206 



INDEX 



grazing angle, 78 



path difference, 74-75 



reflection point determination, 71-74 

 Raindrop diffraction, 59 

 Range loci construction, 133-134 

 Rayleigh criterion, radiation theory 



application, 176 

 Receiver sensitivity, 17-19 



definition, 18 



noise figure, 17-19 



radar receivers, 19 



thermal noise, 17 

 Reciprocity principle, reception and 



radiation, 17 

 Reflection 



Brewster angle, 54 



effect on equipment performance, 

 160-161 



ground reflection, 52-58 



imperfect reflection, interference re- 

 gion, 67-68 



reflection coeflicient, 53, 69-70 



transmission factors, 6-7 

 Reflection point curves, coverage dia- 

 gram construction, 138-139 

 Reflection point determination, 71-74 

 Reflection point variable, 80 

 Refraction, 45-52 



atmospheric sti-atification, 50-52 



curvature relationships, 47-48 



definition, 3 



graphical representation, 46-47 



Snell's law, 45-46 



standard refraction, 45 



transmission factor, 6 

 Refractive index, 48-52 



computation, 48-50 



function of temperature and height, 

 49-50 



function of temperature and relative 

 humidity, 51 



modified refractive index, 46 



standard atmosphere, 61 

 Resonant antennas, 23 

 Rhombic antenna, traveling wave an- 

 tenna, 32-33 

 Ring arrays, antenna, 39 

 RPD (radar planning device) for echo 

 determination, 193 



Scanning loss, radar reception, 19 

 Scattered power, radio wave reception, 



13-14 

 Scattering parameters, radar coverage 



measurement, 182-183 



echo constant, 182 



equivalent plate area, 183 



radar cross section, 182 



scattering coefficient, radar length of 



target, 183 

 target gain, 182 

 Sea water 



dielectric earth behavior, 66-67 

 influence on radio wave transmission, 



54-55 

 radio gain calculation, 108-115 

 Sectoral horn, antenna, 44 

 Shadow zone, 7 



Shielding, permanent, echo control de- 

 vice, 193 

 Ship roll, effect on radar coverage, 160- 



161 

 Ship size estimated by strength of re- 

 turned radar signal, 166 

 Side-by-side array, two-dipole antenna, 



34-35 

 Signal-to-noise ratio, radar equipment 



performance, 161 

 Siting, terrain selection and utilization, 

 187-196 

 geometrical limits of visibility, 188- 



191 

 permanent echoes, 191-195 

 radar, overland transmission, 56 

 requirements of siting, 187 

 trees and jungles, 195-196 

 Siting topography, 187-188 

 maps, 187 



orientation, 187-188 

 profiles, 187 

 Slot diffraction, 175 

 Snell's law of refraction, 45-46 

 Soil as radio wave conductor, 56-57 

 Solar azimuths, calculation methods, 



187-188 

 Spherical earth 



coverage diagrams, 131-132 

 path difference, 74-75 

 radio gain calculation; sec Radio gain 

 calculations, spherical earth 

 Spreading effect, propagation factor in 



interference region, 67 

 Standard atmosphere, refractive index, 



61 

 Standard dry atmosphere, properties, 3 

 Standard refraction, definition, 45 

 Standing-wave antennas, 24-32 

 half-wave dipole, 25-26, 28-29 

 linear antennas, 24-25. 29-31 



multiple half-wave long aiitennas, 



27-28 

 V antennas, 31-32 

 Supersonic method of echo determina- 

 tion, 193 

 Surface craft, estimation of size by 

 strength of returned radar sig- 

 nal, 166 

 Surface craft, radar cross section, 164 

 Sweep-speed loss, radar reception, 19 

 Symbols adopted for frequency I'anges, 

 11 



Target diffraction, 58-59 

 Terrain diffraction, 170-181 

 Terrain selection 



see Siting, terrain selection and util- 

 ization 

 Thermal noise in radio receivers, 17 

 Time computations necessary for radar 



site selection, 188 

 Topographic maps and profiles 



prediction of echoes, 193-195 

 ■ siting selection use, 187 

 Transmission, 6-7, 45-59 



antenna characteristics, 6 



diffraction, 7, 58-59 



divergence, 7 



ground reflection, 52-58 



polarization, 6 



reflection, 6 



refraction, G, 45-52 

 Traveling-wave antennas, 23-24, 32-33 

 Trees as obstacles for high frequencj' 



radio wave, 195-196 

 Troposphei'e, propagation i-ole, 2 



Ultra-short waves in diffraction region 



65-67 

 Unidirectional arrays, antenna, 38 

 Units used in propagation study, 11 

 U-V method of coverage diagram con- 

 struction, 135-138 



V antennas, 31-32 

 Vertical polarization 



angles of lobe maxima, 130-131 



effect on radio gain, 83 

 Visibility, geometrical limits, 188-191 



degree of shielding, 190-191 



horizon distance of transmitter, 

 188-189 



obstacle height, 189-190 



Yagi antenna, multiple parasite, 41 



