Matching in Microstrip array antenna

Hi!
I've designed a 4 element microstrip array antenna at 3GHz. But I got a return loss of -24dB at 2.6GHz instead of 3GHz. Why is that? and What do I have to do to achieve -24dB return loss on 3GHz? Can anyone help me?

Assuming both your simulation of the patch on its own and the array are properly set up and run, this is probably due to inter-element coupling.

In this case, you either have to design the patches to compensate for this coupling, or suppress the coupling somehow.

Actually I'm new to this. Can you please give me slight idea about how to suppress the coupling?

Coupling suppression is still an active research area, as there's currently no great solution. Search "Electromagnetic Bandgap Structures" or "High Impedance Surfaces" for coupling suppression to see some of the more mainstream approaches.

Honestly, if you're new to the field, optimizing the patches in the array may be a more simple approach.

So, I should apply parametrics on Patch length, Width and inset distance?

Yes, I think that's probably your simplest route.

Thanks a lot. That was really helpful. It worked.