RADIO WAVES EXPLAINED

Radio Record, Volume I, Issue 34, 9 March 1928, Page 2

RADIO WAVES EXPLAINED

A SIMPLE ANALOGY. RAvio waves may be compared with .., water waves. Consider a pond of water. The surface is smooth, quict, without ripple or disturbance. That condition represents the ideal state of space through which radio waves travel, Now drop a stone in that pond. Soon @ series of small waves are travelling in ever-widening circles from the point where the stone disappeared. Here we have a close parallel with radio waves, also caused by a disturbance end travelling in eyer-widening circles from the transmitter, | It will be noted that as the water waves travel away from their source their force is spent, So with radio waves. COUNT WAVE FREQUENCY. Again studying the pond waves we note that they travel in even lines. If we count the number of lines or waves reaching a given point in one second re have the frequency of the wave moion. . tf we note the distance from crest to crest of the waves we have the wave length. The power of the waves is indicated by the height of crest which obviously has nothing to do with frequency or wave length. In radio the invisible waves travel throughout space at the- amazing rate of 300,000,000 imetres (186,200 miles) a second, which is also the speed of light. The-wave length of radio waves is the distance between two consecutive crests or points of maximum (disturbance, while the frequency is the number of waves reaching a given point in one second, Wave length and frequency are so related that their product gives the velocity to wave motion, USE OF KILOCYCLES, Formerly the universal practice was, to designate radio signals in terms of

wave-length. ‘lo-day the practice tends to the frequency designation, expressed in kilocyeles (thousands of cycles). Radio waves range from wave lengths of 20 metres and less, termed short waves, to 12,090 metres and over for transoceanic communication, while the corresponding frequencies range from 3300 kilocycles for the short waves to 20 kilocycles for the tong waves. The frequency is highest for the shorter waves, lowest for the long waves,