Simple Beam Scanning SIW Cavity-Backed Slot Antenna Using Postloaded Varactor

A reconfigurable beam-scanning substrate integrated waveguide (SIW) cavity-backed slot antenna (CBSA) is presented. By adopting three transverse radiating slots and inserting four pairs of postloaded varactors, the field distributing in the SIW cavity can be moderately perturbed. To be specific, two pairs of varactors, flanked by the adjacent slots, are placed in the vicinity of the cavity longitudinal centerline; while the other two pairs are symmetrically embedded at two end parts of the bilateral slots. As such, manipulating biasing voltage applied to each pair of varactors independently could offer very fine control of the amplitude and phase of every single-slot element. Accordingly, the main beam direction of the proposed antenna is electronically controlled. A prototype was designed and fabricated to validate the proposed method. Measured results demonstrate the proposed CBSA with a beam scanning from -30° to 41° and a gain varying between 6.4 and 9.2 dBi.