Millimeter-wave Slot Array Antenna with Low Sidelobe Levels for Foreign Object Debris

Abstract

A methodology of designing an E-band ridge waveguide 48 × 48 slot array antenna with low sidelobe levels (SLLs), high gain and wide bandwidth characteristics is proposed in this paper. A 2 × 2 cavity-backed slot subarray acts as the unit cell of the array which consists of three layers. The top metal layer contains two radiating slots with different sizes to achieve wide bandwidth. The intermediate layer contains the back cavity and coupling slot and the third layer is the ridge waveguide with a metal step, so that the electromagnetic wave can be better transmitted through the coupling hole to the back cavity in the second layer. The array antenna is composed of 576 (24 × 24) unit cells with equal space and excited by a nonuniform corporate-feed-network. The SLLs are suppressed by the Taylor amplitude-tapering distribution, which is implemented by the unequal power dividers. It should be noted that we adopt a special feeding network topology and a large power distribution ratio to achieve the Taylor distribution because the array is composed of 576 unit cells, the number of which is not the n th power of 2. Simulation results of the array antenna show the -10 dB impedance bandwidth is from 70 to 77GHz, the peak gain is up to 41.6dBi and the first SLL is lower than -21 dB. In addition, the grating lobes around 40 degrees have also been suppressed to a certain extent. The antenna proposed in this paper is competitive for foreign object debris applications because of its wide bandwidth, narrow beamwidth, high peak gain and low SLLs.