Multioctave wideband mode-0 operation of spiral-mode microstrip antennas

The multioctave impedance and pattern bandwidths ofa 2-arm spiral mode microstrip (SMM) antenna with mode-0 excitation have been demonstrated. Although the amplitude and phase of the radiation patterns are fairly constant throughout a 9.1 (2-18 GHz) band, reactive loading in the SMM antenna structure can modify the pattern shape somewhat. Of practical significance are: (1) possible wideband applications similar to that of a monopole on a finite ground plane and (2) possible low-loss and low-cost applications presently utilizing high-cost and high-loss mode-2 operations.