More on Antennaes...
A quick consult with Michael Chaldil supports my original thought which is that I am essentailly talking about live/real-time signal processing. A mic could be used to bring in the signal (an omni-directional) and then the signal could be processed—reverb, feedback, delay etc—and then output/amplified.
But how do you wear the equivalent of a rack-mounted signal processor? Michael suggests hacking a Wah-Wah pedal...