ESM Detection Range
The applet plots the path loss between a radar transmitter and an ESM receiver over sea paths and indicates the likely detection range.
A standard atmosphere is modeled including the interference, diffraction and tropospheric scatter zones, for all prime polarizations, wave structure and some rainfall conditions.
The free space propagation loss curve is displayed for comparison.
Heights 1 and 2 are the transmitter and receiver heights above local ground/sea level.
Rain loss for dry, light (0.25 mm/hr), medium (2.5 mm/hr), and heavy (25 mm/hr) rain conditions are selected from the Rainfall drop-down box at the bottom of the applet.
Signal polarization is selected by mouse-clicking the relevant radio buttons
Wave height assumes the conventional peak-to-trough definition.
Moving the mouse in Range-loss space displays the plotted curves coordinates referred to the mouse x-axis position.
The ESM detection range (if within the plot range) is displayed for the signal frequency, transmitter ERP, and ESM system sensitivity selected.
Default ranges in the Range text boxes may be modified and the display updated using the relevant applet or keyboard Enter button.
The display automatically scales, dependent on the parameter values selected.
In addition to the cursor display values, a marker position scrollbar and readout enables detailed inspection of points on the loss curve to changes of the propagation parameters.
For example, the dependence of within horizon nulls and null loss rates to small surface swell, wave height and transmitter/receiver heights can be determined.
To assess the range effects of atmospheric refraction, the normal 4/3 (standard well-mixed atmosphere) radar Earth Diameter is adjustable over the range 2/3 to 3.