Here are some physical constants and other data in the MKS system which are useful in microwave engineering.

Sources: NIST website and the CRC Handbook of Chemistry and Physics

Constant | Description | Value | Units |
---|---|---|---|

k | Boltzmann's constant | 1.38065030E-23 | Joule/Kelvin |

c | Velocity of light in free space | 2.99792458E+08 | meters/second |

e | Base number of natural logarithms | 2.71828183E+00 | none |

h | Planck's constant | 6.62606876E-34 | Joule-second |

Z_{0} |
Impedance of free space | 3.76730313E+02 | Ohms |

ε | Permittivity of free space | 8.85418782E-12 | Farad/meter |

m_{e} |
Electron mass | 9.10938188E-31 | kilogram |

N | Avagadro's constant | 6.02214199E+23 | mol-1 |

π | Pi | 3.14159265E+00 | none |

q | Electron charge | 1.60217646E-19 | Coulombs |

μ_{0} |
Permeability of free space* | 1.25663706E-06 | Henry/meter |

* exact value is 4πx10-7