Transmission-Type Wide-Band Periodic Filter.

The transmission-type periodic branching filter presently is used as the multiplexer/demultiplexer for communication satellites. This type of filter can be applied to the submillimeter band multibeam communication satellite, in an attempt to realize large-capacity communication for the efficient use of frequencies in the future. It can also be applied to the branching filter in the optical communication, aiming similarly at the large-capacity communication, if the filter is constructed using the dielectric transmission line. To realize such an application, it is desired to improve the performance of the conventional periodic branching filter to realize a wider bandwidth and sharper roll-off of the amplitude transmission response. The conventional periodic branching filter is composed of two 90-deg hybrids, a quarter-wavelength transmission line and a resonator. This type of filter has a narrow usable relative bandwidth of approximately 6 percent, with a frequency response of third-order elliptic function type. This paper proposes a new transmission-type periodic branching filter with two resonators. It is composed of two hybrids and two resonators of different kinds. A bandwidth of approximately twice the width of the conventional filter end an approximately three-times sharper roll-off of the amplitude transmission response, with the frequency response of fifth-order elliptic function type, are obtained. This paper discusses the theoretical characteristics, design method and the result of experiment for this periodic branching filter. As a result of experimental construction, it was verified that the wide-band, low-loss property and the sharp roll-off of amplitude characteristic can be realized. [ABSTRACT FROM AUTHOR]