The Birmingham age-herald., 1922-11-19
RADIOS PROGRESS
 SHOWS THE TREND
 ID SHORT AER|ALS
Best Results in Tuning Are Obtained With Low, Short, But Clear
 Antenna
 By JACK BINNs

| One Of the most interesting phases of radio development Is the evolution of the receiving aerial, which in itself is indicative of the trend of all prog ress in the art. With the improve ment in sensitivrty of receivers the aerial itself has become smaller and more efficient
 In the early days of wireless work aerials were made as long as existing particularly on ships At that time the general theory seemed to be that that longer the aerial the greater would be the distance over which sig nals could be received.
 This undoubtedly was to a certain extent true in those days, when the art of tuning was little understood, when laws governing wave length were non-existent and park signals wandered in over every possible ad- l 1ustment on a wireless receiver. l Short. Clear Wire Best The remarkable change that has | taken place in the understanding of what constitutes an efficient aerial was emphasized in a recent paper road by Frank Codrad before the h. Stllute ol INdulo EHBlneeTS OH recent experiments which laid specific em- phass on the need of using a low clear, singlewire antenna for recep- ton. For use on short-wave recep- l ton this wire should not be more than loo feet in length in order to get | the best possible tuning and selec- tivity. Of course, 1t Is necessary to use very efficient receiving set un- der those conditions.
  development of the loop aerial, which. of course, can only be used eff ciently, so far as broadcast reception is concerned. with three types of re- ceiving equipment, namely, radio-f fre- quency amplfication, super-hetero- dyne and super-regeneration, al- though for wireless telegraph work results can be obtained with 1t in certain cases with a regenerative type of receiver.
 | The indications for the future are will be entirely eliminated. and even loop aerials will only be used as an adjunct to tuning because of their directional effect.
 Twenty years ago an operator at i sea would have wept in anguish at the thought of being assigned to a transatlantic liner which had an ! dtTldi ieSS tudH 3OU from end to end, while a single wire aerial was un- heard of.
 Only One Receiver Used Of course at that time there was only one receiver in general" use. and 1t was the coherer set. The mag netic detector was just making It's appearance, and the possibilities of crystals were becoming apparent. So far as the coherer was con-  tuning. It is true that there was coupled circuit in the antenna, which was known by the elegant name of 1 "jigger." It consisted of two coils each with a fixed number of turns and fixed coupling between them in reality 1t was a fixed transformer. Everything picked up by the aerial was supposed to pass through 1t and actuate the coherer. and there is no doubt that his supposition was maintained In practice.
 More efficient tuners came very slowly, but as there was but little i'm provement In the sensitvity of de- 1 tectors, the advantage was at first not very great. In fact, the ineffi- ciency of transmitting equipment practically nullified the advantages of the tuners, and operators suffered in patience by trying to receive through interference rather than cut down the strength of signals by | tuning
 The two things which made the radiophone possible also brought about more efficient receivers and tuners-the invention of the vacuum tube. and the production of un- damped or continuous waves in trans- mission.
 l Development Trend Outlined Of course, what I have outlined here is the trend of development For ordinary radiophone reception those who can erect a good. clear aerial should use it. The shape, length and