Study On The Electromagnetic Coupling Characteristic Of Microstrip Resonator And Its Application In Microstrip Filters

With the developing of the Mechanics of wireless Communication, people pursuethe communication device being simple, portable and stable. Simultaneously, it ismore important to improve the processing capacity of the filter which locates on thefront-end of the communication device. A new technology which named LowTemperature Co-fired Ceramic (LTCC) comes into being.This dissertation is mainly focused on the design technology of compact, highperformance microstrip filters. Based on the advantages of harmonic suppression,compact size and wide band, ring resonators and SIR have been applied in microwavefilters’ design. Microstrip filters with significant improvement in size and performanceare designed, fabricated and measured. Therefore, in order to increase the outbandsuppression, it can be fulfilled by introducing the transmission zeros.The main innovations in this dissertation are as follows.(1)Analysis the design principle and procedure about the filter’s design, theseprocedure including the normalized Chebyshev lowpass prototype filter, frequencyconversion and impedance transformation and so on. But traditional filter presents aworse outband suppression. Therefore, in order to increase the outband suppression, itcan be fulfilled by introducing the transmission zeros. Based on the traditionalresearches of the transmission zeros, this paper proposes a method to introduce twotransmission zeros on both side of the passband to increase the outband suppression,that is to summate the Y parameters in circuit network between two ports.(2)Based on the above theory, we describe the application and benefits aboutfolded Stepped impedance resonator (SIR) and design two dual-band LTCC bandpassfilter.①Proposing folded Stepped impedance resonator (SIR).Through analysis, itsphysical size smaller than a traditional1/4wavelength uniform stripline resonator.Based on the resonance unit, put forward a dual band bandpass filter which centerfrequency is5.24/6.65GHz.②Proposing dual-layer hexagonal shape SIRs and puttingforward a new dual band bandpass filter which center frequency is2.45/5.2GHz.