Characteristics of new types of quasi‐optical diplexers

Abstract

AbstractThe quasi‐optical diplexer presently is considered to be as interesting as a special‐purpose filter, which divides or mixes the electromagnetic waves above microwave frequency in free space. This paper reports on the new types of diplexers: the gridded square, gridded square frame and gridded double square frame types. The feature of these new types is that various frequency characteristics from broad to sharp, can be realized by adjusting independent parameters, and the symmetry or linearity around the resonant frequency can also be realized. This has been difficult in past diplexers. By a systematic experiment, the frequency characteristics of the new types of diplexers are examined. Empirical formulas are derived for the resonant and anti‐resonant frequencies, as well as fractional bandwidth as functions of dimensional parameters. Based on these expressions of the characteristics, the design protocols are presented to meet various requirements. Although there still exists an error in the sense of reproducibility, which is less than 15 percent, the design for the proposed diplexers is established. Thus, the diplexers proposed in this paper have desirable characteristics, which have not been observed in the past. With the detailed design formulas for a wide range of frequencies from roughly 1 to 100 GHz, the diplexers can cope with various requirements, and a diversity of applications can be expected.