Effects of dielectric losses on the performance of evaporated thin-film distributed RC notch filters

The effects of dielectric dissipation have been included in studies of distributed RC notch filter networks, and it is shown that these may have considerable influence on the magnitude of the optimum notch parameter /spl alpha//SUB 0,1/ and the location of the lowest order optimum notch frequency /spl omega//SUB 0,1/. Voltage transfer function relationships, incorporating a frequency-dependence dissipation factor B(/spl omega/), are given for uniform and exponentially tapered structures. The measured transfer responses of aluminium-silicon monoxide-nichrome evaporated thin-film notch structures were in good agreement with these values predicted. Uniformly distributed RC notch filters exhibited optimum notch attenuations of 71 dB, while exponentially tapered RC filters with taper D=+1 gave 62-dB optimum notch attenuation together with reduced rejection band width.