Compact coaxial slotted-cavity feed antenna with shaped-beam pattern for high-power microwave using high-order modes and polarisation cancellation techniques

摘要

The coaxial slotted-cavity antenna is an easily-manufactured, novel high-power microwave antenna developed specifically for its compact and shaped-beam characteristics. It can directly cascade with the high-power microwave source, and radiate linear-polarisation electromagnetic wave without extra power dividers and mode converters, which obtains a low profile. In this study, a double-layer coaxial cavity operating in two high-order modes is introduced to eliminate the high-order interference modes caused by structural discontinuities, and three shaped beams on the compact aperture can be achieved by the polarisation cancellation technique. Unique proprieties of three shaped beams, namely the peak of gain enhancement beam, the ripple of Gaussian beam and the null depth of conical beam are investigated, all of which can be controlled by the rotation angle of three phase adjusted slot pairs. This study demonstrates the design process of such antenna, and verifies it against simulation and experimental results. The measured return-loss of all three shaped beams are higher than 13 dB, while the corresponding radiation efficiencies are not lower than 98.9%. Furthermore, the estimated minimum power capacity of such antenna exceeds 1.26 GW at 9.375 GHz, making it a highly potential candidate in application towards high-power microwave.