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 substrate integrated waveguides (SIWs) or stub-based walls of CSIWs have been replaced with an interdigitated 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 cutoff 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 p-i-n diodes. The antenna is fed at either end using a single-pole–double-throw (SPDT) switch to achieve a 2-D 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 2-D beam steer with a stable gain of $\sim 13.5$ dBi and an efficiency greater than 80%.