Comments and technical contributions are welcome.
Here's a very good program for computing the design of a DL6WU type yagi. This program has been recommended by Wes WA5TKU in his HamCom and Microwave Update 2009 presentations on building 23 cm. band yagis. It is written by VK5DJ and he makes it freely available for download from his website at: http://www.vk5dj.com/yagi.html
Another treasure chest of information may be found at http://www.ifwtech.co.uk/g3sek/diy-yagi/
N0EDV with 4 foot Andrew dish for 902 MHz with stock dipole feed.