homebrew antenna question

[Dave_W6DPS]

Well, I didn't expect the vitriol over this. A new guy asked a practical question, I tried to answer clearly and simply, from a practical experience perspective. Obviously the theoretical minutia are more important to some than the practical applications.

The quarter wave groundplane should work very well, with a minimum of trouble. It will have the same gain as a dipole, but should have a very consistent omni-directional pattern if mounted with nothing around it....

Please ammend the first paragraph of my original post to read like this:

The quarter wave groundplane should work very well, with a minimum of trouble. It should have a fairly consistent omni-directional pattern if mounted with nothing around it....

In the real world, the performance difference between a vertical dipole and a 1/4 wave ground plane is no big deal. There is a definate advantage for the 1/4 wave from a practical view, being that is is much easier to mount in the clear.

I understand that there are people who take the letter of the theories very seriously, and believe their modeling programs over an analyzer--but in the real world where I smolder antennas together, the actually performance of a given antenna counts for more than what the book says it should do.

I hope the OP got what he needed. If not, PM me.

Dave_W6DPS

 

[BIONIC_TEXAN88]

ok, well, not like ya'll might care, but, I finally met a couple local hams and borrowed a heathkit swr/power meter from him. swr is 1.2 on 146mhz. I did no adjustments to it, followed as close as possible to the measurements I obtained from the net. 19.1" vertical element and 20" ground radials (6 of them).

 

[freecell]

there's no vitriol here. the radiation field of a dipole antenna is dependent (among other factors) on its near-field environment for proper pattern development, it's as simple as that. you don't need a modelling program or a network analyzer to figure it out.

 

[Dave_W6DPS]

ok, well, not like ya'll might care, but, I finally met a couple local hams and borrowed a heathkit swr/power meter from him. swr is 1.2 on 146mhz. I did no adjustments to it, followed as close as possible to the measurements I obtained from the net. 19.1" vertical element and 20" ground radials (6 of them).

Actually, the only point some of us really care about is whether you were able to put together a workable antenna.

Have you tried it on the air yet? If so, does it do what you need?

Dave_W6DPS

 

[BIONIC_TEXAN88]

ok, well, not like ya'll might care, but, I finally met a couple local hams and borrowed a heathkit swr/power meter from him. swr is 1.2 on 146mhz. I did no adjustments to it, followed as close as possible to the measurements I obtained from the net. 19.1" vertical element and 20" ground radials (6 of them).

Actually, the only point some of us really care about is whether you were able to put together a workable antenna.

Have you tried it on the air yet? If so, does it do what you need?

Dave_W6DPS

i will be workin it tonite, I just got my callsign this morning and i am not around the radio at work, its gonna have to wait till tonite.

 

[W5LZ]

BIONIC_TEXAN88,
Good for you. Glad it's working and also glad that you made it (antenna and the license). Making antennas really is fun, especially when they work.


Dave & BIONIC_TEXAN88,
Sorry 'bout the 'vitriol', sometimes it happens.
- 'Doc

 

[Dave_W6DPS]

... I just got my callsign this morning...

Congratulations! I hope things work out when you give it a try!


(W5LZ, I tend to approximate, round numbers off, and use "rules of thumb". An approach that works very well in antenna construction, at least for me. My recommendations come from that perspective. I didn't mean to imply that I had taken offense, just that it seemed better to me to lighten up on the theory and help someone get on the air easily.)

Dave_W6DPS

 

[Captain Kilowatt]

You can help someone get on the air easily today by telling him what to do or you can explain to him how and WHY and he will be able to do it himself again tomorrow,next month,year etc.

 

[rfoverlord]

BT88 so is it working for you? it sounds like it should. now for a simple 3ELE. beam

 

[BIONIC_TEXAN88]

BT88 so is it working for you? it sounds like it should. now for a simple 3ELE. beam

doing great so far, hit the houston repeater 55 miles away.

 

[Seminoles]

doing great so far, hit the houston repeater 55 miles away.

Great news know you'll be up all night. How high do you have it? Sound like it is working great for you.

 

[BIONIC_TEXAN88]

doing great so far, hit the houston repeater 55 miles away.

Great news know you'll be up all night. How high do you have it? Sound like it is working great for you.

32ft. to the base

 

[Seminoles]

32ft up, 1/4 wave ground plane, 55 miles to repeater sounds like you hit the gold mind great work now pat yourself on the back and get back on the air and have fun. Thanks for all of the info everyone.

 

[BIONIC_TEXAN88]

The 1/4 wave will be the easiest to make and match.A 1/2 wave will offer a very high impedance in the order of many hundreds if not thousands of ohms that must be transformed back to 50 ohms. The same thing applies for a full wave. Multi wave verticles are actually a series of 1/4 wave fed in phase and isolated from each other by design.You could try a 3/4 wave design as it will present something very close to 50 ohms at the feedpoint. As a matter of fact any odd multiple of 1/4 wave will but going really long brings other factors into play.try 19 or about 57 inches and see what happens.Anything else will require some sort of matching device that will probably introduce more losses that is gained by going bigger.

hey QRN, I was listening to somebody the other day running mobile. He took a 102" whip and cut it down to about 59" and had a flat swr. should wind up being a 3/4 wave (am I right??) Anyhow, he says he has flat swr and was hitting the repeater very well for his location. I tried it out and have a flat swr as well and she's performing great on my truck or setup on my base mount with 1/4 wave ground plane elements.

 

[rfoverlord]

once you get bitten buy the antenna building bug, it becomes kinda addictive. It also seems that you can never have enough of them even though after a while you seem to have more than you have radio's for. Glad to hear it worked out for you. wait til you start building moxons and such just becuase you can. 73