Abstract

Filters designed using the microwave prototype techniques described by Baumeister (ref. 1 and 2) have decreasing cuton and cutoff edge slopes with increasing numbers of cavities. If we neglect the effects of phase dispersion narrowing, the edge slopes for maximally flat designs are found to be proportional to bandwidth and depend only on the number of cavities in the design. The proportionality constants for designs having up to eight cavities have been determined and are reported. In addition, the proportionality constant is found to differ from that for the true maximally flat case in quasimaximally flat and Chebyshev type designs. In the Chebyshev case, the slope is found to decrease with decreasing passband transmittance. This variation in proportionality constant with passband transmittance has been plotted for the three—cavity case and equations are presented that can be used to design three—cavity filters with specific minimum passband transmittances.

© 1988 Optical Society of America