Amateur Radio Ground For Vertical HF Antenna 3 Floors Up

How about making a discrete connection to the cold water plumbing, I am assuming it is copper pipe not pvc/nylon pipe.

Using the mains earth may not be desirable as the imposition of RF may upset the RCD's (if your building is fitted with them). It may create EMI issues with the other tennants depending on how much RF you are transmitting.

Anything up to 100watts should be ok, but I'd be inclined to use the waterpipes assuming that they are copper.

Thanks for the reply. I forgot to mention that the water pipes are all pvc.

John, I would not use the AC ground as it is likely to be an RFI problem.

Any chance there is a metal water pipe or drain pipe that you could use? Do not use a gas pipe!

What about a lightning ground wire? However, that may not be my first choice.

The problem with creating a virtual ground that is not tied to earth is that the RF inside your dwelling will also be very high. This is not a good healthy thing (regardless of the RFI potential), so be careful what you do and if possible run QRP.

No nearby metal pipes of any kind. I didn't think about the stray RF causing health problems. Thanks . QRP maybe if we had excellent condx again!

John

I have forgotten the trade name, but there is a small surface-mounted raceway/conduit system that comes in various colors. This could be run inconspicuously down corners of the building without disrupting the aesthetics. Maybe you could speak to the manager and some other tenants about this. They might get interested in your project and give you the go-ahead.

Many, many years ago, in the Army, we would occasionally use for HF transmission a ground plane antenna that consisted of a quarter wave vertical whip with three equally-spaced radials at the base of the whip, angled something below the horizontal (I want to say 30º, but I can not confirm that- it's been too many years). This might be the easiest solution for you- no additional ground connection.

Hello, it might also not please the building administration but could be done unsuppiciously. You need to know more details about the construction of the ceilings in your appartent building. If this is a concrete "mono slab" design, you could try to use the reinforcement of the ceiling to the floor below. In many countries the rebar is designed using a narrow grid of interconnected steel rods. So if you can get better design information it might be possible to find an access point to the rebar.

Many years ago we did that basically for another reason but found that it also provided an excellent RF ground connection. Especially in this country the rebar was connected to foundation ground due to regulations in the building code.

Naturally as this will be an open area ansd subject to rain you need to have an excellent cover of the point where you pass through the waterproofing of the roof.

Since your present antenna setup is already "working well" with no problem and without any ground plane, I'm just wondering what the purpose will be of the vertical antenna? If you just wanted to increase the propagation range or effective distance of your signal, you may just need to increase a bit your transmitted power, via adjusting modulation index or by peaked-tuning your transmitter output with the present antenna system. By adding a ground plane, you may also be increasing your system losses due to more SWR, specially if antenna length (physical) and electrical length (wavelength) are not properly matched! why tamper if ain't broke!

The Elmers are coming out of the woodwork now...

Cuba_Pete earlier asked if there was a metal downspout.

I didn't see a reply to that question, but if there is any downspout nearby, then let the gnd cable down through the drain and ground it at the bottom.

John

There have been a number of comments about RFI on the building power ground. But if you have a safety ground connection to your transmitter, unless you have a balanced antenna output (and a truly balanced antenna - difficult with all the surrounding metalwork and dielectrics), you cannot avoid RF in the safety ground. If you use a vertical antenna, the better the antenna current and radiation, the more RFI is likely to go to power ground. So the balanced dipole would be good.