3
$\begingroup$

I live in a retirement center. The rule here is “Never do anything anywhere at anytime.” That translates to “No Antennas” which I have been told means I can put out an antenna as long as it is unobtrusive and is immediately taken down when not in use or when told to do so.

I have an ~60 foot piece of 22ga wire fed through 33 feet of coax and a 9:1 unun. It’s mounted on the ground (that’s right, no masts and no trees) when run north (0 degrees magnetic = 344 degrees true), what is my radiation pattern, if any?

The coax/wire connection is on a hook ~8’ in the air. The end of the wire is connected to the top of a 4’ fiberglass rod driven 1’ into the ground.

Depending on how far I can get it from my doorway, the center can be up to a foot off the ground, but can also be on the ground for >⅔ of its length.


OK, a couple of updates based on your answers.

  1. Yes, I use the antenna mostly for 40 meters, although, if I can get away with it, I might lengthen to permit use on 80 meters.

  2. I added a better 9:1 unun and a 1:1 choke. I have tested the swr at 40 meters and, surprisingly, it is less than 2:1.

  3. I have a ground floor apartment. All of my neighbors, and I mean ALL, are so araid of radiation that I gave been requested to not use my iPhone in the common areas (yes, they’re that paranoid). I could terminate the antenna in the one tree within 100 yards of my apartment, but, if anyone saw it, stuff would hit the fan.

  4. This town is built on a strawberry bog, filled with rocks and covered with topsoil. The wire is on grass which, because of our climate, is usually damp. I have sealed the end of the insulated wire to prevent the conductor coming into contact with the ground.

  5. And finally, YES, I want to move. This is not a retirement housing complex; it is a gulag!

$\endgroup$
  • 2
    $\begingroup$ It will vary depending on the exact operating frequency/frequencies. Could you please advise? $\endgroup$ – Richard Fry Apr 4 at 8:39
  • $\begingroup$ The whole thing is on the ground? $\endgroup$ – hobbs - KC2G Apr 4 at 17:17
  • 1
    $\begingroup$ Bill, do you per chance live in a room that's not on the ground floor? just dangling a wire out of your window down might be easier and more sensible in terms of being an antenna. Then: start with higher frequencies! that means your antenna can be smaller. A 1m piece of wire can be pretty effective on a 2m band. On 200m --- not so much. $\endgroup$ – Marcus Müller Apr 5 at 11:10
  • 1
    $\begingroup$ Added information: The coax/wire connection is on a hook ~8’ in the air. The end of the wire is connected to the top of a 4’ fiberglass rod driven 1’ into the ground. Depending on how far I can get it from my doorway, the center can be up to a foot off the ground, but can also be on the ground for >⅔ of its length. My neighbors are almost all eccentric seniors who are convinced my SmartMeter will give them cancer. Therefore I must keep the antenna as unobtrusive as possible. FYI, I am trying to use the antenna for 40 meters. For VHF/UHF, I use an indoor home brew ¼ wave dipole. $\endgroup$ – Bill Apr 5 at 12:05
  • 1
    $\begingroup$ Thanks, @Bill! The 40m info was so crucial, I edited your post and even added it to its title! $\endgroup$ – Marcus Müller Apr 5 at 23:45
2
$\begingroup$

The radiation pattern of an antenna laying on the ground can be easily approximated for the transmit case: it's roughly equivalent to a dummy load. Unless of course you are in Antarcitca: ice is transparent enough to HF that it's basically invisible. But I don't think there are any retirement centers in Antarctica.

For a receive application, you might hear some things. There are antennas that deliberately work near or on the ground, such as the Beverage antenna. Beverage antennas actually make great receive antennas on the low HF bands and below, but a proper Beverage antenna involves terminating one end of the antenna and installing a low-impedance ground.

It's likely as installed that you get as much radiation from the feedline and the electrical wiring in the building as you do from the wire on the ground, so trying to determine the radiation pattern is a futile effort. In any case, it won't be of much use for transmitting, I'm afraid. The antenna really has to be away from the ground at least a little bit.

In your situation, you might look at a "small transmitting loop" antenna. These have a very narrow bandwidth and require some careful construction to handle more than a couple watts, but they're small and unobtrusive.

| improve this answer | |
$\endgroup$
  • 3
    $\begingroup$ Phil I respectfully disagree - depending on ground conditions a dipole on or just under the ground can work reasonably well. I've tested one above ground and on ground, in an area with "poor" ground conductivity and found the impedance is still similar to a dipole, with a resonance at the expected place. And even if it has 10 dB of loss, that will beat a small loop or super-shortened dipole any day. I agree there might be better things he could do, like a flagpole, a wire in the attic, etc. $\endgroup$ – tomnexus Apr 5 at 12:20
  • $\begingroup$ I have experimented with "loop on ground" receive antennas (for RX only) and I was blown away by the results. A/B switching with a short vertical, I heard the "the same" but it was like turning off the noise. When really noisy, the LoG takes a little edge off the noise so it doesn't sound as harsh. Signal is very low, but SNR is greatly improved. $\endgroup$ – hjf Apr 7 at 12:10
0
$\begingroup$

See if you can make a connection to a rainwater downspout near your window. downspouts and gutters can sometimes make decent "invisible" antennas of the end-fed random wire type; as such you'll need an antenna matching device to load your transmitter correctly.

| improve this answer | |
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.