I have been thinking about this for a while, the only problem i see is the pole has a few feet that are under ground. Ther is a pvc pipe in cement with a muffler clamp on the pole to stop it. Would there be a way to choke off the pole at the right length? And add ground radials. I can easily fabricate a a piece to attack to the pole with a male pl259 just not sure about the length of pole and if possible to choke it off at proper length? Any ideas?
-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
Is it possible to make a 5/8 wave antenna from the 23' flag pole in my yard?
- Thread starter cjruger
- Start date
B
BOOTY MONSTER
Guest
Antenna Notes
you will need LOTS of ground radials .
http://www.dx-antennas.com/Height versus take off angle.htm
you will need LOTS of ground radials .
http://www.dx-antennas.com/Height versus take off angle.htm
Last edited by a moderator:
A choke is usually a coil, or it could be a combination of a coil and a capacitor. Being as the flag pole goes straight into the ground it wouldn't be easy to choke it, if at all reasonably possible.
I could potentially see gamma matching work as it lets the main radiator be connected directly to ground.
You would want the feed line to connect 1 1/2 feet up or more depending on how wide the flag pole is, otherwise the antenna will be to long which will cause the antenna to start shooting the RF energy up, this would hurt local communications, although DX may be affected less depending on conditions at the time.
Being at ground level you would want many radials, and even more if they are buried. Make them at least 9' long, even if you have to fold then to fit them in the area of the antenna.
Using a setup like this, I hope you are not at the bottom of a hill.
The DB
I could potentially see gamma matching work as it lets the main radiator be connected directly to ground.
You would want the feed line to connect 1 1/2 feet up or more depending on how wide the flag pole is, otherwise the antenna will be to long which will cause the antenna to start shooting the RF energy up, this would hurt local communications, although DX may be affected less depending on conditions at the time.
Being at ground level you would want many radials, and even more if they are buried. Make them at least 9' long, even if you have to fold then to fit them in the area of the antenna.
Using a setup like this, I hope you are not at the bottom of a hill.
The DB
the radiator needs to be have a tapped coil in series with it. This means breaking the pole, inserting a HEAVY insulator to support the entire thing, and tuning the coil for as close to 50 ohms as you can get. The coil has a tap to ground which has to be adjusted as well as the total overall number of turns. A gamma match is not suitable for matching a 5/8 wave. Gamma matches are used when the feedpoint impedance is lower than the feedline impedance which is not the case when feeding a 5/8 wave.n Is this idea doable....yes. Is it easy and practicable....not really. Make a simple 1/4 wave vertical and you need no matching coil of any sort. Simply adjust the length and be done with it.
this and a few other antennas, much simpler to make...
you could use the flag pole to mount antenna
B
BOOTY MONSTER
Guest
a gamma can be used for tuning on a 5/8 or .64 wavelength antenna
Wolf Radio.com CB, Ham, Pirate Radio Antennas [CB Antenna]
Is this to be a disguise type antenna? Do you want it to remain looking like a flag pole? Would wires hanging in parallel along the side or raised radials be allowed?
Yes and no, just that the pole is there already, and there is no way the wife will go for a visable white antenna in the yard or on house, currently using a Home made horizontal 1/2 wave diploe on my roof peak, you can hardly see it looking right at it from 30 ft away. Ive had good dx contacts with it, but want to try a 5/8 verticle for fun, i have a home made wire 5/8 ready to try but cant really get it up in a tree yet, still workingnon that. Do you think i could hang it from the flag pole? It is insulated wire. Also on the 5/8 matching coil, can it be a simple coil of copper wire(12 gage) off to the side but in series and tap it to radiator at proper spot to get the match. Does the location of the coil matter?
Also does it matter if its a copper wire coil or a piece of aluminum rod in a arc?
Last edited:
Just to clarify, Captain Kilowatt is correct about not being able to use a gamma to match a 5/8 wave groundplane and his reason is correct also. The antennas impedance is too high and the gamma can only match antennas that are below the line impedance.
That means in order for Wolf to have added the gamma into the mix and still provide a good VSWR, the matching loop near the base already had to drop the input impedance from several hundred ohms to below 50 ohms so the gamma could bring it back up to 50.
That means in order for Wolf to have added the gamma into the mix and still provide a good VSWR, the matching loop near the base already had to drop the input impedance from several hundred ohms to below 50 ohms so the gamma could bring it back up to 50.
B
BOOTY MONSTER
Guest
always wondered why those two loops and top-hat didn't make it too long electrically
could he could put a basket on the bottom and add several feet to its height and make a vector 4000 ?
Last edited by a moderator:
Yes, he could do that but then his impedance matching loop would have to be eliminated too. This is because the basket also places the feedpoint another 1/4 wave down the radiator. That puts it right at a low impedance current node rather than the high impedance point on the end fed 5/8 wave.
Only considering the original circumstances, a flag pole, and probably a little 'stealth', the simplest solution would be to insulate the pole from ground, bridge that insulator with an impedance matching coil, tap that coil at the appropriate spot for 50 ohms impedance, and laying in all the ground radials possible connected accordingly. That would result in a 5/8 wave (or close) vertical antenna. The 'key' proposition in all that is the 'stealthy' thing. If it doesn't have to be stealthy then there are a number of options.
I think that fairly well sums it up.
- 'Doc
I think that fairly well sums it up.
- 'Doc
The Captain and Shockwave are correct, however, is there any reason he couldn't put a small gamma on the flag pole and use an antenna tuner with it? It wouldn't be the most efficient way of doing things but it should still work. It would also likely be the least noticeable of his options for the flag pole.
The DB
The DB