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Author Topic: 33 Ft. 40m Vertical  (Read 20239 times)
N3OX
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« Reply #30 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.
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
W5DQ
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« Reply #31 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 Smiley  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
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
W8JX
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« Reply #32 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. 
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K9IUQ
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« Reply #33 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.. Grin

Stan K9IUQ


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W8JX
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« Reply #34 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.
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W5DQ
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« Reply #35 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
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
W5DQ
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« Reply #36 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 Sad
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
N4JTE
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« Reply #37 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
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W8JI
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« Reply #38 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

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W5DQ
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« Reply #39 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
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
K9IUQ
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« Reply #40 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

 
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W6RMK
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« Reply #41 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>



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N3OX
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« Reply #42 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. 
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
W4FID
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Posts: 132




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« Reply #43 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.
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G0CVL
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« Reply #44 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 Huh
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
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