DLOC TOPIC 3 LESSON 1
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Probert-Jones Radar Equation
Nearly all weather radars transmit a series of discrete pulses of energy that have been concentrated into a relatively narrow beam. Each pulse or packet of energy contains a certain amount of energy that propagates through Earth's atmosphere and illuminates targets of various sizes. The amount of energy returned to the radar is very small (~10-8 to 10-14 watts) and can be as much as 20 orders of magnitude smaller than the peak transmitted power.
The Probert-Jones (P-J) radar reflectivity equation will help to quantify the physical aspects of pulsed E-M energy and the associated limitations of target (e.g., precipitation) detection. The P-J equation is described below as
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where:
| Pr = power returned to the radar from a target (watts) | Pt = peak transmitted power (watts) | ||
| G = antenna gain |  = angular beamwidth |
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| H = pulse length |  = pi (3.141592654) |
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| K = physical constant (target character) | L = signal loss factors associated with attenuation and receiver detection | ||
| Z = target reflectivity |  = transmitted energy wavelength |
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| R = target range |
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