# physconst

Physical constants

## Description

example

const = physconst(name) returns the value of the physical constant const specified by the name argument.

## Examples

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Determine the wavelength of a 1 GHz electromagnetic wave.

freq = 1e9;
lambda = physconst('LightSpeed')/freq
lambda = 0.2998

Determine the thermal noise power per unit bandwidth in the in-phase (I) and quadrature (Q) channels of a receiver. Specify a receiver temperature of 290 K.

T = 290;
k = physconst('Boltzmann');

Compute the noise power per unit bandwidth, split evenly between the I and Q channels. Units are in dB.

Noise_power = 10*log10(k*T/2)
Noise_power = -206.9855

## Input Arguments

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Name of physical constant, specified as 'LightSpeed', 'Boltzmann', or 'EarthRadius'. See Physical Constants for a list of values for physical constants used in Phased Array System Toolbox™.

Example: 'LightSpeed'

## Output Arguments

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Value of physical constant, returned as a real-valued scalar. All values are in SI units.

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### Physical Constants

This table lists the supported constants and their values in SI units.

ConstantDescriptionValue
'LightSpeed'Speed of light in vacuum299,792,458 m/s. Most commonly denoted by c.
'Boltzmann'Boltzmann constant relating kinetic energy to temperature$1.\text{3806504}×{10}^{-23}$ J/K. 2006 NIST value, most commonly denoted by k.