WIRELESS WORLD.

Taranaki Daily News, 19 June 1925, Page 11

WIRELESS WORLD.

SHORT WAVE LENGTHS. MAY REVOLUTIONISE WIRELESS WORK. “The greatest discovery in the wireless field since the introduction of the third electrode into the Fleming valve.” Thus, in the opinion of “Sparks” in the Lyttelton Times, could be described the latest discoveries in the use qf the shorter waves for long-distance wireless communication, which possibly may result in the revolutionising of all our present ideas regarding power and wavelengths. Briefly it has been discovered that the shorter waves of about twenty in length are far more efficient for communication during certain hours when daylight predominates over the distance between transmitter and receiver than are longer waves, even the waves as short as forty metres. This has opened up a vast new field for investigation, which now is being searched by experimenters, both amateur and professional. Mr. R. Slade, of 4AG Dunedin, is a pioneer in this field in New Zealand, and since the beginning of this month he has been carrying out tests in conjunction with Metropolitan-Vickers, Ltd., England. The British station has been sending yjut test signals to schedules arranged by cable with 4AG, who has been forwarding reception reports by cable. It ig not necessary to enter into the details of the transmissions, but the general results of the tests may be noted.

Using a power of 1.25 kilowatts on various wave-lengths varying from 19.8 to 28j8 metres, signals from the British station have been received by Mr. Slade from their commencement at about 10 a.m. each day until they faded out at about 2.30 p.m. on the same day. The signals from their commencement at 10 a.m. (New Zealand time) gradually increased in strength until about 11.50 a.m. of each day, when maximum strength was attained. The signals then invariably became gradually weaker, until they were lost altogether about 2.30 p.m. Signals transmitted from England at mid-day Greenwich time (11.30 p.m. New Zealand time) were not heard at all by Mr. Slade. This last sentence contains the germ of further interesting problems.

It is noteworthy that when British S ™ mol,cis ) and Australian 2GM (Mr. C. D. Maelurcan) are working on twenty metres in davlight, 4AG cannot hear 2OD at all. This is probably accounted for by the one and a half hour’s difference between the time. , 'lt would now appear that there is a direct relationship between the height of the sun and the carrying power of the shorter waves; and, further, that given the wave-length to be transmitted and the height of the sun, it is possible to calculate the spot at which a transmitted signal will best be received. /

Tins, of course, is a tremendous new v P ,f orward - S P ac e will not permit or the theory being given here, but more notes on this subject will appealnext week.

The set used by MG at present is ft four-coil Meissner. The aerial coils consist of three and a half turns of quarter inch copper tubing, wound to a diameter of five and a half inches, for the plate eoi] four and half turns of number 10 gauge wire wound to a diameter of about three inches is used. The grid coil consists of one and a half turns o f number 8 gauge wire and is untuned. The plate coil is tuned with a .00025 condenser. The input to the transmi varies from 70 to 200 watts on a 20.3 metre wave-length. The fifth harmonic of the aerial is used when transmitting on 20.3 metres, the aerial having a natural wave-length of about 1)15 metres.

HIGH-SPEED TRANSMISSION.

BETWEEN DOMINIONS AND GREAT BRITAIN.

The imminent establishment of wireless communication between the Dominions' and Great Britain on the new Marconi “beam” system was commented on at Auckland by Mr. E. T. Fisk, managing director of Amalgamated Wireless Ltd., of Australia and New Zealand, who, together with Mr. G. Mason Allard, chairman of directors, is a through passenger by the Niagara. Mr. Fisk is to visit London to make final arrangements for a high-speed wireless beam service between Australia and England. “The scheme, in which Australia, India. South Africa, and Canada will participate, is to be put into immediate operation, ” he says, “and already beam radio stations are being erected. The service is intended for use in the samd way as the submarine telegraph, greater speed and elimination of relays being facts on which superiority is claimed. The foundation of an organised radio service between Australia and Britain is

in itself a scientific feat, made possible only by the application of the beam or concentrated power system. Mr. Fisk has been personally conducting experiments with beam transmitting during the last 18 months, and is convinced of its utility and commercial possibilities. The capital of the company which he represents is £1,000,000, and the Australian Government holds shares to the value of £500,000. A beam transmission station is in course of erection about 50 miles from Melbourne, and a receiving plant is to be installed about 15 miles from the city. All the other capital cities in the Commonwealth are to provide feeder stations to work in conjunction with main overseas beam service. The beam station is to be operated from these centres by automatic apparatus. A message handed in at a depot in Sydney for transmission to Britain will be despatched by the local wireless station and automatically retransmitted direct from the beam station. 'The entire operation will occupy but a few minutes.

“The Australian stations are designed to work continuously at high speed,” said Mr. Fisk. “So great is the efficiency of the beam system that the stations will work at remarkably lower power. The energy for the Melbourne beam station is to be only 25 kilowatts, it being estimated that the results will equal those of a 15,000kilowatt plant of the ordinary type.” Mr. Fisk expressed the opinion that there was no mechanical obstacle to jnow Zealand being included in the beam service.

SCRAMBLED AND MOTTLED.

This has nothing to do with eggs. In America one of the most striking innovations is a mottled finish for the paint work. It is difficult to describe, except to say it has a very high lustre and a mottled or wave-like effect, in which a vast number of colours can be used. The ears at New York Show were done in scrambled shades, in which golds and browns and different greys predominated. The advantages are stated to be that the finish is exceedingly hard and cannot be scratched in ordinary usage, while at the same time it conceals dust and dirt, an excellent feature in the hands of the average careless owner. The general opinion, however, seems to be that this particular effort is a little ahead of the times.