Magellan was able to acquire detailed information about Venus because of the fact that it used sophisticated equipments and radar technology.
Most of the communication equipments were housed into forward equipment of the craft. These equipment included modulators, receivers, transmitters, data encoders, switches to connect various devices etc.
The transmitter system was used to transmit the data related to experiments, spacecraft conditions from Venus to earth.
Antennas were used to collect the information about craft, experiments etc in the form of signals. Not only this, antennas were used to collect the radar pulses and encoded commands sent from the earth. Then it was given to receivers and then to decoders from where signals were decoded to get the desired task done in the craft.