Broadband hybrid microstrip couplers—Amplitude and phase

Several designs for a 180° hybrid coupler are discussed. Using the stepped-impedance method, the bandwidth of an 11 GHz hybrid coupler is increased to approximately 1.6 times the bandwidth of a conventional hybrid coupler. Comparisons are made between conventional and broadband hybrid couplers, as well as between circular and rectangular designs, and the phase behavior of each is compared for the first time. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 254–259, 2002.