Microstrip diode phase shifters for S-band and C-band

Two 4 bit PIN diode phase shifters operating at S band and C band are described. Both devices, constructed in microstrip on 0.635 mm thick alumina dielectric, consist of 22.5 deg and 45 deg loaded line configurations and of 90 deg and 180 deg rat-race hybrid coupled sections. Details of the design of the single bits, carried out with computer aided design techniques, are presented. Measured results are included. They indicate for the S band phase shifter (2.85 to 3.15 GHz) + or - 4 deg phase shift accuracy, 1.7 dB average insertion loss, and 1.4 maximum VSWR; for the C band phase shifter (5.4 to 6.0 GHz) there is + or - 0.7 deg phase shift accuracy, 1.3 dB average insertion loss, and 1.5 maximum VSWR.