Access CALIBRATE menu from main menu to mainly perform calibration, access cal setup and choose a calibration method and so on.

In order to perform a proper calibration, several parameters must be set before the calibration procedure is started. These parameters are: TYPE, LINE, METHOD, MODE, PORT 1 DUT, PORT 1 CAL KIT and THRU DEVICE as shown in Figure: CAL SETUP Window. To access Cal Setup window, press the CAL SETUP submenu from CALIBRATE menu.

MS2085A/89A Site Master supports the following calibration types in VNA mode as shown in Figure: CAL SETUP Window.

Refer to Cable Antenna Analyzer (CAA) Measurement Guide (PN: 10580-00493) for detailed information on each calibration type except Reflection Response. Some of the calibration types are option dependent, please refer to your instrument’s technical data sheet for the list of available options.

For all measurement except Transmission (USB Sensor), you can manually calibrate the unit using an external precision OSL calibration kit.

The combined calibration type OSL + Trans (USB Sen) allows the instrument to be calibrated once for all the supported measurement types, eliminating the need to re-calibrate when switching from one type of measurement to another, such as return loss to transmission.

OSL + Transmission (2-Port) type involves calibrating the port one with OSL and then calibrating the transmission from port 1 to port 2. The cable used to connect the two ports would be normalized.

The 2-port transmission measurement is used to verify the performance of tower-mounted amplifiers, and duplexers, and to verify antenna isolation between two sectors. The excellent dynamic range makes it suitable for repeaters as well. The second port is a selective receiver which provides up to 100 dB dynamic range which makes it possible to test the band pass filters common on many networks.

The system will automatically switch between open, short and load during the calibration process. Note that this calibration type is only available when InstaCal ICN51A is connected and LINE is set to Coax.

The system will automatically switch between and open, short and load. ICN51A InstaCal is used in this type instead of traditional OSL. External USB power sensor is necessary to carry out this calibration type. Note that this calibration type is only available when InstaCal ICN51A is connected and LINE is set to Coax.

Just like OSL+ Trans (USB Sen) the iOSL + Trans (2-Port) uses the ICN51A instead of a traditional OSL. The system will automatically switch between and open, short and load. Note that this calibration type is only available when InstaCal ICN51A is connected and LINE is set to Coax.

This calibration type simply performs normalization for Port 1. This cal type requires one connection to Port 1 reflection measurements only. Connect Open or Short on Port 1, load connection can be skipped, but if used, will improve the effectiveness of this calibration.

Follow the steps below to perform Reflection Response calibration:

Figure: Reflection Response Calibration, Standard Cal illustrates the reflection response of S11 forward reflection.

Notice that when the Site Master is connected with ICN51A InstaCal and if TYPE is set to any one of the

calibration types such as iOSL, iOSL + Trans (USB Sen) and iOSL + Trans (Port 2), the PORT 1 DUT and PORT 1 CAL KIT parameters disappear from Cal Setup window as shown in Figure: CAL SETUP Window - TYPE. Also notice that InstaCal calibration types are not available when LINE is set to Waveguide, as shown in Figure: CAL SETUP Window - TYPE.

The Site Master supports measurements and calibrations for both coaxial and waveguide media. In the Cal Setup window, set the LINE to either Coax or Waveguide before starting the calibration. Figure: Cal Setup Window - Coaxial Line (left) and Waveguide Line (right) shows the selection window for the Line, within the CAL SETUP window.

In Vector Network Analyzer, calibration is required when the test port cable or adapters have been changed or when no valid calibration is available (Cal: Off). The following sections describe how to perform calibrations.

For coaxial line types, the calibration method that is most commonly used is the Short, Open, Load, Thru method, or SOLT. For waveguide line types, the calibration method that is most commonly used is the Offset Short 1 (1/8th wavelength), Offset Short 2 (3/8th wavelength), Load, Thru method, or SSLT. Use METHOD to set the appropriate method for the type line being used during the calibration and measurements, as shown in Figure: Cal Setup Window - SOLT Method (left) and SSLT Method (right)

You can manually calibrate the instrument or use the ReadyCal factory calibration for quick measurements. The instrument automatically applies the default ReadyCal to all vector network analyzer measurement types. The instrument needs to be manually re-calibrated if a test port cable is used and has been replaced, or when changing frequency in Standard Cal Type (not in Flex Cal).

To manually calibrate the instrument:

Follow the steps below to perform SOLT calibration method:

 

Figure: SOLT Calibration Method, Standard Cal illustrates S21 forward-path transmission measurement of coaxial media, after applying standard OSL + Trans (Port 2) calibration.

Follow the steps below to perform SSLT calibration method:

 

 

 

Figure: SSLT Calibration Method, Standard Cal illustrates S21 forward-path transmission measurement for waveguide media, after applying standard OSL + Trans (Port 2) calibration.

 

The available calibration modes are Standard Cal and Flex Cal. Standard Cal applies to the currently set frequency range. Changing either the Start or Stop Frequency setting requires turning off User Cal, in which case the factory default 1-Port ReadyCal will apply to all measurement types except Transmission (USB Sensor). You may subsequently re-calibrate the instrument as appropriate.

Flex Cal calibrates the instrument over the entire frequency range and interpolates data points if the frequency range is changed. This method saves time as it does not require the user to re-calibrate the system for frequency changes. The trade-off is fewer data points and less accuracy when compared to Standard Cal.

Table: Summary of Calibration Types lists the main characteristics of the Standard and Flex calibration types. If you do not expect to change the frequency range often, Standard Cal is recommended for best accuracy.

For the most accurate calibrations, you must select the connector of the DUT that will be attached to Port 1 of the instrument. After you select the DUT connector, you must then select the desired calibration kit that will be used for the Port 1 correction. If you do not select a desired calibration kit, then the analyzer defaults to one of the built-in kits.

Figure: Cal Setup Window - Coaxial Port 1 CAL KIT (left) and Waveguide Port 1 CAL KIT (right) shows the selection window for the Port 1 DUT connector. For easier identification of the DUT connector, a representative picture is shown for each selection. After a connector is chosen, the Port 1 Cal Kit selection is updated in order to list only the available calibration kits that are associated with the selected DUT connector. Figure: Cal Setup Window - Coaxial Port 1 CAL KIT (left) and Waveguide Port 1 CAL KIT (right) also shows an example of the selection of calibration kits that are available for the K (female) coaxial DUT connector.

For each coaxial kit in the list, the values of the Offset Lengths for the Open, Short, and Thru (if applicable) are listed. The Capacitance and Inductance values for the Open and Short are also listed, as shown in Figure: Cal Setup Window - Coaxial Port 1 CAL KIT (left) and Waveguide Port 1 CAL KIT (right). For waveguide calibration kits, the Cutoff Frequency and the Offset Short 1 and Short 2 lengths are listed, as shown in Figure: Cal Setup Window - Coaxial Port 1 CAL KIT (left) and Waveguide Port 1 CAL KIT (right).

 

 

The selection list for DUT connectors includes all of the common connectors that you may encounter. Table: Coax DUT Connectors and Cal Kits and Table: Waveguide DUT Connectors provide complete list of Coax and Waveguide connectors and corresponding calibration kits that are selectable through the Cal Setup window.

After you have set up Port 1 DUT and PORT 1 Cal Kits, you must also set the Thru device that is used in the Thru step of the calibration that is being conducted, if applicable. The Thru device accounts for any extra length that is used during the calibration steps (such as an adapter) but is removed for the actual measurement of the DUT. In these cases, if the Thru device length is not accounted for, then the resulting measurements will have an offset error. The Thru device length can be set in units of distance or time, or it can be set to equal the Thru length offset of the cal kits that are used for Port 1, if applicable. Figure: Cal Setup Window - Thru Device shows the selection window for the Thru device setting. Press LINE LENGTH to enter the length of the Thru device using the numeric keypad, you can also select appropriate units. Alternatively, you can press LINE DELAY to enter the device length in unit of time.

 

 

If INTERPOLATE toggle is turned off and the current Cal status is on and valid, you cannot modify the frequency range or the source power level, or increase the number of points above 16,001 points (assuming the calibration was performed with 16,001 points or less). Any of these changes will require the USER CAL to be turned off and a new calibration to be performed. You can, however, adjust the number of points from 2 to 16,001 without forcing the calibration to become invalid. To use 2065 points, the number of points must be set to 2065 before the calibration is started. If your current Cal status is on and you turn INTERPOLATE on, you can then change the frequency range (smaller and anywhere within the calibrated range) or modify the number of points without invalidating the calibration. In that case, the calibration coefficients are regenerated (interpolated) to match the new settings. You cannot increase the frequency range, however, beyond the range that was used during calibration. For example, you could perform a calibration from 1 MHz to 6 GHz using 2065 points. With Interpolate toggle on, you could then make a measurement by zooming in on a desired frequency range, 410 MHz to 435 MHz, for example. The trace in your measurement would use the full 2065 points within this much narrower frequency range.

USER CAL toggle in CALIBRATE menu is turned on automatically after the calibration process has been completed successfully. When USER CAL is on, the calibration coefficients are applied to the measured data, resulting in corrected S‑parameter data. You can turn USER CAL Off, which results in trace data using uncorrected (or raw) S‑parameter data and losing the calibration status.

When measuring the transmission (or insertion loss) response of a DUT, the calibration requires a Thru measurement to be performed. This requires at least one external cable to be introduced into the calibration. The additional cable component is the most susceptible to changes from environmental conditions, such as temperature changes and mechanical flexing. The Thru Update allows you to quickly eliminate the effects of temperature changes or of changes caused by mechanical flexing of the cable without having to repeat the entire calibration process. The Thru update is particularly useful when viewing DUT transmission responses with small scale resolution (0.5 dB/division or less).

Figure: Thru Update - Thru shows the calibration wizard window depicting the calibration setup and calibration steps.

 

In order to perform a proper calibration, several parameters must be set before the calibration procedure is started. These parameters are: TYPE, METHOD, MODE, LINE, PORT 1 DUT, PORT 1 CAL KIT and THRU device.

To view a summary of these settings, begin from the CALIBRATE main menu and press CAL INFO submenu. A summary of the Active Cal Settings and the Current Settings of the instrument are displayed (see Figure: CAL INFO Window). Press CLOSE to close the CAL INFO window.

The CAL INFO window displays all of the key setup parameters for the calibration. The current settings are shown on the left, and the settings of the instrument at the time of the last calibration are shown on the right.