High-Gain L-Probe Excited Substrate Integrated Cavity Antenna Array with LTCC-Based Gap Waveguide Feeding Network for W-Band Application

Abstract

The W-band high-gain L-probe excited substrate integrated cavity (SIC) antenna and its arrays on a low-temperature cofired ceramic (LTCC) substrate are presented in this paper. To achieve a high gain, the SIC antenna is excited using L-probe feeding techniques. The SIC of the antenna servers as main radiator and the L-probe is involved in the radiation. A novel low-loss LTCC-based ridge gap waveguide (GWG) is also designed in this work. This GWG forms a compact hybrid two-layer low-loss feeding network with a substrate integrated waveguide (SIW) feeding network for an $8 \times 8$ antenna array. A high-gain antenna array is achieved by combining the high-gain antenna element and low-loss hybrid feeding network. In addition, a reference antenna array with a feeding network composed solely of SIW is designed for comparison. With the reconfiguration of the radiating element, feeding network, and transition, the proposed antenna array shows a wide measured impedance bandwidth of 14.9% from 87 to 101 GHz for $\vert \text{S}11\vert and a gain of up to 23.8 dBi. The measured aperture efficiency of the proposed array is 42.3%, which is 8% higher than that of the reference array.