Millimeter-wave beam steerable slot array antenna using an inter-digitated capacitor based corrugated SIW

A new class of electronically beam-steerable corrugated substrate integrated waveguide (CSIW) slot array antenna operating at 26 - 29 GHz has been developed. The conventional via based walls of SIWs or stub-based walls of CSIWs have been replaced with an inter-digitated capacitor (IDC) structure to enable reconfigurability. This novel IDC-CSIW is shown to have a lower transmission loss compared with conventional CSIWs in the literature. A new mathematical method has been described to calculate the cut-off frequency of IDC-CSIWs. The surface of the IDC-CSIW is then loaded with longitudinal slots, building a leaky-wave architecture. Radiation from individual slots is controlled by shorting the IDC at specific points using PIN diodes. The antenna is fed at either end using a single-pole-double-throw (SPDT) switch to achieve a 2D reconfigurable beam. A compact switched array of two IDC-CSIWs is demonstrated to produce a continuous full sector coverage of 120° in the azimuth plane, and ±15° in the elevation plane, providing a 2D beam-steer with a stable gain of ~13.5 dBi and an efficiency greater than 80%.