From ARRL site:
A new, highly informative article on how the world's first Amateur Radio satellite, OSCAR-1, came to be designed, built and launched has been posted to the ARRL's Space Communication web page (see the "Articles" section). Written by Andreas Bilsing, DL2LUX, "OSCAR-1 Launched 50 Years Ago" was first published in the German magazine Funkamateur. It is reprinted with their permission. OSCAR-1 was launched just over 50 years ago, on December 12, 1961.
Link the the article in English http://www.arrl.org/files/file/Technology/Bilsing.pdf
73 Trevor M5AKA AMSAT-UK http://www.uk.amsat.org/ ----