Search radars scan great volumes of air by emitting short radio waves, which are reflected back to the radar by ships and aircraft. They do this by continuously completing volume coverage patterns (VCPs), or a series of 360deg scans around a defined elevation angle. VCPs are surprisingly accurate at determining the direction of an approaching ship or airplane, since the pulses are very small.
Some sites also have a special capability, known as “anomalous propagation,” which allows them to detect echoes from a variety of sources, including ground clutter, a phenomenon that occurs when a radar beam is refracted almost directly into the ground at some distance. The fact that these echoes are visible to the eyes is a technological feat, and is often a sign that a hazard has entered the area.
The safety of radar radiation has been debated in periodic legal cases, but there is no evidence that local adult search radar can cause cancer or other health problems. Radar operators are exposed to microwave energy from the radiofrequencies that are generated by radar systems. The amount of this exposure is measured in dBZ (decibels of Z), which is a common unit used to describe signal strength. A dBZ value ranges from -28 to +28 when the radar is operating in clear air mode and from 5 to 75 when it is in precipitation mode. These dBZ values are shown in color, which shows how much power is being returned to the radar from each elevation scan. The dBZ values increase as the intensity of the transmitted signal increases. This is why it is important to have a strong awareness of the intensity of your own dBZ value in order to avoid excessive exposure and to protect yourself from potential health issues.