Agilent Technologies 8510-58 Fixed or sliding, Offset delay, Delay seconds =, Terminal impedance

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The inductance as a function of frequency can be modeled by specifying the coefficients of a third- order polynomial (L0 + L1  f + L2  f2 + L3  f3), with units of L0(nH), L1(10-24H/Hz),

L2(10-33H/Hz2) and L3(10-42H/Hz3).

For the waveguide example, the inductance of the offset short circuits is negligible. L0 through L3 are set equal to zero.

Fixed or sliding

If the standard type is specified to be a load or an arbitrary impedance, then it must be specified as fixed or sliding. Selection of “sliding” provides a sub-menu in the calibration sequence for multiple

The WR-62 waveguide calibration kit example does not contain an arbitrary impedance standard.

Offset delay

If the standard has electrical length (relative to the calibration plane), a standard is specified to have an offset delay. Offset delay is entered as the one- way travel time through an offset that can be obtained from the physical length using propaga- tion velocity of light in free space and the appro- priate permittivity constant. The effective propagation velocity equals √cεr . See Appendix B for a further description of physical offset lengths for sexed connector types.

slide positions and measurement. This enables cal- culation of the directivity vector by mathematically

Delay (seconds) =

√εr

eliminating the response due to a non-ideal termi- nal impedance. A further explanation of this tech- nique is found in the Measurement Calibration section in the Agilent 8510 Operating and Programming manual.

The load standard #4 in the WR-62 waveguide cali- bration kit is defined as a fixed load. Enter FIXED in the table.

Terminal impedance

Terminal impedance is only specified for “arbitrary impedance” standards. This allows definition of only the real part of the terminating impedance in ohms. Selection as the standard type “short,” “open,” or “load” automatically assigns the termi- nal impedance to be 0, ∞ or 50 ohms respectively.

c

=precise measurement of offset length in meters εr = relative permittivity (= 1.000649 for coaxial

airline or air-filled waveguide in standard lab conditions)

c = 2.997925 x 108 m/s

In coaxial transmission line, group delay is con- stant over frequency. In waveguide however, group velocity does vary with frequency due to disper- sion as a function of the cut-off frequency.

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Contents Product Note 8510-5B Table of contents Measurement errors IntroductionMeasurement calibration Calibration kit Standard definition Class assignmentStandard definitions table Standard class assignments Modification procedure Select standardsDefine standards Standard definition models Standard number Standard type Open circuit capacitance C0 , C1 , C2 and C3 ΠfX ΠfZ∆∅radians = 2πf ∆length Short circuit inductance L0 , L1, L2 and L3Offset delay Delay seconds =Fixed or sliding Terminal impedanceLinear delay Actual delay = Fco/f2 Offset Z0Offset loss 1GHz =1GHz c Z0 10 log10e εrLower/minimum frequency Upper/maximum frequency Fupper = 2 x FlowerCoax or waveguide ∅radians =Assign classes Standard labelsStandard Classes S11 A,B,C and S22 A,B,C Forward transmission match and thruReverse transmission match and thru IsolationTRL Thru TRL ReflectTRL Line TRM ThruStandard Class labels TRL optionsCalibration kit label Enter standards/classes Verify performanceUser modified cal kits and Agilent 8510 specifications Modification examplesModeling a thru adapter Modeling an arbitrary impedance standardAppendix a Calibration kit entry procedure Disk procedureTo load calibration kits from disk into Agilent To store calibration kits from the Agilent 8510 onto a diskFront panel procedure P-band waveguide example Pshort Appendix B Dimensional considerations in coaxial connectors Mm coaxial connector interfaceType-N coaxial connector interface Mm Coaxial connector Type-N coaxial connector interface Female type-NPage Appendix C Cal coefficients model EquationTheir first order approximations, R is small and G=0, are Then Online assistance Phone or Fax United States
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