THz 2-D Frequency Scanning Planar Integrated Array Antenna With Improved Efficiency

A THz 2-D frequency scanning planar integrated array antenna is developed in this letter. Eight THz leaky-wave antennas are combined with a true-time-delay (TTD) phase-shifting feeding network to steer the beam in two directions by sweeping the frequency. Several H-plane 90° bends with linearly increased length are adopted to achieve the scalable TTD phase shift. The feeding lines are closely spaced to reduce the phase-shifting network occupied area in this progressive phase-shifting scheme. Besides, the E-plane 180° bend is used to construct the double-layer phase-shifting network, maintain the number of multiple scanning sweeps and improve the aperture efficiency. Moreover, in the used microelectromechanical systems (MEMS) fabrication technique, the minimum height of the radiation slot is 0.2 mm, which is too thick and deteriorates the radiating performance. When the double-layer step-profiled radiating slot is used instead of the thick slot, a THz leaky-wave antenna with higher radiation efficiency and better gain flatness can be achieved. Finally, a prototype antenna is fabricated and experimentally validated. The operating frequency range is 325-400 GHz and the beam scanning range is 22.7° × 60° with a maximum radiation gain of 25.28 dBi.