THE BELL SYSTEM 



TECHNICAL JOURNAL 



VOLUME XXXVI MAY 1957 number 3 



Copyright 1957, American Telephone and Telegraph Company 



Radio Propagation Fundamentals* 



By KENNETH BULLINGTON 



(Manuscript received June 21, 1956) 



The engineering of radio systems requires an estimate of the power loss 

 between the transmitter and the receiver. Such estimates are affected by many 

 factors, including reflections, fading, refraction in the at7nosphere, and 

 diffraction over the earth's surface. 



In this paper, radio transmission theory and experiment in all frequency 

 bands of current interest are summarized. Ground wave and sky wave trans- 

 mission are included, and both line of sight and beyond horizon transmission 

 are considered. The principal emphasis is placed on quantitative charts 

 that are useful for engineering purposes. 



1. INTRODUCTION 



The power radiated from a transmitting antenna is ordinarily spread 

 over a relatively large area. As a result the power available at most re- 

 ceiving antennas is only a small fraction of the radiated power. This 

 ratio of radiated power to received power is called the radio transmission 

 loss and its magnitude in some cases may be as large as 10^^ to 10"" (150 

 to 200 decibels). 



The transmission loss between the transmitting and receiving anten- 

 nas determines whether the received signal will be useful. Each radio 



* This paper has lieen prepared for use in a proposed "Antenna Handl^ook" 

 to be published by McGraw-Hill. 



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