ULTRA-SIIORT-WAVE TRANSMISSION PHENOMENA 225 



Appendix III 

 Quantitative Check on the Beer's Hill-McCatharn 

 Hill Transmission 

 The Beer's Hill antenna was set at the height of 22 feet, and the 

 receiver taken to the McCatharn Hill where it was operated out of a 

 portable antenna 18 feet high. The optimum height here was 35 feet, 

 and to reach it a more elaborate antenna w oukl have had to be erected. 

 The height used was just as good for a quantitative check as the 

 optimum height. The effective radius of curvature of the earth's 

 surface, corrected for air refraction, is taken as 5260 miles. 

 Intermediate Reflection Component 



Beer's Hill antenna 365 feet above sea level 



Intermediate reflection surface 67 feet above sea level 

 McCatharn Hill antenna 768 feet above sea level. 



Referring to the equations of Appendix I, we have 



D = 39.2 miles 



A = 13.7 " tan * = 0.00278 



B = 25.5 " 



and path difference between direct and reflected rays 

 2AB tan2 6 



D 



= 0.727 feet, or at 4.45 



meters wave-length an equivalent phase difference of 17.9 degrees 

 results. 



The angle of incidence is 90 — ^ = 89.84 degrees and hence 

 K = 0.977 for vertical polarization 

 = 1.0 for horizontal polarization 

 6 = 180 degrees for both polarizations. 

 Adding the middle distance reflected component to the free space field 

 " Ea\ we obtain 



£ = £o(l + Xe'i^^-n 

 and, 



^ = 0.308 = - 10.24 db 

 Eo 



f^= 0.311 = - 10.14 db. 

 Eq 



Local Hill Reflection Components 



By the same process as for the above, and taking the geometry of 

 Figs. 9 and 12 we obtain the site gains, 



