Cell of the waveguide band-pass filter with poles of attenuation on finite frequencies

Waveguide band-pass filters with cavity have high characteristic stability and small losses; however, the dimensions and weight of such filters are too big. As a rule, it is polynomial filters with direct coupled cavity or more seldom with quarter-wave coupled ones. In such filters all zeros are located in a passband, and the poles are on a zero frequency and in infinity. The greater selectivity can be achieved if the frequencies of these poles are given the finite values. Frequently in practice, the monotonous increasing of attenuation in stop-band is not required, and the distribution of poles by Butterworth or Chebyshev is not effective, and filters have superfluous electrical and constructive characteristics. A band-pass section is described.