vi PREFACE 
systems, particularly their directivity and gain; 
gives the reflecting properties of targets such as 
airplanes for use in detection by radar; teaches the 
reader how to calculate field strength or obtain the 
coverage diagrams given a particular set, power, and 
site; gives the fundamental information required in 
the above calculations for application to the radar 
and communication sets used in operational theaters; 
and provides illustrative material and sample calcu- 
lations which show how the laws of propagation 
may advantageously be used in the location and 
operation of radar systems, communication sets, and 
countermeasure equipment designed to deceive the 
enemy and to prevent jamming of equipment by 
enemy action orby mutual interaction of our own sets. 
The reader [will find in the Appendix] a summariz- 
ing review of six transmission experiments carried 
out in widely separated geographical locations; 
namely, Massachusetts Bay, San Diego, Arizona, 
Antigua, West Indies, and Great Britain. The basic 
objectives here have been to learn the facts concern- 
ing transmission, and, as far as possible, to correlate 
them with the transmission theory given in Volume 1 
and with the meteorological factors presented in 
Volume 2. 
One of the main functions of the NDRC Com- 
mittee on Propagation was to bring about a rapid 
exchange of information between the laboratories 
and Service units working on the subject, and make 
the results available to all workers technically con- 
cerned with the military application of radar and 
other short wave radio equipment. To fulfill this 
function the Columbia University Propagation 
Group operating under contract with the Committee 
periodically published a comprehensive bibliography 
on propagation, beginning in the spring of 1944. 
Its fifth and last edition, issued in August 1945, is 
included [in the General Bibliography]. [This] 
General Bibliography lists reports “on tropospheric 
propagation issued by numerous Service and civilian 
organizations and is a rather exhaustive accumula- 
tion of the efforts made during the war in this field by 
Great Britain, Canada, New Zealand, Australia, and 
the United States. With a few exceptions, original 
reports listed in the Bibliography have been micro- 
filmed. A few, such as summary reports issued by 
the Columbia University Wave Propagation Group 
and the compiled Propagation Reports, are included 
in the present series. 
STEPHEN S. ATTwoop 
Editor 
