Design of Compact Six-Channel Diplexer

Compact six-channel diplexer (1.575/2.4/5.2 GHz and 1.8/3.5/5.8 GHz) using multipath quarter wavelength stepped impedance resonators (SIRs) is proposed. The sixchannel diplexer includes two pairs of magnetically coupled SIRs by grounded via hole. The resonant frequencies of each channel can be easily determined by changing the impedance ratio (K) and length ratio (α) of SIRs. The diplexer provides the advantages of effective design method, low loss, high passband selectivity, compact circuit size, and very useful for applying on the multiband wireless communication systems.