中文摘要：

提出了一种采用共面波导馈电的小型多模双通带平面滤波器,该滤波器采用内部嵌套的多模谐振器缩小了电路尺寸,利用奇偶模分析方法和弱耦合激励的方式分析了该多模谐振器的谐振特性,并依此推导出其谐振频率与物理尺寸的相互关系。为了满足滤波器的馈电,端口耦合并实现小型化,引入了异面共面波导馈电结构。文中给出了四个谐振模式的分析以及两个通带中心频率和带宽的控制机理,实现了滤波电路的频率和带宽的独立控制。最终实现了中心频率为2.39GHz和4.34GHz,相对带宽分别为8.8%和13.4%的双通带平面滤波器。该滤波器中心频率和带宽独立设计可控,而且谐振器尺寸大小仅为0.09λg×0.09λg。本文所设计的滤波器结构简单、尺寸小,通带间隔离度较高、易加工制作,具有较高实用价值。

英文摘要：

A dual-band planar bandpass filter with co-planar waveguide feeding structure is presented. The size of the filter is reduced by using nested multi-mode resonator,and the resonance characteristic is analyzed by odd-even mode and weak coupling method,and the relationship between resonance frequencies and physical dimensions is also given. To conveniently feed the four modes,obtain desired coupling and miniaturize circuit size,coplanar waveguide feeding method is employed in the filter design. Analysis of the four resonant modes is given and the mechanism to control the center frequencies and bandwidth of two passbands are also shown,and independently control of frequencies and bandwidth of filter circuit are achieved. A prototype filter operating at 2. 39 GHz and 4. 34 GHz with 3d B fractional bandwidth of 8. 8% and 13. 4% has been designed and fabricated. The center frequency and bandwidth can be independently controlled,and resonator has a compact size of 0. 09λg×0. 09λg. Because of simple structure,small size,good isolation between passbands,and easy to be fabricated,the proposed filter is of great value in application.