220 GHz High-Gain Substrate Integrated Antennas With Low Fabrication Cost Based on Higher Order Mode and PCB Technology

In millimeter-wave (MMW) and terahertz (THz) bands, the operation frequency is high and there are challenges in fabrication and microassembly processes, bringing high-accuracy requirements and high manufacturing cost. In this article, high-gain substrate integrated antennas with low fabrication cost are presented for MMW/THz applications. The basic antenna consists of two parallel TE201 resonant cavities and is directly fed by a grounded coplanar waveguide (GCPW). Radiation slot apertures are modified to increase aperture radiation efficiency and improve radiation patterns and gain. The antenna scheme is analyzed and a 220 GHz
$2\times2$
slot array antenna is developed as an example. To further improve the antenna gain with low fabrication cost and low feeding network loss, the basic antenna is explored to feed a modified dielectric plate lens. The high-gain scheme and design flowchart are provided. Both basic and improved structures are fabricated by normal single-layer printed circuit board (PCB) technology and high antenna gains are achieved. The measured peak gain of the basic antenna and the antenna with dielectric plate lens are 13.5 and 20.2 dBi, respectively. The measured return losses are better than 10 dB from 192 to 247 GHz. The antennas have advantages of simple antenna feeding structure, low fabrication cost, wide bandwidth, and high gain.