Mode Composite Ridged Substrate Integrated Coaxial Line for Multichannel Operation

In this article, a mode composite ridged substrate integrated coaxial line (MCRSICL) is proposed for concurrent multichannel operation. The TEM and TE10 modes of the MCRSICL are excited simultaneously with high isolation. Consequently, the operation frequency band of the ridged substrate integrated coaxial line (RSICL) is expanded without necessitating additional physical space. The transmission performance and design principle of the MCRSICL are studied. Based on the low-temperature co-fired ceramic (LTCC) technology, an MCRSICL prototype is designed and fabricated to enable parallel TEM and TE10 operations. The measurement results show that the TEM and TE10 channels operate from dc to 40 and from 18 to 40 GHz, respectively, and the crosstalk between the two channels is below −35 dB. Besides, a multichannel high-speed signal transmission system is designed based on the MCRSICL prototype for high-speed interconnect applications, and the measured output signals exhibit good eye diagrams with 25- and 10-Gb/s pseudorandom binary sequence (PRBS) input signals. Subsequently, a dual-band bandpass filter (BPF) is proposed based on the MCRSICL, whose two channels operate at 5.7 and 29 GHz in a large frequency ratio of 5.1. In addition, a reconfigurable RF front end is designed using the MCRSICL BPF operating in both the sub-6G and Ka bands for an integrated communication and navigation system. The innovative MCRSICL establishes a novel platform for multichannel interconnect and component, characterized by compact dimension, simple transition, versatile design flexibility, and weak coupling between channels.