A MULTIPLE UNIT STEERABLE ANTENNA 381 



from the E layer is indicated. This was predicted by Mr. Goodall 

 on the basis that the E region ionization at noon became so great 

 that 24-degree waves should be reflected. For completeness the table 

 shows an alternative interpretation of a first E reflection and a third 

 reflection from a 185- to 195-kilometer height. The first E reflection 

 and second F reflection are perhaps more likely. The 11 :03 record is 

 not explained. 



Something similar appeared to happen on December 31 (D). On 

 January 22 (H) normal first and second F reflections occurred with 

 angles of 24.5 and 43 degrees. In addition a third wave of 34 degrees 

 appeared. Two interpretations of this are shown but neither seems 

 very plausible. 



As a general rule propagation from Halifax is simpler than from 

 Daventry on the same wave-length. In particular GSL waves re- 

 ceived by the two MUSA branches are definitely less discrete and 

 include sufficient delay differences in themselves to prevent the nicety 

 of equalization possible with VE9HX. If multiple reflection takes 

 place, which we have no reason to doubt, it is generally so distorted by 

 non-uniformity over the path or by other factors as to be unrecog- 

 nizable. In view of the occasional complexity of the Halifax circuit, 

 only one-sixth as long, this is perhaps to be expected. 



The absence from these observations on Halifax of any third reflec- 

 tions from the F layer is likely due to the fact that they would fall in 

 the neighborhood of the first null of the rhombic antenna and would 

 have to be much stronger in space in order to appear comparable with 

 the second or first. There have been momentary appearances of waves 

 which might have been third reflections but they did not persist long 

 enough to work with. 



When single waves were present, which was not unusual in the later 

 evening hours, the angle more often corresponded with the first F 

 reflection rather than the second. 



Additional Numerical Data on Reception with the MUSA 



The data shown in Fig. 31 are submitted to supplement the rather 

 meager numerical data on transatlantic reception thus far presented. 

 Here, relative delays and angles taken from the MUSA operating log 

 are shown in plots A, B, and C. Only the end points of the lines are 

 significant; they denote by their abscissas the angles at which the two 

 receiving branches were set. The ordinates of the upper end points 

 denote the equalizing delay. The lines merely connect coexistent 

 points. The data shown were selected from the rather extensive log to 

 present a fair cross section of conditions, omitting, however, all cases 



