28 



TRANSMISSION EXPERIMENTS NEAR SAN DIEGO 



agree closely, including the field at 130 miles, due 

 solely to partial reflection. No attempt was made to 

 calculate the detailed variation with altitude. 



The agreement between calculated and observed 

 fields at 534 me is excellent above, but poor below, the 

 tangent ray. At 130 miles 20- to 30-db difference ap- 

 pears. Note that the measured field is about 20 db 

 greater than the 170-mc field at that range. This 

 contradicts the trend of the calculated reflection coef- 

 ficients which should decrease exponentially with rela- 

 tive thickness of the layer measured in wavelengths. 

 The observed 524-mc fields at 130 miles on some other 

 days of pronounced high-level inversions were well 

 below the 170-mc fields and thus in qualitative agree- 



ment with theory. At 3,250 mc there is again good 

 agreement above the tangent ray, but again, in the 

 region below, the observed fields were high though the 

 calculated values became very small. 



Thus a preliminary check of analysis versus meas- 

 urements indicates : 



1. Discrepancy of absolute values except where the 

 field at the maximum of a lobe was measured. 



3. Excellent agreement as to variation with range 

 and altitude above the geometric tangent as well as 

 in the diffraction-partial reflection zone, except that 

 at 524 mc and 325 mc strong fields were observed 

 below 4,000 ft to 130 miles in contradiction with 

 theory. 



