Compact duplexer with miniaturized dual loop resonator

This work presents a very compact duplexer based on novel miniaturized loaded-close-loop dual resonators. Two different dual resonators are used to establish the two bands, corresponding to the transmitter and the receiver bands. The two filters are connected to the antenna through a matching network. We have fabricated a prototype using a 10.2 dielectric constant substrate. The duplexer fits in a 16 × 10 mm² area and has less than 2dB insertion loss and more than 20 db of isolation. Measurement results are in good agreement with the simulation.