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DLOC Principles of Meteorological Doppler Radar:
WSR-88D Fundamentals

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Previous Page: Section #2: Radar Equation and Reflectivity

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 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) compared to 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

  Equation 1.  Probert-Jones Radar Equation.  Click for Long Description.  

where:

  Pr = power returned to the radar from a target (watts)   Pt = peak transmitted power (watts)
  G = antenna gain   greek symbol theta = angular beamwidth
  H = pulse length   greek symbol pi = pi (3.141592654)
  K = physical constant (target character)   L = signal loss factors associated with attenuation and receiver detection
  Z = target reflectivity   greek symbol lambda = transmitted energy wavelength
  R = target range    

 

Next Page: Simplified Radar Equation and Signal Attenuation