battery degrades GSM signals
thank you
Since a microstrip antenna will usually have ground plane, the most obvious approach is to put the battery below the ground plane. You would generally want to move large objects away from the antenna.
If the battery is on the same board and the same size as the antenna, then there are going to be numerous effects, which you could best model with a program like HFSS, FEKO, EMPro etc. The battery is obviously going to change the radiation pattern, polarisation, input impedance etc, but in ways which I think would be impossible to predict without a full 3D EM simulator. If the battery has a metal outer case, then it would be very easy to model, since you don't need to know anything about the internal structure of the battery. I would model it as a perfect electrical conductor.
Note a patch antenna radiates from the fringing fields at the edges. There might be tricks you could play like putting the battery in the middle of the antenna, though again I think you would need to model this.
If you don't have such sofware, you could try to see if FEKO Lite can do it. I think this problem would be beyond Sonnet Lite, as that's not a full 3D simulator.
Another approach might be to move the battery away from the antenna and look at the resonate frequency with a VNA. Then slowly move the battery towards the antenna in the lab, seeing the effect it has on the resonate frequency. That would allow you to predict a way in which you could change the antenna dimensions. But reallly I feel this is a complex problem, best sorted out with a full 3D EM simulator. I warn you, such programs are not cheap!
Deborah