ATMOSPHERIC ATTENUATION AT MILLIMETER WAVELENGTHS 



Table I 



911 



has the antenna on one arm and an impedance composed of an adjustable 

 attenuator and shorting phniger on another arm. This impedance is ad- 

 justed to balance out reflections from the antenna so that a negligible 

 amount of the power flowing toward the antenna enters the converter 

 which is on the remaining arm of the coupler. The delayed energy that 

 re-enters the antenna after reflection from a corner reflector passes 

 through the 3-db coupler to the converter. 



The intermediate frequency amplifier shown in Fig. 4 operates with a 

 bandwidth of 300 kc centered at/=750 kc. The output of the amplifier 

 is fed to a sciuare law detector and meter for accurate measurement and 

 to an oscilloscope for checking operation of the equipment. Oscillograms 

 of the pulses obtained from the three corner reflectors are shown in Fig. 6; 

 these are all on the same time scale. The gap between the pulses is the 

 delay, r, shown schematically in Fig. 2. 



12.6 



12.4 



IXJ 



o 



LU 

 Q 



z 

 < 



LU 



< 



12.2 



12.0 



11.8 



u 



LU 



< 



CC 



1.5 



11.4 



1.2 



11.0 



5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 6.0 6.1 



WAVELENGTH, \, IN MILLIMETERS 



Fig. 3 — Calibration of corner-reflectors R2 and R3 using Rl as a standard. 



