Black Cat Systems ( announces that RF
Toolbox version 3.8.0 has been released The latest version adds a
resistor calculator, which computes the required series and parallel
combinations for a desired resistance.

RF Toolbox is an antenna design package for amateur (ham) radio
operators, and other radio enthusiasts, as well as those in the
communications professions. It’s available for Mac OS X and Windows.
RF Toolbox costs US$19.99; a demo is available for download.