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The Windows ® program for designing helical-resonator-based filters

This is a graphics-intensive bandpass filter design and analysis program based on the helical resonator.

Here are the highlights of this program:
  • The program designs bandpass filters with a selection of the order from 2 to 12, odd or even.

  • Center frequency, bandwidth, and passband ripple are all adjustable. The ripple value may be set to zero for a Butterworth response.

  • The dimensions of the individual resonators are set by specifying an impedance value. Then the actual terminating impedances are separately chosen.

  • Analysis is based on an equivalent circuit using capacitive input, interstage and output coupling.

  • Analysis is delivered in both tabular and graphical form and includes transmission, return loss, phase, envelope delay and input impedance with its angle.

  • The dimensions of the resonator(s) delivered by the program are shown in graphical form.

Adjusting your own helical-resonator-based bandpass filters can be tricky. Consider visiting a commercial operation such as this one:
(We can vouch for the quality of their products.)

Updated to 2.07 - Total rewrite of Pictorial page, error trapping of impedance entry
Updated to 2.06 - Major rewrite of every part of the program to greatly improve the interface
Updated to 2.05 - added note "Dimensions are in inches"
Updated to 2.04 - corrected failure to use correct value of Q for inductors in analysis via equivalent circuit
Updated to 2.03 - show unloaded resonator Q values, both round and square chambers


Coaxial Resonators with Helical Inner Conductor
W. W. Macalpine
Proceedings of the I.R.E., December 1959

Need A Helical Filter?
Lee R. Watkins
RF Design, May/June 1981

Realization of a Filter With Helical Components
A. I. Zverev and H. J. Blinchikoff
I.R.E. Transactions on Component Parts
Volume CP8, September 1961

Design Of A New, Low-Cost Helical-Resonator Filter
Solomon I. Hecht
Microwaves, February 1966

Helical Filters (Chapter 9)
A. I. Zverev
Handbook of Filter Synthesis
John Wiley & Sons, 1967
Library of Congress Card Number 67-17352

Helical-Resonator Filter Design,
Vincent G. Heesen
RF Design, July 1985

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