Radar Beam and Radar Zone of Influence
Radar Zone of Influence
The width of the main power beam is determined by the half power points. The half-power point is defined as the location where the energy level has dropped by 50% in relationship to the main power beam axis.
The area outside the main power beam or outside the beam width is known as the zone of influence. Since the zone of influence contains 15% to 20% of the radar 's initial energy, there is definitely enough energy to reflect a frequency and therefore register a vehicle outside the main power beam.
Half Power Point - The main radar beam width is determined by measuring the signal strength along the main power axis and then perpendicular from the axis until the signal strength is dropped to 1/2 of that strength measured at the main axis. This is done several times and at various points along the axis until an outline of the beam is determined at the half-power point. Generally speaking, police traffic
radar utilizes main power beam widths of between 18 and 12 degrees. Each of radar manufacturer publishes the actual degree of beam angle for each radar unit.
Lines of Equal Sensitivity
A radar beam contains an infinite number of conical shaped lines of energy which are equal in sensitivity. In other words, if two identical vehicles are located an equal distance from the main power axis, the returned signal would be equal for both vehicles.
Since the radar beam consists of the main power beam and zones of influence on each side of the main power beam; and since vehicles will be located at varying distances within the main power beam and within the zones of influence, other factors must be considered when studying the reflected signal.
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