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Author Topic: 4 Way antenna test ( Hand held )  (Read 20679 times)
VK3FORK
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Posts: 54




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« on: December 30, 2014, 08:38:09 PM »

The aftermarket is littered with antenna , in fact there is so much to chose from its not funny . And the opinions regarding these antenna are equally thick and fast . Im amazed that antenna with SWR readings in the order of 9 or more are so well accepted by the hand held radio market ( enthusiasts ) . Just check out youtube , so many product reviews singing the praises of antenna with high SWR . Its no wonder that so many people suffer from radios that get a little warm with use , as I have noted SWR readings completely off the scale for some antenna .

So for the sake of doing something to help bring ballance back to the force ( hand held radios ) , I offer this simple little test .  What it is is a little bit better than screwing on an antenna and then seeing how well it receives local repeaters or radio stations .  Im going to give you some SWR figures with your burger and fries . I would love to have better ( more expensive ) gear , but this is what I have ...





































Wasn't that interesting ?  It looks like the Baofeng UV-B5 antenna might still be the antenna of choice for a factory product . The poor Nagoya did not fare well at all , and it looks like the KINNOT//A might be a choice aftermarket replacement if you want a antenna with improved reception .

Now I did use all the antenna on my UV-82 to see how they went , and the Nagoya NA-666 was outstandingly the worst of the bunch !  Also the KINNOT//A was clearly the better receiving antenna from the bunch tested as well as the tightest SWR for a dual band antenna ( Over dual bands ) .

I will be posting results for other antenna I have as time permits .. 
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W8JX
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Posts: 12204




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« Reply #1 on: December 31, 2014, 05:35:29 AM »

Ultimately it is how it performs that matter. It could have great SWR and be little more than a dummy load.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
AA4HA
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Posts: 2384




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« Reply #2 on: December 31, 2014, 08:09:59 AM »

I understand where you are coming from on this and I agree, most portable rubber duckie antennas are terrible performers.

What is going to make it very difficult for you to test is your setup. Rubber duckie type antennas assume that the radio chassis is "the other half" of the antenna. It is like a dipole where the case of the radio is the ground plane. When you install adapters and a wattmeter between the two then you are making the ground plane longer than the driven element (the whip). It will significantly skew your results.

You almost need a junker radio that you can strip down to the frame, then to insert a wattmeter in-line, between the transmitter section and the antenna mount on the radio. Then when you do your testing you will get a more accurate number because the frame of the radio is now being taken into consideration.

-----------------------------------

One time I was dealing with a police department that had suffered from a sudden loss of system coverage to every voting receiver site. You know, you get that sort of call and you are trying to figure out what is common, to narrow it down a bit. What they did not say was that the problem was only with portables and not mobles. I figured that out after asking more questions. Also, the problem was hitting every receiver site? Impossible! Then I am trying to figure out what might be wrong with the voting controller (that determines what receiver site hears a remote best).

After a day of chasing that down I went out and did a little test driving with my own portable that was on their system...  Hmm, no problems, things work great. I got an officers portable, now the problem appears. Then I notice that every portable has a brand new stubby antenna.

The shift commander who was acting as their de-facto radio person decided to get these nifty little stubby antennas so the antenna would not be poking the officers in the ribs. Before morning shift he went to the charger rack and changed out every antenna on the portables.

Those antennas were 800 MHz stubbies, trying to be used on a VHF system. They were horrible performers.

The problem is, they took the old antennas and threw them away, now three days into this problem I had to order about 25 new VHF antennas. I did get a better model than what they had (a more flexible whip and a little bit better gain numbers) so they ended up with a slight improvement in performance, and they had an antenna that was not so rib-stabbing.
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
Free space loss (dB) = 32.4 + 20 × log10d + 20 × log10 f
VK3FORK
Member

Posts: 54




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« Reply #3 on: December 31, 2014, 06:46:29 PM »

I understand where you are coming from on this and I agree, most portable rubber duckie antennas are terrible performers.

What is going to make it very difficult for you to test is your setup. Rubber duckie type antennas assume that the radio chassis is "the other half" of the antenna. It is like a dipole where the case of the radio is the ground plane. When you install adapters and a wattmeter between the two then you are making the ground plane longer than the driven element (the whip). It will significantly skew your results.

You almost need a junker radio that you can strip down to the frame, then to insert a wattmeter in-line, between the transmitter section and the antenna mount on the radio. Then when you do your testing you will get a more accurate number because the frame of the radio is now being taken into consideration.

-----------------------------------

One time I was dealing with a police department that had suffered from a sudden loss of system coverage to every voting receiver site. You know, you get that sort of call and you are trying to figure out what is common, to narrow it down a bit. What they did not say was that the problem was only with portables and not mobles. I figured that out after asking more questions. Also, the problem was hitting every receiver site? Impossible! Then I am trying to figure out what might be wrong with the voting controller (that determines what receiver site hears a remote best).

After a day of chasing that down I went out and did a little test driving with my own portable that was on their system...  Hmm, no problems, things work great. I got an officers portable, now the problem appears. Then I notice that every portable has a brand new stubby antenna.

The shift commander who was acting as their de-facto radio person decided to get these nifty little stubby antennas so the antenna would not be poking the officers in the ribs. Before morning shift he went to the charger rack and changed out every antenna on the portables.

Those antennas were 800 MHz stubbies, trying to be used on a VHF system. They were horrible performers.

The problem is, they took the old antennas and threw them away, now three days into this problem I had to order about 25 new VHF antennas. I did get a better model than what they had (a more flexible whip and a little bit better gain numbers) so they ended up with a slight improvement in performance, and they had an antenna that was not so rib-stabbing.

Interesting ...
So there is no Accurate way of knowing :
A Low SWR in the test could possibly be a High SWR on Tx alone .. 

  What about one of those antenna testers ?
  They are about the size of a hand held Tx ...  ??   

PS , those stubby antenna - They are off the scale for SWR on 2 meter ..  On UHF though ... 

Anyhow , my issue is all these reviews giving glowing recommendations on Rx performance , hitting a local repeater is not that hard ..
And some of the reviews I have seen , from apartment buildings , ?? meters above the ground .  So if your already @ 20 meters + , yeah that antenna is going to work . 
A coat hanger would work !   
Oh well , Im not going to use high SWR antenna ( That's just me ) , and I will have to find a more accurate way of testing ..
I guess the other issue might be the Tx itself , if it is a part of the antenna . 
So if we have to live with an imperfect situation , is imperfect testing so bad ? 
Are the results worth something ? 
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K4ISR
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Posts: 222


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« Reply #4 on: December 31, 2014, 09:50:51 PM »

The na666 is not a recent enough antenna, the antenna of choice is the na701 or na771... Or for the UV-82X, the na702.
Another big issue is the number of cheap Chinese fakes that somehow made it to the U.S. A majority of the fakes had the blue lettering on it.

Also, where did you find that SWR meter? Wouldn't mind picking one up myself. I have 2x UV-5Rs and a BF-F8HP, the uv5r stock antenna, the slightly different f8hp antenna and a legit na701 antenna, plus a 3800mah extended battery which is less subject to voltage drops upon transmitting.
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de K4ISR
VU2NAN
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« Reply #5 on: January 01, 2015, 03:10:20 AM »

Bring the 'ANT' connector of the SWR Meter in contact with a 20" whip and watch the SWR going down!

73,

Nandu.
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W9FIB
Member

Posts: 2112




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« Reply #6 on: January 01, 2015, 04:54:18 AM »

Are the results worth something ? 

That is a good question. As AA4HA said when you add something between the antenna and the radio, you change antenna length, and you disturb how it will react with the radio. It is much different then just adding a meter to a feedline going to the antenna. How much it will react has many variables. Even something as simple as how you are holding the radio can cause changes in the SWR as it reacts to what else is around it. And changing angles held, changing what objects are in proximity, whether the objects have much metal or very little, antenna construction...and many more things. Also the antennas are designed (hopefully) to be working at their best when properly installed on the radio.

So the results MAY give you a ballpark idea of what is happening. But JX is right; ultimately it is how they perform in everyday use is what really matters.
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Happy being an Amateur Extra!
Nothing says CB on my printed license.
Ares/Races but no lights or crown vic.
WB6BYU
Member

Posts: 17270




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« Reply #7 on: January 01, 2015, 08:17:13 AM »

I seem to remember also some radios (a particular vintage of Kenwoods perhaps?) that were
optimized for a different output impedance like 25 ohms, and the corresponding antennas were
built for that impedance.  Note that, for simple construction methods (no shunt or series matching)
the input impedance of a helical whip is expected to be rather low - on the order of 10 ohms,
depending on length.  What raises the impedance is loss resistance.  So some more efficient whips
ducks may have a higher SWR.

I remember talking with one manufacturer about 30 years ago who had built an SWR meter into
a case about the size of the then-current HTs, with ferrite decoupling chokes on the lead from there
to the signal source, to try to simulate the working environment of an HT antenna.

In the end, while SWR is a useful indicator of something being wrong, the actual radiated signal
strength from a specific combination of HT and antenna still seems to be the best indicator of
performance.
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AA4HA
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Posts: 2384




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« Reply #8 on: January 01, 2015, 11:55:02 AM »

Using the receiver with some way to accurately track what the RSSI (receiver signal strength indicator) value when the radio is kept in the exact same mounting position, at the same location and to the same distant site will give you a pretty good way to compare one antenna to another. Antenna performance on receive and transmit is reciprocal, what is good for the receiver on a frequency will usually be a benefit for the transmitter as well.

Reading reviews of antennas, opinions given by people is mostly subjective. If working on a test bench or antenna test range it is all objective. Testing is based upon measurements that can be duplicated by someone else if they follow the exact same rules that you did when you set up the experiment.

When I read a review of an antenna I usually am not looking for details on performance (unless there are some big negatives out there on the subjective opinion). From people without a test setup I am looking for details about how robust something is and to what degree does this antenna connect up well to a particular radio.

I only urge caution when trying to do a comparison between antennas when you have that much metal that is extending the ground plane of the antenna. It changes its resonant length, the ratio between the two elements (antenna and chassis), the gain and the pattern. You can make a pretty decent antenna perform just terribly once you shift around those dimensions. Also, you can accidentally make a really bad antenna look better than it actually is.

This is one of those applications that just begs for a NEC computer model (or whatever PC version of NEC you have). You can wireframe create the metallic parts of the radio case, accurately dimension how far away the driven element of the antenna is and what materials or techniques are used to make a "springy" antenna.

Unfortunately an antenna may have been purpose-built with certain assumptions. With most third party antenna manufacturers like Diamond they need to assume a generic HT dimension. We all know how HT's are getting shorter and more phone-like, I doubt that anyone other than insomniac antenna engineers have considered what that does to pattern, SWR or efficiency. A midget radio attached to a giant whip antenna with a loading coil in the middle for loading or dual (triple) band support is not going to test the same as if that antenna was screwed down to a big flat plate of copper.

I use a Diamond SRH320A on a VX8; Subjectively speaking, it "seems" to be a better antenna than the stock antenna for the radio. Also it is more springy but I worry about possibly breaking the antenna connection on the radio as it does not have the same larger flat area for securing the antenna to the radio.

One day I was demonstrating an "AIM UHF" vector impedance analyzer to another ham so I took the whip off of my HT and used an N-male to SMA adapter to connect the antenna to the radio. Then I stood up the radio and did a frequency sweep from 100-500 MHz. That was really interesting, I could see where the antenna was resonant across several bands.

Note: I do not recommend that you go out and buy an AIM, most amateurs just do not need to get that deep into antennas;
http://www.arraysolutions.com/Products/AIMUHF.htm
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
Free space loss (dB) = 32.4 + 20 × log10d + 20 × log10 f
K4ISR
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« Reply #9 on: January 01, 2015, 12:23:27 PM »

The other issue is that too many people rely solely on SWR.

I can stand there with my 8W HT and cleanly hit repeaters 15 miles away with an antenna that shows over 2:1 SWR, yet not be able to get more than 6 miles with the stock antenna rated at 1.3:1.
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de K4ISR
VK3FORK
Member

Posts: 54




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« Reply #10 on: January 01, 2015, 04:14:41 PM »

I haven't solely relied on the SWR meter ..
I also did some testing by seeing what repeaters I could hit ( Tx power )
And the repeater test seemed to back up the SWR meter ..

I also have a couple of signal strength meters that can give a read out on ( Signal strength ) ... 
But I was a little fixated on SWR ..

 But would the test still be relative - SWR might not be 100% but could the variable between the antenna be valid ?
( Seeing what repeaters I could hit seemed to mirror the SWR results )

SWR meter is available on Ebay http://www.ebay.com/sch/i.html?_odkw=VJF+UHF+SWR+meter&_from=R40%7CR40%7CR40&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR2.TRC1.A0.H0.XVHF+UHF+SWR+meter&_nkw=VHF+UHF+SWR+meter&_sacat=0
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AA4HA
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Posts: 2384




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« Reply #11 on: January 01, 2015, 05:42:49 PM »

I haven't solely relied on the SWR meter ..
I also did some testing by seeing what repeaters I could hit ( Tx power )
And the repeater test seemed to back up the SWR meter ..

I also have a couple of signal strength meters that can give a read out on ( Signal strength ) ... 
But I was a little fixated on SWR ..

 But would the test still be relative - SWR might not be 100% but could the variable between the antenna be valid ?
( Seeing what repeaters I could hit seemed to mirror the SWR results )

That "is" one of the nice thing of that AIM UHF vector impedance analyzer. When it does a sweep on an antenna it shows you the resonant frequencies, losses and SWR as the analyzer sends out a blip and measures the response. Usually I set it to ping every 50 KHz and average 8 samples on each frequency as it moves through a wide range and takes 2-3 minutes to do all of the testing and to plot the antenna up on your computer screen.

What it does not show you is if the antenna is radiating power in a useful direction. You may know that on a dipole antenna with low gain that the radiation pattern around the antenna is shaped like a doughnut. When you increase antenna gain that doughnut gets smashed down.. the same amount of total power is there, just directed more out to the sides of the doughnut instead of up and down.

When you elevate the ground feed on a dipole antenna the doughnut does weird things. It becomes funnel shaped and the signal may fan outwards in a higher or lower cone. If you are right out to the side of the antenna you would notice a decrease in performance and signal level. The shape of that doughnut-funnel is dependent upon that distance of elevation of the ground plane and the frequency in question. This is because you have made the "other" element of the dipole (the radio chassis and your body, holding the radio) electrically longer.
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
Free space loss (dB) = 32.4 + 20 × log10d + 20 × log10 f
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