Checking the limits of uncertainty
Determining whether or not your VNA is giving you precise results on not just a fairly good transmission line but also on a known bad one is difficult to measure but typically done so with a Beatty line. The “check standards” tools used to do this essentially collect data on a measurement process to expose errors that plague the process over time.
Pico Technology brings down the size and cost of that process with their CHK-INS-MF insertable check standard or what they refer to as their version of a Beatty line. The device is a deliberately mismatched transmission line (75 mm of 25 Ω) and comes with a USB stick with the data about the mismatch. The stick is inserted into the VNA to give the precise measurement. You can then check that against the data that is being provided with a traceable check standard.
“The idea is that you can plot what’s measured together with limits of uncertainty and you plot what the real data is within limits of uncertainty and check that the VNA is giving good results,” says Trevor Smith, Pico’s VP WW Sales and Marketing, “What have here is a type of a Beatty line at a reasonable price and with high precision in a traceable small standard.”