SICL-based wideband crossover with low phase imbalance and group delay

This study presents a wideband crossover developed using substrate integrated coaxial line (SICL) technology. The proposed SICL-based crossover isolates the two physically overlapping channels by routing the signal in a middle conductor of SICL through the transmission line created in the top and bottom ground plane using a metalised blind via. An equivalent model is proposed to study the role of substrate height in the proposed crossover. The design methodology is affirmed by fabricating and testing the experimental prototype. The measured results show isolation between channels are more than 19 dB with better than 18 dB return loss and less than 1.2 dB insertion loss from 0.2 to 20 GHz. Owing to the non-dispersive nature of SICL line and simplistic design technique with minimal discontinuities the designed crossover demonstrates low peak-to-peak group delay variation, less than 0.04 ns over the entire bandwidth. The proposed crossover due to its symmetric design provides low path difference of less than ±2.45° up to 20 GHz (≤ ±1° up to 10 GHz) without any additional phase compensation technique. Utilization of electromagnetically robust self-packaged components designed in SICL technology provides superior front-end communication system within a small footprint.