Synthesis of phase shifters based on a single stepped transmission line with a stub

A two-criteria problem of the synthesis of differential phase shifters designed on the basis of a new structure-a symmetric stepped transmission line with a stub connected in the middle of the structure—is solved. Optimum parameters of such phase shifters are calculated for phase shifts φ0 = 11.25°−135° and bandwidths of 40% and 67%. It is found that the wave impedances of the steps monotonically decrease from feeding lines to the structure center and optimum wave impedances of the stub and sections decrease with increasing φ0. It is shown that structures with different stubs are analytically equivalent. Parameter values of the phase shifter are improved as compared to the parameter values of a known design. A 90° microstrip phase shifter is experimentally studied in a frequency band of 2–4 GHz. It is found that the maximum discrepancy between the theoretical and experimental characteristics is 5° and the maximum value of the standing-wave ratio is 1.11