken care of by the intent of the power fold back circuit that detects the high SWR and reduces transmitter output.
This is what is behind the term 'makes the radio happy'.
Since solid state radios are a no tune device unless they incorporate an adjustable impedance matching (AT) device, you need to use one when the antenna system does not offer a match closer than about 2 to 1.
.
On antennas, guess what? A dipole cut to resonance is not 50 ohms. It is nearer to 70 +/- and affected by height and nearby conditions.
As you move away from the resonant frequency it changes impedance even more.
When you make it appear as 50 ohms at the frequency of interest at the radio, there is actually a reactive component (+/-j) introduced in the attempt to make it 50 ohms. At this point it is never a purely resistive match impedance and feedline length has some effect.
The reactive component is what a tuner mainly works with for correction.
For example a 50 ohm non inductive shielded dummy load is 'technically' never frequency sensitive like an antenna such that fed any frequency the match should never change and remain 50 ohms with no reactive part.
Granted it may be nit picking but it illustrate some of what has been discussed when one looks deeper into the mechanics from end to end.
Good luck.
 
RE: Antenna Tuners -- Do They Work?  
by VE7BML on January 31, 2014 Mail this to a friend!
steppIR.antenna tuner. sounds similar?
 
RE: Antenna Tuners -- Do They Work?  
by W8IFI on February 1, 2014 Mail this to a friend!
Here is my impression:

Maxwell has impressive credentials. By observation he came up with a theory. He tested it mathematically and the results showed he was on the right track. Then he tested by seeing if he got the results his math predicted. The results showed his theorem was correct.

That is good enough for me think a tuner does work.
 
Antenna Tuners -- Do They Work?  
by AE5QB on February 1, 2014 Mail this to a friend!
Don't overcomplicate things. Unless you plan to work on one frequency (or a relatively narrow band) and have antennas for every band you want to work on, the antenna tuner is a necessity. Plug it in, push the button, if the light goes green start transmitting. That is all there is to it. It is magic and it does work, or there wouldn't be so many people selling them and buying them.
 
Antenna Tuners -- Do They Work?  
by AI2IA on February 2, 2014 Mail this to a friend!
This is the wrong question.

Good, better, best.

The real question is, "How well do tuners work?"

If you want to operate with the herd, wait for the little LED to light up green, go ahead.

If you have the space, the time, and the parts to experiment with resonant antennas, join the few who take ham radio beyond the boxes that tuners come in, or have a little of both. Learn by experience.
 
Antenna Tuners -- Do They Work?  
by KD4SBY on February 2, 2014 Mail this to a friend!
After reading all the comments and learning quite a bit from it, many things are a lot clearer as far as tuners go. In short, as I understand it, the Tuner is part of the total Antenna system, and the power absorbed in the Tuner depends on how close the antenna was to the resonance of the frequency used. The closer the antenna is to that, the less the Tuner has to compensate for the difference, and the less losses we occur. Correct?
 
RE: Antenna Tuners -- Do They Work?  
by W5DXP on February 2, 2014 Mail this to a friend!
A tuner may suffer more loss in transforming a resonant 10 ohms to 50 ohms than it does in transforming a non-resonant 500+j500 ohms to 50 ohms. An antenna tuner is just one of a number of ways that an antenna system can be tuned to resonance by causing a conjugate match which is the key to the maximum transfer of available power from the source to the load. In reality, a resonant antenna length doesn't radiate any better than a non-resonant antenna length. An Extended Double Zepp is a non-resonant antenna that will beat a 1/2WL dipole by about 3 dB in the dipole's favored direction.

Of course, if a conjugate match can be achieved without a tuner, then there are no tuner losses. One way of avoiding a tuner is to use the transmission line to tune the non-resonant antenna length to system resonance. That's what I did for my notuner HF antenna system.

http://www.w5dxp.com/notuner.htm
 
RE: Antenna Tuners -- Do They Work?  
by AA4PB on February 3, 2014 Mail this to a friend!
Of course if you avoid using a tuner then you have no tuner losses. However, if you use a tuned feed line to do the matching then by definition the feed line must have a greater than 1:1 SWR which in turn means it will have additional loss :-) Granted, such losses are usually not very significant.
 
RE: Antenna Tuners -- Do They Work?  
by W5DXP on February 3, 2014 Mail this to a friend!
Since ladder-line virtually never has an SWR of 1:1, we might as well make use of the impedance transforming characteristics of the medium SWRs on low-loss ladder-line in order to avoid tuner losses. A trivial example is using 1/2WL (61.5') of 450 ohm ladder-line with an SWR of 9:1 feeding a resonant 1/2WL 50 ohm dipole on 40m. A good wide-range tuner will turn that dipole into a multi-band antenna.
--
73, Cecil, w5dxp
 
Antenna Tuners -- Do They Work?  
by WO4V on February 8, 2014 Mail this to a friend!
Throw up as much wire as you have space to, and feed it at a convenient point with ladder or open-wire line, strain with a decent matchbox/balun. This recipe has worked well when I had a 45 acre antenna farm, and continues to work well on my 1.7 acre lot.

I ALWAYS learn a lot from these discussions, and I really appreciate the (few) hams that have the curiosity, gumption, and intellect to research these areas and be willing to share their findings with the rest of us (without a fist fight)... :)
 
RE: Antenna Tuners -- Do They Work?  
by W7CY on February 8, 2014 Mail this to a friend!
I am curious about the description "resonant 50 ohm dipole". What does this mean? A dipole in resonance (j=0) is approximately 72 Ohms.

Rod Mack
 
RE: Antenna Tuners -- Do They Work?  
by W5DXP on February 9, 2014 Mail this to a friend!
Take a look at the resonant feedpoint impedance of a dipole above ground in "The ARRL Antenna Book", Chapter 3, Fig 1 in my 20th edition. It varies from 45 ohms to 98 ohms depending on height. Where the dotted line crosses the 50 ohm line at about 0.03 and 0.13 wavelengths, the resonant feedpoint impedance is 50 ohms.
--
73, Cecil, w5dxp.com
 
RE: Antenna Tuners -- Do They Work?  
by K4PIH on February 11, 2014 Mail this to a friend!
Just got my complimentary copy of ARRL's "Small Antennas for Small Places" as a new subscriber. I was struck by a caption on one of the illustrations that reads something like:

"Antenna turners can match the feed line between the radio and the tuner however the SWR from the tuner to the antenna remains unchanged".

So in effect are we “talking on the tuner”? Some of my failed attempts at making antennas have resulted in just that! Hi HI
 
RE: Antenna Tuners -- Do They Work?  
by AD7II on February 11, 2014 Mail this to a friend!
How about just saying the tuner catches the reflected power and sends it back toward the antenna?
 
RE: Antenna Tuners -- Do They Work?  
by K1CJS on February 13, 2014 Mail this to a friend!
>>>Just got my complimentary copy of ARRL's "Small Antennas for Small Places" as a new subscriber. I was struck by a caption on one of the illustrations that reads something like:

"Antenna turners can match the feed line between the radio and the tuner however the SWR from the tuner to the antenna remains unchanged".<<<

Re: the quoted--exactly my point. The antenna tuner may fool the transmitter into thinking the antenna is a 50 ohm load, but the loss remains the same, and is present whether or not the antenna tuner is in the circuit. As I said earlier, it just removes the battle between the power fed into the antenna and the reflected power--the SWR--from the finals of the transmitter, but that battle is still present.

The only thing the tuner may do is to let the transmitter feed full power to the antenna system, but the more power, the more of a battle--and the higher the SWR, the worse the battle. That is why parts of some antenna tuner may arc and overload if presented with excessive power and high SWR.

The effect of the increased power versus the increased reflected power just about cancels out any advantage that the greater power feed produces. I submit that any supposition of increase of transmission range or better signal reception may well be due to changing conditions, not to the effects of any tuner in the antenna system itself.
 
Antenna Tuners -- Do They Work?  
by AC5WO on February 14, 2014 Mail this to a friend!
Yes, provided that the transmission line between the antenna and the antenna tuner is relatively low-loss and the match between the antenna and the transmission line is good enough. Hams traditionally use ladder line to achieve the combination of low-loss and high enough impedance for moderate mismatch vs. frequency, but there's no inherent reason one couldn't use really low-loss 50-ohm coaxial cable combined with an impedance transformation at the antenna. Hams obsess over 1:1 VSWR and resonance because it's easy to measure, but sometimes it's more useful to achieve moderate mismatch across a bunch of bands, avoiding lengths that result in high-impedance resonances, and letting the antenna tuner make the transceiver happy.
 
RE: Antenna Tuners -- Do They Work?  
by W8JI on February 22, 2014 Mail this to a friend!
People arguing about silly things like the name of the box on the table aside, there are two ways to look at this that work equally well in the context of this discussion. Also ignoring the equally silly idea that "resonance" has something to do with "efficiency" or low SWR.


The tuner matches the 50-ohm radio to the antenna system impedance that presented at the tuner output terminal.

or

Wave theory where you have a forward and reflected wave, and the tuner "re-reflects the reflected wave".

Either method,m when properly used, works perfectly for a system like we use.

By the way, the reflected power does not make it back int a PA output device and cause "heat". It simply changes the operating load line of the PA device. It can make the PA run cooler, hotter, or even stay the same temperature. This is because, like any mismatch, it causes the PA have more voltage at different points or more current at different points.

Take this example. If I have a 600 ohm line with a 5 600 ohm resistor load it is NOT resonant, yet the line is matched to the load and the line has a 1:1 SWR. There is no reflected power. Connected to a PA stage, the 600 ohm system that has a 1:1 SWR and is NOT resonant looks exactly the same as a 50 ohm line with a 12:1 SWR when at the voltage peak.

The PA behaves exactly the same into either load. If the PA tank or matching and filter system reflects a high impedance back to the PA devices, the voltage soars but generally efficiency stays the same or improves as current and conduction angle is reduced. The PA becomes LESS hot.

If the PA tank or filter/matching system happens to reflect a low impedance at the output device, current increases, conduction angle increases, and the PA device is hotter. Same SWR, no reflected power in one case, and the same results.

Think about this more that worrying about silly things like we call antenna tuners.

73 Tom
 
RE: Antenna Tuners -- Do They Work?  
by W8JI on February 22, 2014 Mail this to a friend!
People arguing about silly things like the name of the box on the table aside, there are two ways to look at this that work equally well in the context of this discussion. Also ignoring the equally silly idea that "resonance" has something to do with "efficiency" or low SWR.


The tuner matches the 50-ohm radio to the antenna system impedance that presented at the tuner output terminal.

or

Wave theory where you have a forward and reflected wave, and the tuner "re-reflects the reflected wave".

Either method,m when properly used, works perfectly for a system like we use.

By the way, the reflected power does not make it back int a PA output device and cause "heat". It simply changes the operating load line of the PA device. It can make the PA run cooler, hotter, or even stay the same temperature. This is because, like any mismatch, it causes the PA have more voltage at different points or more current at different points.

Take this example. If I have a 600 ohm line with a 5 600 ohm resistor load it is NOT resonant, yet the line is matched to the load and the line has a 1:1 SWR. There is no reflected power. Connected to a PA stage, the 600 ohm system that has a 1:1 SWR and is NOT resonant looks exactly the same as a 50 ohm line with a 12:1 SWR when at the voltage peak.

The PA behaves exactly the same into either load. If the PA tank or matching and filter system reflects a high impedance back to the PA devices, the voltage soars but generally efficiency stays the same or improves as current and conduction angle is reduced. The PA becomes LESS hot.

If the PA tank or filter/matching system happens to reflect a low impedance at the output device, current increases, conduction angle increases, and the PA device is hotter. Same SWR, no reflected power in one case, and the same results.

Think about this more that worrying about silly things like we call antenna tuners.

73 Tom
 
RE: Antenna Tuners -- Do They Work?  
by W8JI on February 22, 2014 Mail this to a friend!
People arguing about silly things like the name of the box on the table aside, there are two ways to look at this that work equally well in the context of this discussion. Also ignoring the equally silly idea that "resonance" has something to do with "efficiency" or low SWR.


The tuner matches the 50-ohm radio to the antenna system impedance that presented at the tuner output terminal.

or

Wave theory where you have a forward and reflected wave, and the tuner "re-reflects the reflected wave".

Either method,m when properly used, works perfectly for a system like we use.

By the way, the reflected power does not make it back int a PA output device and cause "heat". It simply changes the operating load line of the PA device. It can make the PA run cooler, hotter, or even stay the same temperature. This is because, like any mismatch, it causes the PA have more voltage at different points or more current at different points.

Take this example. If I have a 600 ohm line with a 5 600 ohm resistor load it is NOT resonant, yet the line is matched to the load and the line has a 1:1 SWR. There is no reflected power. Connected to a PA stage, the 600 ohm system that has a 1:1 SWR and is NOT resonant looks exactly the same as a 50 ohm line with a 12:1 SWR when at the voltage peak.

The PA behaves exactly the same into either load. If the PA tank or matching and filter system reflects a high impedance back to the PA devices, the voltage soars but generally efficiency stays the same or improves as current and conduction angle is reduced. The PA becomes LESS hot.

If the PA tank or filter/matching system happens to reflect a low impedance at the output device, current increases, conduction angle increases, and the PA device is hotter. Same SWR, no reflected power in one case, and the same results.

Think about this more that worrying about silly things like we call antenna tuners.

73 Tom
 
RE: Antenna Tuners -- Do They Work?  
by W8JI on February 22, 2014 Mail this to a friend!
Excuse the triple post, eHam has some posting errors that are occuring for me.
 
RE: Antenna Tuners -- Do They Work?  
by ZL2MC on February 22, 2014 Mail this to a friend!
The problem is the desire to use coax cable between the PA of the transmitter and the antenna. Yes, it's very convenient and gets around the noise generated by the domestic environment but in itself that is a handicap. You have to 'tune' the PA to the 50ohm coax by means of a balun, then at the other end convert the 50ohms back to the resonant impedance of the antenna remembering that if it's a resonant dipole it won't be 50ohms without another balun, an "unbal" in fact! Putting a "tuner" in the line is just to make the VSWR on the cable back to 50ohms to suit the transmitter output balun.

Back when I was a Radio Officer in the Merchant Navy, most often the 100Watt transmitter PA was 3 x 807's in parallel to a Pi coupler then open wire to a "T" or "L" long antenna. No coax, just copper tube to the bare hard-drawn copper antenna which started just outside the radio room bulkhead insulator. You didn't care about SWR or impedances, you matched the 807's to the antenna with the Pi coupler directly.

I believe that system would still work, a long wire to the "tuner" directly without the inherent losses in two (or more?) impedance transformations and make the antenna/"tuner" combination truly "resonant". Unfortunately most modern solid state rigs don't give you the opportunity to feed directly from the PA, they've already 'converted' to 50ohms.

Just my 10cents worth.
 
RE: Antenna Tuners -- Do They Work?  
by K1LLR on February 25, 2014 Mail this to a friend!
WRONG WRONG WRONG..a tuner wont give you more power fool
 
RE: Antenna Tuners -- Do They Work?  
by W8JI on February 25, 2014 Mail this to a friend!
Thanks for the contribution about wrong, but actually a tuner can improve power. It reduces mismatch at the rig and, if moved toward the antenna, can reduce feedline losses between the tuner and the transmitter.
 
Antenna Tuners -- Do They Work?  
by RADIOPATEL on March 8, 2014 Mail this to a friend!
This is very good session and benefits nontechnical hams also.
Such technical discussions need to be concluded by a Elmer/technical ham with appropriate summary so that it helps non technical Hams understand the topic better.
TNX,
73
Dinesh Patel-VU2DCI
 
Antenna Tuners -- Do They Work?  
by K7NM on March 9, 2014 Mail this to a friend!
Reading the comments is interesting! It is hard to understand how we hams get stuck in the "50 Ohm" mentality! The first rule to remember is that maximum power transfer occurs when the load matches the internal output impedance of the source - with reactance removed. Air is about 388 Ohms and the radio is about 50 Ohms. The antenna is a matching network to transform the two to each other. Sometimes the match isn't good enough - indicated by SWR greater than 1. So an additional box (tuner) is placed in line as a "negotiator" such that the antenna side sees what it wants to see and the radio side sees what it wants to see. The tuner aligns phases and scales power to do it. The "negotiation" is not "free", however. It costs some percentage of the power to primarily pay off the Q of the inductor in the tuner. But overall, the better power transfer is usually worth it.
 
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