I am trying to make a reconfigurable patch antenna but have trouble with simulation.
The first patch should be at 2.4GHz and then the first + second patch should be 2.1GHz.
Theoretically the frequency should decrease from 2.4 to 2.1GHz when the second patch turns on (I.e when the length of patch gets longer).
However the frequency actually increases!!!
How have you configured your microstrip , stubs and slots for polarization and reactive loading?
Have you considered linear and circular polarization with two near-degenerate orthogonal resonant modes with equal amplitudes and a 90◦ phase difference?
The big difference between your antenna and the paper is that
- your antenna has a single connection to the extension in the center, not many distributed, and
- your antenna does not switch that patch extension on/off.
Oh, ok...
I changed the design to this so that the extension is distributed.
The transmission line represents a switch (pin diode) to turn the patch extension on.
But the frequency is still increased instead of decreasing?