Calibration Procedures

Calibration Kit Selection

The calibration kit employed during a calibration should be selected according to the following procedure. If it is not specified in the list of the predefined calibration kits, you should add it. The procedure of adding and editing of the calibration kits is described in the section 5.2.14.

To open the list of the calibration kits (See Figure 46), use the Cal Kit softkey.

Highlight the required line in the list of the calibration kits and use the softkey to select it. Make sure that the selected calibration kit is check-marked.

Reflection Normalization

Reflection normalization is the simplest calibration method used for reflection coefficient measurements (S₁₁ orS₂₂). Only one standard (SHORT or OPEN) is measured (See Figure 47) in the process of this calibration. You can also perform directivity calibration by measuring a LOAD standard.

Before starting calibration perform the following settings: select active channel, set the parameters of the channel (frequency range, IF bandwidth, etc.), and select the calibration kit.

To open reflection normalization submenu, use the Calibration menu softkeys. -Select the test port to be calibrated using Select Port. Clicking this softkey you can switch between the test ports (measured parameters). | -Connect an OPEN or a SHORT standard to the test port. Perform measurement using Open or Short softkey respectively. | -To perform the optional directivity calibration, connect a LOAD standard to the test port and perform measurement using Load (Optional) softkey. | -To complete the calibration procedure, click Apply. | -To clear the measurement results of the standards, click Cancel. |

Transmission Normalization

Transmission normalization is the simplest calibration method used for transmission coefficient measurements (S₂₁ orS₁₂). One THRU standard is measured in the process of this calibration. You can also perform isolation calibration by measuring two LOAD standards.

Before starting calibration perform the following settings: select active channel, set the parameters of the channel (frequency range, IF bandwidth, etc.), and select the calibration kit.

To open transmission normalization submenu, use the Calibration menu softkeys.

• Select the direction of the calibration using Select Ports softkey. The label on the softkey indicates the following: receiver port – source port (measured parameter).
• Connect a THRU standard between the test ports. If the port connectors allow through connection connect them directly (zero electrical length thru). Perform measurement using Thru softkey.
• To perform the optional isolation calibration, connect two LOAD standards to the test ports and enable measurement using Isolation (Optional) softkey.
• To complete the calibration procedure, click Apply.
• To clear the measurement results of the standard, click Cancel.

Full One-Port Calibration

Full one-port calibration is used for reflection coefficient measurements (S₁₁ orS₂₂). The three calibration standards (SHORT, OPEN, LOAD) are measured in the process of this calibration.

Figure 49 Full one-port calibration

Before starting calibration perform the following settings: select active channel, set the parameters of the channel (frequency range, IF bandwidth, etc.), and select the calibration kit.

To open full one-port calibration submenu, use the Calibration menu softkeys.

• Select the test port to be calibrated using Select Port. Clicking this softkey you can switch between the test ports (measured parameters).
• Connect SHORT, OPEN and LOAD standards to the selected test port in any sequence. Perform measurements clicking the softkey corresponding to the connected standard.
• To complete the calibration procedure, click Apply.
• To clear the measurement results of the standards, click Cancel.

One-Path Two-Port Calibration

One-path two-port calibration is used for measurements of the DUT parameters in one direction, e.g. S₁₁ and S₂₁. This method involves connection of the three calibration standards to the source port, and connection of a THRU standard between the calibrated source port and the other receiver port). You can also perform isolation calibration by measuring two LOAD standards.

Before starting calibration perform the following settings: select active channel, set the parameters of the channel (frequency range, IF bandwidth, etc.), and select the calibration kit.

To open one-path two-port calibration submenu, use the Calibration menu softkeys.

• Select the direction of the calibration using Select Ports softkey. The label on the softkey indicates the following: receiver port – source port (measured parameters).
• Connect SHORT, OPEN and LOAD standards to the source port in any sequence. Perform measurements clicking the softkey corresponding to the connected standard.
• To perform the optional isolation calibration, connect two LOAD standards to the test ports and enable measurement using Isolation (Optional) softkey.
• To complete the calibration procedure, click Apply.
• To clear the measurement results of the standards, click Cancel.

Full Two-Port Calibration

Full two-port calibration combines two one-port calibrations for each test port with measurement of transmission and reflection of a THRU standard in both directions. You can also perform isolation calibration by measuring two LOAD standards.

Before starting calibration perform the following settings: select active channel, set the parameters of the channel (frequency range, IF bandwidth, etc.), and select the calibration kit.

To open full two-port calibration submenu, use the Calibration menu softkeys.

• Connect SHORT, OPEN and LOAD standards to the 1 and 2 ports in any sequence. Perform measurements clicking the softkey corresponding to the connected standard.
• To perform the optional isolation calibration, connect two LOAD standards to the test ports and enable measurement using Port 1–2 Isol (Optional) softkey.
• To complete the calibration procedure, click Apply.
• To clear the measurement results of the standards, click Cancel.

Unknown Thru Calibration (except Planar 304/1)

The unknown thru calibration procedure is same as the one for a full two-port calibration described in the previous section.

To start unknown thru calibration, first add UNKNOWN THRU standard to the description of the calibration kit and assign the class to it. After that, the unknown thru measurement softkey will become available in the two-port calibration menu.

See section 5.3.2 for a calibration standard definition in a calibration kit. When adding the unknown thru standard to a kit you should specify just two parameters: UNKNOWN THRU type of the standard and approximate delay of propagation in one direction. You can enter zero value for delay for it to be automatically determined during calibration (See section 5.1.6.8).

See section 5.3.4 for the calibration standard class assignment. A newly added UNKNOWN THRU standard is to be assigned to “Thru, Port 1-2” class.

TRL Calibration (except Planar 304/1)

TRL calibration is the most accurate calibration method for two-port measurements. Before starting calibration, perform the following settings: select active channel, set the parameters of the channel (frequency range, IF bandwidth, etc.), select the calibration kit.

To open TRL calibration submenu, use the Calibration menu softkeys.

• Connect a TRL THRU (THRU or LINE) standard between the test ports. Perform measurement using 1–2 Thru/Line softkey.
• To complete the calibration procedure, click Apply.

To clear the measurement results of the standards, click Cancel.

Multiline Option of TRL Calibration (except Planar 304/1)

The procedure of Mulitline TRL calibration is the same as the procedure of TRL calibration described above. The number of the LINEs of various lengths should be no less than three.

First of all create and edit the calibration kit for the Multiline TRL calibration. For details on the data to be entered for the normal and Multiline TRL calibrations see section 5.1.6.10.

Switching between the normal and Multiline TRL calibrations is performed by a specific button in TRL calibration menu.

To toggle between normal and Multiline TRL calibrations, use Multiline softkey.

Calibration Using Subclasses

When several calibration standards of one class are used for calibration, you should assign subclasses to these standards using the calibration kit editing function. The procedure of subclass assignment is described in section 5.3.4.

When assigning two or more subclasses to one class of calibration standards, the standard measurement softkey is replaced by the softkey, which opens the subclass menu containing the list of all the standards of this class.

TRL Calibration Example Using Subclasses (except Planar 304/1)

It describes an example of calibration using the calibration kit for TRL calibration, in which the "TRL LINE/MATCH" class contains 3 subclasses: load (Lowband), line 2 (TRL Line2), and line 3 (TRL Line3).

In the main menu of TRL calibration the 1-2 Line/Match softkey will open the subclass menu (if the above mentioned condition is met).

If two standards have an overlapping frequency range the last measured standard will be used in the overlapping region.

Sliding Load Calibration Example Using Subclasses

This section describes an example of calibration using the calibration kit 85054B, in which the "load" class contains 3 subclasses: fixed low-frequency load (Lowband), sliding load (Sliding), and fixed broadband load (Broadband). Only first two standards are used for calibration.

In the main calibration menu the Load softkey will open the subclass menu (if the above mentioned condition is met).

If two standards have an overlapping frequency range the last measured standard will be used in the overlapping region.

Calibration Using Sliding Load

The SLIDING LOAD can be used instead of a FIXED LOAD in full one-port and two-port calibrations.

If a calibration kit contains a SLIDING LOAD, the standard measurement softkey is replaced by the softkey, which opens the submenu containing the SLIDING LOAD calibration logic.

The sliding load calibration involves a series of measurements in different positions of the sliding element. The minimum number of measurements is 5, the maximum number of measurements is 8.

In the main menu of one-port or two-port calibration the Load softkey will open the sliding load menu (if the above mentioned condition is met).

Error Correction Disabling

This feature allows the user to disable the error correction function, which automatically becomes enabled after completion of calibration by any method.

To disable and reenable the error correction function, use the Corrections softkey.

Error Correction Status

The error correction status is indicated for each trace individually. Also there is a general status of error correction for all the traces of a channel.

The general error correction status for all the S-parameter traces of a channel is indicted in the specific field on a channel status bar (See Table 20). For channel status bar description, see section 4.2.6.

Table 20: General error correction status

The error correction status for each individual trace is indicated in the trace status field (See Table 21). For trace status field description, see section 4.2.2.

Table 21: Trace error correction status

System Impedance Z₀

Z₀ is the system impedance of a measurement path. Normally it is equal to the impedance of the calibration standards, which are used for calibration. The Z₀ value should be specified before calibration, as it is used for calibration coefficient calculations.

For waveguide calibration, the system impedance must be set to 1 Ω.

The impedance of the both test ports is the same for most of measurement types. The Analyzer can perform measurements when Z₀ values of the test ports are different, for example Type N50 – Waveguide. For such measurements, make different impedance settings of the test ports, Z₀₁ and Z₀₂.

Manual Z₀ Setting

-To set the system impedance Z₀, use the corresponding softkey.

Automatic Z₀ Selecting

The automatic system impedance selecting function sets Z₀ in the process of calibration standard measurement using data from the definition of the calibration standard in a calibration kit. When measuring one-port standards, Z₀ of the corresponding port is set. When measuring two-port standards, Z₀ of the two ports is set. The UNKNOWN THRU standard does not make any changes in Z₀ of the ports. By default, the function is enabled. The user can disable it.

To enable/disable the function of automatic selecting of port impedance Z₀, use the softkeys.

Port Extension

The port extension function enables you to eliminate the fixture (with or without losses) effects on the measurement results. The function virtually extends the test ports moving the calibration plane to the terminals of the DUT (by the length of the fixture). The fixture parameters are defined by the user for each port individually.

The feature of removing a lossless fixture is similar to the feature of electrical delay setting for a trace (See section 4.9.7), but unlike the latter it applies to all the traces of the channel. It compensates for a fixture length in transmission measurements and for a double fixture length in reflection measurements.

To remove a fixture with losses, the following methods of loss defining (in one, two or three frequency points) are applied:

1. Frequency-independent loss at DC - L₀

2. Frequency-dependent loss determined by the losses in two frequency points: L₀ at DC, and L₁at frequency F₁

3. Frequency-dependent loss determined by the losses in three frequency points: L₀ at DC, L₁ at frequency F_1, and L₂ at frequency F₂

,

Automatic Port Extension

The Auto Port Extension function allows for automatic calculation of Port Extension parameters by measuring a SHORT or an OPEN standard. It is also possible to measure both standards; in this case the average value will be used.

The Auto Port Extension function can be used simultaneously for any number of ports from 1 to the number of actual instrument ports. The user should select the number of ports and then connect a SHORT or an OPEN standard to the chosen ports.

Inside the Auto Port Extension menu, the user should specify the frequency range which will be taken into account for calculation of the Port Extension parameter. There are three methods of setting the frequency range:

• Current frequency range;
• User-defined frequency range (within current range);
• User-defined frequency point (selected with a marker).

The result of the Auto port extension function is calculation of the electrical delay value. After Auto port extension completes, this delay value appears in the corresponding field of the Port Extension menu, and the Port Extension function is automatically enabled, if it was disabled.

If the option “Include Loss” is enabled prior to the Auto Port Extension function running, the loss values L_1, L₂ at the respective frequency values F_1, F₂ will be calculated and applied. The F_1, F₂ values are calculated as ¼ and ¾ of the frequency range set by one of the following two methods: current or user-defined. If the frequency range is defined by a marker, frequency point F₂ is not calculated.

If the “Adjust Mismatch” option is enabled prior to the Auto Port Extension function running, the frequency-independent loss at DC, the L₀ value, is also set. The value of loss at the lower frequency of the current range is used as the L₀ value.

To open the menu of the Auto Port Extension function, use the Auto Port Extension softkey.

• Select the number of ports
• Enable the Include Loss function L_1, L₂, if required
• Execute the Auto Port Extension function after connecting a SHORT and/or an OPEN to the ports

Non-Insertable Device Measuring

In the simplest case, a non-insertable device has connectors of same type, for example N50, and of same gender. In such case, it is appropriate to apply the unknown thru calibration, described in Section 5.1.6.8. This Section explains more complex cases of non-insertable device measurements: devices having ports of different types and/or having different characteristic impedances, for example N50 – 3.5, N50 – N75, N50 – Waveguide.

The Analyzer offers two calibration methods of the setup used for measurements of non-insertable devices with connectors of different types:

1. Adapter Removal/Insertion method
2. Unknown Thru Addition method

In the above-listed methods, the adapter and THRU parameters should be specified:

• Set delay or length of the adapter or THRU, or select AUTO setting the value to zero. The uncertainty of the length setting is within an accuracy of 1/4 of the minimum wavelength in adapter or THRU media. The uncertainty of the delay setting is within an accuracy of 1/2fmax. AUTO is set by default.
• Select the measurement units: for delay or length, set seconds or meters. By default, the measurement units are set to seconds.
• Set relative permittivity for converting length to delay. When delay or AUTO are chosen, this setting is not required. By default, the value is set for air.
• Set the line type: TEM or Waveguide. TEM LINES are the LINES without dispersion; they include coaxial lines. For waveguide-coaxial adapters, set Waveguide type. The default setting is TEM.
• Cutoff frequency must be set for a Waveguide.

Adapter Removal/Insertion

1. Adapter Removal / Adapter Insertion

The method of adapter removal (See Figure 48, a) allows removing an adapter from the calibration plane of one of the test ports.

The method of adapter insertion (See Figure 48, b) allows inserting an adapter into the calibration plane of one of the test ports.

To remove/insert an adapter, proceed as follows:

1. Perform full two-port calibration using any of the following methods: SOLT, SOLR, TRL, AutoCal.
2. Remove or insert the adapter.
3. Set the adapter parameters. If the length or delay settings are other than AUTO, set the value with “minus” for removing, and with “plus” for inserting.
4. Measure three standards: OPEN, SHORT, and LOAD, for the corresponding test port.

To open the Adapter Removal/Insertion submenu, use the corresponding softkey.

• Select the port number for Adapter Removal/Insertion using Select Port. |
• Enter the adapter delay or length, or set 0 for AUTO using Adapter Delay. |
• Connect SHORT, OPEN and LOAD standards to the selected port in any consequence as shown in Figure 49. Perform measurements clicking the softkey corresponding to the connected standard. |
• To complete the Adapter Remove/Insert procedure, click Apply. |

Unknown Thru Addition

The method of Unknown Thru Addition involves fewer standard connections than Adapter Removal/Insertion method does. The number of standard connections is 7 as in SOLT calibration compared to 10 in Adapter Removal/Insertion method.

To add an UNKNOWN THRU, proceed as follows:

1. Perform full one-port calibration for each port. First, select in the program the calibration kit being used.
2. Connect the ports directly using an appropriate adapter and perform the measurements. Eventually the full two-port calibration coefficients will be computed.

• To open the Unknown Thru Addition submenu, use the following softkeys: |
• Enter the THRU delay or length, or set 0 for AUTO using Thru Delay. |
• To complete the Unknown Thru Addition procedure, click Calibrate Unknown Thru. |