Diplexer - from Tonne Software

The Windows ® program for designing diplexers of both
the highpass/lowpass and bandpass/bandstop types

This program is copyrighted and is not to be placed on another website
nor is it to be placed on any medium for distribution excepting the
CD accompanying the ARRL Communications Handbook.
If you have obtained it from another site, they are posting it illegally.
Such copies may contain spyware or other malware and are probably obsolete.

Included on the CD accompanying the 2010 ARRL Handbook

Diplexer is one of the programs included on the Bonus CD accompanying the 2010 ARRL Handbook

Current revision is 2.09; revision history is at the bottom of this page

This program expedites the design of lumped-element diplexers using both the lowpass/highpass and the bandpass/bandstop topologies.

Here are the highlights of this program:

This interactive program accepts for its inputs the crossover frequency (for the highpass/lowpass topology) or the lower and upper bandedges (for the bandpass/bandstop topology), the order (number of parts), the passband ripple and the system impedance.
Click on the Design button and you see the schematic drawn on the screen including component values.
On the Plot screen, you can "tune" the crossover or bandedge frequencies, the passband ripple and the order and get instant feedback regarding how those items affect the transmission to the two ports as well as the return loss looking into the common port.
Click on the Print button and send the data plot and the schematic to the printer using a very high resolution - presentation quality - plotting system (not just a screen dump).
Diplexer generates schematic files for LTspice. (Tonne Software has no connection with Linear Technology.)
On exiting the program the current design is saved to enable a simplified program restart.

Click on these graphics to see larger Design and Plot screens:

Updated to 2.09 - allow the user to enter up to five marker frequencies

Updated to 2.08 - lowered minimum-allowed crossover frequency to go as low as .1Hz to allow determining normalized (one ohm, one radian/second) values

Updated to 2.07 - added LTspice schematic routine to Bandpass/Bandstop version

Updated to 2.06 - added LTspice schematic routine to Highpass/Lowpass version

Updated to 2.05 - extended frequency range to 10 Hz-10GHz

Updated to 2.04 - added bandpass/bandstop topology.

Updated to 2.03 - added plotting for return loss.

Updated to 2.02 - added plotting for transmission. This also allowed the tuning of various items to be added.

Released as 2.01 - December 2005