A novel method of passive harmonic wave suppression based on frequency selection for waveguide filter

A novel method of passive counteraction technique is proposed to suppress harmonic waves of waveguide filter. The method is to attach a new one-port device to pass harmonic waves only and then echo them to counteract the waves in the direction of transmission. The general design procedure and its technical details are studied, especially the skills how to set the position of the probes. Experiments prove that the method is easy to adapt the traditional waveguide filter to achieve wide stop band, both 2nd and 3rd spurs are below -20 dB overall.