Ground plane For Monopole antenna.

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bugsbunnyboss

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Hi,

How to calculate the size of the ground plane when using a monopole antenna? Is it w.r.t. the frequency that we use or the physical length of the antenna or any other factor?

I want to use a monopole antenna in 434.7 MHz transmitter and the antenna's physical length is 16 Cm. I checked the antenna with SWR meter , but it did not match for 434.7MHz, and I was told that it is a monopole antenna and needs ground plane to work. what should be the size(area or volume) of the ground plane that I should use with this antenna?

Is there any calculation for the size of the ground plane?


Thanks in advance.
 

it can be as large as you like, but the minimum size should be a 1/4 wave out to the edge in any direction away from the base (feedpoint) of the monopole

Dave
 

Thanks for your reply Dave. Can you please explain what u meant by "1/4 wave out to the edge in any direction"?
Do you mean I should have at least 4 cm(16/4) in all directions(x,x',y,y',z & z'), from the antenna feedpoint?
If yes, then how can you put ground plane above the antenna (sorry if that is a stupid question!)
 

Both electrodes of the antenna can be any size. Such antenna will not be resonant by itself, but can be resonated using discrete components for example.
Once I tuned antenna for RFID tag on 435 MHz. The whole device: antenna and ground plane - 1" diameter and 1/8" thick.

The efficiency of small antenna will be low, the bandwidth can be very low but this is different story.
My Tag when tuned worked just fine for the application.
 

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