WIRELESS NEWS.

Press, Volume LXII, Issue 18888, 31 December 1926, Page 9

WIRELESS NEWS.

THE BEAM SYSTEM. A LANDMARK IN RADIO. (SOCIALLY WRITTKS FOR THE MESS.) (By "Electra.") A little over, a month ago a pen<"-il-ike beam of wireless waves was released from the curiously shaped aerials of a south-west Cornwall station in England. With the accuracy of a searchlight beam they shot directly to the place toward which they had'been directed, some 2400 miles distant. There they automatically registered themselves. The first signals that reached the small receiving station in Montreal, Canada, established the initial radio link between Great Britain and its world-wide empire. What has just been accomplished with the mysterious beam wireless transmitter is second in importance only to the original trnns-Athntie wireless" experiments of a quarter of a century ago, when Marconi sent his first signal across the Atlantic. Canada shares a second time the honour of pioneering in wireless cor.nuiuitation, and in the genius of Mareoni. Long ago it had been the dream of the British Government to have art intercolonial communication system second to none. The reliability of the system can now be appreciated through the remarkable network of cables whieh connect Great Britain with everyone of her colonies, east, west, and, south. The war had shown what could happen to cables, and wireless had demonstrated its reliability in ease of emergencies. So plans were made to establish radio channels to supplement the cables.

The- beam wireless transmitter was Marconi's answer to the Government experts who asked him about positive communication by means of radio. The Canadian station is the first of a series of similar installations to bo erected in India, Australia, South Africa, and South America.

A £030,000 super-power station, now in operation at Rugby and originally constructed as the nucleus of this intercolonial system, has been scrapped in favour of the less expensive and more efficient beam plants recently developed by Marconi. Beam stations, such as the one just opened in Canada, cost about £oo,ooo to build, and require about 20 k.w. of power for reliable operation. This is one-tenth the power ordinarily used by transatlantic stations of the old type and of similar range. What is a wireless beam? As every one knows who has listened-in on broadcasting, waves emanating from the ordinary type of antenna) spread out in all directions more or less equally. The classical illustration of the concentric rings which form on the surface of a quiet pool of water, when a stone is thrown into it, probably gives the best idea of the principle. When these waves eventually reach far-away aerials the energy they contain represents a fraction of their original strength and an infinitesimal part of the energy which left the transmitting aerial. In the beam method, however, the waves aro gathered together and sent out into space as though they were rays from a powerful searchlight. The waves can thus be directed iti any direction in an intense beam from 10 to 15 degrees wide.

This Testriction of energy to such a narrow path, as contrasted to the scattering " over a 360-dcg. circle, gives a remarkable increase of signal strength at tho receiving station. In fact, the signals from a beam station are twenty-four times stronger when they originate from a beam transmitter than when they come from an ordinary station of the same power and wavelength. An economy in power is at once apparent. The most marvellous thing about this system, however, is the possibility of intensifying the signals at the receiving end. Working in the same way that a cupped hand placed behind the ear to catch stray sounds does tho reflector in the back of the receiving sereen aerial reinforce the signals by intercepting a greater amount of energy from tho advancing wave front. With this arrangement, incredible as it may seem, the signals will be several hundred times louder than they would be ordinarily. Extreme -ange, with comparatively low power at tho transmitter, is thus possible. A small twenty kilowatt station transmitting on a short wave can do all of the long distance work ordinarily accomplished by a station ten times as powerful and working on long waves. Marconi's experiments with directed waves began shortly after the war, and his original beam transmitter was shown at a meeting of tho 1.8. E. in New York in 19"1. His model consisted of a single vertical brass rod a few feet hiffh placed in the focus of a parabolic reflector made of a wire curtain mounted on a wooden frame. Tho waves, which were emitted b> the conductor, were supposed to be reflected by the parabolic screen and thus intensify the signals on the open „d of the parabola, The idea wa. too revolutionary to impress he radio engineers at the time. But the pnn S e worked and has been applied to tireless beacons for warning ships in foggy weather when light houses are transmitter was Cornwall, beam S ' both nstallations i.'in be the heart of the greatest wire ess network on this planet. Canad, h,s second beam at trans e mitter and t ieceiver, a. r% b n rTESa:Sn«i»g Pla-t and retinent. mi- u«« 0 ; f „nr P (l in two ditivirg station fcr c„t towns io hag been n . stations a ca -"' l ', Thc apparatus is a duplicate of tl at d origl naily Thf beam sj stem es , developed Im dim broa dcast may bllt itß , -"if coSn«i«. with long-dis-be onb. ">. c °"" f .jrogramines from tance ot tSor distribuone conutij to ti stations, tion to local & predicted Although *"£*" wil | improve that ''l £>llv'and broadcasting, it wireless tetelhon>»n C(S he is sipufiennt that ne will devote all his t, The ment for in connexion of beam tiaiisniitter» reyo _ wit h Afield. Tho conutiomse the «i is yery stnlC , tio "nd akS description of Ihem" will *«" j " week ' column.

BROADCASTING NOTES. t .ncrht 3VA wi» be putting on an--2° social three-hour continuous other spec ai n o ' clock dance broadcast last A 5, « 5,,a ' ffairlv good and was much Monday »« ,f n^forit y of listeners. c "S' C O"MI ln« Wednesday night inV ,T i idea into the transmission tr «°«-i tha* has been in vogue for a of 31A tl.a- ' i. Allstralian Nations, long , -"dun transmission. While the namely, dual [isteners that B , n,loUnC J c ina to -witch over to an thev are ?o'ng * . , the or . orchestra in «ce p slow chestra itself can n SX and by the time

he has finished his advice the orchestra is going at full strength. This gives a novel effect, and is an improvement over the old method of coming on to a theatre with a burst. The Australian stations are still very ! hard to receive at good loud talker strength, and some nights it has been practically impossible to hear them at all, even" with large multi-valve sets. The same applies even to the West Coast, where they usually come in at good strength. -Just why this should be is hard to say, and one can only surmise that the atmospheric conditions are right against radio. Even 4YA. Dunedin, is not as loud as it should be, and fading is very bad. CORRESPONDENCE. "Radio Fan." —I will be answering your letter in full next week. Users of the W.A.S. crystal set will be pleased to know that J. I. Smail. Radio Specialist, Carey's Buildings. Colombo street, supplies all W.A.S. component crystal set parts. Complete W.A.S. sets made to order. —1 The SFERAVOX reproduces with remarkable clarity, is free from distortion, and so constructed that no matter if the terminals are connected the wroi'c way, the masnets cannot become de-magnetised. £5 ss. of all leading radio dealers.,—New Zealand Representatives, Brown and Bureau, Ltd., Wellington. —1