Handheld Network Analyzer Peek Inside

May 19, 2017 by Al Williams 20 Comments

[Shahriar] recently posted a review of a 6.8 GHz network analyzer. You can see the full video — over fifty minutes worth — below the break. The device can act as a network analyzer, a spectrum analyzer, a field strength meter, and a signal generator. It can tune in 1 Hz steps down to 9 kHz. Before you rush out to buy one, however, be warned. The cost is just under $2,000.

That sounds like a lot, but test gear in this frequency range isn’t cheap. If you really need it, you’d probably have to pay at least as much for something equivalent.

[Shahriar] had a few issues to report, but overall he seemed to like the device. For example, setting the step size too broad can cause the spectrum analyzer to miss narrow signals.

If your needs are more modest, we’ve covered a much simpler (and less expensive) unit that goes to 6 GHz. If you need even less, an Arduino can do the job with a good bit of help. The Analog Discovery 2 also has a network analyzer feature, along with other tools at a more affordable cost, too. Of course, that’s only good to 10 MHz.

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Hackaday Links: May 14, 2017

May 14, 2017 by Brian Benchoff 18 Comments

Maker Faire Bay Area is next weekend, and you know what that means: we’re having a meetup on Saturday night. If you’re in the area, it’s highly recommended you attend. It’s a blinky bring-a-hack with booze. You can’t beat it. I heard the OPShark is showing up. All hail the OPShark. You’re gonna want to RSVP if you’re going k thx.

It only took twelve years, but [ladyada] finally got herself on the cover of Make.

Nvidia has the Jetson, an extremely powerful single board computer + GPU meant for machine learning, imagifying, and robotics applications. If you want to do fancy ML stuff with low power devices, I’d highly recommend you check the Jetson out. Of course, the Jetson is only the brains of any Machine Learning robot; you also need some muscle. To that end, Nvidia released the Isaac robotic simulator. It’s a simulator for standard bits of hardware like quadcopters, hovercrafts (?), robotic arms, and yes, selfie drones. What does this mean? Standardized hardware means someone is going to produce 3rd party hardware, and that’s awesome.

This is just an observation, but fidget spinners are just now hitting the mainstream. We didn’t know what they were for a year ago, and we don’t know now.

A Hebocon is a shitty robot battle. DorkbotPDX just had their first Hebocon and the results were… just about as shitty as you would expect. Since this is a shitty robot battle, a MakerBot made an appearance. This robot, SpitterBot, was designed to blow extruded filament all over its opponent. Did the MakerBot win? Yes, SpitterBot won the ‘Poorest Quality’ award.

Supplyframe, Hackaday’s parent company, hosts monthly-ish electronic get-togethers in the San Fransisco office. The focus of these meetups is to find someone cool who built something awesome and get them to talk about it. The March meetup featured [Pete Bevelacqua] who built a Vector Network Analyzer from scratch. The video is worth a watch.

A VNA On A 200 Euro Budget

August 13, 2016 by Jenny List 24 Comments

If you were to ask someone who works with RF a lot and isn’t lucky enough to do it for a commercial entity with deep pockets what their test instrument of desire would be, the chances are their response would mention a vector network analyser. A VNA is an instrument that measures the S-parameters of an RF circuit, that rather useful set of things to know whose maths in those lectures as an electronic engineering student are something of a painful memory for some of us.

The reason your RF engineer respondent won’t have a VNA on their bench already will be fairly straightforward. VNAs are eye-wateringly expensive. Second-hand ones are in the multi-thousands, new ones can require the keys to Fort Knox. All this is no obstacle to [Henrik Forstén] though, he’s built himself a 30MHz to 6 GHz VNA on the cheap, with the astoundingly low budget of 200 Euros.

On paper, the operation of a VNA is surprisingly simple. RF at a known power level is passed through the device under test into a load, and the forward and reverse RF is sampled on both its input and output with a set of directional couplers. Each of the four couplers feeds what amounts to an SDR, and the resulting samples are processed by a computer. His write-up contains a full run-down of each section of the circuit, and is an interesting primer on the operation of a VNA,

[Henrik] admits that his VNA isn’t as accurate an instrument as its commercial cousins, but for his tiny budget the quality of his work is evident in that it is a functional VNA. He could have a batch of these assembled and he’d find a willing queue of buyers even after taking into account the work he’s put in with his pricing.

[Henrik]’s work has appeared on these pages several times before, and every time he has delivered something special. We’ve seen his radar systems, home-made horn antennas, and a very well-executed ARM single board computer. This guy is one to watch.

Thanks [theEngineer] for the tip.