Bandpass Filters Using Strip Line Techniques

Strip lines provide a convenient transmission medium for the realization of microwave filters. Since bandpass filters designed in waveguide and coaxial lines would be large at ultra-high frequencies, strip lines afford a practical means of realizing filters which are simply fabricated, are readily reproduced, and, in most cases, represent an appreciable savings in size and weight. Of the different types of strip transmission lines currently in use, the so-called "sandwich" structure has been employed at Melpar for two reasons: (1) very broad-band coax-to-strip-line transitions are easily realize; and (2) the electromagnetic field is essentially confined between the two ground planes, thus reducing problems in packaging.