Have to show this as it is an excellent idea for the PMR Band and can only say congratulations and take my hat off to him for the antenna. In the old days I was running a Carant 18 element from the hills for 446Mhz for the PoMeRanc events in the Czech Republic as there was not these antennas available. But take a look and seems an easy antenna to make and so as before congrats and if you build it then let me know how many miles or KM you are working with it.

And if like me this antenna building melts your mind then there are commercially made antennas for PMR and Freenet and I buy mine from the company below:

http://www.lambdahalbe.de/drahtantennen/freenet-pmr-duoband/index.html