I have built helix antennas from the sites of G6LVB and N4WYK all with PVC.   Here are some good websites for 2.4GHz helix antennas.   1. http://webpages.charter.net/n4wyk   Click on satellite website, then click on "2401MHz Helix" above the picture of the antenna.   2. http://ve2zaz.net/   Select 2.4 GHz helix.   3. www.g6lvb.com/   Select quadruple helix for AO-40.   4. www.qsl.net/ve3cvg/antennas/2400/   5. http://members.aol.com/k5oe   A site for good reading and links.   There are advantages and disadvantages to each type, dish, yagi, or a helix antenna.   If I can be of any help, please email me.   73, Mike K9QHO (AMSAT 33589)