Vector Network Analyzers (VNAs) are based on the use of either mixers or samplers. In traditional sampling VNAs, samplers are gated by pulses generated with a Step-Recovery Diode (SRD) circuit, with the Local Oscillator (LO) and RF source phase locked to a common frequency reference. An alternative architecture is a VNA based on Nonlinear Transmission Line (NLTL) samplers and distributed harmonic generators. This paper provides an overview of the high-frequency technology deployed in Anritsu’s VNA families. It is shown that NLTL technology results in miniature VNA reflectometers that provide enhanced performance over broad frequency ranges, and reduced measurement complexity when compared with existing solutions.