Elliptic Designs:

Elliptic  designs eight different coupled line filters with Elliptic type frequency response.  all of the parameters needed for filter construction are computed.   The program accounts for "T", cross, and step junction effects. Data is supplied in tabular and graphical form for either English or Metric units.  Two classes of filters having Elliptic-type response characteristics may be designed.  Flat group delay filters may be designed but with varying performance depending on the type of filter.

CONVENTIONAL ELLIPTIC

First it designs four types of traditional Elliptic filters illustrated in this page:  the Half-Wave Parallel Coupled, Interdigital, Combline and Hairpin filters. For these filters, transmission zeros are formed by adding two additional lines to the array of lines comprising the filter.   Zeros may be selected to trap out any two frequencies. When placed close to the filter passband edges a filter characteristic is created which has much steeper filter rejection at the band edges. However, the return loss may be degraded.

CROSS-COUPLED FILTERS 

Secondly it designs  four types of filters known as Cross-Coupled filters.  These are designed by lightly capacitively coupling a line to a more distant line, e.g. coupling the first line to the fourth.  

OTHER

Also designs coupled lines separated by a septum opening