A rectangular coaxial line low-pass filter with simple structure

In this paper, a simple structure of low-pass filter with low passband insertion loss is proposed. The filter is composed of a rectangular coaxial line and two lines of symmetrically arranged screws on the opposite sides. And a unit circle will be analyzed. Furthermore, this paper will show the realization of an order-11 low-pass filter, whose cutoff frequency is 20 GHz, based on this structure. This new-type filter have a sharp rejection, low insertion loss and relatively high power handing capacity. The simulation results indicate that the rejection is better than 40dB from 22 to 30.5 GHz and the reflection coefficient is lower than -10dB over the full pass band from 0 to 20 GHz.