To reduce the length of the whole filter device, to satisfactorily keep a voltage standing wave ratio and an insertion loss and to suppress the spurious of a wide range in the case of applying the filter device to a radar.
At the input/output opening of a waffle-iron filter 11, resonance windows 14A and 14B having the thickness of λ g/50 to λ g/5 are formed as reactance elements and to connect a waveguide 15 through these windows 14. Thus, a conventional matching device is unnecessitated and the whole filter device can be shortened. At a boss within this filter 11, acrylic resin of a thickness ≤0.3 mm is formed on its surface and an upper surface corner part is chamfered to improve power endurance. A stab for adjusting a phase can be provided at the input/output part of the filter 11. In a corrugate type filter, the resonance window of a gap expanded by the size of λc/400 to λc/15 compared with the gap of a filter center part as a reactance element can be formed simultaneously.
YAMASHITA TOSHIHIKO
AKASHI NAOKI
SAKUMA AKIYOSHI
