PCB-Based Hybrid Series/Corporate-Fed 4 x 4 D-Band Phased Array With Wide-Angle Scanning

Abstract

A wideband 4 × 4 planar phased array, based on four hybrid series/corporate-fed 4 × 1 subarrays with an asymmetrically positioned wide-stripline stub, is proposed for next-generation D-band applications. Each subarray consists of a stripline power splitter and 180∘ phase shifter serving as a corporate feed for two co-optimized back-to-back series-fed arrays, each with two stripline-fed aperture-coupled stacked patch antennas. This hybrid feed approach minimizes the number of required feed layers, reducing both structural complexity and fabrication costs, while ensuring stable gain across a wide bandwidth. As a proof of concept, prototypes of a 4 × 1 subarray and a 4 × 4 array, with respective dimensions of 0.96 mm × 4.8 mm and 3.8 mm × 4.8 mm, were fabricated using a standard any-layer high-density interconnect printed circuit board process for operation in the (120 to 150) GHz frequency band, demonstrating a 22% fractional bandwidth. The 4 × 1 and 4 × 4 arrays achieve peak gains of 10 dBi and 14.5 dBi, with total efficiencies of 58% and 55%, respectively, and support beam steering over ± 45∘. Furthermore, a 5Gbaud 16-QAM wireless communication link over 26 cm distance was successfully established using the 4 × 4 array, achieving an error vector magnitude of less than 8%. This validates the use of the proposed antenna array at three carrier frequencies, enabling a 60 Gbit/s aggregated data rate for future multicarrier D-band applications.