A Compact Single-Layer Balanced Phase Shifter With Wide Bandwidth and Uniform Reference Line

A single-layer balanced phase shifter with uniform reference line is proposed to achieve the advantages of compact size and wide bandwidth compared with state-of-art single-layer balanced phase shifters. The odd-mode equivalent circuit with one quarter-wavelength coupled line and two quarter-wavelength short-ended stubs makes wideband differential-mode (DM) impedance matching and phase shift. The even-mode equivalent circuit with two transmission paths provides wideband common-mode (CM) suppression without affecting the DM responses. The prototype of 45° (90°) phase shifter is designed with the operating bandwidth of 81% (82%), with the phase deviation of ±2.3° (±4.7°), with the minimum insertion loss of 0.29 dB (0.31 dB), and with the size of 0.27 λ
_g
²
(0.35 λ
_g
²
, λ
_g
is the guided wavelength at the center frequency f
₀
).