To provide a high-performance and small-sized delay line electromagnetic wave frequency selection filter having large extinction ratio with a side lobe.
The delay line electromagnetic wave frequency selection filter has structure that two dielectric waveguides each having a straight line part 21 of the dielectric waveguide and a delay line part 24 of the dielectric waveguide are coupled a plurality of times periodically through different paths by directional couplers, wherein the coupling degrees of the directional couplers 22-1 to 22-N are adjusted so that directional couplers 22-1 to 22-N located at center of the delay line electromagnetic wave frequency selection filter have coupling degrees of the maximum value and coupling degrees of directional couplers 22-1 to 22-N of peripheral parts become smaller as they get away from the center of the filter. Thus, extinction ratio with side lobe of the delay line electromagnetic wave frequency selection filer having the above structure is increased.
MATSUO SHINJI
ITABASHI SEIICHI
FUKUDA HIROSHI
Kazuo Abe