Abstract :
December 3, 1934, Westinghouse radio station KYW began broadcasting from its new facilities in Philadelphia, Pa., on a frequency of 1,020 kilocycles per second. Prior to that time, the station was located at Chicago, Ill., the first program having been broadcast from there in 1921. The new transmitter, which is shown in the accompanying illustration, is at Whitemarsh, Pa., a few miles north of Philadelphia; although designed as a 50 kw station, it will operate initially at 10 kw. The design of the station is notable for its compactness. Two features that resulted in saving much space are the use of extremely compact nitrogenfilled radio capacitors and a high voltage rectifier of new design. Foremost among the other technical innovations of the station are its directional antenna system, the use of alternating current for all transmitting tube filaments, and the use of a cathode ray oscilloscope for monitoring. The antenna system consists of 4 245-foot vertical masts each connected separately to the transmitter; by controlling the phase relationship of the current delivered to these 4 masts it is possible to adjust accurately the direction of the radio beam so that maximum signal will be delivered into Philadelphia and Allentown, Pa., and minimum signal in other directions where, if a signal were present, interference might result with other radio stations. Each mast consists of a 200 foot length of telescopic steel tubing mounted on insulators at the top of a wooden framework tower 45 feet high. A specially designed counterpoise is used to improve the ground system; this consists of a total of about 55,000 feet of copper wire formed into special cages which are suspended horizontally between insulators on poles at a height of 10 feet above the ground around the bases of the 4 antenna masts.
