Arduino RF Network Analyzer

What do you get when you combine a direct digital synthesis (DDS) chip, a power detector, and an Arduino? [Brett Killion] did make that combination and wound up with a practical network analyzer.

The project uses an Analog Devices AD9851 DDS chip clocked at 180 MHz which will output a sine wave at any frequency from 0 Hz and 72 MHz. A Butterworth low pass filter processes the DDS signal and then feeds a two-transistor amplifier. The circuit will output about 0dBm into 50 ohms. The power detector is an Analog Devices AD8307 along with a 50-ohm input load. There is no filtering on the power detector so it can measure from very low frequencies to 500MHz.

[Brett] uses a Python program to process the data from the Arduino. For example, here’s a plot of a 10 MHz crystal from the software:


If you want to know more about DDS, our own [Bil Herd] has you covered (see the video, below). We’ve also seen similar antenna analyzers that are about the same thing.

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