Spectrum Aggregation Dual-Band Real-Time RF/Microwave Analog Signal Processing From Microstrip Line High-Frequency Hilbert Transformer

A uniplanar microstrip line RF/microwave real-time analog signal processing (RAP) units are proposed in this article to operate concurrently at two frequencies for spectrum aggregation applications. First, a fundamental building block novel microstrip line dual-band Hilbert transformer (DBHT) is developed by integrating a dual-band 180° coupler and a dual-band delay line (DBD). The theoretical analysis is carried out to determine the relation of coupler and delay line forming closed loop resonance in the proposed circuit topology. Then, a dual-band edge detector from DBHT and a dual-band single-sideband (DBSSB) modulator composed of dual-band power divider/combiner (DBPD/DBPC), DBHT, and DBD are developed for dual-band real-time RF/microwave signal processing. To verify the proposed concept, a prototype of microstrip line DBHT working at 0.9 and 1.98 GHz is designed, and the measurement and simulation agree well with theoretical analysis. To demonstrate the real-time RF/microwave analog signal processing, a dual-band edge detector composed of DBHT is verified in the experiment. Furthermore, a prototype of microstrip line DBSSB modulator is fabricated and validated in the experiment to demonstrate the real-time single-sideband modulation at two concurrent RF/microwave frequencies.