Two power levels are available with 2‑port measurements: High and Low. The Low Port Power setting should be used when making direct gain measurements of amplifiers. This will help to ensure that the amplifier is operating in the linear region. The High Port Power setting (default setting) is ideal when characterizing passive devices but can also be used when making relative gain or antenna‑to‑antenna isolation measurements in the field. For performance details and measurement uncertainties, refer to the Technical Data Sheet (Anritsu part number 11410‑00501).

The internal bias tee is typically used to put voltage on the RF port that is feeding the bias to the amplifier under test. Because of its full reversing architecture, the MS20xxC VNA Master can support amplifier measurements with the amplifier input connected either to Port 1 or to Port 2. To support this flexibility, the internal bias tee can be directed to either port via a user selection. Each port selection has its own Voltage setting and Current Limit setting that can be saved with the setup (refer to Figure: S21 Log Magnitude (VNA Measurement Menu)).

The voltage setting for the internal bias tee, when selected for either port, can be set from 12.0 VDC to 32.0 VDC in steps of 0.1 V. The Current Limit value, with a maximum setting of 450 mA, sets the trip point. If the current draw of the device under test exceeds this trip point level, then the VNA Master shuts off the internal bias tee, the LED indicator on the connector panel turns from green to flashing red, and the actual voltage and current readings that are displayed on the screen turn red.

With external bias tee voltage input, you can connect an external voltage of ± 50 VDC to both ports simultaneously, although for most applications biasing is required on only one port. When the bias tee is set to External, the actual measured voltage and current at both ports are displayed on the screen, as shown in Figure: Bias Tee Set to External (MS20xxC models only). The maximum current that is allowed when using external bias tee is 500 mA. If that current level is exceeded, then the VNA Master switches the external bias tee away from the ports, the LED indicator on the connector panel turns from green to flashing red, and the actual voltage and current readings that are displayed on the screen turn red.