A 220 GHz Integrated Sensing and Communication System Based on Orthogonal-Polarization Multiplexing

A 220 GHz integrated sensing and communication (ISAC) system based on orthogonal-polarization multiplexing is presented for simultaneous high-speed wireless communication and radar ranging. To achieve broadband operation, low insertion loss, and high polarization isolation, a dual-symmetric reverse-coupled orthomode transducer (OMT) is designed and fabricated. The OMT covers 170–260 GHz, with a measured return loss better than 15 dB and polarization isolation exceeding 45 dB, while relaxing the required fabrication tolerance to 10 μm. The OMT is integrated with solid-state frequency-conversion circuits, amplifiers, waveguide components, and a dual-polarized antenna to construct a dual-polarization transmit front end. The resulting system achieves polarization isolation exceeding 25 dB between the communication and radar channels over 204–222 GHz, together with a receiver noise figure of 9.8 dB at 220 GHz. Using coherent-reference techniques and real-time baseband processing, the system achieves a data rate of 2 Gbit/s over a distance of 0.25 m, with a bit error rate below 5×10−8. Radar ranging experiments using a single corner-reflector target at distances of 0.25 and 0.40 m yielded a maximum observed absolute ranging error of 1 cm. These results demonstrate the feasibility of orthogonal-polarization multiplexing for jointly supporting high-speed THz communication and centimeter-level radar sensing.