Ground plane for a dummy

[scankid2591]

Hi everyone...

I've been wondering for a while about what a ground plane is and what the purpose/benefits of one would be.

Can someone help me out?

TIA,

 

[kb2vxa]

Hi John and all,

The most common type of ground plane antenna is a quarter wave electrical length which believe it or not works out to a half wave. Picture this, a quarter wave radiator mounted on the ground with a phantom quarter wave below ground making it a half wave. Naturally this is electrical theory and not actual practice. AM broadcast towers are usually quarter wave ground mounted (ground plane) radiators so it's pretty easy to visualize.

Now raise the radiator above ground and add 3 or 4 quarter wave radials, electrical ground above actual earth ground and you have a ground plane antenna. I suppose it's easier to understand if you think of it as "the plane of electrical ground" geometry.

 

[rescuecomm]

A ground plane is the other half of a vertical antenna. With only a quarter wavelength vertical and nothing else under it, the antenna RF resistance (impedance) is too low for a 50 ohm radio transmitter (remember your coax rating) to send power to it. By putting a ground plane of conductive elements or solid plate under it, the RF impedance is raised to somewhere around 50 ohms.

Bob