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Calculating Return-Loss Uncertainty

Jan. 16, 2007
For reflection measurements, the uncertainty in magnitude VRC, U(|*|) can be converted to the equivalent return loss uncertainty, U(RL), using Eq. 38: where: * = the measured VRC. Calculating phase uncertainty: For a given S-parameter, Sij (i ...

For reflection measurements, the uncertainty in magnitude VRC, U(|*|) can be converted to the equivalent return loss uncertainty, U(RL), using Eq. 38:

where:
* = the measured VRC.
Calculating phase uncertainty:
For a given S-parameter, Sij (i = 1, 2; j = 1, 2), the uncertainty in phase, U(*), can be estimated using Eq. 49:

where:
U(|Sij|) = the uncertainty in |Sij|.
When calculating the uncertainty in transmission phase, it is first necessary to determine the uncertainty in the magnitude of the linear transmission coefficient (i.e. U(|S21|) or U(|S12|)). This can be derived from the measured attenuation, A, and the uncertainty in the measured attenuation, U(A), using Eq. 58:

About the Author

Jack Browne | Technical Contributor

Jack Browne, Technical Contributor, has worked in technical publishing for over 30 years. He managed the content and production of three technical journals while at the American Institute of Physics, including Medical Physics and the Journal of Vacuum Science & Technology. He has been a Publisher and Editor for Penton Media, started the firm’s Wireless Symposium & Exhibition trade show in 1993, and currently serves as Technical Contributor for that company's Microwaves & RF magazine. Browne, who holds a BS in Mathematics from City College of New York and BA degrees in English and Philosophy from Fordham University, is a member of the IEEE.

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