# skrf.calibration.calibration.EightTerm¶

class skrf.calibration.calibration.EightTerm(measured, ideals, switch_terms=None, isolation=None, ut_hook=None, *args, **kwargs)[source]

General EightTerm (aka Error-box) Two-port calibration

This is basically an extension of the one-port algorithm to two-port measurements, A least squares estimator is used to determine the error coefficients. No self-calibration takes place. The concept is presented in [1] , but implementation follows that of [2] .

Notes

An important detail of implementing the error-box model is that the internal switch must be correctly accounted for. This is done through the measurement of switch terms.

References

 [1] Speciale, R.A.; , “A Generalization of the TSD Network-Analyzer Calibration Procedure, Covering n-Port Scattering-Parameter Measurements, Affected by Leakage Errors,” Microwave Theory and Techniques, IEEE Transactions on , vol.25, no.12, pp. 1100- 1115, Dec 1977. URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1129282&isnumber=25047
 [2] Rytting, D. (1996) Network Analyzer Error Models and Calibration Methods. RF 8: Microwave Measurements for Wireless Applications (ARFTG/NIST Short Course Notes)

Attributes

 T_matrices Intermediate matrices used for embedding and de-embedding. biased_error Estimate of biased error for overdetermined calibration with multiple connections of each standard caled_ntwk_sets Returns a NetworkSet for each caled_ntwk, grouped by their names caled_ntwks List of the corrected calibration standards coefs Dictionary or error coefficients in form of numpy arrays coefs_12term Dictionary of error coefficients for 12-term Model coefs_12term_ntwks Dictionary or error coefficients in form of Network objects coefs_3term Dictionary of error coefficients for One-port Error model coefs_3term_ntwks Dictionary of error coefficients in form of Network objects coefs_8term Dictionary of error coefficients for 8-term (Error-box) Model coefs_8term_ntwks Dictionary of error coefficients in form of Network objects coefs_ntwks Dictionary of error coefficients in form of Network objects error_ntwk The calculated error Network or Network[s] family frequency Frequency object of the calibration measured_unisolated measured_unterminated normalized_directivity the directivity normalized to the reflection tracking nstandards number of ideal/measurement pairs in calibration output_from_run Returns any output from the run(). residual_ntwk_sets Returns a NetworkSet for each residual_ntwk, grouped by their names residual_ntwks Dictionary of residual Networks total_error Estimate of total error for overdetermined calibration with multiple connections of each standard.This is the combined effects of both biased and un-biased errors unbiased_error Estimate of unbiased error for overdetermined calibration with multiple connections of each standard verify_12term verify_12term_ntwk

Methods

 __init__ EightTerm Initializer apply_cal Apply correction to a Network apply_cal_to_all_in_dir apply_cal_to_list Apply correction to list of dict of Networks. embed from_coefs Creates a calibration from its error coefficients from_coefs_ntwks Creates a calibration from its error coefficients plot_caled_ntwks Plots corrected calibration standards plot_errors Plots biased, unbiased and total error in dB scaled plot_residuals Plot residual networks. pop Remove and return tuple of (ideal, measured) at index. remove_and_cal Remove a cal standard and correct it, returning correct and ideal renormalize Renormalizes the calibration error boxes to a new reference impedance. run Runs the calibration algorithm. terminate Terminate a network with switch terms unterminate Unterminates switch terms from a raw measurement. update_coefs update currect dict of error coefficients write Write the Calibration to disk using write()