Concurrent Dual-Band Microstrip Line Hilbert Transformer for Spectrum Aggregation Real-Time Analog Signal Processing

In this paper, a microstrip line Hilbert transformer is proposed to operate concurrently at the dual-frequency for spectrum aggregation real-time analog signal processing applications. The proposed dual-band Hilbert transformer consists of a dual-band 180° coupler and dual-band delay line. The theoretical analysis is carried out to find the relation of coupler and delay line forming closed loop resonance. To verify the proposed design concept, a prototype of Hilbert transformer working at 0.9 GHz and 1.98 GHz is designed and tested, and the simulated and measured results correlate well with each other.