Wideband Microstrip Ring Resonator Bandpass Filters Under Multiple Resonances
Wideband Microstrip Ring Resonator Bandpass Filters Under Multiple Resonances
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DOI：
10.1109/tmtt.2007.906510
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发表时间：
2007-10
影响因子：
4.3
通讯作者：
Sheng Sun;Lei Zhu
中科院分区：
文献类型：
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作者：
Sheng Sun;Lei Zhu
在非对称环形谐振器的多重谐振下提出了一类新型宽带微带带通滤波器。两个电容耦合元件放置在方形环的两个垂直位置，而在这两个激励端口的对称平面内形成一对开路短截线，其形状类似于双模环形滤波器。通过将成对的短截线拉伸到接近八分之一波长，前两个偶数阶谐振向下移动到准相等地位于第一个奇数阶谐振的两侧，从而形成三重谐振环形谐振器。由于在两个端口安装叉指耦合线而不是集总电容器，因此可以将两个额外的谐振移入通带，从而组成五重谐振环形谐振器。为了深入了解其工作机制，这些环形谐振器根据传输线理论进行了表征。随后，优化设计并制作了具有一个或两个非对称环形谐振器的各种宽带微带环形谐振器带通滤波器。模拟结果通过实验得到证实，显示出良好的宽带滤波性能，具有加宽/加深的上阻带和锐化的宽通带外抑制裙边。
A new class of wideband microstrip bandpass filters is proposed under multiple resonances of an asymmetric ring resonator. Two capacitive coupling elements are placed at two perpendicular positions of a squared ring, whereas a pair of open-circuited stubs is formed in the symmetrical plane of these two excited ports similar to a dual-mode ring filter in shape. By stretching the paired stubs close to one-eighth of a wavelength, the first two even-order resonances move down to be quasi-equally located at two sides of the first odd-order resonance, thus forming a triple-resonance ring resonator. As interdigital coupled lines are installed at two ports instead of lumped capacitors, two extra resonances can be moved into passband, thereby making up a quintuple-resonance ring resonator. To provide an insight into their operating mechanism, these ring resonators are characterized in terms of transmission line theory. Afterwards, various wideband microstrip ring resonator bandpass filters with one or two asymmetric ring resonators are optimally designed and fabricated. Simulated results are confirmed via experiment, showing good wideband filtering performance with widened/deepened upper stopband and sharpened rejection skirts outside the wide passband.