TRL Thru
TRL Thru corresponds to the measurement of the S-parameters of a zero-length or short thru connec- tion between port 1 and port 2. The Thru, Reflect and Line classes are used exclusively for the three steps of the TRL 2-PORT calibration. Typically, a “delay/thru” with zero (or the smallest) Offset Delay is specified as the TRL Thru standard.
TRL Reflect
TRL Reflect corresponds to the S11 and S22 meas- urement of a highly reflective 1-port device. The Reflect (typically an open or short circuit) must be the same for port 1 and 2. The reflection coeffi- cient magnitude of the Reflect should be close to 1 but is not specified. The phase of the reflection coefficient need only be approximately specified (within ± 90 degrees).
TRL Line
TRL Line corresponds to the measurement of the S-parameters of a short transmission line. The impedance of this Line determines the reference impedance for the subsequent error-corrected measurements. The insertion phase of the Line need not be precisely defined but may not be the same as (nor a multiple of pi) the phase of the Thru.
TRM Thru
Refer to “TRL Thru” section.
TRM Reflec
Refer to “TRL Reflec” section.
TRM Match
TRM Match corresponds to the measurement of the S-parameters of a matched load. The input reflec- tion of this Match determines the reference imped- ance for the subsequent error-corrected measurements. The phase of the Match does not need to be precisely defined.
Adapter
This class is used to specify the adapters used for the adapter removal process. The standard num- ber of the adapter or adapters to be characterized is entered into the class assignment. Only an esti- mate of the adapter’s Offset Delay is required
(within ± 90 degrees). A simple way to estimate the Offset Delay of any adapter would be as fol- lows. Perform a 1-port calibration (Response or S11 1-PORT) and then connect the adapter to the test port. Terminate the adapter with a short cir- cuit and then measure the Group Delay. If the short circuit is not an offset short, the adapter’s Offset Delay is simply l/2 of the measured delay.
If the short circuit is offset, its delay must be sub- tracted from the measured delay.
Modifying a cal set with connector compensation Connector compensation is a feature that provides for compensation of the discontinuity found at the interface between the test port and a connector. The connector here, although mechanically com- patible, is not the same as the connector used for the calibration. There are several connector fami- lies that have the same characteristic impedance, but use a different geometry. Examples of such pairs include:
3.5mm / 2.92 mm
3.5mm / SMA SMA / 2.92 mm
2.4mm / 1.85 mm
The interface discontinuity is modeled as a lumped, shunt-susceptance at the test port refer- ence plane. The susceptance is generated from a capacitance model of the form:
C=C0 + C1 x f + C2 x f2 + C3 x f3
where f is the frequency. The coefficients are pro- vided in the default Cal Kits for a number of typi- cally used connector-pair combinations. To add models for other connector types, or to change the coefficients for the pairs already defined in a Cal Kit, use the “Modifying a Calibration Kit” proce- dure in the “Calibrating for System Measurements” chapter of the 8510 network analyzer systems Operating and Programming Manual (part number 08510-90281). Note that the definitions in the default Cal Kits are additions to the Standard Class Adapter, and are Standards of type “OPEN.”
