A compact phase shift unit for analogue beamforming

A novel phase shift unit for analogue beamforming is proposed. It is based on a defected microstrip structure (DMS). The DMS unit has a phase shift of 15° with insertion losses below 0.5 dB at 5.2 GHz. It is etched on a 50 Ohm conventional microstrip line and the length of which is only 0.07 wavelengths long. Due to the low insertion loss and compact size, the DMS units can be easily cascaded to realize a higher phase shift. As an example, a 1-bit phase shifter made by cascading 3 DMS units is designed. It has a phase shift of 45°±1.8° with the insertion losses still below 0.5 dB across the 5.2 GHz band (5.15 GHz to 5.35 GHz). The phase shifter design based on DMS is compact, low cost, and easy to be fabricated and integrated in microstrip systems. Therefore, it provides a low cost solution for analogue beamforming which usually employs a large number of phase shifters.