Phased array simulation using circular patch radiators

The circuit properties of a circular patch with center short-circuit pin is investigated in a rectangular grid array. It is found that feed probe direct radiation produces large variations in element-to-element coupling coefficients in the -plane. For the investigated pairwise arrangement of feed probe positions the additional effect is unsymmetric -plane coupling with respect to the direction toward the coupled element; this leads to unsymmetric -plane scanning-induced impedance variation. The principal method of investigation is the small-array method using an element array, but two waveguide simulators are used to check the results. It is concluded that the small array calculation provides reliable results for scanning angles greater than off broadside. Active element match is observed to vary from -8.5 dB at broadside to about -20 dB on a scanning cone. Finally, a direct measurement of the dissipation losses of the patch radiator is presented using a waveguide simulator as a two-port network. At 5.5 GHz a - 0.3 dB dissipation loss is found.