Novel Capacitor-Loaded Substrate-Integrated-Waveguide Structure and Its Electronically Controlled Leaky-Wave Antenna Application

A capacitor-loaded slotted substrate-integrated waveguide structure is presented to realize a tunable composite right-/left-handed substrate-integrated waveguide structure. The capacitor-loaded slotted substrate-integrated waveguide structure is realized on a half-mode substrate-integrated waveguide structure to reduce the size. The inter-digital slots and varactor diodes are inserted to offer series-tunable capacitance of the composite right-/left-handed circuit model. A long slot is inserted to isolate DC bias, and the chip capacitors are mounted on the long slot to create a path for RF signal flow. Based on the tunable capacitor-loaded slotted substrate-integrated waveguide structure, an electronically controlled composite right-/left-handed leaky-wave antenna is designed. It is experimentally demonstrated that the direction of the main beam is continuously varied from +4° to −6° at 5.6 GHz as the bias voltage increases from 1 to 20 V.