US4853613A
Expired / Lapsed
US
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Calibration method for apparatus evaluating microwave/millimeter wave circuits
Assignee: Lockheed Martin Corp
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Filing: 1987-10-27
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Granted: 1989-08-01
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Expires: 2007-10-27
Abstract
Abstract A calibration procedure for vector network analyzers utilizing a known standard, an unknown standard and a pair of offsets bearing a known length ratio (2:1) between them whereby measurements taken on the standards and their combinations with the offsets result in self-verifying redundant equations which furnish: (1) error terms according to well-known flow graph models, (2) the reflection of the unknown standard, (3) the transmission factor of the waveguiding medium from which the offsets are realized regardless of the waveguide's loss or dispersion, and (4) a figure of merit (corruption coefficient) for the quality of the acquired raw data without the necessity for computing the error terms, connecting verification standards or otherwise completing the calibration process.
Inventors
- 👤 Hermann B. Sequeira
- 👤 Michael W. Trippe
- 👤 Rajendra S. Jakhete
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:31
CPC Classifications
G; G01; G01R; G01R35/00; G01R35/005
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
196 words
A method for calibrating measurement apparatus including a vector network analyzer for making evaluations of circuits operating at microwave and millimeter wave frequencies comprising the steps of: (a) measuring and storing data for a plurality of measurement conditions utilizing a first standard termination, alone and in combination with a pair of termination offsets having respective lengths defining a predetermined ratio; (b) measuring and storing data for a plurality of measurement conditions utilizing a second standard termination different from the first standard termination, alone and in combination with said pair of offsets as set forth in step (a); (c) computing a figure of merit of the quality of the measured raw data measured in steps (a) and (b); (d) computing the electrical length of the offsets expressed as a function of the wavelength used in steps (a) and (b); (e) computing a plurality of error terms also known as error coefficients based on a predetermined error model; (f) computing the reflection coefficient of the second standard; and (g) determining the corrupting influences on said terminations by comparing the computed values as obtained in steps (d) and (f) with corresponding measured values obtained in steps (a) and (b).
Claim 2
Independent Claim
196 words
A method for calibrating measurement apparatus including a vector network analyzer for making evaluations of circuits operating at microwave and millimeter wave frequencies comprising the steps of: (a) measuring and storing data for a plurality of measurement conditions utilizing a first standard termination, alone and in combination with a pair of termination offsets having respective lengths defining a predetermined ratio; (b) measuring and storing data for a plurality of measurement conditions utilizing a second standard termination different from the first standard termination, alone and in combination with said pair of offsets as set forth in step (a); (c) computing a figure of merit of the quality of the measured raw data measured in steps (a) and (b); (d) computing the electrical length of the offsets expressed as a function of the wavelength used in steps (a) and (b); (e) computing a plurality of error terms also known as error coefficients based on a predetermined error model; (f) computing the reflection coefficient of the second standard; and (g) determining the corrupting influences on said terminations by comparing the computed values as obtained in steps (d) and (f) with corresponding measured values obtained in steps (a) and (b).
Claim 3
Dependent Claim
26 words
The method as defined by claim 1, wherein the first standard comprises a short circuit, an open circuit, or a termination with known but arbitrary response.
Claim 4
Dependent Claim
36 words
The method as defined by claim 1 wherein the second standard comprises a load, a short circuit, an open circuit, or other termination with unknown and arbitrary response different from the response of said known standard.
Claim 5
Dependent Claim
21 words
The method as defined by claim 1 wherein said offsets are comprised of waveguide shims and have a ratio of 2:1.
Claim 6
Dependent Claim
25 words
The method as defined by claim 1 wherein said step (c) comprises the step of computing the corruption factor K Cor of the raw data.
Claim 7
Dependent Claim
42 words
The method as defined by claim 1 wherein said step (e) comprises the step of computing the parameter including frequency response tracking, E R , directivity, E D , and selectively source match, E S , and load match, E L .
Claim 8
Dependent Claim
30 words
The method as defined by claim 6 wherein said step (e) additionally includes the step of computing the parameters including isolation, E X , and transmission tracking, E T .
Claim 9
Dependent Claim
66 words
The method as defined by claim 1 wherein said step (c) comprises the step of computing the corruption factor K Cor according to the expression: ##EQU15## where C S0 , C S1 , C S2 , C L0 and C L2 comprises measured data values of the reflection coefficients for a short, offset short, doubly offset short, a load, offset load, and doubly offset load, respectively.
Claim 10
Dependent Claim
29 words
The method as defined by claim 8 and additionally including the step of computing the parameter defined as the offset z from the roots Z+ of the expression: ##EQU16##
Claim 11
Dependent Claim
40 words
The method as defined by claim 8 and wherein said step (g) of determining corrupting influences includes the step of comparing, for an offset short (-Z -1 ), the computed and measured value of a parameter defined by expression ##EQU17##
Claim 12
Dependent Claim
29 words
The method as defined by claim 9 and wherein said step (e) includes the step of computing the parameter source match, E S , according to the expression: ##EQU18##
Claim 13
Dependent Claim
29 words
The method as defined by claim 11 wherein said step (e) includes the step of computing the reflection tracking error coefficient, E R , according to the expression: ##EQU19##
Claim 14
Dependent Claim
28 words
The method as defined by claim 12 wherein said step (e) includes the step of computing the directivity error coefficient, E D , according to the expression: ##EQU20##
Claim 15
Dependent Claim
28 words
The method as defined by claim 13 and wherein said step (f) comprises the step of computing the reflection coefficient Γ L , in accordance with expression: ##EQU21##
Claim 16
Dependent Claim
60 words
The method as defined by claim 14 wherein said step (g) of determining corrupting influences additionally includes the step of computing the parameter C LO of the load termination in accordance with the expression: ##EQU22## and by using both sides of this equation obtaining estimates of Γ L as set forth in step (f), and thereafter comparing the two estimates.
Claim 17
Dependent Claim
41 words
The method as defined by claim 10 wherein said step (g) of determining corrupting influences includes the step of comparison, for a simple short (-1) with no offset, the computed and measured value of a parameter defined by the expression: ##EQU23##
Claim 18
Dependent Claim
42 words
The method as defined by claim 10 and wherein said step (g) of determining corrupting influences includes the step of comparing for a doubling offset short (-Z -2 ), the computed and measured value of a parameter defined by the expression ##EQU24##
References Cited (Backward Citations)
US4680538A
Cited
US4721901A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-07-31 | 1993-01-30 | 1993-08-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-07-31 | 1997-01-30 | 1997-08-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-07-31 | 2001-01-30 | 2001-08-01 | $7700.00 | Window Closed / Lapsed |