Helical 2.10

Helical is a graphics-intensive bandpass filter design and analysis program based on the helical resonator.
Main features:
- 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.