MORE LISTENERS WANTED

Evening Post, Volume CVI, Issue 90, 13 October 1923, Page 21

MORE LISTENERS WANTED

The number of aerials visible all about the city and suburbs shows the hold that wireless has already taken, upon the community, but there is room for a vast number more of listeners-in. There ib wireless enough to go all round. The .question ■ is sometimes asked' by those who are not "up" in the ways of wireless, whether the multiplication of aerials does not ■weaken the signals received owing to the abstraction of the energy transmitted. Of course it does, but no difference can possibly be measured. As a matter of fact, if every house in Wellington had an aerial, the total amount of energy absorbed by the aerials would be only a minute fraction of that which i s and ■would be absorbed in setting up electrical oscillations in trees, metal structures of all kinds, such as roofs, steel frames of buildings, telephone wires, and overhead electric lines of all kinds. And by far the greatest part of the transmitted energy nevertheless flies off into distant space, losing small instalments to various artificial or accidental aerials on its way. If there were 15,000 aerials :n the' city,' and they absorbed every particle of energy delivered by the present broadcasting stations (15 watts) there would be one-thousandth of a watt apiece. This is an amount of current so small that one would think it could a-> nothing. About one watt is absorbed for each candlepower of an electric light, _ and' it takes 500 watts to run an olecfcric iron. But if by any chance onetbousandth of a watt struck the average wireless antenna, the operator's head would hit the ceiling in sheer astonishment at the noise. Audible sounds are made i» the telephones by less than a ten-millionth part of a watt. It is an astonishing fact that several miles from broadcast stations evon of such low power as are now being used in Wellington, music and speech are clearly audiblo using a. crystal detector set, on. which all the energy available is 'that which is picked up by the aerial.' The Wellington stations will, it is understood, sooii" be operating with considerably higher power, Which will increase the rango at which they can be. heard by means of simple outfits. There is not, in any case, the slightest fear that a few extra aerials 'will-injure the supply. There is more than enough for everyone.

On the other hand, some users of valve sets, by means of which the received signals, music, or whatever it is,

are greatly magnified, are philanthropic enough to add considerably to the amount of energy available for the others. But their kindness (usually unintentional) is generally not appreciated. It is not as a rule pleasant; it interferes with ot-hor-folks' pleasure, a-nd it ought nol to bo allowed to happen. When the re-radiatipn fiend sets'to work he fills the night with squealing and never.seems to realise that the noise he makes is heard by everyone for miles around. The nuisance to others is greatly increased by the use of a prohibited circuit, which should be altered to comply with tho rules.

Many experimenters have found that re-radiation from properly operated circuits (which means circuits that are regenerating short of the squealing point) increases the apparent sensitiveness of other sets in the neighbourhood. Tho reason is that the receiving set, picking up waves and greatly amplifying them for the benefit of the owner of the set, is acting as a transmitter, and in its immediate neighbourhood its radiation is stronger than that due to the original transmitting station, but otherwise is similar. (It is when it is dissimilar that the thing becomes a nuisance.) This fact makes it necessary to look carefully into the conditions* when any claim is made ■ for phenomenally long-range reception of broadcast by non-amplifying crystal receivers.