THE BUGBEAR—STATIC

Radio Record, Volume I, Issue 21, 9 December 1927, Page 3

THE BUGBEAR—STATIC

VARIOUS ‘THLORIES. ° Many theories have been advan¢ed to explain the cause of static, and it is probable that a variety cf different factors contribute to this annoying interference with wireless communication. ‘Thunderstorms undoubtedly play their part, and electrical discharges in the atmosphere are certainly one of the chief causes of the trouble in summer, An interesting suggestion which has been made to account. for. some of the trouble is that it is sometimes caused by meteorites entéring the earth’s atmosphere. Meteorites are masses of material, usually metal, ~ of varying sizes, which wesider at ‘high speeds through space. Occasionallythat is, im proportion to the number of these bodies which are free in space -one will strike the earth’s atmosphere, and the intense heat gencrated by the friction as it rushes through the upper layers of the atmosphere heats the outer surface of the-body to white heat, catieing the "shooting stars’ seen in the night sky. It is estimated that tens of thousands of these visitors strike ‘the earth’s atmosphere daily, and the larger ones are believed on occasions to proince some of the static which is heard. Itlectrical disturLances in the. sun gre also said to cause trouble sometimés. Indeed; mysterious noises which wireless operators once believed to be signals from other planets were later considered to be caused by distutbances'in the sun. : ; To Minimise Effect. Although the interference caused by static cannot be entirely eliminated froin. a receiver, its effects can be considerably reduced. ‘Ihe fortunate possessor of a superheterodyne receiver or similar supersensitive set is in the best possible position t6 combat the nuisance, because he can use a loop aerial for receptton. When the loop is pointed directly at the desired station it reduces interference to a minimum, because only the signals coming 1m one direction will affect it strongly. Next to using a directive loop for reception, the best way to reduce the nuisance caused by static is to reduce signal strength to the set. It is found that for a given intensity ratio between a signal and static the interference which the static canses is least when the set is so adjusted that signals are as weak as it is possible to make them without causing discomfort to listeners. Signals can be reduced in a variety of ways. The casiest is to use a plug and jack arrangement, by which one or two valves in the receiver can be taken out of use. If this equipment is not included in the set the filaments of the valves can be turned down until the signals begin to weaken. Another method which: is often nsed is to eimploy a very small aerial for reception when static is bad. This arrangement, in addition to giving the desired general strength reduciicn, appears often to possess the further advantage. of being less responsive to static, i: proportion to the signal, than is a large aerial. 9