ULTRA-SIIORT-WAVE TRANSMISSION PiIENOMENA 



201 



denser unit to operate the antenna meter. The antenna current was 

 of the order of 0.6-0.8 ampere ordinarily. 



For the entire northwestern half of the horizon the nearby Mt. 

 Pleasant hills screened the country beyond from direct radiation com- 

 ponents. The reception in these directions was thus entirely a diffrac- 

 tion phenomenon. Fig. 2 gives the result of a cross-country transit 



60 



400 FEET 



Fig. 2 — Transmission along radial line from Holmdel 

 laboratory to Watchtung Mountains. 



out beyond these hills. The wave-length was 4.6 meters and at each 

 point the field intensity was obtained by averaging over several 

 maxima and minima. As closely as possible a fixed direction was 

 maintained. The field strengths were first observed as decibels left in 

 the set attenuator and were afterwards corrected as described in a 

 later paragraph. An inverse square of distance curve is drawn in for 

 comparison purposes. Up to the hills a direct plus a reflected radiation 

 component constitutes the transmission; back of the hill a diffraction 

 phenomenon occurs. The transmitting antenna was vertical and the 

 radiation was received by a short rod antenna projecting through the 

 top of the light truck carrying the receiving set. 



The observed values are rather erratic, and later experience has 

 shown that this irregularity may be expected for measurements taken 

 on or at the ground level and that it is due to an almost universal and 

 highly irregular standing wave pattern. 



