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eHam Forums => Station Building => Topic started by: AD5MD on July 28, 2011, 07:54:49 PM



Title: 33 Ft. 40m Vertical
Post by: AD5MD on July 28, 2011, 07:54:49 PM
I have installed a 33ft 40m mono band vertical and with the mediocre radial/counterpoise installation that I have I know that even if its swr is 1:1 - 1.3 across the band, its performance is marginal. 

Now my question is this...will a vertical current feedline choke help improve its overall performance like what a manufacturer/store website claims?  If so, is there another model/brand which is not too expensive? I was thinking of giving it a try but the cost of the choke is almost the same as the antenna...so I have to research more before pulling the trigger. Any inputs from experienced vertical users in the forum?  Thank you

73,
de Ernie, AD5MD


Title: RE: 33 Ft. 40m Vertical
Post by: N3OX on July 28, 2011, 09:23:33 PM
Now my question is this...will a vertical current feedline choke help improve its overall performance like what a manufacturer/store website claims?  

That depends on how much current is actually flowing on your feedline ;D You could have a lot or a little just based on the exact details of the installation... and if you have only a little the choke won't do anything.  (if you want to measure, current meters are pretty simple:  http://www.w8ji.com/building_a_current_meter.htm)

For transmitting performance it really depends on what your radial system is.  If it's on-ground radials it probably won't do anything much for transmitting, but might still help on reception.  If you have a bad common mode current problem with elevated radials a choke could help a fair bit on both transmit and receive.

Chokes CAN be cheap if you are willing to roll your own.  They're just coax wound on a ferrite core, installed in a box.  Some choke ideas are here:

http://www.karinya.net/g3txq/chokes/

The "17 turns RG-58 on a FT-240-43" (about nine bucks plus shipping) would be a good choice for 40m.  For high power, you can substitute teflon coax types for RG-58 and still get the same common mode performance but not have to worry about the power limit of the coax.  

That said, radials are important but sometimes people go overboard and make you think you will get BAD performance unless you plate your backyard with copper (or install the mythical 113 radials 0.5 wavelength long).  Really 60 radials 1/4 wavelength long is a small fraction of a dB from "perfect"  and things like 8 or 16 radials 20 feet long on 40m are probably a dB or two down at worst and plenty to prevent the coax from being an "important radial"

So what do you actually have?  Does it actually seem deficient?



Title: RE: 33 Ft. 40m Vertical
Post by: K9IUQ on July 29, 2011, 05:33:30 AM
I have installed a 33ft 40m mono band vertical and with the mediocre radial/counterpoise installation that I have I know that even if its swr is 1:1 - 1.3 across the band, its performance is marginal. 

Now my question is this...will a vertical current feedline choke help improve its overall performance like what a manufacturer/store website claims? 
73,
de Ernie, AD5MD

Here is my experience. 3 years ago I built a 40 mtr 1/4 wave vertical. A friend gave me 33ft of large (2 1/2 inch) tapering fiberglass rod. I ran a 10 ga wire up the middle. I feed it with RG-213 and use a DX Engineering feedline choke at the base of the antenna. There are 60 radials of 16ga 33' wire spaced evenly under the vertical. This setup provides excellent DX and domestic coverage. It outperforms my 40mtr horizontal wire antennas 95% of the time.

The SWR on this antenna is 1.5:1 or less across the whole band.

When I first put up the antenna I only had 8 radials under it. The SWR was around 1:1 almost like my dummy load. As I put more radials on the antenna the SWR went up until it stabilized around 36 radials at 1.5:1

The more radials I put on it, the better the antenna performed.

Does the feedline choke help? I really do not know as I have always fed the antenna with it.

Stan K9IUQ
 


Title: RE: 33 Ft. 40m Vertical
Post by: AD4U on July 29, 2011, 05:52:59 AM
When you use a ground mounted 1/4 wave vertical (33 ft is a 1/4 wave on 40M) and you have a GREAT SWR over the entire band, that just about guarantees that your antenna system is very lossy and inefficient - dummy load.  A 1/4 wavelength vertical on 40M with a good ground plane (lots of radials properly installed) will not exhibit a low SWR over the entire band.

As so many have posted in the past you need to add more radials.  How many you "need" depends on lots of factors such as (but not limited to) soil conductivity in your area.  There is no magic number of radials needed  and there is no magic length.  

Old broadcast handbooks suggest installing 120 radials each 1/4 wavelength long.  In practical situations you often have to get by with fewer radials that are not 1/4 wavelength long.

In most cases having just a few radials under a ground mounted vertical makes a very poor antenna.  I am not aware of any "add on" devices that will compensate for the lack of radials.

Dick  AD4U



Title: RE: 33 Ft. 40m Vertical
Post by: N3OX on July 29, 2011, 07:25:49 AM
When you use a ground mounted 1/4 wave vertical (33 ft is a 1/4 wave on 40M) and you have a GREAT SWR over the entire band, that just about guarantees that your antenna system is very lossy and inefficient - dummy load.  A 1/4 wavelength vertical on 40M with a good ground plane (lots of radials properly installed) will not exhibit a low SWR over the entire band.

That really depends on what you mean by "low SWR."    I think it's important to be specific because a 33.5 foot #12 wire fed against a PERFECT copper ground plane will show less than 1.7:1 50 ohm VSWR across the entire 40m band with a minimum SWR in the center of the band of 1.4:1.

That's certainly usable with almost all solid state transmitters  "low" in some measure. Not as low as the OP's 1.1-1.3 which may indicate substantial losses.

However, I do think it's worth remembering that just inserting 15 to 30 ohms of loss resistance at the feedpoint of a vertical doesn't make a "dummy load."  It's more like something between 1 and 5dB  of loss.  So if you have  a nice 50 ohm VSWR, it's still going to radiate pretty okay.

I think we do a bit of a disservice calling quarter wave verticals with sad radial systems "dummy loads," because really, even if you mount the thing on a single ground rod, probably not more than half or two thirds of your power goes into the dirt.  This is a lot better than some other types of terrible antennas, especially "no radials" verticals, which massively concentrate the fields around the antenna in a way that can cause even more loss than having a sparse or terrible radial field.

I'm not saying that a quarter wave on a ground rod or a few short radials is a GOOD antenna, nor is it one to be recommended as a matter of course, but I think hyperbole about how much there is to gain by adding radials makes verticals very unattractive to some people. If a certain installation is within 1dB of perfect on 40m with 16 radials 17 feet long, even thinking or talking about 60 or 120 radials 33 feet long or longer is not worthwhile.

You're not "getting by" if you're 1.2dB or 0.7dB away from perfection.  Rather, you're in the range where you wouldn't even notice if the copper fairies came and made your backyard a clean shiny disc of high conductivity copper.  In fact, if you're running a radial field that's within 1dB of perfect and the copper fairies come, you should probably rip it back out, sell it for scrap, and buy some ham radio stuff that actually makes you substantially louder like a beam and tower.

The problem is always about knowing if you're 6dB away from perfect (worth working on, kind of a lot of improvement to be had) or 1dB away from perfect (probably not worth working on unless you're a good measurer and 1dB keeps you up at night)  The problem is knowing when to stop and really the best tool there is field strength measurements.

And reading all of N6LF's articles is pretty illuminating:

http://www.antennasbyn6lf.com/design_of_radial_ground_systems/


Title: RE: 33 Ft. 40m Vertical
Post by: AD4U on July 29, 2011, 10:32:09 AM
When you use a ground mounted 1/4 wave vertical (33 ft is a 1/4 wave on 40M) and you have a GREAT SWR over the entire band, that just about guarantees that your antenna system is very lossy and inefficient - dummy load.  A 1/4 wavelength vertical on 40M with a good ground plane (lots of radials properly installed) will not exhibit a low SWR over the entire band.

That really depends on what you mean by "low SWR."    I think it's important to be specific because a 33.5 foot #12 wire fed against a PERFECT copper ground plane will show less than 1.7:1 50 ohm VSWR across the entire 40m band with a minimum SWR in the center of the band of 1.4:1.

That's certainly usable with almost all solid state transmitters  "low" in some measure. Not as low as the OP's 1.1-1.3 which may indicate substantial losses.

However, I do think it's worth remembering that just inserting 15 to 30 ohms of loss resistance at the feedpoint of a vertical doesn't make a "dummy load."  It's more like something between 1 and 5dB  of loss.  So if you have  a nice 50 ohm VSWR, it's still going to radiate pretty okay.

I think we do a bit of a disservice calling quarter wave verticals with sad radial systems "dummy loads," because really, even if you mount the thing on a single ground rod, probably not more than half or two thirds of your power goes into the dirt.  This is a lot better than some other types of terrible antennas, especially "no radials" verticals, which massively concentrate the fields around the antenna in a way that can cause even more loss than having a sparse or terrible radial field.

I'm not saying that a quarter wave on a ground rod or a few short radials is a GOOD antenna, nor is it one to be recommended as a matter of course, but I think hyperbole about how much there is to gain by adding radials makes verticals very unattractive to some people. If a certain installation is within 1dB of perfect on 40m with 16 radials 17 feet long, even thinking or talking about 60 or 120 radials 33 feet long or longer is not worthwhile.

You're not "getting by" if you're 1.2dB or 0.7dB away from perfection.  Rather, you're in the range where you wouldn't even notice if the copper fairies came and made your backyard a clean shiny disc of high conductivity copper.  In fact, if you're running a radial field that's within 1dB of perfect and the copper fairies come, you should probably rip it back out, sell it for scrap, and buy some ham radio stuff that actually makes you substantially louder like a beam and tower.

The problem is always about knowing if you're 6dB away from perfect (worth working on, kind of a lot of improvement to be had) or 1dB away from perfect (probably not worth working on unless you're a good measurer and 1dB keeps you up at night)  The problem is knowing when to stop and really the best tool there is field strength measurements.

And reading all of N6LF's articles is pretty illuminating:

http://www.antennasbyn6lf.com/design_of_radial_ground_systems/


Read the original post.  He said the SWR on his antenna was 1:1.3 ACROSS THE ENTIRE 40M BAND.  Not much but a dummy load is that good.

Dick  AD4U


Title: RE: 33 Ft. 40m Vertical
Post by: N3OX on July 29, 2011, 02:47:23 PM
Quote
Not much but a dummy load is that good.

That's not really true.  Let me give you an example with modest loss but less than 1.3:1 VSWR across the 40m band.  If I add 10 ohms of ground loss to a quarter wave #12 wire fed against a perfect solid copper ground and then feed that with 100 feet of RG58 coax, that adds an extra 2.25dB (1dB warms worms, 1.25 dB warms coax) of loss in total but makes the VSWR across the 40m band less than 1.3 to 1.  If you're a careful measurer you could measure 2dB maybe, and you could improve it a bit with more radials and better coax, but most people wouldn't notice it on the air and it's hardly "dummy load" level.

This example shows lower SWR with broader bandwidth because of loss, but it's just not that much loss.  You don't NEED a dummy load disaster to get under 1.3:1 across forty meters.  It's not a bad thing to remind people that dummy loads show good flat VSWR without radiating anything.  I agree with the spirit of that.  But turning an antenna with 20-30 ohm radiation resistance into a 50 ohm dummy load is not straightforward.  You can't just add loss resistance to dial up an arbitrarily large amount of loss while lowering the 50 ohm VSWR.  Eventually the SWR will start to go up again when you cross over 50 ohms.

This is in contrast with something like an 80m hamstick dipole or a 40m mobile antenna.  The radiation resistance a few ohms or even a fraction of an ohm.  You can EASILY get 20dB of loss and a 50 ohm impedance by adding series resistance to a short mobile antenna.  One ohm of radiation resistance and 49 ohms of loss resistance is nearly 17dB of loss.  But for a quarter wave vertical, the loss of "series resistance matching" probably tops out at 3-4dB in the absolute worst case.  That's nothing to sneeze at but it's also not really a "dummy load."

Adding to the problem here is that radial systems are more complicated than adding a simple series resistor because standing waves aren't actually completely damped out on the radials (the current variation on radials has been confirmed in measurements on real systems, not just theorized).   W8JI reports that he can get 50 ohm feed impedance with the exact same field strength as an elevated radial antenna that shows 30 ohm feed impedance.  The complicated nature of real wire ground screens might mean if you shoot for low feed impedance and narrow VSWR bandwidth as a GOAL, that might be all you get.  And a decent broad bandwidth with low SWR doesn't always mean a disaster.  I'm not trying to say adding radials is bad advice, just that the right tool to check if they're helping is a measurement of signal levels, not the feed resistance at resonance or the VSWR bandwidth.

I also think that exaggerating the maximum losses of bad radials is going to put people off of using verticals even if they're the best choice.  Radials are important and they're a cheap way to improve your signal.  Ultimately, 3dB or 4dB of amplifier is big big bux and 3dB or 4dB of radials is just some wire.  But when I look at the lossy monstrosities that some people pick because the manufacturer says "no radials," eventually I just want to tell people to start with a fifteen dollar fishing pole with a quarter wave wire up the side fed against an 8ft ground rod.  It might work better than the other thing they're looking at.  Radials are unquestionably important from a dollars to dB perspective, and communicating that well is important, but inadvertently exaggerating how important they are does not serve a useful purpose.


Title: RE: 33 Ft. 40m Vertical
Post by: AD5MD on July 29, 2011, 05:40:29 PM
At present I only have 20 radial wires cut randomly because of space limitations.  I have just bought some more wires and will try to add at least 15-20 more which I will try to squeeze in to the available space.  Thanks for the input guys, I've used beams since the mid 80s so I'm familiar with it but not with verticals.  I appreciate all the info/help I've been reading. 

Ernie, AD5MD


Title: RE: 33 Ft. 40m Vertical
Post by: N3OX on July 29, 2011, 06:00:47 PM
At present I only have 20 radial wires cut randomly because of space limitations.  I have just bought some more wires and will try to add at least 15-20 more which I will try to squeeze in to the available space.  

How big is the available space?
 


Title: RE: 33 Ft. 40m Vertical
Post by: AD5MD on July 29, 2011, 07:12:59 PM
more or less 40ft x 20ft.  Here is how the antenna is mounted:

                                                    Fence
                                  -----------------------------------
                                  '                                            '         
                                  '                                            '
                                  '                                            '
                                  '                     X                     '
                                  -----------------------------------
                                              Side of the house
                                                 "X" - Antenna

Looking at the above you will notice that I don't have any space to lay the radials at the back of the antenna (mounted approx 5ft from the house wall) so I only have the radials towards the fence and diagonally to the sides.  At present I only have 20 radial wires.  Tnx


Title: RE: 33 Ft. 40m Vertical
Post by: W8JX on July 29, 2011, 08:17:30 PM
Why did you place antenna so close to house. I would have placed it near or on fence


Title: RE: 33 Ft. 40m Vertical
Post by: AD5MD on July 29, 2011, 10:59:06 PM
The upper right corner of the space is occuPied by a hex beam antenna


Title: RE: 33 Ft. 40m Vertical
Post by: K9IUQ on July 30, 2011, 04:19:49 AM
Why did you place antenna so close to house. I would have placed it near or on fence

This is why verticals get a bad name. Hams stick them right next to the garage/house hook up a ground wire to the outside water faucet pipe and then tell everyone verticals suck.

A vertical is one of the hardest antennas to install properly. They need to be away from obstacles like houses and they need an extensive radial system. Properly installed, a vertical will perform beyond your dreams.

Stan K9IUQ



Title: RE: 33 Ft. 40m Vertical
Post by: W3LK on July 30, 2011, 07:11:40 AM

This is why verticals get a bad name. Hams stick them right next to the garage/house hook up a ground wire to the outside water faucet pipe and then tell everyone verticals suck.

A vertical is one of the hardest antennas to install properly. They need to be away from obstacles like houses and they need an extensive radial system. Properly installed, a vertical will perform beyond your dreams.

Stan K9IUQ



AMEN!!!


Title: RE: 33 Ft. 40m Vertical
Post by: AD5MD on July 30, 2011, 07:50:09 AM
I answered a question hoping to receive a remedy or solution. Thank you


Title: RE: 33 Ft. 40m Vertical
Post by: W8JX on July 30, 2011, 09:06:34 AM
I answered a question hoping to receive a remedy or solution. Thank you

A vertical likes to be at least 1/4 wave away from metal that could possibly resonant or effect antenna performance. House it full of electrical wire. All the radials in the world is not going to help much next to house. How about roof mounting it?


Title: RE: 33 Ft. 40m Vertical
Post by: N3OX on July 30, 2011, 09:35:49 AM
If you get 20-40 radials in that 20x40 foot space that's actually pretty okay for 40m.

Unfortunately, I have to agree with the others that moving the vertical away from the house will probably give the biggest performance boost of anything.   If you feel that the vertical is weak on transmit or noisy on receive, that is probably going to make the biggest difference of anything you can do.

The hexbeam itself and the vertical won't interact much.  Being 10 feet from the the hexbeam mast wouldn't be great for the vertical, but I think if you could put the vertical in the middle on the fence side it probably would work better, even though that puts it somewhat closer to the mast in the upper right corner.





Title: RE: 33 Ft. 40m Vertical
Post by: AD5MD on July 30, 2011, 10:01:49 AM
Don,

That makes sense but unfortunately I won't be able to move the vertical from its present location.  The remaining space in the backyard will be used soon so moving and taking it out later will be useless.  I guess adding more radials and see what the difference will be would be most I could do at the moment.  Otherwise I'll just wait 'til I put up a free standing tower and string a dipole.  Tnx very much


Title: RE: 33 Ft. 40m Vertical
Post by: W8JX on July 30, 2011, 11:39:56 AM
Don,

That makes sense but unfortunately I won't be able to move the vertical from its present location.  The remaining space in the backyard will be used soon so moving and taking it out later will be useless.  I guess adding more radials and see what the difference will be would be most I could do at the moment.  Otherwise I'll just wait 'til I put up a free standing tower and string a dipole.  Tnx very much

Personal I would not waste anymore time or radials with that antenna next to house.  A full sized 1/4 wave vertical is a good antenna. You just then to move it either away from house or on top of it.


Title: RE: 33 Ft. 40m Vertical
Post by: AD5MD on July 30, 2011, 11:51:10 AM
Making more researches now I am planning on just home brewing a pancake antenna and install it at 20ft on the same spot where the vertical is.  If that works, the vertical will be either up for sale or kept for future use.


Title: RE: 33 Ft. 40m Vertical
Post by: W8JX on July 30, 2011, 12:33:37 PM
Making more researches now I am planning on just home brewing a pancake antenna and install it at 20ft on the same spot where the vertical is.  If that works, the vertical will be either up for sale or kept for future use.

I have used a Hustler 5BTV vertical for close to 20 years and it has always performed well on 40 and it is not fullsized either but it is located well away for house.


Title: RE: 33 Ft. 40m Vertical
Post by: N3OX on July 30, 2011, 01:23:30 PM
Making more researches now I am planning on just home brewing a pancake antenna and install it at 20ft on the same spot where the vertical is.  

Many of those types of antennas, especially the tiny ones (http://www.para.org.ph/membersarticles/Pancake%20Antenna/) just end up being a way to top feed the coax shield and/or mast, making it a vertical as tall as the mast.  As such, it will probably work the same as your vertical.  If it works like it looks, just a little short end loaded dipole, it's too short for 40m.  The much bigger ones would be better as a self contained antenna, but you'd want something maybe 15-20 feet long between the spirals minimum.

I guess your vertical is giving disappointing performance if you're looking to replace it with something like that?  Is it too noisy or what?  

Is it manmade noise if so?

Certainly, whenever you're really constrained, experimentation is a good idea so you might just want to try things and see what sticks.  


Title: RE: 33 Ft. 40m Vertical
Post by: AD5MD on July 30, 2011, 01:43:09 PM
Dan,

I've been reading about the pancake and so far I'm not totally convinced about it.  It just came as a thought of an alternative antenna.  Incidentally, the link that you posted is from a friend from DU where I'm originally from, hi.

The noise is I'd say between S6 to S8 at night and right now (0338 CST) it is at S5 but I don't hear anyone at this time, must be the propagation.  I've worked stations from HA, LZ, I, SM, PY on both ssb and cw though so not really that frustrating, hi.  It could just be the propagation I suppose?  Oh well, I still have a spool of 250ft of aluminum electric fence wire here so maybe I'll gamble and try to lay down some more radials.  Tnx

Ernie


Title: RE: 33 Ft. 40m Vertical
Post by: K9ZM on August 01, 2011, 06:40:53 PM
I don't know if if will help you, but you can see mine at QRZ.  I have added more radials to a total of 44.  It's in a side yard, so space is tight.  But I had plenty of room for 20 1/4 wave radials and added 22 more with some as short as 6ft and some 1/4 wave long.  It's not always the best choice for a close in antenna.  But it gets the job done.  At times it's like magic it works so well.  It works DX.  I have ST0R on both 40 and 30m with it.  The FT-2000D tunes it for 30m just fine. 

For reception, if noise seems to be a problem, I use the RX antenna port and use the Force12 C3E as a receive antenna.  I have an ICE RX antenna port protection box.



Title: RE: 33 Ft. 40m Vertical
Post by: W8JI on August 02, 2011, 04:01:12 AM
I want to point one thing out people miss. We really need to nip this myth about SWR and bandwidth in the bud and **stop repeating it**.

Base impedance and SWR bandwidth of an antenna by itself tells us next to NOTHING about efficiency. Narrowness of bandwidth by itself tells us virtually nothing about efficiency. Feed resistance also tells us nothing universally definitive about losses.

It would be best to IGNORE all the wild projections about efficiency of your vertical that are based on unreliable pretty much meaningless data like feed efficiency, SWR, and bandwidth. They can never be more than the wildest of guesses. It's sounds like expert theory and advice to say "you have 51.0 ohms base impedance and it should be 36.259 ohms, so you have 14.741 ohms loss resistance"  or "only dummy loads are 300 kHz wide" but none of that really relates to losses or efficiency.

73 Tom









Title: RE: 33 Ft. 40m Vertical
Post by: W3WN on August 03, 2011, 12:18:10 PM
Two words:  Add radials



Title: RE: 33 Ft. 40m Vertical
Post by: N2EY on August 03, 2011, 12:52:51 PM
its performance is marginal. 

What does "marginal" mean to you?

What do you want the antenna to do - DX, stateside ragchewing?

I agree that being so close to the house is a big problem. What sort of construction is the house? Stucco? Aluminum siding?

73 de Jim, N2EY


Title: RE: 33 Ft. 40m Vertical
Post by: W8JX on August 03, 2011, 01:35:47 PM
Two words:  Add radials

It has a bigger problem than lack of more radials. Its caused by back off house 5 foot from it. No amount of radials is going to fix this.


Title: RE: 33 Ft. 40m Vertical
Post by: W5DQ on August 03, 2011, 01:41:08 PM
I find it interesting that many say that a 33 ft 40M vertical is a poor performer. I have a 33 ft (appx) 40M vertical with thirty 40M 1/4 wave length radials on the ground plus 3 extra radials appx 50-65 ft long in the mix. The anttenna is tuned to cover 7.0 to 7.2 with a 1.5:1 SWR at the edges and roughly flat at midpoint. I feed it with 50-60 ft of 9096-IIA low loss air core without a tuner and have 12 RG-213 sized split ferrite blocks (roughly 1.25" square) at the feed point. The antenna tubing is 1.5" at the base and tapers up to 3/4" at top. There is no cap hat although it was suggested to me to use on to improve the performance and bandwidth. Not sure if that is a fact or fantasy as I haven't modeled it nor tried it. The antenna easily handles up to 600W as I use a AL-811 to drive it with no problems.

As far as performance, I have had very good success with this vertical on DX into all areas of the world. It is mounted appx 60+ ft from any buildings and next to a fence. Only issue I have noticed is when my neighbor moved his converted Greyhound type bus next to fence about 10-15 ft from antenna. Everything went squirrelly for a bit until I figured it out. Since then he has moved the bus and all is back to normal or what I call normal.

Curious what others might suggest to make this a better performer although I find it currently great?

Gene W5DQ



Title: RE: 33 Ft. 40m Vertical
Post by: W8JX on August 03, 2011, 03:15:37 PM
It is best to have a Vertical at least 1/4 wave away for house and metal structures. Further is better still.  Being that close to house and wiring in it I imagine is radiation pattern is pretty squirrely. Take any good antenna and mount/install it wrong and it will not work well.


Title: RE: 33 Ft. 40m Vertical
Post by: N3OX on August 03, 2011, 04:13:35 PM
Curious what others might suggest to make this a better performer although I find it currently great?

Add three more, phase appropriately.


Title: RE: 33 Ft. 40m Vertical
Post by: W5DQ on August 03, 2011, 04:42:17 PM
It is best to have a Vertical at least 1/4 wave away for house and metal structures. Further is better still.  Being that close to house and wiring in it I imagine is radiation pattern is pretty squirrely. Take any good antenna and mount/install it wrong and it will not work well.

I think you misread what I wrote. The only time it acted poorly was when the neighbor moved his bus to that side of his property. Other than that I have no bad things to say about its performance. I'm sure it could be better if I had more room but I only have 4/10 of an acre and the house and workshop/ham shack is there too. Also have 2 small (40') towers and a OCFD 'strategically' arranged to minimize interference.

My vertical is situated as far away from everything as possible to put it any farther away would require me to put it my neighbors yard and I really don't think that is possible. I realize there are optimum configurations and then there are limitations we have to live with. Not everyone has 100 acres of land to put antennas everywhere .... but I sure would like to :)  I have 53 acreas in Arkansas that I am thinking of trying to setup a remote station on. Still in the planning stages on that one.

Gene W5DQ


Title: RE: 33 Ft. 40m Vertical
Post by: W8JX on August 03, 2011, 05:34:02 PM
It is best to have a Vertical at least 1/4 wave away for house and metal structures. Further is better still.  Being that close to house and wiring in it I imagine is radiation pattern is pretty squirrely. Take any good antenna and mount/install it wrong and it will not work well.

I think you misread what I wrote.


No not at all. I am sorry if you thought that comment was aimed at you. It was not. It is follow on to original post. Adding all the radials in the world is not going to help a antenna that close to house.  A full sized 1/4 wave vertical for 40 is a good antenna "if" it is not mounted 5 feet from house. 


Title: RE: 33 Ft. 40m Vertical
Post by: K9IUQ on August 03, 2011, 07:09:32 PM
I find it interesting that many say that a 33 ft 40M vertical is a poor performer.

I am happy most hams think a dipole is better on 40m. Makes working DX that much easier for me and my 1/4 wave vertical. I have both, a 40 mtr dipole and 40 m vertical. The dipole gets used very rarely simply because the vertical outperforms it considerably on DX and domestic.

I stomped on many dipoles last night on 40 mtrs and worked ST0R easily.. ;D

Stan K9IUQ




Title: RE: 33 Ft. 40m Vertical
Post by: W8JX on August 03, 2011, 08:19:07 PM
I have always been a bit fond of verticals. Been using them for most of my 42+ years now as a ham.


Title: RE: 33 Ft. 40m Vertical
Post by: W5DQ on August 03, 2011, 09:13:05 PM
It is best to have a Vertical at least 1/4 wave away for house and metal structures. Further is better still.  Being that close to house and wiring in it I imagine is radiation pattern is pretty squirrely. Take any good antenna and mount/install it wrong and it will not work well.

I think you misread what I wrote.


No not at all. I am sorry if you thought that comment was aimed at you. It was not. It is follow on to original post. Adding all the radials in the world is not going to help a antenna that close to house.  A full sized 1/4 wave vertical for 40 is a good antenna "if" it is not mounted 5 feet from house. 

Ok, understand. Since you used the word 'squirrelly' like I did, I thought it was a reply to my reply. I wish I had a 1/4 or larger acre plot for decent 40M antennas. But what I have does admirably considering the location.

Gene W5DQ


Title: RE: 33 Ft. 40m Vertical
Post by: W5DQ on August 04, 2011, 08:55:42 AM
Curious what others might suggest to make this a better performer although I find it currently great?

Add three more, phase appropriately.

Not sure the neighbors would like the other three in their yards :(


Title: RE: 33 Ft. 40m Vertical
Post by: N4JTE on August 04, 2011, 03:22:44 PM
Earnie, to summerize, your vertical is too close to your house, adding a choke will not be a cost effective improvement.
Invest in relocating to center of yard, 20 radials should be a good start point, pay less attention to swr, measure ohms at antenna, best case around 38 ohms, my guess your above that now, after relocation shoot for the 38 ohms by adding radials.
Have built mucho verticals phased etc.
Bob


Title: RE: 33 Ft. 40m Vertical
Post by: W8JI on August 05, 2011, 06:35:24 PM
A dipole at 30-40 feet on 40 meters will pretty much be a toss up with a good vertical for DX.

Put a dipole at 60-90 feet, and it is no comparison.

This isn't saying the vertical, properly located and with a good ground system, is a dog. Just that a dipole will do just as well at similar height and much better when higher.

The exception is around salt water.

73 Tom



Title: RE: 33 Ft. 40m Vertical
Post by: W5DQ on August 05, 2011, 07:17:17 PM
A dipole at 30-40 feet on 40 meters will pretty much be a toss up with a good vertical for DX.

Put a dipole at 60-90 feet, and it is no comparison.

This isn't saying the vertical, properly located and with a good ground system, is a dog. Just that a dipole will do just as well at similar height and much better when higher.

The exception is around salt water.

73 Tom



Providing the dipole has a good broadside to the desired direction. My problem, besides the 40M vertical in a not prime location, is I also have an OCFD for 80-10 and had to orient it mainly E to W so on 40M the main pattern would be off sides to N and S with less off the E and W ends. It does do ok for EU but not so well for central / southern AF. Oh well I do the best what I have now and maybe better someday with more property for antennas.

Gene

Gene


Title: RE: 33 Ft. 40m Vertical
Post by: K9IUQ on August 06, 2011, 05:35:17 AM
A dipole at 30-40 feet on 40 meters will pretty much be a toss up with a good vertical for DX.

This is my first hand experience. I have a 40mtr dipole at 50 ft and a 40 mtr 1/4 wave monoband vertical ground mounted and 60 radials. After 3 years of this arrangement I can truthfully say that the vertical is by far the better antenna for DX and most of the time it is better for Domestic.

These antennas are easy switchable back and forth and I have tested performance countless times.

Why this is, I do not know. It could be my environment, it could be because the dipole is directional. It could be because I live near the top of a hill, and the hill slopes are affecting performance. Perhaps antenna modeling shows them to be equal but my experience has shown that actual performance does not always follow antenna modeling. I believe more should be written about antennas and how they perform in different environments.One of My favorite antenna books  "HF Antennas for all Locations" by Moxon G6XN has a whole chapter devoted to antennas and their environment. This chapter explains how different environments affect antenna performance.

Whatever, my vertical is definitely my antenna of choice for 40 mtr contacts at this time. I rarely use the dipole, in fact I am taking it down this fall and replacing it with a different wire antenna.

I really hate to say this because it sounds like a ham cliche but there are DX signals I have heard on the vertical that have been uncopyable on the dipole.

For the average ham getting a dipole at 60-90 ft is not achievable. On the other hand getting a vertical in the clear away from objects is difficult for the average city bound ham.

Stan K9IUQ

 


Title: RE: 33 Ft. 40m Vertical
Post by: W6RMK on August 07, 2011, 07:40:49 AM
*.

Base impedance and SWR bandwidth of an antenna by itself tells us next to NOTHING about efficiency. Narrowness of bandwidth by itself tells us virtually nothing about efficiency. Feed resistance also tells us nothing universally definitive about losses.


You've hit the nail squarely on the head there..

after all, a coax stub with no antenna has very narrow SWR bandwidth <grin>





Title: RE: 33 Ft. 40m Vertical
Post by: N3OX on August 07, 2011, 05:33:07 PM
Why this is, I do not know. It could be my environment, it could be because the dipole is directional. It could be because I live near the top of a hill, and the hill slopes are affecting performance. Perhaps antenna modeling shows them to be equal but my experience has shown that actual performance does not always follow antenna modeling. I believe more should be written about antennas and how they perform in different environments.

A lot of people focus on the gain of a dipole vs. vertical which is really very relevant on the higher HF bands but things get more complicated on the lower bands.

The thing that matters is the ratio of response to signal coming from the right direction to that coming from all the other directions.  Part of that is captured by the antenna pattern itself, corrected for the fact that the gain doesn't really matter on HF because there's lots of surplus signal strength:

http://www.w8ji.com/receiving.htm

The RDF for a vertical is going to be quite a bit better than a 30 foot high dipole, I'd guess.  Better soil will make that better too.

But I wonder if the noise is really uniformly distributed in elevation ... if you have quiet local noise and are just picking up skywave noise, I wouldn't be surprised if the noise at higher angles was somewhat higher.  That might make the signal to noise difference even more striking between a dipole and vertical.  If you have a couple of strong thunderstorms at medium range dominating your noise floor, there could be dozens of dB improvement on a vertical.  I don't know if there would be any AVERAGE improvement... that depends on there being steady differences average noise level as a function of elevation, and I don't know about that.  But certainly, at times, a vertical can be amazingly better than a dipole for reception even if it's equal or worse on transmission.

On the higher bands this matters less because there's nothing but weak noise from space coming in at higher angles. 


Title: RE: 33 Ft. 40m Vertical
Post by: W4FID on August 10, 2011, 07:24:38 AM
Let's not get SWR and radiation mixed up. The ultimate in low SWR is a dummy load ............ but as we all know (at least I hope we all know) it's a very poor radiator.

Yes -- SWR matters -- a lot. Too high and it means some of your RF is converted to heat in the feedline and less arrives at the antenna to be radiated. Too high and the finals of your solid state rig are at risk. Too high and most rigs have a "foldback" protection that automatically reduces the RF power to help protect the finals.

But the basic thing is a vertical needs an RF ground to radiate effectively ........... and a decent SWR reading does not automatically mean you have a decent RF ground.

Here in FL our soil is highly sand oriented. 30 minutes after a rain my yard is a ground up glass bottle. So a large pipe down a ways still isn't much of an RF ground. Decent antenna base mechanical mount -- but a poor ground. A few radials still aren't much of a ground. Depending on your soil you need as many radials as you can as long as you can and each one terminated with a ground rod doesn't hurt either. In the IL "farm country soil" of my former life I had a simple 4BTV and it did great. But I had 3 each 1/4 wave long bare copper wire 40, 20, 10 meter radials burried about 6" deep and terminated with an 8 ft copper ground rod.


Remember -- if above ground the radials will be "hot" so consider if they could be touched or electrify something or start a fire with anything combustable.


Title: RE: 33 Ft. 40m Vertical
Post by: G0CVL on September 06, 2011, 06:42:26 AM
He could of course, simply raise the radiating element OFF the floor, and use considerably LESS radials for increased efficiency, and, if sloping, better matching, Nes Pas ???
I have done this myself, particularly on 160m, where my 1/4 wave inverted L with 2 raised radials (about 6ft off the deck, running on the top of my wooden fence), was a LOT superior on tx, than anything I'd created over the last 5 years.

Spike - G0CVL


Title: RE: 33 Ft. 40m Vertical
Post by: K0OD on September 06, 2011, 12:05:02 PM
K9UIQ: 
Quote
This is my first hand experience. I have a 40mtr dipole at 50 ft and a 40 mtr 1/4 wave monoband vertical ground mounted and 60 radials. After 3 years of this arrangement I can truthfully say that the vertical is by far the better antenna for DX and most of the time it is better for Domestic.

I ran long term comparisons between a dipole (broadside) at 45' and a 40 meter vertical with an excellent radial system. DX was generally a toss-up; stateside, the dipole was better. Pretty much what others have suggested.

I tend to use verticals just because my dipoles--while they can work very well if up >50'-- keep falling down.


Title: RE: 33 Ft. 40m Vertical
Post by: W3HKK on October 18, 2011, 01:55:19 PM
Ive used assorted qtr wave 40m verticals for years...in a variety of  less than ideal locations  and with  0-16  qtr wave radials.  they all worked pretty good.  So dont sweat what you cant control

I would use  c. 33 ft radials ( adjusted if  plastic jacketed)  and bend the excess to conform to your property line.
Put the vertical wire as far as you can from trees/structures.  If you cant, then go with it.

Radials on the ground give a higher swr.  Sloping radials give  close to 1:1 swrs.   


Title: RE: 33 Ft. 40m Vertical
Post by: KD0TRG on October 20, 2011, 03:33:34 PM
Great topic.


Title: RE: 33 Ft. 40m Vertical
Post by: W3HKK on December 06, 2011, 05:53:59 PM
A vertical next to the house is the worst possible location.  Putting it as far from your house and the neighbors houses as possible will be a major boost in signals.  For 40m at least 33 ft away from buildings helps the pattern be more normal.



Title: RE: 33 Ft. 40m Vertical
Post by: KQ6Q on December 07, 2011, 12:21:33 PM
The vertical is close to the house because the Hexbeam is up in the air closer to the fence....Up in the air! The high current portion of the vertical is radiating right into the house.... how well would the hexbeam work if it were located down next to the house?
As has been stated, a vertical needs to me in the clear to radiate effectively. If he could raise the vertical so the feedpoint is level with the eaves of the house, and run some resonant counterpoise wires level with the eaves, it might work a lot better!