Coupling Loop in Smith Chart

Hi....

I am working on Microstrip Stacked Patch Antenna for Broadband Application.

In Stacked patch configuration, size of loop in smith chart caused due to coupling between two patches (top and bottom) governs the bandwidth improvement. Tighter the coupling, bigger the loop is and lower the coupling, smaller the loop is.

I am not able to understand what is the reason behind loop formation in smith chart in any this type of coupled multi resonance conditions? I know the concept of staggered tunning in this case. But i dont able to understand what does physically happen there?

Can you please help me?

Thank you

Pratik

Hi,

Perhaps because like filter you can modify the bandwidth thanks to coupling. When resonator are decoupled each resonate independently and the loop on the smith shart is large. When the resonator are strongly coupled, we can rise the bandwith and multy resonnance appear on smith chart.

Could you give me a shematic of your staked microstrip antenna ?