THEORY AND EXPERIMENT OF THE HEMISPHERICAL CAVITY-BACKED SLOT ANTENNA

The hemispherical cavity-backed slot antenna is studied theoretically and experimentally. The exact magnetic field Green's function of the c avity is derived rigorously and expressed in a form convenient for num erical computation, The moment method is used to find the equivalent m agnetic current in the slot and, hence, the input impedance of the ant enna configuration. The effects of the cavity size, of the slot length , and of the slot offset on the input impedance are studied and very g ood agreement between theory and experiment is obtained. The variation of the magnetic current around the slot and cavity resonances are dis cussed. Comparisons between the rigorous solution and the single-mode theory are given and the limitation of the single-mode theory is discu ssed.