This section includes Vector Network Analyzer measurement capabilities and instrument architecture information. It also describes calculating and displaying S‑parameters, and describes using markers to provide additional measurement information.

VNA is Vector Network Analyzer or Vector Network Analysis. The MS2085A/89A Site Master is a Vector Network Analyzer that measure the magnitude and phase characteristics of 1‑port or 2‑port networks, including cables, antennas, filters, isolators, attenuators, and amplifiers. The Vector Network Analyzer compares the signal that leaves the analyzer port (the reference signal) with either the signal that is transmitted through the test device (the transmitted signal) or the signal that is reflected from the input or the output of the test device (the reflected signal).

Compared to a Scalar Network Analyzer (SNA), a VNA has the added capability for measuring phase characteristics. While phase measurements are important in themselves, the availability of this phase information unlocks many new features for complex measurements. These features include Smith Charts, Time Domain, and Group Delay. Phase information also allows greater accuracy through vector error correction of the measured signal.

A VNA can have 1-port only, in which case it measures only reflection signals. A VNA can have 2-ports, in which case it can measure both reflection and transmission. A 2-port VNA can also have two different capabilities: 1-path 2-port, or full-reversing. The 1-path 2-port design allows reflection measurements only at one of the two ports and allows transmission measurements only in one direction.

The MS2085A/89A Site Master is a two‑port, 1‑path VNA instruments that allow S11 and S21 measurements with a single connection.