Low-Pass Filters Using Coaxial Transmission Lines as Elements

Transmission-line low-pass filter design is in large measure dependent upon the frequency band in which the filter is to be used. Certain approximations may be made at comparatively low frequencies which simplify the problem, refinements in the analysis having to be introduced as the filter pass band is extended to higher and higher frequencies. Four transmission-line low-pass filter designs are presented which specify the mechanical dimensions required for constructing low-pass transmission-line filters having pass bands with a width of as much as 4000 Mc.