Compare this with the price of a few VNAs suggested by Keysight Technologies (the former instrument division of Agilent) as replacements for the 8757D. It’s possible to find used versions of this instrument, which can handle measurements in the tens of gigahertz, for under $1,000 on eBay. To understand the price difference, consider the now-discontinued Agilent 8757D scalar network analyzer. However, budget-minded engineers and engineering firms may still find the scalar version attractive when there’s no need to gather S-parameter or phase information. The now-obsolete Agilent 8757D scalar network analyzer. Those that once manufactured these devices now generally argue that the prices of VNAs have come down to a point where it makes sense to simply go with the more capable instrument. In fact, it is hard to find instrument makers that still make scalar network analyzers. Vector network analyzers are far more common. These instruments are available in two varieties: scalar network analyzers, which measure only the amplitude of the test signal, and vector network analyzers, which measure amplitude and phase. The instruments characteristically operate at 5 Hz to 1.05 THz, mostly at the higher end, though some models are sensitive down to 1 Hz. Network analyzers measure network parameters of electrical networks, such as two-port amplifiers and filters.

Vna network analyzer