Very-low-sidelobe printed tapered arc-shaped wide-slot antenna array

This study proposes two unique techniques to increase the impedance bandwidth and reduce the sidelobe level (SLL) of printed antenna arrays. In the first, a printed tapered wide-slot antenna array fed by an array of printed patch elements placed above a metal reflector is introduced. The impedance bandwidth of this antenna array is 10.3-23.1 GHz, that is, 76.6%. By tapering the width of each of the slot elements, a very low SLL of -33.5 dB is obtained. The proposed antenna has a stable radiation pattern over the range 14.7-17 GHz, that is, the 3 dB gain bandwidth is 14.5% and has a front-to-back ratio (F/B) level of 40 dB and a low cross-polar component < -45 dB at broadside and < -35 dB off-broadside direction. In the second technique, to achieve further improvement in the SLL of the antenna array the length of each of the slot array elements is tapered, in the form of an arc-shape, leading to an antenna array with very low SLL of -35 dB at a centre frequency of 16.26 GHz, a wide bandwidth of 78.8%, 20 dB SLL bandwidth of 8.8%, and high F/B of 38 dB. A prototype of the antenna array is fabricated and the simulated and measured results are presented and discussed.