An analysis of the second-order mixed-coupled bandpass filter (BPF) of a general form is carried out. The resonators in this BPF are presented by a resonant frequency $f_{0}$ and a susceptance slope parameter $b$ . The position of the transmission zero (TZ) generated by the mixed coupling is determined. A correspondence is established between the mixed coupling representation as the sum of magnetic $K_{\mathrm{ m}}$ and electric $K_{\mathrm{ e}}$ components and the linear representation form $m (\Omega) = m_{0} {-} a \,\,\Omega $ . It is shown that the slope of the frequency dependence $m(\Omega $ ) is negative. The conditions for equidistant arrangement of two TZs in BPF with mixed couplings between adjacent resonators are formulated. A fourth-order microstrip quazi-elliptic BPF with two pairs of antiparallel mixed-coupled stepped-impedance resonators (SIRs) is proposed. It reduces the parasitic interaction between nonadjacent resonators and makes it possible to obtain the required frequency responses more accurately. The results of the measurements and simulation are presented.

中文翻译：

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具有两对反并联混合耦合SIR的微带Quazi-椭圆带通滤波器

对一般形式的二阶混合耦合带通滤波器（BPF）进行了分析。该BPF中的谐振器由谐振频率表示 $ f_ {0} $ 和电纳斜率参数 $ b $ 。确定由混合耦合产生的变速器零位（TZ）的位置。在混合耦合表示形式之间建立了对应关系，即磁和 $ K _ {\ mathrm {m}} $ 和电 $ K _ {\ mathrm {e}} $ 组件和线性表示形式 $ m（\ Omega）= m_ {0} {-}一个\，\，\ Omega $ 。结果表明，斜率与频率有关 $ m（\ Omega $ ）为负数。公式化了BPF中两个TZ等距排列的条件，并在相邻谐振器之间进行了混合耦合。提出了具有两对反并联混合耦合步进阻抗谐振器（SIR）的四阶微带拟椭圆形BPF。它减少了不相邻谐振器之间的寄生相互作用，并有可能更准确地获得所需的频率响应。给出了测量和仿真的结果。