On Dec 1, 2007, at 9:31 PM, Bruce wrote:

you can't make it circular because you would need either 2m elements or 70cm elements on both planes. the arrow is designed as a 2m yagi on one plane and a 70 cm yagi on the other. you rotate your hand left and right to change polarity as you listen to the bird.

Thanks Bruce, but I actually have two 70 cm antennas at 90 deg to each other:

http://www.arrowantennas.com/437x14ii.html

As I understand things, I should be able to use a phasing cable to circularly polarize it.