Waveguide reflective harmonic filter

Claim 1

In a microwave waveguide reflective filter, means forming a hollow primary waveguide to be connected in circuit between a source of microwave energy and a load, the microwave energy from the source being characterized by having a desired fundamental mode of energy at a frequency within a fundamental passband of frequencies and having undesired harmonic energy within harmonic frequency bands of the fundamental passband, said primary waveguide being dimensioned to be cut off for frequencies below the fundamental passband for transmission of the fundamental mode energy to the load, means forming an array of resonant secondary waveguides dimensioned to be cut off for the fundamental mode energy and to be above cutoff for the frequencies of the harmonic bands, said secondary waveguides being coupled through the walls of said primary waveguide to the harmonic microwave energy in said primary waveguide for reflecting harmonic band energy toward the microwave source, the improvement wherein, said array of secondary waveguides includes a first portion of said array being resonant within the second harmonic band, a second portion of said array being resonant within the third harmonic band, and a third portion of said array being resonant within the fourth harmonic band, said resonant secondary waveguides being tuned to different frequencies within each of the harmonic bands for broadbanding the filter.