After rather a long time, we finally have the design files for the communications tower online at:
https://github.com/servalproject/foss-comms-tower
We also have a paper that we will present at the IEEE Global Humanitarian Technology Conference in San Jose in October 2014.
Once the conference has been held, we will post a link to an open-access copy of the paper. However, you can already get more detail from the thesis of Greg, the lead student on the project. His thesis is included as a PDF in the GitHub repository mentioned above.