摘要:
利用滤波器综合设计方法设计了一款新型的具有高带外抑制性的微带滤波器天线。滤波器天线由五个开口谐振环、平行耦合线和倒L 天线组成。设计思路是使用倒L 天线代替滤波器的最后一个谐振器,然后利用平行耦合线等效为导纳变换器将谐振器与天线进行耦合,从而设计出既有滤波性能又有辐射性能的滤波器天线。滤波器天线采用交叉耦合结构,在带外有两个传输零点,大大提高了滤波器天线的带外抑制能力。滤波器天线经过仿真和测试,结果显示其反射系数S11 <-10 dB 的相对带宽为8%(2.37 ~2.57 GHz),带内增益约1.6 dBi,传输零点在带外50 MHz 处,增益下降到-25 dBi,带外整体下降到-20 dBi 以下,带外抑制特性显著。
Abstract:
In this paper, co-design approach is used to design a new micro-strip filer-antenna with high stop-band rejection. This filter-antenna consists of five open-loop resonators、parallel coupled line and invert L-shaped antenna. The design method is in the following: replace the last resonator of filter by antenna on account of its resonance characteristic, connect antenna with filter resonator by parallel coupled line which can be equivalent to admittance inverter. In this way the filter-antenna with filtering and radiation characteristic is obtained. Filter-antenna adopts cross-coupled structure with two transmission zeros outside the band. It greatly improves the performance of stop-band rejection. After simulating and testing, the result shows that filter-antenna has about 8% (2. 37 ~2. 57 GHz) fractional bandwidth in condition that S11 <-10 dB, and the gain in band is about 1.6 dBi. Transmission zeros locate 50 MHz outside the band, where the gain decreases to -25 dBi.The gain drops to -20 dBi in whole stop-band. The results indicate that the designed filter-antenna has remarkable stop-band suppression characteristics.
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