A Low Profile and Low Sidelobe Wideband Slot Antenna Array Feb by an Amplitude-Tapering Waveguide Feed-Network

A low profile slot antenna array is designed to operate over a wide bandwidth with low sidelobe levels. Taylor synthesis is used to taper the power distribution among array aperture. An efficient approach to design an equal-phase but unequal-power symmetric waveguide divider is proposed for constructing an amplitude-tapering feed-network for the array. Phase differences are balanced by adjusting the waveguide phase velocities. The basic radiator is a 2 x 2 slot subarray, uniformly fed by such a waveguide divider. A 16 x 16 array is then constructed by 8 x 8 of such subarrays. A 1-to-64 way corporate-feed waveguide network is designed to excite all subarrays instead of individual slots, and the required power distribution is obtained by adopting a 30 dB Taylor (N) over bar = 4 synthesis. Measured results indicate that the array can achieve a 13.8% bandwidth and a gain of more than 29.5 dBi. The first sidelobe level is -26.5 dB in the E-plane and -30.4 dB in the H-plane. The holistic sidelobe levels in both planes are better than -25 dB with a better than -40 dB cross-polarization.