Configuring a 2 Couplers Per Port, 1 VST System

  • Refer to the hardware requirements listed in 2 Couplers Per Port, 1 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 one vector signal transceiver (VST) and two couplers 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. 2 Couplers Per Port, 1 VST System Connections


  1. Install one attenuator to each output port of the RF OUT switch or switch bank.
  2. Connect the RF OUT or IF IN/OUT 0 port of the VST to the COM port of the RF OUT switch or switch bank using an SMA cable.
  3. Connect the output ports of two couplers together to form a coupler group using an SMA male-to-male adaptor. Repeat this step for the remaining two couplers.
  4. Connect the attenuators installed on the RF OUT switch or switch bank to the coupler groups using SMA cables.
  5. Connect the coupled port of each coupler to the channels of the RF IN switch or switch bank using SMA cables.
  6. Connect the COM port of the RF IN switch or switch bank to the RF IN or IF IN/OUT 1 port of the VST using an SMA cable.
  7. Connect the remaining input ports of each coupler group to the DUT for measurement or to the calibration kit adapters for calibration using SMA cables.
  8. If using the PXIe-5841, share the local oscillator (LO) signal by connecting the TX LO OUT port to the RX LO IN port of the VST using an MMPX-to-MMPX cable. If using the PXIe-5831 or PXIe-5842, no additional connection needs to be made as the LO is shared internally.
The following figure shows a specific implementation of the 2 Couplers Per Port, 1 VST system using the Analog Devices HMC-C058 as the solid-state switch. Control this switch using the PXIe-6535 DIO board and any commercially available 3.3 V to 5 V voltage converter.
Figure 1. 2 Couplers Per Port, 1 VST System Connections using external Solid-State Switches


2 Couplers Per Port, 1 VST System Hardware Requirements

In this hardware configuration, use one vector signal transceiver (VST) and two couplers on each port of the DUT to measure the reflection and transmission waves of the DUT in sequence.

You can implement this configuration with an RF multiplexer switch module or alternately with a digital I/O module and solid-state switches.

The following tables list the NI and third-party accessories required to perform an S-parameter measurement with two couplers per port and one VST.

Table 3. Required NI Hardware
Hardware Model Minimum Requirements Quantity
PXI Vector Signal Transceiver PXIe-5831, PXIe-5841, or PXIe-5842 — 1
PXI Chassis PXIe-1095 — 1
PXI Controller — 16 GB/s bandwidth and 16 GB RAM 1
PXI RF Multiplexer Switch PXI-2597* — 2
PXI Digital I/O PXIe-6535 — 1, if using an external HMC-C058 RF solid-state switch
MMPX-to-MMPX Cables 122 mm Flexible Cables —

0, if using a PXIe-5831 or PXIe-5842

1, if using a PXIe-5841
* Using a solid state switch instead of PXI-2597 hardware increases measurement speed with this setup, but the limited isolation between channels may degrade the measurement accuracy.
Note PXIe-6535 hardware is required to implement this configuration using an external solid-state switch. An image of this configuration is shown in the Configuring a 2 Couplers Per Port, 1 VST System section.
Table 4. Required Third-Party Accessories
Hardware Model Quantity
Directional Coupler RD Microwave C1-C31-C20 4
SMA Cables Velocity Microwave Conexus 3.5 mm Cables 10
SMA Male-to-Male Adapter Mini Circuit SM-SM50+

2

4, if using an external HMC-C058 RF solid-state switch
6 dB Fixed Attenuator Mini-Circuits BW-S6-2W263+ 2
3.5 mm VNA Calibration Kit Maury Microwave 8050CK51 Characterized Device (CD) Fixed Load SOLT Kit with Adapters 1
18 GHz RF SPDT Switch Analog Devices HMC-C058* 4
* The HMC-C058 and PXIe-6535 hardware are required to implement the 2 Couplers Per Port, 1 VST configuration using a solid-state switch.