THz spectrum analysis with a vector network analyzer

Device characterization can be challenging and complicated when venturing into the terahertz frequency range. During a typical measurement session, the need to frequently connect, disconnect and reconnect the device under test (DUT) is both inconvenient and time-consuming. One solution is to incorporate VNA and SA capabilities into a single instrument. Keysight offers an integrated system under a single model number, the N5251A mmWave network analyzer. This configuration covers 10 MHz to 110 GHz and currently offers extensions to 1.1 THz. The core instrument is a Keysight PNA microwave network analyzer. The optional spectrum analyzer mode includes a user interface that presents the typical array of setup parameters: center frequency and span, start and stop frequencies, step size, resolution bandwidth (RBW), detector shape, averaging and receiver attenuation. The integration of SA capabilities into a VNA offers two key advantages over the multi-instrument approach: multiple simultaneous measurements and calibrated accuracy. Through its multiple test ports, a VNA enables multi-channel spectrum analysis that is synchronized with the internal swept signal generators. A PNA or PNA-X, through a single connection, provides simultaneous measurements on all DUT ports. With the integrated high performance SA capability, a PNA or PNA-X can perform fast spurious searches across a broad frequency band, improving test time compared to a stand-alone signal analyzer.