Transmitting Antenna in Wireless Telegraphy. 



9 



As is known, in this system earth connection is usually not 

 made,* but in place of it an earth plate is used, intended to 

 balance the antenna and thus give symmetry to the oscillating 

 system. The earth plate supplied with the apparatus was a 

 hollow metal cylinder, 20 cms long and 8 cms in diameter. It was 

 joined to a binding post, B, of the transformer secondary by a 

 wire 40 cms long. When it was desired to join B to earth the 

 cylinder was securely bound to a large metal plate, which, 

 along with other metal sheets, was connected to the heating- 

 radiator. When employing a wire similar to the antenna to 

 balance it, this wire was joined to B and, as in the experiments 

 described above, was drawn up towards the ceiling. 



In supplying the apparatus the makers stated that it was 

 designed to emit waves of length 10 meters. It was very con- 

 stant in its action and easy to handle. 



An extended series of observations was made with antennse 

 varying from 200 to 1000 cms , and with four different attach 

 ments to the end B of the transmitter transformer, as follows : 



A. With cylinder joined by a wire 40 cms long. 



B. With earth joined to this cylinder. 



C. With a wire similar to the antenna joined to B. 



D. With the end B free. 



A view of the results obtained is given in Table II, and figs. 

 6, 7, 8, 9. 



Table II. 

 Inductive Method. 



Length 



Distance 



in cms., of minima from free end of 



wire. 



of 



A. With 









antenna. 



cylinder 



B. With earth 



C. With equal 



D. With end 



cnis. 



capacity. 



connection. 



wire. 



free. 



200 



. 





140 



225 



184 



190 



(70), (190). None 





250 



200 



180 



(90). None 



.-. 



300 



[238] 



187 



[2251 



148 



400 



187, (265) 



185 



185 



160, i-280?) 



500 



180 



180 



180 



183 



600 



186, (375), (520) 



200, (520) 



182 



167, (415) 



700 



188, (637) 



200 



180 



148, 617 



800 



191, (745) 



200 



189 





900 



200, (790) 



200, (380), (790) 



193, (790) 







1000 



180, (320) 



208, (800), (920) 

 193 



180, (860) 

 184-1 



...: 



Mean 



188-4 







Mean oi 



: 184-4, 193, 184-1 = 188-5 cms . 





On examination it will be seen that the curves obtained by 

 the three methods, A, B, C, are hardly distinguishable from 



*See discussion on a paper by M. Wien, read before the 74. Versamm- 

 lung deutscher Naturforscher und Aerzte at Carlsbad, Sept., 1902. — Phys. 

 Zeit., Oct., 1902. 



