Design of Interstage Coupling Apertures for Narrow-Band Tunable Coaxial Band-Pass Filters (Correspondence)

The design technique to be described in this note is applicable to tunable coaxial baud-pass filters having narrow bandwidths (i.e., less than 10 percent). In the frequeucy range of 1500 Mc to about 10,000 Mc, coaxial band-pass filters usually employ coupled λ/4 resonant cavities. Unlike direct coupled waveguide band-pass filters which are often amenable to a complete paper design, these coaxial band-pass filters require empirical developmental methods to supplement the filter theory customarily employed. The purpose of this note is to present a technique for simplifying the empirical development.