Silent Antenna Tuning

If you want to deliver the maximum power to a load — say from a transmitter to an antenna — then both the source and the load need to have the same impedance. In much of the radio communication world, that impedance happens to be 50Ω. But in the real world, your antenna may not give you quite the match you hoped for. For that reason, many hams use antenna tuners. This is especially important for modern radios that tend to fold their power output back if the mismatch is too great to protect their circuitry from high voltage spikes. But a tuner has to be adjusted, and often, you have to put a signal out over the air to make the adjustments to match your antenna to your transmitter.

There are several common designs of antenna tuners, but they all rely on some set of adjustable capacitors and inductors. The operator keys the transmitter and adjusts the knobs looking for a dip in the SWR reading. Once you know the settings for a particular frequency, you can probably just dial it back in later, but if you change frequency by too much or your antenna changes, you may have to retune.

It is polite to turn down the power as much as possible, but to make the measurements, you have to send some signal out the antenna. Or do you?

Several methods have been used in the past to adjust antennas, ranging from grid dip meters to antenna analyzers. Of course, these instruments also send a signal to the antenna, but usually, they are tiny signals, unlike the main transmitter, which may have trouble going below a watt or even five watts.

New Gear

However, a recent piece of gear can make this task almost trivial: the vector network analyzer (VNA). Ok, so the VNA isn’t really that new, but until recently, they were quite expensive and unusual. Now, you can pick one up for nearly nothing in the form of the NanoVNA.

The VNA is, of course, a little transmitter that typically has a wide range coupled with a power detector. The transmitter can sweep a band, and the device can determine how much power goes forward and backward into the device under test. That allows it to calculate the SWR easily, among other parameters.

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The 2024 Hackaday Supercon SAO Badge Reveal

We’ve been hinting at it for a few months now, running a series of articles on SAOs, then a Supercon Add-On Challenge. We even let on that the badge would have space for multiple SAOs this year, but would you believe six?

Way back in 2017ish, Hackaday’s own [Brian Benchoff] and the [AND!XOR] crew thought it would be funny and useful to create a “standard” for adding small custom PCB art-badges onto bigger conference badges. The idea was to keep it quick and dirty, uncomplicated and hacky, and the “Shitty” Add On was born. The badge community took to this like wildfire. While the community has moved on from the fecal humor, whether you call these little badgelets “SAOs”, “Simple Add-Ons”, or even “Supercon-8 Add Ons”, there’s something here for everyone. So if you’ve already got some SAOs in a drawer, bring them to this year’s Supercon and show them off!

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2024 Supercon: Third Round Of Super Speakers

The third and final round of the 2024 Supercon talks announcements brings us to the end, and the full schedule is now up on Hackaday.io.

With Supercon just a couple weeks away, we hope you have your tickets already! Stay tuned tomorrow for a badge reveal.

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Hackaday Links: October 20, 2024

When all else fails, there’s radio. Hurricane Helene’s path of destruction through Appalachia stripped away every shred of modern infrastructure in some areas, leaving millions of residents with no ability to reach out to family members or call for assistance, and depriving them of any news from the outside world. But radio seems to be carrying the day, with amateur radio operators and commercial broadcasters alike stepping up to the challenge.

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Hackaday Hacked!

Well, that was “fun”. Last week, we wrote a newsletter post about the state of Hackaday’s comments. We get good ones and bad ones, and almost all the time, we leave you all up to your own devices. But every once in a while, it’s good to remind people to be nice to our fellow hackers who get featured here, because after all they are the people doing the work that gives us something to read and write about. The whole point of the comment section is for you all to help them, or other Hackaday readers who want to follow in their footsteps.

Someone decided to let loose a comment-reporting attack. It works like this: you hit the “report comment” button on a given comment multiple times from multiple different IP addresses, and our system sends the comments back to moderation until a human editor can re-approve them. Given the context of an article about moderation, most everyone whose comment disappeared thought that we were behind it. When more than 300 comments were suddenly sitting in the moderation queue, our weekend editors figured something was up and started un-flagging comments as fast as they could. Order was eventually restored, but it was ugly for a while.

We’ve had these attacks before, but probably only a handful of times over the last ten years, and there’s basically nothing we can do to prevent them that won’t also prevent you all from flagging honestly abusive or spammy comments. (For which, thanks! It helps keep Hackaday’s comments clean.) Why doesn’t it happen all the time? Most of you all are just good people. Thanks for that, too!

But despite the interruption, we got a good discussion started about how to make a comment section thrive. A valid critique of our current system that was particularly evident during the hack is that the reported comment mechanism is entirely opaque. A “your comment is being moderated” placeholder would be a lot nicer than simply having the comment disappear. We’ll have to look into that.

You were basically divided down the middle about whether an upvote/downvote system like on Reddit or Slashdot would serve us well. Those tend to push more constructive comments up to the top, but they also create a popularity contest that can become its own mini-game, and that’s not necessarily always a good thing. Everyone seemed pretty convinced that our continuing to allow anonymous comments is the right choice, and we think it is simply because it removes a registration burden when someone new wants to write something insightful.

What else? If you could re-design the Hackaday comment section from scratch, what would you do? Or better yet, do you have any examples of similar (tech) communities that are particularly well run? How do they do it?

We spend our time either writing and searching for cool hacks, or moderating, and you can guess which we’d rather. At the end of the day, our comments are made up of Hackaday readers. So thanks to all of you who have, over the last week, thought twice and kept it nice.

Hackaday Podcast Episode 293: The Power Of POKE, Folding Butterflies, And The CRT Effect

This week on the Podcast, Hackaday’s Elliot Williams and Kristina Panos joined forces to bring you the latest news, mystery sound, and of course, a big bunch of hacks from the previous week.

First up in the news: we’ve extended the 2024 Supercon Add-On contest by a week! That’s right, whether you were held up by Chinese fall holidays or not, here’s your chance to get in on this action.

A square image with the Supercon 8 Add-On Contest art featuring six SAOs hanging from lanyards.We love to see the add-ons people make for the badge every year, so this time around we’re really embracing the standard. The best SAOs will get a production run and they’ll be in the swag bag at Hackaday Europe 2025.

What’s That Sound pretty much totally stumped Kristina once again, although she kind of earned a half shirt. Can you get it? Can you figure it out? Can you guess what’s making that sound? If you can, and your number comes up, you get a special Hackaday Podcast t-shirt.

Then it’s on to the hacks, beginning with what actually causes warping in 3D prints, and a really cool display we’d never heard of. Then we’ll discuss the power of POKE when it comes to live coding music on the Commodore64, and the allure of CRTs when it comes to vintage gaming. Finally, we talk Hackaday comments and take a look at a couple of keyboards.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Download in DRM-free MP3 and savor at your leisure.

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This Week In Security: Quantum RSA Break, Out Of Scope, And Spoofing Packets

Depending on who you ask, the big news this week is that quantum computing researchers out of China have broken RSA. (Here’s the PDF of their paper.) And that’s true… sort of. There are multiple caveats, like the fact that this proof of concept is only factoring a 22-bit key. The minimum RSA size in use these days is 1024 bits. The other important note is that this wasn’t done on a general purpose quantum computer, but on a D-Wave quantum annealing machine.

First off, what is the difference between a general purpose and annealing quantum computer? Practically speaking, a quantum annealer can’t run Shor’s algorithm, the quantum algorithm that can factor large numbers into primes in a much shorter time than classical computers. While it’s pretty certain that this algorithm works from a mathematical perspective, it’s not at all clear that it will ever be possible to build effective quantum computers that can actually run it for the large numbers that are used in cryptography.

We’re going to vastly oversimplify the problem, and say that the challenge with general purpose quantum computing is that each q-bit is error prone, and the more q-bits a system has, the more errors it has. This error rate has proved to be a hard problem. The D-wave quantum annealing machine side-steps the issue by building a different sort of q-bits, that interact differently than in a general purpose quantum computer. The errors become much less of a problem, but you get a much less powerful primitive. And this is why annealing machines can’t run Shor’s algorithm.

The news this week is that researchers actually demonstrated a different technique on a D-wave machine that did actually factor an RSA key. From a research and engineering perspective, it is excellent work. But it doesn’t necessarily demonstrate the exponential speedup that would be required to break real-world RSA keys. To put it into perspective, you can literally crack a 22 bit RSA key by hand.

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