maybe a single conductor wire ran in the attic and the other was ran to a ground, I could be mistaken but i used to take apart many old radios that would have these, back when the electromechanical speaker would weigh like 25 lbs :), with a big autotransformer driving the speaker.
Obsolete? Absolutely - especially since all TV has since gone digital.
The 300 ohm aerial system in my house is alive and well with clean digital signals issuing forth on both VHF and UHF. It's only the modulation that's changed, not the bands in which it is transmitted.
