About 22 years ago, I decided to get my fly fishing mojo together. Understanding that casting was fundamental to my goal, I took a class with an instructor donned with a colorful name by the local fly-fishing club. I practiced my casting, dealt with the instructor's salty personality, and of course, fished.
For the first couple of years, I was a bit unbalanced. Then I went on a salt water fly-fishing trip for redfish in a guided flats boat in Florida. The wind was howling over 25mph, the boat was moving, the fish were moving, and the guide was shouting over the wind in frustration trying to help me place the fly. I felt so defeated, seeing how long the journey would be before I would become a fly fishing "Master." I wasn’t even close.
Redfish went back into the water.
But eventually, I got better.
You can apply the same persistence to making better measurements.
Assuming you’re past the basic issues with making a good measurement, what does it take to be a master at making VNA measurements from a signal-integrity practitioners' perspective? I am talking 40GHz, hybrid or multi-tier calibrations, launch design -- the whole picture.
A good fraction of the S-parameters I encounter have serious issues. They're plagued with passivity violations for any number of reasons -- the VNA wasn’t set up properly, there are fixturing issues, the calibration was not validated or even checked, the cables are loose, etc. Around 2002, I proposed a Test-and-Measurement track in DesignCon, and after a bit of arm wrestling, it was adopted and has turned out to be a valuable track. I now co-chair that track with a few other engineers, so I see a lot of energy focused on getting good S-parameter models.
My technical background includes making a lot of measurements to 50GHz, including fast TDR, designing platforms to validate S-parameters, and corresponding them to 3D-EM analysis. My company has conducted quite a bit of VNA training and we market products for the SI type engineer. I want to share my observations in this blog.
Although I consider myself good at using a VNA, I'm still no master, but I keep trying. My next blog will show how to work towards becoming a VNA measurement master.