Extending the Realizable Bandwidth of Edge-Coupled Stripline Filters

This paper discusses the physical realizability of wide-band parallel-coupled filters in edge-coupled stripline form. Based on the sine-plane approximation, a design procedure that permits the presently realizable bandwidth to be extended from 20 to 45 percent is developed. The new design optimizes the interior impedance level and replaces the end-coupled line sections by quarter-wavelength transformers.