RegisterFresnel zonesIn free space, assume a transmitter V and a receiver P as depicted in the figure. In an arbitrary planar cut, which is perpendicular to the line VP, such points A1 are searched so that the pointed line VA1 P can be half wavelength longer than the direct distance VP. There is infinite number of such points and form together a circle of the center in O . Surface bounded by this circle is so called first Fresnel zone, and OA1= r01 is its radius. The same way, the other points A2, ... An can be found, which meet The annulus surface between A2 and A1 is the second Fresnel zone, etc. Radius of nth zone can be computed using the approximate relation Repeating the above-described consideration for points A1 in different positions (cuts) along the line VP, different values of the radius of the first Fresnel zone are obtained. All the points A1 are part of a rotational ellipsoid, which is called the first Fresnel ellipsoid. Back
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