Propagation between these two buildings at a frequency of 177 megacycles has been studied with the object of providing a radio circuit with flat response over three megacycles. It was found that the received signal arrived over several paths, some of which were due to reflections from ground and from near-by buildings. The effects on the indirect rays of horizontal and vertical directivity, and change in angle of polarization were observed. The theoretical response curve for an assumed combination of rays was compared with the curves obtained experimentally.HE propagation studies discussed in this paper were undertaken 2 in connection with providing a radio circuit for the transmission of television images from the studios in the RCA Building to the transmitter in the Empire State Building. A relatively high carrier frequency was required to transmit both side bands at modulation frequencies up to 1.5 megacycles, and to minimize man-made noises generated in electrical equipment. A frequency of 177 megacycles was selected to avoid possible inteiference from the Empire State television and sound transmitters which will operate in the neighborhood of fifty megacycles.The two buildings are approximately 4600 feet apart, and are considerably higher than the buildings lying directly between them. Over this relatively short path, between high buildings, the signal at the receiver would be expected to consist of a direct and a number of reflected rays. The effect of this combination of rays on the radio circuit response curve was investigated in an effort to provide a flat response curve over a frequency band at least three megacycles in width.During this investigation, the receiving antenna was located in a small balcony outside of the eighty-fifth floor, on the north side of the Empire State Building. The transmitting antenna and transmitter were located first on top of an elevator shaft at the fourteenth floor level of the RCA Building, and later moved to a large balcony at the sixty-seventh floor.The transmitter was a line controlled master oscillator, followed by a power amplifier stage. Frequency variation was accomplished by
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