Analysis and development of 2.45 GHz phase shifters for adaptive antennas

A complete analysis of 4-bit branchline hybrid coupled phase shifter for phased array antenna operated in Bluetooth access-point is presented. The analysis is based on the transmission line equivalent model which does not take account of the losses of the substrate material. The analysis includes the performance of the cascaded phase shifters with different phase-bit combinations. Different values for impedance of reflective network are allowed for having an additional degree of freedom. Based on the theoretical results a 4-bit hybrid coupled phase shifter is fabricated. The results of theoretical analysis agree well with the results obtained from the measurements. In addition these results show that a high performance digitally controlled phase shifter can be realized with this method.