WIRELESS MESSAGES

Otago Daily Times, Issue 23806, 12 May 1939, Page 7

WIRELESS MESSAGES

GROWTH OF SERVICE NEW AERIALS BEING ERECTED DIRECTIVE TRANSMISSION PLANNED (Special to Daily Times) WELLINGTON, May 11. Six new wireless aerial masts of steel trellis-work are to be erected along the crest of the Tinakori hills. Radio officials of the Post and Telegraph Department explained tonight that these masts were the outward sign of the modernisation of certain aspects of the wireless telegraph transmission system. With the growth of the popularity of radio telegraph and telephone services in recent years, the department has found it necessary, it was explained, to extend its aerials in order to obtain greater efficiency in the number of services operated collaterally. Some 15 years ago, when the activities of the station were restricted to ship-to-shore and shore-to-ship services and the demands upon it were comparatively few, the old-fashioned method of alternately transmitting and receiving was satisfactory. The modern method of simultaneous transmission and reception was more exacting, however, and it was no longer possible to obtain the maximum efficiency from aerials erected on one mast or a pair of masts. It had become necessary to erect new aerials, and it was planned to put up six steel-work towers. These would not all be the same height because of the conformation of the ground, but would stand level at the summits. It was understood that directive transmission would be applied to certain of the department’s services after the erection of the new aerials Directive transmission was, as its name implies, the despatch of wireless waves in certain desired directions only, instead of broadcasting them all round the compass. That was to say, that a message sent to Sydney would be despatched by directing the beam of the radio waves in the direction of that city instead of wasting power by permitting the waves to spread through the complete circle. The activity of this branch of the Post and Telegraph Department was stated to have trebled in the past four or five years.