Multiwire T aerial of radio station WBZ in Springfield, Massachusetts, USA, in 1925. Licensed on September 15, 1921, it is claimed to be the first commercially licensed broadcast station in the US (although other stations like WWJ and KDKA had been broadcasting under other licenses for several years). Located at the Westinghouse plant in East Springfield, it broadcast on a wavelength of 360 meters (833 kHz) with a power of 2000 W. The antenna is typical of the wire antennas used for mediumwave broadcasting in the 1920s. The vertical wire connecting to the middle of the antenna is the radiating element, and the multiwire horizontal part is the capacitive "top load"; its function is to increase the oscillating currents in the vertical wire to increase the radiated power.