An amateur radio set installed in a car by A. H. Grebe, a radio manufacturer of New York in 1919, who is shown speaking into the microphone.  The bulky <a href="https://en.wikipedia.org/wiki/vacuum_tube" class="extiw" title="en:vacuum tube">vacuum tube</a> set is visible in the back seat. It used <a href="https://en.wikipedia.org/wiki/medium_wave" class="extiw" title="en:medium wave">medium wave</a> frequencies around 2 MHz, requiring the cumbersome "<a href="https://en.wikipedia.org/wiki/T_antenna" class="extiw" title="en:T antenna">inverted L</a>" wire antenna mounted on the bumpers, which could be quickly put up and taken down and stowed under the car's chassis.   The car's body was used as a <a href="https://en.wikipedia.org/wiki/counterpoise_(ground_system)" class="extiw" title="w:counterpoise (ground system)">counterpoise</a>.  The radio set was powered by a separate storage battery, with a small <a href="https://en.wikipedia.org/wiki/dynamotor" class="extiw" title="w:dynamotor">dynamotor</a> to generate high voltage for the tube's <a href="https://en.wikipedia.org/wiki/plate_electrode" class="extiw" title="w:plate electrode">anode</a> supply.  Grebe noted that he could hear other cars approaching on the road, as the receiver would pick up the radio noise from their unshielded spark plugs. Broadcasting began in 1920, about the time that vacuum tube <a href="https://en.wikipedia.org/wiki/radio_receiver" class="extiw" title="en:radio receiver">radio receivers</a> became available, sparking a "radio craze" during the early Roaring 20s.  Many car owners installed home radio sets in their cars as a novelty. Car radios weren't manufactured until 1930, and did not become standard in vehicles until a number of years later.<br><br>
Caption:"<i>CUMBERSOME - BUT ESSENTIALLY PRACTICAL.  Here is a real antenna, easily dismantled, that A. H. Grebe, of New York, uses for transmitting and receiving.</i>"
Picture credited to Pacific and Atlantic
1919
Retrieved March 7, 2014 from <a rel="nofollow" class="external text" href="https://books.google.com/books?id=r9Y6AQAAMAAJ&amp;pg=PA249">Frederick Siemens, "Radio on your motor car" in <i>Popular Radio</i> magazine, Popular Radio, Inc., New York, Vol. 2, No. 4, December 1922, p. 249</a> on Google Books.  Picture originally published in <a rel="nofollow" class="external text" href="https://earlyradiohistory.us/1919auto.htm">in   A. H. Grebe, "The Auto Radiophone" in <i>Radio Amateur News</i> magazine, August 1919, p. 58,59</a>