﻿Radiation from Bent Antemnr. 589 



explanation of the nature of the electric radiation from such a 

 bent antenna, and subsequently expanded it into a more 

 detailed mathematical theory *. 



In this last Paper it was analytically proved (as previously 

 discovered experimentally by Mr. Marconi) that a bent 

 antenna radiates unsymmetrically, that is, not equally in all 

 directions but most energetically in its own plane and in a 

 direction opposite to that in which the free ends point. The 

 theory showed that this inequality in fore and aft radiation 

 depends upon the ratio of the lengths of the vertical and 

 horizontal portions of the antenna and upon the ratio of the 

 wave-length employed to tiie distance between the transmitter 

 and receiver. Hence it appeared clear that with a suitable 

 bent antenna the effect should be obtained just as well at 

 comparatively short distances when using relatively small 

 wave-lengths as at lon<>- distances with long wave-lengths. 



During the past summer numerous experiments and 

 measurements have been made for me by Mr. G. B. Dyke in 

 the quadrangle of University College, London, employing 

 short bent antenna? 10 or 20 feet in length receiving at 

 distances varying from a few yards up to 140 feet or so, with 

 the object of confirming the general theory of the action 

 given by the writer. 



It may be convenient in the first place to explain generally 

 and briefly the reasons for the unsymmetrieal radiation of 

 such a bent oscillator. 



Suppose a pair of rods terminating in spark-balls to be 

 placed with the balls in apposition and the rods in one 

 straight line. It is obvious by reason of symmetrv that this 

 radiator must radiate equally in all directions which have the 

 line of the rods for an axis. If, however, the rods each have 

 a bend made in them so as to make an oscillator resembling 



Fijr. 1. 



in shape three sides of a rectangle (see fig. 1) then the 

 symmetry of radiation is destroyed. 



* See J. A. Fleming, ei A Xote on the Theory of Directive Antennae 

 or Unsymmetrieal Hertzian Oscillators/' Proc. Roy. Soc. A. vol. lxxviii. 

 p. 1 (1906). 



