An Equal-Length Multiway Differential Metamaterial Phase Shifter

In a conventional differential phase shifter (DPS), to realize arbitrary phase shifts, the reference and main microstrip lines are of different lengths. This difference results in suboptimal integration density, which renders the wireless communication system implementation complex and bulky. This paper presents an equal-length multiway DPS based on metamaterials. The reference lines have identical dimensions and are of equal lengths with the main lines. The proposed structure covers a wide bandwidth by aligning the main line phase slope without degradation in return and insertion losses. A design optimization methodology is presented for wideband DPSs in the 0°-90° range. For demonstration, a six-way DPS has been designed and fabricated. The measurements show that the phase shifters have less than 5° differential phase stability and better than a 10-dB return loss, with an insertion loss less than 1.24 dB from 1.6 to 3.2 GHz.