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The change of repetition frequency allows the radar, on a pulse-to-pulse basis, to differentiate between returns from its own transmissions and returns from other radar systems with the same PRF and a similar radio frequency. Consider a radar with a constant interval between pulses; target reflections appear at a relatively constant range ...
Coastal radar systems, over-the-horizon (OTH) radars; 'high frequency' VHF: 30–300 MHz: 1–10 m: Very long range, ground penetrating; 'very high frequency'. Early radar systems generally operated in VHF as suitable electronics had already been developed for broadcast radio.
This convention began around World War II with military designations for frequencies used in radar, which was the first application of microwaves. There are several incompatible naming systems for microwave bands, and even within a given system the exact frequency range designated by a letter may vary somewhat between different application areas.
A radar system uses a radio frequency electromagnetic signal reflected from a target to determine information about that target. PRF is required for radar operation. This is the rate at which transmitter pulses are sent into air or space.
The frequency of radio waves used by most radars, in the form of microwaves, travel in straight lines.This generally limits the detection range of radar systems to objects on their horizon (generally referred to as "line of sight" since the aircraft must be at least theoretically visible to a person at the location and elevation of the radar transmitter) due to the curvature of the Earth.
The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum.In some cases, such as in communication engineering, the frequency range of the X band is rather indefinitely set at approximately 7.0–11.2 GHz.
The National NEXRAD Radar network operates with S-band frequencies. Before implementation of this system, C-band frequencies were commonly used for weather surveillance. In the United States, the 3.55 to 3.7 GHz band is becoming shared spectrum under rules adopted by the Federal Communications Commission in April 2015 as a result of the ...
The radar frequency is also chosen in order to optimize the radar cross-section (RCS) of the envisioned target, which is frequency-dependent. Examples of propagation windows are the 3 GHz (S), 10 GHz (X), 24 GHz (K), 35 GHz (Ka), 77 GHz (W), 94 GHz (W) propagation windows.