theremin question

hi,

I builded the theremin with the antenna

http://interface.khm.de/index.php/lab/experiments/theremin-as-a-capacitive-sensing-device/

and is kind of working as I realized I dont fully understand something: one question, is not clear to me where the antenna´s second contact should go?? I connect the first in the pin 1 after the 10pf capacitor as indicated in the diagram, but where is the other side of the antenna supposed to go? I build the experiment and it works, I connect the other side to it self in a loop? or to ground? or where? thank you... :D