Refractivity - Revision history

Cassieg at 19:32, 21 February 2020

2020-02-21T19:32:33Z

2020-02-21T19:01:21Z

2020-02-21T19:00:56Z

2020-02-21T18:38:28Z

Created page with "The refractive index (n) of air is defined as: \dfrac{c}{v} = n"

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The refractive index (n) of air is defined as:

\dfrac{c}{v} = n

@@ Line 4: / Line 4: @@
 where:
-c is the velocity of light in a vacuum.
+*c is the velocity of light in a vacuum.
-v is the velocity of light in air.
+*v is the velocity of light in air.
 A typical value of n is 1.000301. For convenience the refractive index is expressed as refractivity (N)
@@ Line 15: / Line 16: @@
 where:
-P is the atmospheric pressure.
+*P is the atmospheric pressure.
-T is the absolute temperature.
+*T is the absolute temperature.
-e is the water vapor pressure.
+*e is the water vapor pressure.
-N varies with elevation. In a well mixed troposphere, the variation is exponential; however, in the range from 1 to 2 kilometers above sea level, the variation is approximately linear. This is referred to as a constant refractivity gradient. The refractivity gradient determines the microwave beam-bending.
+*N varies with elevation. In a well mixed troposphere, the variation is exponential; however, in the range from 1 to 2 kilometers above sea level, the variation is approximately linear. This is referred to as a constant refractivity gradient. The refractivity gradient determines the microwave beam-bending.
 Handling the variations of refractivity with elevation is the major challenge in the design of high reliability microwave links

← Older revision		Revision as of 19:00, 21 February 2020
Line 1:		Line 1:
	The refractive index (n) of air is defined as:		The refractive index (n) of air is defined as:

−	~~\dfrac{~~c}{v} = n	+	n = c/v
		+
		+	where:
		+	c is the velocity of light in a vacuum.
		+	v is the velocity of light in air.
		+	A typical value of n is 1.000301. For convenience the refractive index is expressed as refractivity (N)
		+
		+	N = (n-1) x 10^6
		+
		+	which results in a typical value of 301 Refractivity is defined by the equation:
		+
		+	N = 77.6 x (P/T) + 3.732 x 10^5 x (e/T^2)
		+
		+	where:
		+	P is the atmospheric pressure.
		+	T is the absolute temperature.
		+	e is the water vapor pressure.
		+	N varies with elevation. In a well mixed troposphere, the variation is exponential; however, in the range from 1 to 2 kilometers above sea level, the variation is approximately linear. This is referred to as a constant refractivity gradient. The refractivity gradient determines the microwave beam-bending.
		+
		+	Handling the variations of refractivity with elevation is the major challenge in the design of high reliability microwave links