![]() The sun may be spotless, but that doesn’t mean it isn’t doing interesting things. Posted in Fail of the Week Tagged AD8302, fail of the week, filter, fotw, harmonics, RF, thesis, vector network analyzer, vna We understand ’s disappointment, but there were a lot of wins here, from the excellent build quality to the top-notch documentation. Ambitious, perhaps, but with a spate of low-cost VNAs coming on the market, we can see where he got the inspiration. Confounding these issues was the time constraint might well have gotten the issues sorted out had the clock not run out on the school year.Īfter reading through ’s description of his project, which was a final-year project and part of his thesis, we feel like his rating of the build as a failure is a bit harsh. He has a complete analysis of the failure modes in his thesis, but the short story is poor filtering of harmonics from the local oscillator, unexpected behavior by the AD8302 chip at the heart of his design, and calibration issues. ![]() ![]() Unfortunately, found the performance of the completed VNA to be wanting, especially in the phase measurement department. decided to port a lot of functionality for his low-cost VNA to a host computer and concentrate on the various RF stages of the design. At least that’s the lemonade made from his lemon of a low-cost vector network analyzer.įor the uninitiated, a VNA is a versatile test instrument for RF work that allows you to measure both the amplitude and the phase of a signal, and it can be used for everything from antenna and filter design to characterizing transmission lines. A complex project with a lot of subsystems has a greater chance of at least partial success, as well as providing valuable lessons in what not to do next time. If you’re going to fail, you might as well fail ambitiously.
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