OCR Text |
Show SHADOWS INTERFERE WITH RADIO MESSAGES I By PAUL i GODLJ 1 meiioa' Foremost Radio Authorltj With electric -aves, as with light waves, there are certain objects what mil east shadows. A radio receiving station which chances to bo in one of these shs-dows shs-dows will no more receive the radic signals than will the eye ot an observer ob-server if he is shadowed from a source of light I Ll In some cases the cause of radic Iff' Shadows has been traced. But In many instances, the causes are still unknown, ocean-going vessels carrying com-I com-I uaratlvcly hign power telegraphic Eraneniltters find great difficulty In or.imunlcatlng 60 miles across cer-.ciln cer-.ciln portions of E ng Island. No one know.', why. The broadcasting station at Newark, New-ark, N. J . Is seldoun satisfactorily received re-ceived In Atlantl? City where clear signals are heard from the station at Pittsburg, several hundred miles away. Yet the power of the two stations sta-tions Is practically the same: STEEL STRl Tl RES. In large cities, a group of steel outldtngs frequ ntly casts radio shadows sha-dows that make It difficult to receive Uv signals of any character trom points "an the direction of these buildings. Sometimes mountains may have the same effect, although In many cases I they have no effect al all Keccntly a serb r. of tests were car-. car-. ricd out 9n boir.l a moving train of ihc Delaware. Lackawanna i: Wester D railroad. The operators In charge I stated that In some cases, even when I passing through a deep cut. tlfon j would be no noticeable effect w hat-over hat-over on the strength of the received 11 signals while at other limes, even a small hlli Seemed to throw a decided shadow. It is quite likely that the geologi-H geologi-H eal formations have ' something to do with these "dead spots." ThMr ex-; ex-; istence has been known for many i years. But it is onl yof late that any definite effort ha-t been made to ex-I'll ex-I'll ploro them FORESTS. 1 Forests, when in leaf, lend to ab sorb radio energy Stations planted i In the heart of .'. Lhlck woods frequently fre-quently find great difficulty In effecting ef-fecting a reception of radio signal.-i signal.-i rom distant points. Vessels plying up and down the mazon river are seldom able to communicate com-municate with i-ai h other over distances dis-tances greater than 25 or 30 miles. although their -lOfinal daytime range !l is 250 miles j A large radio company recently tJ undertook the exploration of the At-I At-I I antic coast In an effort to locate places which are shadowed In all dl-j dl-j rec-tlons -xcep' s. -award. S. vcr il s'i h ! polr.ts were local cd. Large stations ID for the communication with -hips at; sea will probably be erected there Such stations would b- shielded from Interfering effects produced in inland directions Some day ire ma- be able to fully indcrstand the causes of radio shadows sha-dows and find out how to master H them. Radio Sbadowd 1 round v. VTork Shown lJ Sliadod iroaa |