As a ham radio operator, aside from writing software, I have always been an antenna freak. I'm not one to spend a lot of money on a commercial antenna that I can build from parts laying around or found at the local hardware store. Recently I was playing around with a 5/8 wave vertical antenna and needed to construct a matching unit. I spent more time researching the information I needed to build the matching unit than I did actually building the antenna, matching unit, and testing the thing.

 

That got me to thinking ( a dangerous thing according to my XYL ), why not build a simple program that would allow others to use those formulas found strewn across the following references:

Practical Antenna Handbook, Joseph J. Carr. ISBN: 0-83069-270-3

ARRL Antenna Handbook, American Radio Relay League, ISBN: 0-87259-206-5

Antenna and Techniques for Low-Band Dxing, John Devoldere, 0-87259-466-2

Download the Setup File.

The program consists of tabbed pages for various antenna and transmission line calculation. Here we can compute the values for an inverted L network that will allow you to match the 50 ohm output of the radio or Source impedance to the low impedance normally found in a vertical antenna. Al that is now required is to locate a 150pF capacitor and wind a coil of 0.13uH and you should have a pretty good match to the antenna.

Need a 5/8 wave vertical for 10 meters, here we can compute the necessary length in the units of choice. This will get you into the ballpark, and your handy-dandy MFJ antenna analyzer will get you into resonance and produce the load impedance for calculating the matching unit.

If you have ever had a burning need to get a bearing and distance to Drumsite on Christmas Island along with the local sunrise and sunset time, this is the place. You even get a Google overhead shot of the location. ( NOTE: The data for this is stored on my Linux Server and will require an internet connection to access )