One Kind Of Dul-duplexer Desigh With Coasial Resonant Cavity And High Stability

By the high speed developing of mobile communication during recent years,especially the application of3G and4G network，it brings the higher quest to improve thecurrent base stations and setup new base stations. The RF Pass Band Duplexer, as one ofthe most important factor, was getting to rapidly develop. The research of the theory, thenew design idea, the new design method of duplexer, are focused on in domestic andforeign.The paper focuses on the radio-frequency cavity pass-band filter as the basic studyobject, apply the RF duplexer to mobile communication system as Front-End of antenna. Ittransfers the filtered signals into inner system and coveys the transmitted signals fromamplifier to antenna at the same time.At the beginning of the design, we will use the software “CoupleFilter” to get theapproximate of numbers of resonant cavity, construction, Q value, and the couplingbandwidth; by the request of mechanical outline size and the cavity quantity, we can layoutthe housing. And use HFSS to obtain the single cavity model and simulate until theeigenmode close to the center frequency of pass-band, and at the same time, its unloaded Qvalues at least should be larger than the value of80%which gotten by CoupleFilter. Nowwe have the mechanical size of single cavity and resonator. Then we can create thedouble-cavity-model based on the previous finished single cavity model, optimize andsimulate the coupler window model and get its coefficient. In General, the duplexerstructure can be founded basically by previous results. And we can create the materialdrawings, such as housing, resonators, cover and etc. At last, we make the samples by thesematerials’ drawings, try to tune and modify,2nddesign, again and again, until we get thegood unit which is up to the required outline size and performance. The import of transmission zero, brings in the good rejection. The new ideaapplication of riveting structure, not only makes the unit very stable, but also reduces thebuilding time. It means the manufacture cost is saved. I hope the paper can serve as amodest spur to induce someone else to come forward with his more valuable contributionsto the filter developing of new wireless mobile period.