Most amateur radio operators who are involved in portable operation spend a fair amount of time looking for antenna systems that are light and portable, easy to set up and take down and that demonstrate high performance. Based on the original design (QST Magazine, April 2004, p.37) by Brian Cake, KF2YN, here’s a vertical that’s small, light and portable, needs no counterpoise and performs as well as many home antennas. Visit http://www.qsl.net/hb9mtn/hb9mtn-c-pole.html to see construction details for this antenna.
The HB9MTN web site shows an antenna that is designed for use on the 20 meter band, however this can be scaled for use on other bands. This page contains a calculator that will give you the appropriate length of each segment in the drawing. It uses the base reference frequency of 14.24 MHz and directly scales the length of each segment based upon your desired operating frequency.
To use the following calculator, enter your desired operating frequency in the “Target Frequency” box and click the “Calculate Lengths” button. Then use the resulting calculated lengths with the corresponding lettered segments on the diagram to cut your antenna to the right length. Always check your antenna with a reliable SWR meter to avoid damage to your transceiver.
Thanks to Brian V. Cake, KF2YN, for the original antenna design, to Ed Bosshard, HB9MTN, for the graphics, photos and construction details, and to Tim McDonough, N9PUZ, for providing the spreadsheet that the calculations are based upon.