Elsie is an uncommon commercial-grade lumped-element ("L-C") electrical filter design and network analysis program, directed toward the engineer or technician involved in that line of work.
Elsie is 32-bit Windows electrical filter design software nicely written to help engineers design and analyze lumped-element filters in the audio through microwave range. Thanks to the standard interface, all of the various aspects of program operation are quite easy to use. Most options are selected by clicking on buttons. No scripts. Not a DOS lookalike.

This filter design program designs and then analyzes filters with a wide variety of topologies and families and with specified orders, bandwidths, impedances and the like. The usual filter families of Butterworth, Chebycheff, Cauer (including the zig-zag transform), Bessel, Gaussian, Constant-K and M-derived are covered.

The quality of the screen graphics is very high (dependent on your monitor), and include transmission (S21), return loss (S11), transmission with its angle, group (envelope) delay, VSWR, input impedance and its angle and more (selected pairs of these items).

To maintain this level of quality, the outputs to the printer are not "screen dumps" but instead are from a separate set of dedicated routines which write directly to the printer. The quality of the graphics as delivered by the printer will be limited only by that printer and the number of test frequency steps used (up to 2048 steps).

The graphics items automatically adjust themselves to various resolution screens. As an example, the size of the plot on monitors of 800x600, 1024x768 or 1280x1024 is the same in terms of centimeters or inches. Aspect ratio of the screen display can be adjusted so Smith Charts look circular on any monitor width-to-height ratio.