270-GHz LTCC-Integrated High Gain Cavity-Backed Fresnel Zone Plate Lens Antenna

A compact cavity-backed Fresnel zone plate (FZP) lens antenna, integrated in low-temperature co-fired ceramic (LTCC) is proposed to achieve high gain at 270 GHz band. The gain is enhanced by using the back cavity formed by a via sidewall and a ground plane. A compact feeding transition is proposed to realize the broadband impedance matching in order to reduce the considerably large reflection at high permittivity substrate-air interface when the antenna is directly fed by an external air-filled waveguide. The measured results show that the proposed cavity-backed FZP lens antenna achieves a boresight gain of 20.8 dBi at 270 GHz and a 3-dB gain bandwidth of 9.1 GHz (266.2-275.3 GHz).