Generalized interdigital linear phase networks with optimum maximally flat amplitude characteristics

The closed-form solution is presented for microwave bandpass nonminimum phase transfer functions that exhibit an optimum passband maximally flat amplitude characteristic while maintaining a maximally flat group-delay response about band center. There are two basic transfer functions obtained depending upon whether the degree of the resulting network is even or odd. The transfer characteristics are shown to be capable of being realized by resistively terminated symmetrical generalized interdigital networks. Synthesis procedures are presented for the case of n odd corresponding to the input and output ports being situated at the same physical end of the generalized interdigital line and for the case n even where the ports are at opposite ends. These procedures are based upon the one-port synthesis of the even- and odd-mode forms. Finally, the synthesis procedure is illustrated for the case of
n = 6
, and typical transfer characteristics are shown for this example.