problem in designing finite ground plane microstrip antenna

hello sir,
i am working on designing of microstrip antenna on infinite plane using ie3d zeland software but now to design ultra wide band i want to work on finite ground plane kindly give me the steps to do this i know that to make finite ground plane i should put conductivity=0 but after that what i need to do kindly tell me.

Hello,

I don't know the version of IE3D you have, but the older ones do support limited ground plane, but infinite dielectrics only. This will give zero radiation under zero elevation, while the actual antenna may produce radiation under zero elevation.

You can remove the infinite groundplane by changing the conductivity of the layer 0 under "basic parameters". After this everything you draw on the #0 layer will be just conducting material that can serve as a limited ground plane.

This approach has a limitation that the convenient feed schemes cannot be applied. You can only use the localized feed schemes (horizontally or vertically localized) and maybe the differential feed.

Another thing that will go wrong is drawing microstrips above such infinite ground planes. Limited ground planes have to be meshed like any other structure. When you do the meshing, you will see that the mesh in the ground plane is completely different from the mesh in the microstrip (mostly larger). This will give large simulation errors as the simulator is not able to calculate the steep current density transitions that occur in the ground plane under a microstrip.

Best is to divide the ground plane so that you see your microstrip also in the finite ground plane. You may even divide the ground plane on both sides of the microstrip also. It forces the meshing scheme to use a finer mesh close to the microstrip so the simulator will find the steep current density transitions.

You also have to divide your ground plane to draw a vertical rectangle from ground to the input of the antenna. This vertical rectangle will be converted to a port when selecting the vertical localized port.

You can use another approach. Keep the infinite ground plane, but cut away the ground plane around your patch antenna. This will enables you to fully simulate the edge effects because of the limited ground plane. You can use a width of about the size of the antenna and increase gradually to see whether s11 does change. Now you can change your patch and feed (you can use good feed schemes) to get the required S11, however the radiation pattern will not match that of the real antenna because of propagation issues of wave above a ground plane under almost zero elevation angle.

When you want to simulate the radiation pattern where you expect considerable radiation under zero elevation, you need a version of zeland the supports finite dielectrics and you have to use the limited ground plane (with the feed difficulties).