Design of compact L‐band 180° phase shifters

The practical design of L-band 180° phase shifters faces two problems. One is associated with the size, and the other with the cost. This paper presents the design of two varieties of 180° phase shifters that minimize the size and manufacturing cost. The first variety is a hybrid-coupled phase shifter whose size is reduced by employing a compact 3 dB branch-line coupler. The second variety is a switched-branch-line phase shifter, which uses only two diodes to perform its function. Both phase shifters employ low-cost UHF diodes in their switching networks. An LC compensation technique is applied to make the diodes good-quality on–off switches in the L-band. Using these compensation methods, low-cost, good-quality compact 180° phase shifters are developed.