What will be ground plane size for circular microstrip?

Hi,
I am trying to find out what will be ground plane size, a finite one for a circular microstrip antenna of any radius. Is there any general formula like they have in rectangular microstrip antennas? How do u people analyse a circular microstrip antenna with finite ground? Is this ground plane, a circular or rectangular one in shape?

Hi, Atul:

I think it really depends upon the your situation.

1. If you want to use cavity model to get reasonable starting point, you may leave it at least a few substrate thickness bigger than the patch. However, this limitation is not necessary because you can use modern EM simulators to get almost real time results.

2. The size of the ground plane will affect the front-to-back ratio. If you want large front-to-back ratio, you should increase the ground plane size.

3. Normally, smaller ground plane may degrade the circular polarization parameters in case your antenna is circularly polarized. You may optimize it to get good LHCP or RHCP at some angle. However, the LHCP or RHCP at other angles are normally worse for finite ground plane cases than infinite ground plane cases.

There should be some other considerations too.

Best regards,