Defines, displays or modifies the properties of the calibration standards in a particular calibration kit. This dialog is opened from the Add or View / Modify Calibration Kit dialog (Add Standard... or View / Modify Standard... buttons). Depending on the title, some control elements may not be active.
Calibration standard types.
In its upper part the Add Standard or View / Modify Standard dialog contains several controls to do the following:
Select a standard Type and its Gender (for polarized/not sexless connector types and if the port assignment is not restricted) and assign a Label.
Restrict Port Assignment
Select S-Params From
Qualify whether the standard is described by a Circuit Model from which the analyzer can calculate the S-parameters or by a table of measured or simulated S-parameters stored in a Touchstone file. Pressing the Read Data from File... button opens a file selection dialog where the appropriate file type (*.s1p for one-port standards and *.s2p for two-port standards) is automatically selected.
The Sliding Match and Attenuation are special standard types which must be described by a circuit model. The controls in the S-Params From panel are disabled.
For two-port standards described by a *.s2p file, the implicit ports 1 and 2 (given by the order of S-parameters Re(S11) Im(S11) Re(S21) Im(S21) Re(S12) Im(S12) Re(S22) Im(S22) in the file) are assigned to the test ports that the analyzer actually calibrates as follows: Port 1 is always assigned to the lower-numbered calibrated test port, port 2 to the other (higher-numbered) calibrated test port.
Assigning a label to standards is optional. However, the label is displayed in many dialogs and can help you identify a standard or distinguish different standards with similar parameters.
If Circuit Model is selected in the S-params From panel, then the controls in the central panel of the dialog are enabled. The circuit diagram is adjusted to the selected standard type. The following parameters can be set:
Frequency range (Min. Freq. to Max. Freq) for which the circuit model is valid. During calibration, the analyzer checks whether the sweep range is within the validity range of all measured standards and possibly generates a warning (see Measure Standards dialog).
Offset and Load parameters of the circuit model.
The impedance for waveguides is frequency-dependent. If a waveguide line type is selected in the Offset Model dialog, the circuit model indicates varies instead of a definite impedance value.
Remote control:
[SENSe<Ch>:]CORRection:CKIT:<std_type> [SENSe<Ch>:]CORRection:CKIT:<conn_type>:<std_type> MMEMory:LOAD:CKIT:SDATa
Opens a dialog to define whether the standard can be connected to any port of the analyzer or to just one port (for one-port standards) or a pair of ports (for two-port standards).
The port assignment is displayed in the Add or View / Modify Calibration Kit dialogs.
Port assignment and gender
The standards are handled differently, depending on their port assignment:
If the port assignment is not restricted, the gender belongs to the definition of polarized standards. When the connector type and calibration kit is selected in the calibration wizard, the analyzer checks whether the kit contains the necessary standard types and whether the standards have the right gender.
Standards with restricted port assignment are assumed to have the gender that is appropriate for the calibrated port. In the View Modify Standard dialog, the Gender: input field is disabled. In the calibration wizard, the analyzer checks whether the kit contains the necessary standard types for the required ports. Instead of the gender, the port assignment is stored in the calibration kit file.
This approach simplifies the definition of standards and helps to avoid inconsistencies.
[SENSe<Ch>:]CORRection:CKIT:<std_type>
Specifies the offset parameters for the transmission lines of a particular calibration standard. This dialog is opened from the Add or View / Modify Standard... dialog (Modify Offset... button).
The offset parameters depend on whether or not the circuit model is defined in Agilent Mode (see Add/Modify Calibration Kit dialog):
If Agilent Mode is active, then the standard is characterized by its Delay (in s), its characteristic impedance Z0 (in Ω) and its Offset Loss (in GΩ.
If Agilent Mode is switched off, then the standard is characterized by the ZVR-compatible parameters Electrical Length (in m), its Char. Impedance (in Ω) and its Loss (in dB/sqrt(GHz)). The loss is zero and not editable as long as the electrical length is zero.
Both parameter sets are closely related. The Electrical Length is proportional to the Delay; Z0 corresponds to the Char. Impedance. Moreover the analyzer converts an Agilent-type Offset Loss into a ZVR-type Loss and vice versa using the Relative Permittivity εr for the connector type defined in the Offset Model... dialog.
Offset parameters
The offset parameters have the following physical meaning:
The Delay is the propagation time of a wave traveling through the standard. The Electrical Length is equal to the Delay times the speed of light in the vacuum and is a measure for the length of transmission line between the standard and the actual calibration plane. For a waveguide with permittivity εrand mechanical length Lmech the following relations hold:
The default delay is 0 s, the default step width is 1 ns, corresponding to a step width of 299.792 mm for the electrical length. The relations hold for one-port and 2-port standards.
Z0 is the Characteristic Impedance of thestandard. If the standard is terminated with Z0, then its input impedance is also equal to Z0. Z0is not necessarily equal to the reference impedance of the system (depending on the Connector Type) or the terminal impedance of the standard. The characteristic impedance of the standard is only used in the context of calibration.
The default characteristic impedance is equal to the reference impedance of the system.
The Loss is the energy loss along the transmission line due to the skin effect. For resistive lines and at RF frequencies the loss is approximately proportional to the square root of the frequency.
In Agilent mode the Offset Loss is expressed in units of Ω/s at a frequency of 1 GHz. The following formula holds for two-port standards:
The conversion formula for one-port standards has an additional factor 1/2 on the right-hand side. The reason for this factor is that the Loss in dB accounts for the attenuation along the forward and the reverse path (no matter how often the wave actually propagates through the line), whereas the Offset Loss is proportional to the attenuation of the line.
To determine an offset loss value experimentally, measure the delay in seconds and the loss in dB at 1 GHz and use the formula above.
The default Loss or Offset Loss is zero.
The impedance for waveguides is frequency-dependent. If a waveguide line type is selected in the Offset Modeldialog, the Char. Impedance field is disabled and indicates "varies" instead of a definite impedance value. Moreover no Loss or Offset Loss can be set.
Offset parameters and standard types
Offset parameters are used to describe all types of standards except the Sliding Match and the Attenuation.
The Sliding Match is a one-port standard with variable load parameters (sliding load) and unspecified length. The reference impedance is fixed and equal to the characteristic impedance of the connector type. No load and offset parameters need to be set.
The Attenuation is a two-port standard which is fully matched in both directions (the reflection factor at both ports is zero). No load and offset parameters need to be set.
[SENSe<Ch>:]CORRection:CKIT:<conn_type>:<std_type>
Specifies the load parameters for a particular calibration standard describing its terminal impedance. This dialog is opened from the Add or View / Modify Standard... dialog (Modify Load... button).
The circuit model for the load consists of capacitance C which is connected in parallel to an inductance L and a resistance R, both connected in series.
R is the constant resistive contribution. It is possible to select a special value (Open for Ω so that the inductance coefficients are irrelevant, Short for 0 Ω, Match for the reference impedance of the current connector type) or set any resistance R.
The fringing capacitance C and the residual inductance L are both assumed to be frequency-dependent and approximated by the first four terms of the Taylor series around f = 0 Hz.
Load parameters and standard types
Load parameters are used to describe all types of standards except a Through, a Sliding Match, a Line and an Attenuation.
The Through standard is a through-connection between two ports with minimum loss which is taken into account by the Offset Parameters.
The Sliding Match is a one-port standard with variable load parameters (sliding load), so there is no fixed load model.
The Line standard is a line of variable length with minimum loss which is taken into account by the Offset Parameters.
The following table gives an overview of the different standards and their offset and load models:
Standard Type
Characteristics
Ideal Standard
Offset Model
Load Model
Open
Open circuit (one-port)
Ω
Short
Short circuit (one-port)
0 Ω
Offset short
Short circuit with added electrical length offset, for waveguide calibration (one-port)
Match
Matched broadband termination (one-port)
Z0 (reference impedance of the connector type)
Sliding match
One-port standard consisting of an air line with a movable, low-reflection load element (sliding load). See Measure Standards.
–
Reflect
Unknown mismatched standard (one-port)
Through
Through-connection with minimum loss (two-port)
Line1, Line 2
Line(s) for TRL calibration with minimum loss (two-port)
Attenuation
Fully matched standard in both directions (two-port; the reflection factor at both ports is zero).
Symm. network
Unknown mismatched reflection-symmetric standard (two-port)
The calibration of rectangular waveguides at very high frequencies requires a special set of standards; see Frequency Extension – Calibration.
For an overview of standard parameters see also [SENSe<Ch>:]CORRection:CKIT:<conn_type>:<std_type>