ON FIVE METRES

Radio Record, Volume I, Issue 27, 20 January 1928, Page 4

ON FIVE METRES

|} INTERESTING KRXPHRIMENTS. ee Interesting experiments are being begun by American engineers to investigate the value of waves abont five metres long for wireless communication. So far it has not been found possible to communicate for more than a few miles with such short waves. One of the principal reasons for this is that if the waves are produced close to the ground, as they would be in ordinary circumstances, they are rapidly absorbed by buildings, trees, and hills. ‘The second reason for the failure of waves of five metres and less to cover great distances is believed to be the fact that such short waves are not reflected by the Ileaviside laver--a strata above the earth which bends all ordinary wireless waves gradually round the earth, and makes it possible for them to cover great distances. Instead, it is believed that the five-metre waves pass right through this layer and escape into free space. ON TOP OF TALU MASTS. In order to test this theory and to. find out what commercial use may be made of five-metre waves, a number of special fiye-metre transmitters are being built. Instead of being installed in a building in the ordinary way, these sets, which have been made very compact, are being installed in waterprof cases on the top of tall masts in such a way that they can be controlled from the ground. The effect of this arrangement is that the wave is produced some distance from the ground, and it is not subject to the absorption which has caused five-mnetre transmissions to fail when the equipment was near the ground.