Antenna and Ground Plain

[Gymbag]

Just got to thinking about this topic. All the talk about using a cookie sheet or filing cabinet at as a ground plain got me thinking. I have 2 Radio Shack base scanners and I'm using just the back of set antennas. Would my reception improve any if I set each unit on a cookie sheet or on a metal filing cabinet as to say just setting them on top of a wooden/chipboard cabinet??? I live in Ontario Canada and I'm monitoring mainly the Fleetnet system as well as local Fire Depts

 

[awattam]

I may be wrong

but I think this applies mostly to mag-mount antennas when used indoors.

 

[nd5y]

It would probably work if the scanner has a metal case or chassis that you could get close enough to the metal surface to be capacitively coupled to it.

If the scanner has rubber or plastic feet on the bottom you could remove those and set it on a metal surface and see if reception improves. That would probably be good enough if the scanner had a metal case.

If the scanner has a metal back then you could take something like a pie pan, screw it to the back, bend it under the scanner so that the scanner sits on the metal which would sit on the cabinet or larger ground plane.

You could also attach wires to the antenna connector shell to make ground plane radials.

 

[kc2kth]

I've never done it, but a few quick searches for 'ht ground plane' (since I figure the same concept would apply to handheld amateur VHF/UHF transceivers) brought up a lot of info. You may not need the file cabinet, but just add a "tiger tail" counter poise wire of about 12" to the outer shield on the back of set antenna. You could try connecting that outer shield instead to the file cabinet making sure you scrape off some paint where you are making the connection to ensure you get a good electrical connection there.

Edit - I see nd5y responded while I was reading and typing!

 

[jackj]

Probably not

Just got to thinking about this topic. All the talk about using a cookie sheet or filing cabinet at as a ground plain got me thinking. I have 2 Radio Shack base scanners and I'm using just the back of set antennas. Would my reception improve any if I set each unit on a cookie sheet or on a metal filing cabinet as to say just setting them on top of a wooden/chipboard cabinet??? I live in Ontario Canada and I'm monitoring mainly the Fleetnet system as well as local Fire Depts

I would be surprised if you noticed a ground plane making any difference. The ground plane is the other half of a vertical or monopole antenna. It really doesn't contribute much to the antenna's radiated power although it does change the angle of radiation of the major lobe of the antenna.

You are dealing with an antenna that makes no attempt to be resonate at the received frequency or to even control it's impedance. It is just a short, random length of wire and there isn't much you can do to improve it except replace it with a tuned antenna.