well, in RT, not only do you have to have an antenna catch the Thing you want in its cone of transmission, not only does it have to be close enough for the signal to actually reach, but you also have to transmit BACK from the other ship for the connection to work
so basically for an orbital network you'll want satellites with at least three antennae, four or more preferable
edit: and yes, that means transmitting a signal with your Uber Antenna from kerbin to jool won't work if the receptor craft has some stuffty 100km antenna