﻿648 
  

  

  Messrs. 
  E. 
  Bellini 
  and 
  A. 
  Tosi 
  on 
  a 
  

  

  Fig. 
  6 
  shows 
  diagrainmatically 
  the 
  advantages 
  which 
  the 
  

   employment 
  of 
  the 
  mixed 
  unilateral 
  system 
  has 
  over 
  the 
  

   ordinary 
  circular, 
  or 
  the 
  simple 
  bilateral 
  directive 
  method. 
  

  

  Let 
  it 
  be 
  supposed 
  that 
  a 
  station 
  A 
  ought 
  to 
  transmit 
  to 
  a 
  

   station 
  B. 
  If 
  the 
  station 
  A 
  uses 
  a 
  circular 
  system 
  the 
  energy 
  

   is 
  radiated 
  all 
  over 
  the 
  circular 
  region 
  a, 
  affecting 
  all 
  the 
  

   stations 
  comprised 
  within 
  this 
  region. 
  If 
  A 
  uses 
  the 
  bilateral 
  

   directive 
  system 
  the 
  active 
  area 
  is 
  the 
  region 
  bounded 
  by 
  the 
  

   two 
  tangent 
  curves 
  b, 
  b. 
  If 
  the 
  station 
  uses 
  the 
  mixed 
  

   unilateral 
  system 
  adjusted 
  for 
  M 
  = 
  C 
  and 
  </>=0, 
  the 
  active 
  

   area 
  is 
  considerably 
  smaller 
  than 
  that 
  with 
  the 
  other 
  methods. 
  

  

  The 
  practical 
  realization 
  of 
  the 
  superposition 
  of 
  the 
  two 
  

   systems 
  has 
  been 
  effected 
  by 
  employing 
  as 
  the 
  directive 
  

   system 
  the 
  bilateral 
  system 
  already 
  dealt 
  with 
  in 
  Part 
  I. 
  

   It 
  was 
  evident 
  a 
  priori 
  that, 
  owing 
  to 
  the 
  different 
  conditions 
  

   under 
  which 
  the 
  radiation 
  from 
  the 
  directive 
  circuit 
  takes 
  

  

  