An SIW Pillbox-Based Compact Dual-Polarized Multibeam Antenna With Passive 2-D Beam Scanning Capability

In this brief, a dual-polarized multi-beam antenna is proposed based on substrate integrated waveguide (SIW) pillbox beamforming networks (BFNs). By using a rotationally symmetrical frequency scanning leaky-wave antenna (LWA) array and four SIW pillbox BFNs, the 2-D beam steering capability is realized for two polarizations. Due to the rotationally symmetrical geometric characteristic of the LWA, the orthogonally placed BFNs can excite orthogonally polarized beams. A stable gain with a wide beam scanning range in the limited bandwidth is realized, where only the backward to broadside scanning region of the LWA is used, and the forward radiation is compensated by the axisymmetric BFN. Moreover, the stacked layout of the multi-layer antenna structure greatly helps realize miniaturization. The proposed antenna can provide ±35° beam scanning range by switching 7 ports in the multi-beam plane and ±31° frequency beam scanning range within the bandwidth of 21 GHz to 27.5 GHz. The advantages of the proposed antenna, including dual-polarization, 2-D beam scanning, low profile, compact size, and low cost, make it a very appropriate choice in millimeter-wave multi-beam radars systems.