﻿Radiation from Bent Antenna?. 591 



The field due to this open circuit current at the two 

 selected points a and b will be towards the spectator at the 

 right-hand point b and away from it at the left-hand point a. 

 Hence if It and li' are the magnetic forces due to the open 

 circuit current at the points in question, the resultant fields 

 are H — It at the right-hand point and H + // at the left. But 

 since the open circuit and the adjacent side of the rectangle 

 are traversed at any instant by equal and opposite current-, 

 we may consider them both annihilated, and we have as a 

 consequence that the magnetic field due to a bent oscillator 

 similar to that in fig. 1 at two symmetrical and equidistant 

 points on its axis is greater at that side away from which the 

 free ends point than it is at the other. If we suppose a 

 doubly bent oscillator of the above kind to be half buried in 

 the earth, then we have a singly bent earthed oscillator of the 

 kind used by Mr. Marconi (see fig. 4) *. The antenna: used in 



Fijr. 4. 



the experiments here described consisted of a couple of 

 No. 16 bare copper wires loosely twisted together and from 

 10 to 20 feet in length. On the grass of the Courtyard some 

 large sheets of zinc were laid down to form earth-plates. At 

 one of these posts used as a transmitting station, a bent 

 radiating antenna was constructed by connecting one of a 

 pair of spark-balls to the earth-plate and the other to a length 

 of the above said copper wire which was so arranged and 

 upheld by insulators that any fraction of its length could be 

 placed vertical and the remainder horizontal as in fig. 1. The 

 free insulated farther end of the horizontal portion generally 

 carried a plate of zinc 18 inches square which served as an 

 additional capacity. The receiving antenna consisted of a 

 vertical copper wire upheld by insulators from a light 

 bamboo rod. 



* In the discussion on Mr. Marconi's paper at the Eoyal Society on 

 March 22nd, 1906, Prof. J. Larmor, Sec.R.S., pointed out that a bent 

 oscillator as in fig. 4 is equivalent to a magnetic oscillator plus an 

 electric oscillator. 



