weather forecasting baloons

hi all,
can anyone plz tell me about the kind of antennas used in weather forecasting balloons.

thanks in advance!

http://en.wikipedia.org/wiki/Radiosonde

thank u so much.Dat was really helpful.i wud be grateful if someone cud tell me abt the kind of antennas used for the transmission and reception in weather balloons.

Dipole antenna is used in many weather balloons.

http://www.hard-core-dx.com/nordicdx...al/baloon.html
http://www.textfiles.com/uploads/hamballoon.txt
http://www.freepatentsonline.com/3781893.html