var fDesc=new Array(); fDesc[0] = "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."; function tShowHide(id, show) { var s = document.getElementById("desc"); if ((s.innerHTML.length<=212 || show==1) && show!=2) { s.innerHTML = fDesc[id]; if (document.getElementById('m1')) document.getElementById('m1').style.display='none'; if (document.getElementById('m2')) document.getElementById('m2').style.display='none'; if (document.getElementById('more_txt')) document.getElementById('more_txt').style.display='inline'; } else { s.innerHTML = ''; } }