Mode-Conversion Filters
01 January 1961
A large variety of channel-dropping filters operate through the use of band-rejection filters, and since the microwave art is pushing the usable spectrum to higher and higher frequencies, low heat loss and easy-to-build band-rejection filters are important. This statement is particularly true in the process of separating bands in the long distance waveguide communication system1 that operates with circular-electric mode in the millimeter wavelength region. The information sent from repeater to repeater through the low-heat-loss multimode circular waveguide must be separated into tens of bands for the purposes of regeneration and amplification at each repeater. Since each repeater operates in single-mode rectangular waveguide, one possible solution is to convert the circular-electric wave to fundamental mode in rectangular waveguide and then to drop the different channels with known techniques. This solution has several disadvantages: the filters are relatively lossy because of the low intrinsic Q of parallelepi149