What is a grounding plane?

[tigger_na]

Dear Forumites

I need to find out whether I need a grounding plane for my aerial. Some say this is a metal plate to supply battery ground to the aerial. Others say it is a metal plate to deflect radio waves, without which the aerial will not work properly. I'm building a tube and Dacron plane and want to install the aerial in the perspex roof. If the grounding plane is a simple earth connection to the battery earth, that is easy. Or do I need to install a larger plate for good transmission? If yes, how big (I guess the thickness wouldn't matter, only the length and width).

Blue skies
Arthur

[justin.schoeman]

Gah. RF is the blackest of arts. A standard whip antenna will receive just fine without a ground plane, but won't transmit very well at all. The ground plane is a critical part of the antenna, and should have a radius of approx 60cm (minimum).

You do get other antenna designs that transmit well without a ground plane, but they are a lot bigger.

[ZULU1]

The reason behind the vee rabbit is that it doesnt need a ground plane...

[tigger_na]

I have a RA Miller AV10 antenna. The installation manual is quite clear on the grounding plane, which, in a composite aircraft, isn't a plate but a cross of copper wires. But I don't have a metal skin aircraft, neither do I have a composite or wood aircraft. So which method do I follow?

1.) Metal Skin Aircraft
Determine the desired mounting location on the aircraft. Keep in mind that the antenna should be located at least two feet away from other antennas and reflective surfaces on the airframe (e.g., vertical stabilizer, landing gear, etc.). A good electrical connection must exist between the antenna mounting hardware and
the metal frame or skin of the aircraft.

2.) Composite or Wood Aircraft
Determine the desired mounting location using the guidelines discussed above. Create a “ground plane” on the inside of the aircraft skin by preparing (2) 48 inch long light gage copper wires perpendicular to each other and intersecting at their mid point (forming an X). Strip away insulation at this intersection if using insulated wire. Locate this on the inside of the aircraft skin where the antenna will be mounted externally. Run the wires forward, aft and side to side along the inside wall and secure in place. Attach the (X) intersecting point to one of the antenna’s mounting bolts, making a good electrical connection. This concept is similar to a communications antenna which you would see at an airport terminal building; a vertical radiator with (4) ground plane “radials” equally spaced around the base.