We can see a major difference between the two readings. The device performance starts to degrade past 300MHz. My previous concern appears to be coming true. Return loss characteristics of a 400MHz monopole In order to obtain a very good calibration, I reduce the span further in the range of 100MHz to 200MHz and only then do I see a very flat graph. In my view, nanoVNA PASSES the calibration test. You can’t complain about this kind of error for the price you are paying. For a hobbyist, this error is negligible. Looking at the graph carefully, we see a return loss error in the range of 0.5dB to 0.7dB. Nevertheless, the readings are still good which we will see further in this blog post. As a result, we see reduced dynamic range above 300MHz. Beyond 300MHz, it uses the harmonics for calculating S-parameters. Looking at the circuit of the nanoVNA, we come to know that the stimulus generator works only up to 300MHz. Furthermore, a constantly varying spike also appears at 300MHz. The 300 MHz spike is the transition where the device switches to harmonics instead of fundamental for calculating the S-parameters.Įven after reducing the span, we still see the ringing while keeping the port open-circuited. Return loss of open circuit after reducing the span and calibrating. Whereas, the individual open-short-load will calibrate the nanoVNA.
In the case of the Keysight VNA, we will be using the 85561A 2.92mm 4 in 1 calibration kit. To do so, we will use respective calibration kits that come with the two devices. In this article, we will be testing a a low pass filter and an antenna and then comparing the measurement results from both the instruments.Ĭalibration is the first step before you even begin to use your VNA.
Additionally, this device can also operate as a Spectrum Analyzer mode to observe the frequency spectrum. In short, the N9952A has everything a professional RF design engineer requires. It offers a dynamic range of 70 to 100dB and comes with plenty of features such as Time domain reflectometry, adjustable output power, adjustable IF bandwidth, and so on. The Keysight Fieldfox N9952A can operate over 300kHz to whopping 50GHz. In this post, we will be looking at the two EXTREMES available in the market today the sub-hundred dollar nanoVNA and the Keysight fieldfox N9952A. For example, the $500 miniVNA and the sub-hundred dollar nanoVNA are very much affordable in comparison to the thousands of dollar equipment available out there. Very few VNAs are available to be bought by someone like you and me. Most of them are out of reach for a typical hobbyist. Vector network analysers (VNA) come in all sort of price ranges.
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