﻿

  Directive 
  System 
  of 
  Wireless 
  Telegraphy. 
  651 
  

  

  backwardly 
  radiated 
  energy 
  been 
  obtained. 
  This 
  proves 
  the 
  

   existence 
  of 
  a 
  phase-difference 
  o£ 
  90°, 
  or 
  thereabouts, 
  between 
  

   the 
  emissions 
  from 
  the 
  two 
  systems. 
  The 
  diagram 
  of 
  fig. 
  12 
  

   shows 
  besides, 
  that 
  the 
  problem 
  of 
  the 
  emission 
  of 
  the 
  energy 
  

   exclusively 
  on 
  the 
  useful 
  side 
  can 
  be 
  considered 
  as 
  having 
  

   been 
  practically 
  solved. 
  

  

  Fig. 
  12. 
  

  

  1V.S 
  

  

  It 
  is 
  interesting 
  to 
  note 
  that, 
  even 
  if 
  the 
  phase-difference 
  

   between 
  the 
  radiation 
  from 
  the 
  two 
  systems 
  is 
  as 
  much 
  as 
  

   a 
  certain 
  number 
  of 
  degrees, 
  and 
  the 
  ratio 
  of 
  the 
  partial 
  fields 
  

   is 
  slightly 
  different 
  from 
  unity, 
  the 
  backward 
  radiation 
  is 
  

   always 
  practically 
  zero. 
  The 
  phase-difference 
  has 
  to 
  be 
  over 
  

   45° 
  for 
  the 
  backward 
  radiation 
  to 
  become 
  noticeable. 
  In 
  

   order 
  to 
  see 
  if 
  the 
  energy 
  emitted 
  by 
  each 
  component 
  of 
  the 
  

   system 
  and 
  by 
  the 
  resultant 
  system 
  satisfied 
  the 
  theoretical 
  

   predictions, 
  these 
  have 
  been 
  measured 
  in 
  several 
  cases 
  with 
  

  

  