Radio Notes

Bay of Plenty Times, Volume LII, Issue 8597, 21 May 1924, Page 2

Radio Notes

<3y 'Rkeosfot

The latest advices from Sydney indicate that, after a long and bitter controversy, the sealed set is doomed. The short-sighted policy cf the sealed set has done incalculable harm to broadcasting in Australia during the; past twelve months. It is now intended to adopt in Australia a broadcasting scheme similar to that at present being worked for New Zealand, and all receiving sets will be the same as those used in New Zealand—“'open sets” —with nc restriction on wave lengths. The Australian trans-Common-wealh relay attempted recently was nrt productive of complete success. 3JU, the Melbourne station, was in communication with 7 A A, 2YJ and SBQ for several hours m readiness tclear traffic frem Brisbane, but unfortunately 2YI could not establish communication with Brisbane, and SBQ failed to*receive 6AG, the Perth tevmial. The opening of this route is an important work to be- accomplished as it is essential for Australian States to be linked up .satisfactorily before- attempting twoway international work. The new French, regulations for the control of private wireless have been approved by the Ministerial Council, and will be put into effect as soon as possible. They are specially favourable to possessors or receiving sets. No license fee will b-9 charged and all that it is necessary to do is to make a declaration at the nearest post office, which costs the prospective experimenter cr lis-tener-in absolutely nothing. Stations equipped with sending apparatus will in future be divided into five groups. Broadcasting stations used for propaganda or for musical or educational pin-poses will be regarded as of public utility and will have specially favourable conditions, both as to taxation and facility of working. Inventors using their wireless stations for experimental purposes will also be 1 given privileges. All organisations which can satisfy the authorities of their bona tides and cf their French nationality will be allowed to broadcast. Inquiries are often made regarding the correct dimensions of an aerial suitable for ordinary reception work. It is difficult (says an exchange) to lay down hard and fast rules, because it can hardly be said yet that any particular style or type of aerial has disclosed definite and general advantages over any other kind, and new discoveries and experiences are constantly modifying previous opinions. Certain general principles can, however 1 , bo laid down with a fair degree- of safety. The- height that will give best results depends in a great degree on the objects immediately surrounding the station. ITrider any conditions it should, be at least twenty-five feet, above the ground at both ends. An aerial 30 feet above tire ground in the open country would be Tar better than one 100 feet- if there were a number of buildings surrounding it. On the other hand, if the high aerial werefree cf such obstructions, it would be better than the one 30 feet above the ground. The best length of aerial for general receiving purposes is one of 100 feet to 150 feet in length, although an aerial as short as 60 feet will give good results. «[f the aerial is much more than 150 feet in length difficulty will be experienced in putting, the receiving station in tune with sending stations using short wave lengths. Another type of aerial which has recently found considerable popularity is called the coil cr loop aerial. It is made by winding a few turns cf wire: on a square or circular form. When this type of aerial was fust introduced *it was generally believed that it would be suitable only for short distance reception, but recent results obtained both, in Auckland and In Wellington, where Californian stations were clearly picked nn on loop aerials, go to show that, with properly adjusted instruments they are capable of reception at great ranges. This type, moreover, has the advantage of being able- to receive only in the direction in which it is pointed. Weather conditions have a marked effect on radio work. Sometimes far distant stations will “ccine in” very loud, and then the next night they cannot! be heard at all. It: is hard to- tell what weather is going tc be good for receiving, too,. for sometimes very good results can be obtained when it is raining although rainy weather is usually unfavourable. In the winter time almost every night is good, but in the summer the static electricity in the air causes sc much crackling in the receivers that it is impossible to receive from any considerable distance. However, there are some occasions in mid summer when tho

weather is ideal for receiving, but such occasions are rare. It may be because the trees are full of sap and tend to “ground” the waves just as a s ieel frame building will, or _it may be. that the suu ehinea during su-ii a great portion of the 24 hours, in the .summer and such poor results are secured. It is also a generally accepted theory that broadcast, concerts do not carry so far during the daylight as the sun is said to absorb a portion of the wireless waves thereby decreasing then stiength. Years ago when boys got up to what'were mere or less criminal pranks, the reading of “penny dreadfuls" was attributed as the cause of the lapse.. When the movies came along there was something new on whch'to lay the blame; and the pernicious influence of the pictures on the youthful mind has been stated to be the reason for certain youngsters striving to emulate the old fashioned highwayman. It. seems, that radio is net to get off scolt free as an element of mischief, for, during the hearing of a case in London, recently, a woman declared that the wareless waves came through the gaspipe, burnt her hair and threw hex. out cf bed. Some current! Among the statements made _ in connection with the. broadcasting of the .speeches made at. the opening of the Wembley Exhibition was the assertion that the words were heard in New York before they were audible to the people in the stadium at Wembley. This, surprising as it may appear is an easy demonstrable fact. Sbund travels at the rate of 1100 feet, per second, so that an auditor 1100 feet from a speaker hears each sound cf the speech a tenth of a second after it is uttered. But in a tenth of a second radio travels 18,600 miles, or twothirds of the distance around the globe. The “lag’’ is immeasurably small. Every “listener-in" who wears headphones, may be certain that he hears the sound of a broadcast item before those who happen to be in the studio with the performer. Radio waves travel with the velocity of light—lß6,ooo miles or 300,000 kilometres per second. They are in fact, in every respect similar to- the- waves of light except in length and frequency, and their apparent differences their curvature around the: surface: of the. earth, for example, arc explainable as the result cf their long wave' length.