Design and implementation of a compact microstrip Tx/Rx diplexer for UMTS equipments

This paper deals with the design and implementation of a very compact microstrip Tx/Rx diplexer for future UMTS mobile terminals. Miniaturised loop-resonator filters have been developed and combined into a diplexer structure, satisfying different constraints such as high electrical performance level (especially, a very narrow bandwidth, low insertion losses and a high out-of-band rejection), or great compactness and compatibility with a standard planar integration.