Configuring a 1 Coupler Per Port, 2 VST System

  • Refer to the hardware requirements listed in 1 Coupler Per Port, 2 VST System Hardware Requirements.
  • Ensure all components are installed in the chassis before completing the following steps.
  • If using the PXIe-5842, ensure the modules are properly interconnected, as described in Interconnecting the PXIe-5842.
Complete the following steps to configure your hardware for S-parameter measurements using two vector signal transceivers (VSTs) and one coupler per DUT port.
Note The PXIe-5831 does not have dedicated RF IN/OUT ports. Use the IF IN/OUT 1 port as RF IN and the IF IN/OUT 0 port as RF OUT when using a PXIe-5831.
Figure 1. 1 Coupler Per Port, 2 VST System Connections


  1. Install an attenuator to the RF OUT or IF IN/OUT 0 port of each VST.
  2. Connect each attenuator to the output port of each coupler using SMA cables.
  3. Connect the RF IN or IF IN/OUT 1 port of each VST to the coupled port of each coupler using SMA cables.
  4. Connect the input ports of each coupler to the DUT for measurement or to the calibration kit adapters for calibration using SMA cables.
  5. Connect the PFI0 port of the first VST to the PFI0 port of the second VST using the correct cable type for your VST.
    VSTCable Type
    PXIe-5831/5841 MMPX-to-MMPX cable
    PXIe-5842 SMA (m)-to-SMA (m) cable
  6. Make the following connections between the local oscillators (LO) of each VST.
    VSTLO Cabling Instructions
    Two PXIe-5831 VSTs

    Use MMPX-to-MMPX cables to make the following connections.

    1. Connect LO2 IN on the first VST to LO2 OUT on the second VST.
    2. Connect LO2 OUT on the first VST to LO2 IN on the second VST.
    Two PXIe-5841 VSTs (refer to the following image)

    Use MMPX-to-MMPX cables to make the following connections.

    1. On the first VST, connect TX LO OUT to RX LO IN.
    2. On the second VST, connect TX LO OUT to RX LO IN.
    3. Connect RX LO OUT on the first VST to TX LO IN on the second VST.
    4. Connect TX LO IN on the first VST to RX LO OUT on the second VST.
    Two PXIe-5842 VSTs

    Use SMA (m)-to-SMA (m) cables to make the following connections.

    1. Connect RF IN: LO OUT on the first VST to LO 0 IN on the second PXIe-5655.
    2. Connect LO 0 IN on the first PXIe-5655 to RF IN: LO OUT on the second VST.
    Figure 1. PXIe-5841 LO Sharing


1 Coupler Per Port, 2 VST System Hardware Requirements

In this hardware configuration, use two vector signal transceivers (VSTs) and a coupler on each port of the DUT to measure the reflection and transmission waves of the DUT simultaneously.

The following tables list the NI and third-party accessories required to perform an S-parameter measurement with two VSTs and one coupler on each port.
Table 1. Required NI Hardware
HardwareModelMinimum RequirementsQuantity
PXI Vector Signal TransceiverPXIe-5831, PXIe-5841, or PXIe-5842—2
PXI ChassisPXIe-1095—1
PXI Controller—16 GB/s bandwidth and 16 GB RAM1
MMPX-to-MMPX Cables122 mm Flexible Cables—

3, if using a PXIe-5831

5, if using a PXIe-5841

0, if using a PXIe-5842

SMA CablesNI 137833-03000 SMA (m)-to-SMA (m) Cables, 300 Meter Length, 26.5 GHz—

0, if using PXIe-5831 or PXIe-5841

3, if using PXIe-5842

Table 2. Required Third-Party Accessories
HardwareModelQuantity
Directional CouplerRD Microwave C1-C31-C202
SMA CablesVelocity Microwave Conexus 3.5 mm Cables6
6 dB Fixed AttenuatorMini-Circuits BW-S6-2W263+2
3.5 mm VNA Calibration KitMaury Microwave 8050CK51 Characterized Device (CD) Fixed Load SOLT Kit with Adapters1