A VNA measures the "system," so you must calibrate to remove the effects of cables and adapters.

This shows the amplifier's gain across the frequency sweep. Look for "flatness" (minimal variation) over the desired bandwidth.

Derived from the phase of S21, this measures the time delay of the signal through the device. Consistent group delay is vital for maintaining signal integrity in wideband communications.

Similar to S11, this measures how well the output port is matched to the load.

By performing a Power Sweep at a fixed frequency, you find the input power level where the gain drops by 1dB. This defines the limit of the linear range.

Testing an RF amplifier with a is the gold standard for characterizing gain, impedance matching, and stability. 1. Essential Setup & Safety

Most VNAs have a low damage threshold (e.g., +20 dBm). If your amplifier outputs more power than this, place a high-power fixed attenuator on the output side before connecting it to the VNA Port 2.