Has anyone tried a screwdriver dipole and what kind as performance does it have. I live in a hoa that will allow an antenna but i have limited space so a regular dipole will not work and i know verticals aren't know for good performance. New to hobby and could use some help.
Haven't tried that myself but I do think it's a clever idea for stealthy antennas.
Perhaps you could even add some longer very thin gauge wires on either side to have a more efficient dipole, too.
Hope you get lots of replies; perhaps someone here has actually made one of these before? A vertical screwdriver dipole would also be another good compact antenna, too, come to think of it! (Vertical dipoles do not require radials, either)
There is absolutely nothing wrong with a vertical. You'll want a good ground field but that stays on the ground, so you're good to go there. A vertical has a lower take off angle that really makes it better for DX then a dipole but it will perform just fine. You will get slightly more noise with a vertical. Countless hams all over the world use verticals.
Says who? Stuff and nonsense....
Originally Posted by KC9VCV
"If someone tells you he believes in and talks to an invisible bunny named Harvey, you put him on medication and a regimen of therapy. If someone tells you he believes in and talks to God, well, that's perfectly acceptable. Why that's the case is impossible for me to fathom." - WP2XX
"He's dead, Jim. You take his Tricorder and I'll get his wallet."
"The problem with America is stupidity. I'm not saying there should be a capital punishment for stupidity, but why don't we just take the safety labels off of everything and let the problem solve itself?"
Look at the DX Engineering DXE-ATSA stealth antenna and tuner
My backyard in only 65'x50' is that going to be big enough for ground radials?
Certainly! The more the better! They don't even have to be buried or in a straight line. Lay 'em on the ground, staple them down with some home made wire staples and in the spring the grass will cover them, and you'll never see them again.
I have my 5BTV in a poor location--in corner of yard behind a tall pine tree--up near a chain link fence no less. I guess it's a stealth install, my wife can't see it. I have radials out in a pie shape configuration. I cut the grass pretty low and laid them out and used home made lawn staples. After couple of months the radials dissapeared into the thatch. I'm a casual operator but I get decent reports both stateside and dx.
Oh yeah, absolutely.
Originally Posted by KC9VCV
The tradeoff for performance between a screwdriver dipole vs. a short/small vertical is a little complicated depending on the bands you want to work, etc, but I would say that even for pretty short verticals that's more than enough space for a good ground radial system for many bands.
I built a 10 foot tall 40m vertical and put it over a 27 radial ground system a bit smaller than that, and found that it was only a little worse than 1dB down from a full size 33 foot tall 40m vertical:
What bands do you want to work and what are your specific limitations from the HOA, like how high can you mount a screwdriver dipole? It matters a lot. A screwdriver dipole mounted on top of a two story suburban house on a rotor would have a chance of easily equaling or beating a ground mounted vertical on the higher frequency HF bands, but if you wanted to run on 75m and had relative freedom with antennas, something like an inverted L (with fine wire top wire) fed against ground radials should out-do the screwdriver dipole significantly.
If you have to mount the screwdriver dipole too low and you can't mount it vertically and choke the heck out of the feedline, a ground mounted vertical installation of even a screwdriver might be better overall.
There's not a clear cut answer without more info on your restrictions and what you want to do.
KG4RUL beat me to it but Scorpion Antennas sells them. http://goo.gl/DhOCH
Originally Posted by NH7RO
Beautiful but necessarily big bucks. If I were trying to put one together I would probably rather do one with tubing inboard of the coils and cap hats on short masts to get them a bit beyond the coil at the ends, but that would be an easy mod post-purchase, or maybe could be a custom request.
The short vertical antenna I built was originally going to be a short dipole and is an attempt to get some continuous tuning of a fairly narrow band antenna without having to resort to screwdriver parts.. but it lacks band-switching on the coil at this point so it's less convenient. I'm slowly working on design options for that I also think I might be able to do one for several bands higher up in the HF spectrum withotu tap switching.
Screwdriver dipoles are a nice solution to the continuous multiband problem if you can afford them. They don't seem great on the overall cost vs. performance vs. stealth spectrum.
I would like to see a comparison between a given model of screwdriver dipole and a good magloop to see how the radiation resistance vs. loss resistance tradeoff shakes out... but I supect screwdriver dipoles have the edge in terms of things you can buy. Generally speaking a loaded dipole form factor should be a better bet for a given size of antenna even with the greater losses of a loading coil vs. a magloop loading capacitor and magloop tubing because the radiator isn't folded back on itself. The improvement in radiation resistance more than makes up for the lower Q loading.
Last edited by N3OX; 12-28-2011 at 06:51 PM.