No abstract

No abstract

A novel duplexer design based on cross-coupled resonators is presented which has the advantages of small size and reasonably sharp cutoff frequency. A duplexer for the UMTS upload and download bands is fabricated and the measured response is shown to be in close agreement to full-wave simulations. The fractional bandwidth for both bands is about 3%. The duplexer has an insertion loss of less than 1 dB and provides more than 20 dB of isolation. Lumped-element models for both the resonator and duplexer are derived and their responses are also shown to be very close to the simulated results, which make them potentially very useful since it can simplify the design of systems using the duplexer.

A new method for developing UMTS filters for upload and download bands is proposed. The filters are based on a periodical resonator called the H-type resonator. Simulation results show that the relative mean error is less than 1.5%. The filter designed by this method has an insertion loss less than 1dB and provides low return loss in the bandpass. A periodic network analysis was used for designing the H-type resonator. We have also derived a lumped-element circuit model for the filter whose element's values are found by using genetic algorithms. It is shown that the filter has a suitable frequency response, and that it can be applied quite well in telecommunication systems.