Wideband Phased Array Antennas

Slotted spiral antennas with a ground plane are designed to cover the frequency range 0.5-18 GHz. Various antennas incorporating Archemidan slotted spirals with a ground plane and dielectric thickness less than 100 urn were designed, processed and tested at different frequency ranges using conventional PCBs as well as vertically interconnected and monolithically (MMIC) processed versions. One of the major problems associated with incorporating these radiating elements that cover such a wide frequency range is the physical spacing of the antennas in phased array placements and the resulting beam steering by the application of the phase shifts to the corresponding antennas. Major side lobes appear because of the fixed physical separation of the antennas and these become more problematic when beam steering is applied through phase shifters. Properties of the Archimedean slotted spiral antennas with ground plane and with very thin dielectric layers will be presented and the problems and possible solutions associated with using these widebandwidth elements in a phase array will be presented.