WIRELESS NEWS.

Press, Volume LXI, Issue 18343, 28 March 1925, Page 11

WIRELESS NEWS.

PROGRESS OF RADIO.

FEWER INTENTIONS—MORE IMPROVEMENTS. • v srecULLi nKirnat fox "tm r*aa>. (Bv ''.Hectra.'") A aurvey ot progress in radio reveals that the invention of new devices i> giving place to the perfection of existing ones. This statement i* verv general. There have, of been triumphs of engineering in ih* past history of radio, and on the other hand the "cut and try'' process will continue to be used m the future. But. broadly speaking, radio engineerin;.; has now taken definite form ami is the tool by which further progrera in radio will bo wrought. While a number of outstanding recent developments arrest the attention it is also true that very substantial progress is being made all aloes the lino of radio engineering. Thus, in the development of new and improved radio communication methods or systems, we have marked extension of Unavailable frequency range, great improvement!; in directive radio transmission, advances in the perfection of selective radio systems, and engineering development of line-radio or carriercurrent communication. Among radio devices and applkatMß* of radio there is outstanding progress. in radio beacons, the uses of radio for aircraft navigation, direction finders, and radio vision. Short Wave Work. The most conspicuous recent development in radio engineering is the conquest of the new domain of ultraradio, or very high frequencies (start wavesV Even the existence of tbe vast range of frequencies above 2000 kilo cycles (beluw 100 metres'* was hardlv suspected, and certainly was generally overlooked until less than a year agoOne curious reason for this has bee* the erroneous use of wavelengtb in meters as an expression of radio frequencies. Radio engineering actoalh' deals with currents which bare a certain frequency. The length of the wave as it travels along in space can be calculated from the frequency, but ffc t» a derived and artificial concept. Frequencies np to 20.000 kilocycle* have come into extensive use. Aetaal radio services are being conducted in this region by broadcasters, tramsoceanic communication companies, nu&tary services, amateurs: in abort; every important radio interest baa begfa operations between 3000 and 30.000 kilocycles. Even higher frequeaeiea bare been used in experiments, bat there is every likelihood that in the dwtlepmeut of frequencies above 20,000 k3e> cycles directive transmission win predominate.

$o important are these nigs fieey cies now that the third National BaeSe Conference, held in October, 1924, parcelled out the high frequency terriiee? among the various radio aeiiioee, tkna reaching a solution of a problem wkka only a year ago was regarded aa nsoluole, that of finding more toaamncation channels.

Alternate frequency bands amvnmately ten per cent, wide, were aaagMd to the following different asiikam— Land point-to-point aircraft, shia, relay broadcasting, public service, aatttasw and army mobile. Aa important pviaeiple was followed in this aasigUMa*. namely, each service was pntteM from possible harmonic iate7fete»M from stations of other seriifea by f*»e- ' ing several frequency buds it a«(jr given service on its own hamnaita Bean winlßßS. Great improvements an ia pgfuaa in directive, or "beam" turn mini—,, ( It is accomplished by csing a wmakax of transmitting antennae and » adjaaV ing the phases of the curreat ia «ad), to relation to their distances apart, ttkat reinforcement of radiation ia awtri—j in one direction and mora er 2m an* tralisation in others. An obviMa advantage of beam transmissioa is Oak much lower power ia required tfcaa a* ordinary radio transmuaua, slaw th» transmitting power is all oiSHaed a* sending the waves in the deaired dar**tions.

One of the principal umbos of oswcoming interference between tin tiassv missions from simultaneooslT ing radio stations » cfarioaaly the in* crease of selectivity or bwrmw «t the band of frequency vlnjjk oacfc station uses. Progress in tins •Ssss» tfcion is being made in «D th» iwiim tvpes of transmisskm. as, for exsasphK through the use of fifarinc dtotjess *■*" radio telephony and eoopkd iiic«it» m 6park apparatus. The yiiiyieai safe vance. however, is the inansssnar. aajegv tion of contnraoos ware trssssßjasw*

for radio telegraphy. We also have the advert of ateiaajy constant-frequency systasn. A •***- ing means of aocomptistttng *h»> *» furnished by the pkao-glertrio a«iW ator. A new radio <nsinniniis*i—i system of the utmost ssfciUiiiij awl precision is made available by thai mm device, and services which Kfav* the operation of a large nwufeei ef <mi mitting stations spaaed as tsstaty together as possible in fremeney ant taking fall advantage of G.W. traaav mission will find this a great irspnsa* ment.

The various causes of intetfjmao* divide into two great classes—natal*! and man-made. Progress is bene steadily made against both of thassenemies. As to the natural interference there will probably always ho a. certain residuum of atmospheric disturbances and fading, which will aesessarily limit the distance frost as? broadcasting station at which refiaate satisfactory reception will be yusjhs:i Man-made interference, on the other hand, is curable and of toed caanctar.