High-power Radio Research Articles

Ultra-Short-Wave Wireless Communication

IN his Friday evening discourse at the Royal Institution on December 2, the Marchese Marconi described the important results of his recent investigations into the properties and behaviour of very short electric waves, Numerous distance tests and a few official demonstrations have been given from time to time, and each has proved the availability and practicability of these waves for the purposes of radio communications. Soon after a duplex demonstration over a distance of twenty-three miles between Santa Margherita and Sestri Levante, the Vatican authorities decided to adopt the new system for telephonic communication between the Vatican City and the palace of the Pope at Castel Gandolfo, a distance of 20 kilometres entirely over land, and screened by intervening trees. In connexion with the establishment of this service, successful tests took place towards the end of April this year; during one of these tests waves had to pass through all the masts and aerials of the high power radio station of the Italo Radio Company at Terranuova. Following a series of experiments with waves of the order of 50 centimetres length conducted between Marconi's yacht Elettra and the station at Rocca di Papa, near Rome, the most outstanding result was the successful establishment of communication from Bocca di Papa to Cape Figari, Sardinia, over a distance of 168 statute miles (275 kilometres) on a wave-length of 57 centimetres. All previous distance records of communication by means of wave-lengths less than one metre were thus far surpassed, and it was effectively demonstrated that these very short waves can overcome the supposed obstacle presented by the curvature of the earth, the distance between the two stations being considerably in excess of the optical range. A new technique is thus developed which is bound to extend very considerably the already vast field of the applications of electric waves to radio communications. The new system is unaffected by fog, and offers a high degree of secrecy, by virtue, principally, of its sharp directive qualities.

Radiation Measurements of a Short-Wave Directive Antenna at the Nauen High Power Radio Station

This paper is a report on the experimental investigation of the, raidiation of a short-wave directive antenna at Nauen. Measurements were made on the ground and also in the air, using an airplane. The results, plotted in the form of radiation characteristic curves, were compared with calculated radiation characteristics. In the case of the horizontal radiation characteristic the agreement between measurement and calculation is comparatively good. For the vertical radiation characteristic curves calculations were made for the two limiting cases: a. Nonreflecting earth surface. b. Perfectly reflecting earth surface. The measured vertical characteristic agrees rather well with case b, from which it follows that the surface of the earth, under the conditions prevailing at Nauen, shows a very high reflecting power. This is also confirmed by the fact that the field strength increases very rapidly from 0 at the surface of the earth as the height increases. It is also found that the radiated energy is highly concentrated in the desired direction in the horizontal as well as in the vertical plane.