Dual frequency and offset multilayer microstrip antennae

Influence of some geometrical parameters on the radioelectric characteristics of microstrip antennas are theoretically analyzed. For dual-frequency antennas, monolayer and multilayer geometries are investigated and compared. The aim is to adjust the resonant frequencies and input impedance by acting on geometrical parameters. For multilayer antennas, the influence on the input impedance of parasitic element size, shape and position is investigated. In particular, the effects of patch offset on surface currents is highlighted. The authors´ method is based on a reaction integral equation solved in the spectral domain by a moment method. Use of entire basis functions allows one to take into account both the various shapes (rectangles, discs or triangles) of radiating elements, and patch offset. Computed results and experiments are found to be in good agreement