GSMR频段微带带通滤波器的研究设计.docx

关键词：GSM—R频段；微带带通滤波器；准椭圆函数；耦合系数矩阵；小型化；交指电容加载谐振器 关键词：GSM—R频段；微带带通滤波器；准椭圆函数；耦合系数矩阵；小型化；交 指电容加载谐振器 分类号： j匕塞交通太堂亟±堂垡j金塞 j匕塞交通太堂亟±堂垡j金塞 一 △曼墨!B△￡至 AB STRACT Filters play very important roles in many RF／microwave applications．Emerging applications such as wireless communications continue to challenge RF／microwave filters with ever more stringent requirements--higher performance，smaller size,lighter weight and lower cost． This paper presents the design of a class of miorostrip bandpass quasi—elliptic function filters wim the bandwidth of 4MHz and the fractional bandwidthO．5％,which exhibit a single pair of attenuation poles at finite frequencies． Because of these attenuation poles at finite frequencies，quasi—elliptic function filters performance higher selectivity and sharper filter skirt than Chebyshev ones．This type of filters，which consist of the cross coupling microstrip open-loop resonators，Can not only reduce the difficulty of fabrication，but also result in a compact topology． The locations of two fmitc frequency attenuation poles of the quasi·elliptic function bandpaSS filters are at 883．4MHz and 890．6MHz whose center frequency is 887MHz or at 928．4MHz and 935．6MHz whose center frequency is 932MHz．These planar structures of miorostrip ban@a8s quasi—elliptic function filters have been studied and designed in this paper on account of the reason above．However,the existing narrow-band microstrip filters for fractional bandwidth1％are difficult to fabricated on conventional substrates，because miorostrip cannot even form a complete passband． In this paper,the filter is realized using the configuration based 011 the full-wave EM and fabricated using a copper microstrip Oil an substrate、加m a relative dielectric constant of 1 0．8 and thickness of 1．27 mm．On the basis of the filters above,a kind of slow-wave filters consist of capacitive loaded open-loop resonators are designed．The nov