A Compact and Wideband Variable Microwave Phase Shifter for Phased Arrays and Diversity in S-band

Abstract

Especially in automotive and mobile applications, lean and compact tunable phase shifters are required. We propose a new varactor-based analog phase shifter in a broadband-matched bandpass configuration for a wide frequency range between 2-2.5 GHz. It enables continuous tuning of phase angles between 0° and 180°, which are steered by only one bias voltage. By cascading two implementations of the proposed circuit or in combination with a switchable wideband 0°/180° phase shifter all phase values between 0° and 360° can be obtained with low frequency dependence. The combination with a switchable phase shifter enables a higher usable bandwidth and offers the additional capability of selecting individual antennas in a multi-antenna system. After an analytic explanation of the phase shifter circuit, simulated and measured results of a hardware sample are presented and the influence of parasitic effects is discussed. A matching of better than 10 dB and attenuation of less than 2.5 dB is achieved for all phase constellations. Measurements of a phased array for satellite radio reception around 2.33 GHz using the new phase shifter clearly show the good performance of the circuit even with its small footprint and low component count. Continuous-valued beam steering in azimuth as well as discrete beam steering in elevation is achieved by the combination of a switchable with the new continuously tunable phase shifter.