A new topology for the design of microstrip loop-filters is proposed in this paper. This new geometry is used in a coupled-loop-resonator filter in order to improve the out of band rejection (by introducing an additional transmission zero), as well as insertion loss (thanks to a significant circuit size reduction). The design methodology of these filters is first described and then experimental performances are discussed. Finally, a high performance duplexer, specified for UMTS frequencies and requirements (i.e. in the 1.9 -2.17 GHz frequency band), is presented. Measured insertion loss is lower than 2.S dB and an isolation level greater than 40 dB is achieved between Tx/Rx channels, thanks to the multiple out of band transmission zeros introduced in the filter synthesis.
In view of optimizing a CPW-fed microstrip patch antenna, a composite ceramic-foam substrate is investigated. using a global synthesis technique, a multilayer multitechnology miniature band-pass filter is integrated on the back-side ceramic while a microstrip patch is laid down on the upper foam dielectric. This combination leads to an efficient and compact multi-function module.
We propose original procedures for the design of high performance filters with simultaneously controled band-pass and band-reject responses. Resonators are des cribed as self-filtering structures and contri butes to the in-band and out-of-band trans fer function. The control is achieved either by specifying the resonators synchronization, or by inserting low-pass structures inside resonators
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