360° Reflective Phase Shifter With Independent Tunable Phase in Dual-Band

A reflective dual-band independently tunable phase shifter is proposed in this letter. It consists of a dual-band coupler with reflective loads connected to the coupled and through ports. Each reflective load comprises a coupled line with diodes cascaded at both ends. This design cleverly utilizes the impedance characteristics of the parallel circuit to enable independent control of low-frequency (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{\text {L}}$ </tex-math></inline-formula>) and high-frequency (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{\text {H}}$ </tex-math></inline-formula>) phase shifts. Phase adjustment is achieved by cascading varactor diodes at both ends of the coupled line. A prototype of the phase shifter was fabricated for experiment, and the measured results showed good agreement with the simulated results. The phase shifter achieves a relative phase shift range (PSR) of 397° when operating at 2.4 GHz, with the maximum insertion loss (IL) of 2.45 dB and the minimum return loss (RL) of 10.6 dB. It presents PSR of 360° when operating at 5.2 GHz, with the maximum IL of 2.47 dB and the minimum RL of 10.7 dB. It features excellent performances with simple structure and small size.