Tunable resonance in a superstrate-loaded lossy circular disk microstrip structure

The tunable resonance characteristics of a superstrate-loaded circular disk microstrip structure having a lossy ground plane are analysed for various structural parameters. It is shown that the decrease in the resonant frequency as a result of the occurence of the superstrate layer or increase in the medium temperature can be compensated for by using the opposite effect of an air gap inserted between the substrate and the ground plane. By means of this tuning scheme it is possible to stabilize the resonant-frequency variations and to control radiational loss characteristic of the structure without disturbing the original configuration.