A High-Gain Microstrip Antenna Based on Microcoaxial Technology for Sub-Terahertz Applications

In this article, a high-gain sub-terahertz (THz) microstrip antenna is proposed based on a wafer-level microcoaxial technology (MCT). This process is primarily used to design circuit structures such as filters and transmission lines. A rectangular microcoaxial transmission line evolved into a microstrip antenna element and array, which are subsequently fabricated and tested. The proposed antenna element achieves an impedance bandwidth of 10 GHz (148-158 GHz) for VSWR ≤ 2:0, extending to 17.4 GHz (144-161.4 GHz) for VSWR ≤ 3:0. The element demonstrates a maximum gain of 7.4 dBi across its operational bandwidth. The 8 × 8 antenna array configuration presents a VSWR below 2 across a frequency range of 136-165 GHz. The antenna array achieves a peak gain of 23.8 dBi and maintains cross-polarization suppression better than 30 dB in the normal direction across the operating band. The antenna can generate both patch radiation and waveguide cavity modes, with the mutual superposition of two modes leading to high gain. Furthermore, the elimination of dielectric loss inherent in conventional microstrip antennas enables significantly higher gain. The proposed antenna can be integrated with the backend circuit by MCT and is applicable to various high-density integrated sub-THz electronic systems.