Hams: Antenna / Ground question

[Krupski]

Hey,

I want to put an end fed antenna in my attic using a balun. The setup I'm using requires a good ground (that is, a good RF ground).

I've got cast iron sewer pipe that goes all the way from below ground up through my attic (looks like this):



Since this is a nice solid piece of metal and since it is well buried in the ground, do you think it would make a good ground (counterpoise) for the longwire antenna?

The part in the attic, of course, carries no sewage - it's only a vent, and I plan to drill and tap maybe a 1/4-20 hole in it and use it to mount the balun and connect the ground, then run the longwire out the rear of the attic and to a tree about 50-some feet away.

Is using this pipe as a ground a good idea?

Opinions please.

Thanks.

[l921428x]

Is this pipe grounded into/with your house plumbing. I am not sure what I am trying to convey in tech terms
but you are adding a way for lightening to enter your home. But yeah it is grounded very well.

[Altarboy]

Yeah what he said. A long ground stake or a couple short ones have always worked for me.

[alismith]

What's wrong with getting a 3-4' section of metal pipe and banging it into the ground, outside, and running a ground wire from your antenna to that? Using standoffs, of course.

[5.56NATO]

It will work but the effort may result in a lot of in house rfi as the ground pipe will be the other half of the antenna system. Might be better from rfi standpoint to do a dipole in the attic with the pipe as a ground at the feedpoint as balanced antennas usually have reduced rfi over say a long wire. But try it any way you can and I bet you'll find something that works for ya.

[l921428x]

Well if we still had metal screens on our homes you could use a wire attached to the screen.
We did it when I was a kid........J/K

[7days]

I used the steel I-Beam for the garage door as ground for an electric (bush wacker) fence for my garden and I got zapped many times. If you have a steel I-Beam in your home can you use that for ground?

[l921428x]

I am not really sure he wants to have electrical shock treatments but you can never tell about some here.

[5.56NATO]

I used the steel I-Beam for the garage door as ground for an electric (bush wacker) fence for my garden and I got zapped many times. If you have a steel I-Beam in your home can you use that for ground?

If the I beam is used for supporting the house over the garage, the beam's not grounded save for via the concrete blocks, wich aren't very conductive. The beam could be considered an ungrounded conductor.

[Krupski]

Is this pipe grounded into/with your house plumbing. I am not sure what I am trying to convey in tech terms
but you are adding a way for lightening to enter your home. But yeah it is grounded very well.

Well, the iron pipe is the sewer pipe (the toilets empty into it). It is a continuous run (that is, segments "plugged into" each other) from the roof to underground and to the main sewer line.

Being a 6 inch diameter pipe, it's certainly got low DC resistance and certainly a good intimate contact with earth ground. It is, however quite long (from underground up through the attic of a two story house). Length matters with RF, so I'm not sure if it will be a good counterpoise.

What I ultimately want is an all-band (at least 80M to 15 or 10M) antenna made from a single long wire that isn't a 1/4 wavelength at any frequency of interest (I've got a table of "good" lengths) and then drive it with the balun.

Of course, I want the antenna as high as possible (which for me is from the rear face of the attic to a large tree which is about 30 feet higher than the attic).

No matter what I use for ground / counterpoise, it has to reach from attic to ground. No way around that unless the antenna is mounted near the ground and slopes way up to the tree (which I think would hurt performance).

[Krupski]

I used the steel I-Beam for the garage door as ground for an electric (bush wacker) fence for my garden and I got zapped many times. If you have a steel I-Beam in your home can you use that for ground?

If the I beam is used for supporting the house over the garage, the beam's not grounded save for via the concrete blocks, wich aren't very conductive. The beam could be considered an ungrounded conductor.

A huge steel I-beam supports the house (it's in the basement), but it's not grounded. It protrudes through the concrete floor of the basement, but how far down it goes I have no idea and I would assume it's either not grounded at all or else it's a poor ground. I wouldn't try to use it for a ground.