204 



INUEX 



Equipment pei-formancc, jjrupagation 

 aspects, 160-169 



A scope calibration, 161-102 



communications and radar equip- 

 ment data, 169 



free space high-angle coverage, 162- 

 163 



low-angle and surfaci' coverage, 163- 

 169 



performance figure, measurement of 

 efficiency, 160 



reflection effect, 160-16) 



signal-to-noise ratio, 161 

 Equivalent height, radio gain calcula- 

 tion, 71 



Field strenglli, delinilioii, 5 



Free space distance, nonualized, 1 15- 



147 

 Free space field, definition, 5 

 Free space gain factor 



below interference region, 91 



definition, 5 



equation, 60 

 Free space radio gain, definition and 



formula, 15 

 Fresnel diffraction theory, 170-175 



Fresnel integrals, 172-173 



Fresnel zones, 174-175 



mechanism of diffraction, 171 



l^olarization, 174 



slot diffraction, 175 



straight edge formula, 171-172 

 Fresnel formulas, reflection, 54 

 Fresnel-Kirchoff optical theory 



see Fresnel diffraction theory 



Generalized reflection coefficient, 69-70 



Grazing angle corresponiUng to lobe 

 maxima, 129-130 



Grazing angle in radio gain calcida- 

 tions, 78 



Ground reflection, 52-58 

 analysis of problem, 52-53 

 conductivity of soil, 50-57 

 dielectric constant of soil, 56-57 

 dielectric constant of water, 54-55 

 divergence factor, 57 

 Fresnel formulas, 54 

 irregularity of ground, 57-58 

 overland transmission, 56 

 plane reflecting surface, 53 



Half-wave antennas, 25 

 Half-wave dipole, antenna, 25-29 



comparison of alternate and eoi^hased 

 half-wave dipoles, 28 



cophased dipoles, 28-20 



folded dipole, 27 



gain, 26 



impedance, 20 



quarter-wave dipole, modification, 

 26-27 



radiation field, 25-2() 



radiation resistance, 26 

 Hill diffraction, 175-178 



criterion, roughness of surface, 170 



field near the line of sight, 177 



reflecting ground diffraction, 177-178 



straight ridge diffraction, 170-177 

 Horizontal polarization 



angles of lobe maxima, 129-130 



radio gain curves, 8-10 

 Horns, antenna use, 44 

 Huyghens principle, radio wave diffrac- 

 tion, 7 



Impedance, half-wave dipole antenna, 



20 

 Index of refraction, definition, 3 

 Induction field, definition, 12 

 Integral half-wave antennas, 27-28 

 Interference, propagation factor in 



radio gain calculation, 67 

 Isotropic radiator, hyiiothetical an- 

 tenna, 16 



Jungles, obstacles to radio wave propa- 

 gation, 195-196 



Line of sight, definition, 62 



Linear antennas, diameter lengths, 29- 

 31 



Linear antennas, types, 24-25 



Lobe maxima and minima, defiintion, 

 129 



Lobe-angle method, coverage diagram 

 construction, 138-144 

 basic equation, 138 

 correction for low angles, 141-143 

 lobe angles with horizontal, 139 

 lobe construction, 140-141 

 modified divergence factor, 139-140 

 reflection point curves, 138-139 

 vertical polarization, 143-144 



Maximum rangi', 102-106 



low-angle aircraft coverage, antenna 

 Ireights and target heights, 163- 

 164 

 low-angle aircraft itoverage, heiglit 

 curves versus maximum range, 

 164 

 low-angle antl surface range coverage, 



163 

 one-way comnmnication, 162 

 radar, 102 

 Alicrowave beacons, ring arrays, 39 

 Moist standard atmosphere, propaga- 

 tion, 3-4 



Multidimensional arrays, antenna, 38 

 Multiple half-wave long antennas, 27- 

 28 



Noise figure of radio receiver, 17-19 



definition, 18 



measurement, 18-19 

 Nonstandard atmosphere, propaga- 

 tion, 4 



Operator loss, radar i-eception, 19 

 Optical region, radiation field charac- 

 teristics, 66 

 Optical region, radio gain calculation, 

 62-63 



Parabolic reflectors for antennas, 42-43 

 Parasitic antennas, 39-42 

 corner reflector, 42 

 half-wave dipole and parasite, 39-41 

 multiple parasites, Yagi antenna, 41 

 reflecting screens, 41-42 

 Path difference 



loci construction, coverage diagrams, 



134-135 

 parameters, 145, 147 

 path difference variable equation, 



80-81 

 plane earth, 70 

 spherical earth, 74-75 

 Path gain factor, definition, 5 

 Performance figure, measurement of set 



efficiency, 162-163 

 Permanent echoes, prediction, 193-195 

 profile method, 193-195 

 radar test at site, 193 

 PiPD (radar planning device), 193 

 supersonic method, 193 

 Permanent echoes, site selection fac- 

 tors, 191-195 

 permanent echo diagrams, 191-192 

 shielding, echo control, 193 

 Plane earth 



calculation of radio gain below inter- 

 ference region, 91-92 

 coverage diagrams, 129-131 

 path difference, 70 

 Polarization 



angles of lolie maxima, horizontal 



polarization, 129-130 

 angles of lobe maxima, vertical polar- 

 ization, 130-131 

 Fresnel diffraction theory, 174 

 horizontal versus vertical, optical 



region, 00 

 horizontal versus vertical, radio gain 



calculations, 109 

 radio gain, vertical polarization 



effect, 83 

 radio gain curves, horizontal polar- 

 ization, 8-10 

 radio wave diffraction, 174 



