Feeding antennas in an apartment without RF ground

[WV6U]

I live on the 2nd floor of an apartment building. Because it is on the side on a hill, my deck, that hosts all the antennas, ends being equivalent of being on the 3rd floor. In a nut shell, no place to put ground rounds anywhere

I have to two TX antenna systems - one is a multi-element dipole, similar to a fan dipole, except that elements run parallel to each other along the deck's ceiling - does 40m to 10m. At the feed-point, I have a heavy-duty 1:1 current balun that terminates the dipole elements, then the balun's unbalanced end is fed into a LDG remote tuner via a small 3' coax and then a 50' coax from tuner into the shack. The tuner is required because while 40m and 10m elements get down to below 2:1 VSWR, the 20m element requires some coaxing and of course 15m does not have it's own element so it needs some tuning to run off the 40m element. TX is good. Occasion, I have been able to make contacts in South America, East Coast and Yukon (Canada). On TX, people haven't complained of weird audio nor have I been zapped by RFI via the mic or anything. All good except I can't figure out why my dipole reaches into Yukon and South America when it is facing East - those two places should probably be my nulls but then I am willing to believe that all the objects around the antenna couple with it and distort the pattern such that somehow I never hear Europe.

Second antenna is a small loop antenna built with 3/4" copper pipe, equivalent of 4' in diameter (octagonal), has a vacuum variable capacitor and uses a gamma match. Serves 40-15m. For a while, I had the gamma match terminating directly on a SO-239 connector and then coax. The result was that every time I keyed into the loop, the dipole's tuner remote would activate - I guess because loop's coax would start radiating and induce currents into the dipole's coax. That got fixed after I put a 1:1 current balun between the gamma match and the feed coax. Again, TX is complaint free. Haven't made lots of contacts using the loop yet but no one I talked to complained about audio and nor did I get any burns etc from the mic.

On the transmitter side, the ground connector on the back is connected to 3rd pin of the electrical outlet.

The only issue is noise on both antennas is usually high. On 40m, there is a nearby RFI source that pretty much saturates the dipole. The loop does hear the same RFI but not as loud. Disconnecting the electrical ground from the radio does nothing for the noise.

Since both antennas are surrounded by objects, they probably are not balanced as they should theoretically be. The other issue I have noticed is that the loop antenna picks up stations on bands other than what it is tuned for, pretty well. One reason, I think is, because when tuned to say 20m, and it is inefficient on 40m so S/N ratio probably becomes better. Similarly, tuned to 40m, it picks up 80m stations well. But I thought theoretically, a loop with high Q should reject signals outside the pass-band really strongly unless there are common mode signals?

And, that makes me think, is the lack of RF ground causing higher noise because of some common mode noise creeping in? On the loop, would switching from the unbalanced gamma match to a balanced faraday loop serve the loop better for RX? Is there something I am overlooking in this whole configuration? Or, is it just noise that comes with living in an urban environment?

Thanks.

[KA1DBE]

In our increasingly electronic lifestyle, there is bound to be more noise from all the unlicensed devices. As far as the ground goes, I have always had good luck with a counter poise. I would think that may help your situation a bit but I am by no means an expert on the subject. Good luck and 73's.

[KB4QAA]

Both your antennas are 'balanced' types and require no ground or counterpoise. Adding a ground or counterpoise seldom improves reception of desired signals or decreases noise.

Urban living has brought a massive increase in RFI in the last twenty years. There are plenty of articles, threads, and web articles about hunting down noisemakers around the home.

Good luck. b.

[WV6U]

Both your antennas are 'balanced' types and require no ground or counterpoise. Adding a ground or counterpoise seldom improves reception of desired signals or decreases noise.

Urban living has brought a massive increase in RFI in the last twenty years. There are plenty of articles, threads, and web articles about hunting down noisemakers around the home.

Good luck. b.

The dipole, theoretically, is a balanced antenna. In my case, objects around couple with the dipole and upset that symmetry. The loop is a balanced antenna but the gamma match, as I understand, is an unbalanced feed method.

[KB4QAA]

Reception on the antenna itself is not affected by whether it is balanced or unbalanced regarding noise. The only way you can change signal vs. noise levels is by changing directivity of the antenna (assuming the noise and target signal are not coming from the same direction).

[WV6U]

Reception on the antenna itself is not affected by whether it is balanced or unbalanced regarding noise. The only way you can change signal vs. noise levels is by changing directivity of the antenna (assuming the noise and target signal are not coming from the same direction).

And, that is why my original question isn't just about the antenna but the whole system including feeding. Also, you are overlooking common mode noise.

[WB2WIK]

You might be able to achieve an RF ground if you really try, but if it has to be very "stealth" this might be more difficult.

I worked on transmitters in the World Trade Center that were up over 1000' above ground. The "ground" was the frame of the building itself, and it was really very good. That was also the lightning discharge ground, and the antennas got hit thousands of times a year (direct strikes) without doing any damage.

So, it's possible to achieve a ground up three flights, it takes very big parallel conductors. 6"-12" wide copper flashing would probably be pretty good. "Wire" would probably not be, unless it was enormous.

Whether that would reduce your noise or not I have no idea.

When I lived in a rented town house for 18 months (1988) I tried lots of stuff, and after trying lots of stuff I found it was difficult to beat a good mobile antenna on the car parked outside, with coax hidden behind bushes and things to get it inside to the "shack." I left the coax permanently in place between the condo and some bushes outside, where a barrel connector resided. I'd pull into a parking space near the bushes, pull out a cable from the car, and plug it in. Bingo. Outside antenna in the clear, connected to gear inside.

I remember "busting" the 3Y5X pileup with that on 15 CW, and getting through first call. Also remember working HZ1AB on 40m CW with that, and getting through the pile in maybe three calls, all from Los Angeles.

[N5YPJ]

20+ years ago, there was less gadgetry then than now, I fed a random length magnet wire running from the overhang of my 2nd floor apt to a tree - IDK remember the length. The counterpoise was a piece of indoor 6 conductor telephone cable that had the different conductors cut for a 1/4 wavelength on the different bands. I made contacts, no RFI observed or heard about. In a perfect world those multiple conductors should have been separated instead of touching each other.

15 -16 yrs ago I used the same set up in another second story apartment. Only difference was that it cost me a six pack of Bud Light to get the wire from my over hang over to the other roof top.