## Historical and technical survey |

### From inside the book

Results 1-3 of 14

Page 125

Figure 17.

geometrical edge of the shadow. Only one-half of the wave is effective and the

electric intensity is reduced to one-half, considering the unobstructed wave as

unity.

Figure 17.

**Fresnel zones**on the shadow line. In Figure 17 the observer is at thegeometrical edge of the shadow. Only one-half of the wave is effective and the

electric intensity is reduced to one-half, considering the unobstructed wave as

unity.

Page 159

In order to describe diffraction at a shore line a system of

lobe is considered to be formed on the sea with the reflection point of the lobe as

their center. The zones will be ellipses because of the inclination of the rays.

In order to describe diffraction at a shore line a system of

**Fresnel zones**for eachlobe is considered to be formed on the sea with the reflection point of the lobe as

their center. The zones will be ellipses because of the inclination of the rays.

Page 161

The reflection point is obtained by using m = 0 and equation (77) reduces to: d, =

4hS nX (78) Thus to obtain the range of the near edge of the first

the first lobe, substitute n = 1, m = 1 and use the minus sign in equation (77) : d„ ...

The reflection point is obtained by using m = 0 and equation (77) reduces to: d, =

4hS nX (78) Thus to obtain the range of the near edge of the first

**Fresnel zone**forthe first lobe, substitute n = 1, m = 1 and use the minus sign in equation (77) : d„ ...

### What people are saying - Write a review

We haven't found any reviews in the usual places.

### Common terms and phrases

altitude Anomalous Propagation antenna attenuation azimuth band characteristic values Committee on Propagation computed constant coverage diagram CUDWR curvature curve decibels decrease determine diffraction diffraction region direct distance Division 14 Report duct earth effect elevation equation equipment experiments factor field intensity field strength free space frequency Fresnel zones functions gradient ground height horizontal humidity index of refraction JEIA land layer lobe angles maximum measurements meter method microwave miles mode moisture NDRC nonstandard propagation NRSL obtained operational optical OSRD path difference pattern permanent echoes phase plane plotted polarization problem radar radar cross section Radio Propagation Radio Waves radius range receiver reflection coefficient refractive index region Research signal strength Snell's law standard atmosphere superrefraction target temperature inversion theory tion transmission transmitter trapping Tropospheric variation vertical Wave Propagation Wave Propagation Group wavelength weather X band zone