skrf.calibration.calibration.LRRM

class skrf.calibration.calibration.LRRM(measured, ideals, switch_terms=None, isolation=None, z0=50, match_fit='l', *args, **kwargs)

Line-Reflect-Reflect-Match self-calibration.

The required calibration standards are:

• Line: Fully known.

• Reflect: Unknown reflect, phase needs to be known within 90 degrees.

• Reflect: Reflect with known absolute value of the reflection coefficient, phase needs to be known within 90 degrees. Different from the other reflect.

• Match: Match with known resistance in series with unknown inductance.

Reflects are assumed to be identical on both ports. Note that the first reflect’s magnitude of the reflection coefficient can be unknown, but the second reflect’s magnitude of the reflection coefficient needs to be known. Match needs to be only measured on the first port, the second port of match measurement is not used during the calibration.

If match_fit == ‘lc’ then the second reflect is assumed to be a lossless capacitor. Measurements should then include low frequencies for accurate open capacitance determination. ‘lc_fit_c_freq’ argument can be given to specify the maximum frequency in Hz where open looks like an ideal capacitor, above this frequency open is assumed to only have known absolute value similar to ‘l’ fit. Default is infinity.

Implementation is based on papers [1] and [2]. ‘lc’ match_fit based on [3].

References

[1]

Zhao, W.; Liu, S.; Wang, H.; Liu, Y.; Zhang, S.; Cheng, C.; Feng, K.; Ocket, I.; Schreurs, D.; Nauwelaers, B.; Qin, H.; Yang, X. A Unified Approach for Reformulations of LRM/LRMM/LRRM Calibration Algorithms Based on the T-Matrix Representation. Appl. Sci. 2017, 7, 866.

[2]

F. Purroy and L. Pradell, “New theoretical analysis of the LRRM calibration technique for vector network analyzers,” in IEEE Transactions on Instrumentation and Measurement, vol. 50, no. 5, pp. 1307-1314, Oct. 2001.

[3]

S. Liu, I. Ocket, A. Lewandowski, D. Schreurs and B. Nauwelaers, “An Improved Line-Reflect-Reflect-Match Calibration With an Enhanced Load Model,” in IEEE Microwave and Wireless Components Letters, vol. 27, no. 1, pp. 97-99, Jan. 2017.

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	Return 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	Directivity normalized to the reflection tracking.
nstandards	Number of ideal/measurement pairs in calibration.
output_from_run	Return 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.
solved_c	Solved capacitance of the load.
solved_l	Solved inductance of the load
solved_m	Solved match
solved_r1	Solved reflect1
solved_r2	Solved reflect2
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__	LRRM Initializer.
apply_cal	Applies the calibration to the input network.
apply_cal_to_all_in_dir	Apply correction to all touchstone files in a given directory.
apply_cal_to_list	Apply correction to list or dict of Networks.
apply_cal_to_network_set	Apply correction to a NetworkSet.
embed	Applies the error boxes to the calibrated input network.
from_coefs	Create a calibration from its error coefficients.
from_coefs_ntwks	Create a calibration from its error coefficients.
plot_caled_ntwks	Plot corrected calibration standards.
plot_calibration_errors	Plot 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	Run the calibration algorithm.
terminate	Terminate a network with switch terms.
unterminate	Unterminates switch terms from a raw measurement.
update_coefs	Update current dict of error coefficients.
write	Write the Calibration to disk using write().