# effearthradius

## Syntax

## Description

returns the effective
radius `Re`

= effearthradius`Re`

of a spherical earth computed from the gradient of the
index of refraction of the atmosphere. The radius is in meters. This syntax uses the
default value of `-39e-9`

for the gradient, making the effective radius
approximately 4/3 of the actual earth radius. For more information about the computation,
see Effective Earth Radius from Refractivity Gradient.

returns the effective Earth radius, `Re`

= effearthradius(`R`

,`ha`

,`ht`

)`Re`

, using the average radius of
curvature method (see [1]).
`R`

is the line-of-sight range to the target. `ha`

is the radar altitude above mean sea level (MSL). `ht`

is the target
altitude above MSL. See Effective Earth Radius from Average Radius of Curvature.

`[`

also outputs the effective radius factor, `Re`

,`k`

] = effearthradius(___)`k`

. Use this option with any
of the syntaxes described above. See Effective Earth Radius.

## Examples

## Input Arguments

## Output Arguments

## More About

## References

[1] Doerry, Armin. W.
*"Earth Curvature and Atmospheric Refraction Effects on Radar Signal
Propagation"*, Sandia National Laboratories, SAND2012-10690, January
2013.

[2] Long, Maurice W. *Radar
Reflectivity of Land and Sea*, 2nd Ed. Artech House, 2001.

[3] Mahafza, Bassem R.
*Radar Signal Analysis and Processing Using MATLAB*, CRC Press,
2009.

[4] Skolnik, Merrill I.
*Introduction to Radar Systems*, Third edition, McGraw-Hill,
2001.

[5] Ward, James.
*"Space-Time Adaptive Processing for Airborne Radar"*, Lincoln Lab
Technical Report, 1994.

## Extended Capabilities

## Version History

**Introduced in R2021a**