Duplexer designed on the basis of microstrip filters using high dielectric constant substrates

A microstrip duplexer for a modification of a PCS communication system operating at frequencies of 1.84-1.87 and 1.75-1.78 GHz is described. The duplexer containing microstrip bandpass filters on high dielectric constant substrates (E > (r) = 92) are compared with duplexers manufactured on microwave ceramic materials with high values of E > (r) . The microstrip bandpass filters use stepped-impedance resonators placed one near another with a gap of 0.1-0.2 mm. It is shown that the microstrip duplexer has slightly lower insertion loss and occupies smaller volume than a duplexer using coaxial dielectric resonators having a rectangular cross section of 3 x 3 mm and E > (r) = 92.