The Itty Bitty Radio Telescope (IBT) is a very easy-to-build radio telescope that can be fashioned from a used DirecTV-style satellite dish. This telescope can be used to demonstrate blackbody radiation as it can detect radiation from the Sun as well as any other hot object, like the human body. To learn how to construct the IBT, check out these links:
“Procedure for Making the Itty Bitty Radio Telescope”: http://www.aoc.nrao.edu/epo/teachers/ittybitty/procedure.html
“The Itty Bitty Telescope (IBT): Tips for Building and Using a Simple Radio Telescope”: http://www.gb.nrao.edu/epo/ambassadors/ibtmanualshort.pdf
For experiment guides, lab sheets, and additional info, check out this document prepared by the SETI League:
http://www.setileague.org/articles/lbt.pdf
Finally, if you’d like more of a challenge and want to integrate your Itty Bitty Radio Telescope with open-source software, check out this instructional webpage: http://www.stargazing.net/david/radio/itty_bitty_radio_telescope.html