Dual-Band LTCC Substrate Integrated Cavity Slot Antenna Arrays in D-Band for 6G IoT Applications

High-speed vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications will be crucial for traffic efficiency within intelligent transportation systems in the near future, which necessitates antennas operating at high frequencies with high gains and compact sizes. In this article, we propose a dual-band substrate integrated cavity (SIC) slot antenna operating in D-band along with its array applications. The antenna excites two high-order radiation modes and utilizes four radiating slots on its top surface to achieve dual-band radiation. Compared to antennas using fundamental modes, the employment of high-order modes results in antennas with larger dimensions, which facilitates fabrication especially in D-band. To accommodate different application scenarios, two antenna arrays are designed, fabricated, and measured. By vertically arranging the feeding networks, a significant reduction in overall antenna size is achieved. The proposed antenna arrays are fabricated by low temperature co-fired ceramic (LTCC) technology which guarantees structural stability, high processing precision, and multilayered design. Benefiting from high-performance substrate integrated waveguide (SIW) feeding networks, the measured results are reasonably in agreement with the simulated ones. A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 2$ </tex-math></inline-formula> SIC slot antenna array achieves radiation at 150.8 and 166.5 GHz, with gains of 12.1 and 12.4 dBi, respectively. Additionally, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 4$ </tex-math></inline-formula> SIC slot antenna array achieves radiation at beam pointing angles of −25° and −20° with gains of 7.2 and 10.3 dBi at 147.95 and 163.25 GHz, respectively. As new types of dual-band antenna arrays working in D-band for the first time, they provide promising options for sixth generation Internet of Things (IoT) applications.