Electromagnetic Mechanism Makes Reconfigurable Antenna

February 22, 2023 by Al Williams 10 Comments

Antennas are a key component to any RF gadget. But antennas often only perform well over a narrow band of frequencies. For some applications, this is acceptable, but often you would like to reconfigure an antenna for different bands. Researchers at Penn State say they’ve developed a tunable antenna using compliant mechanisms and electromagnets. The new scalable design could work in small areas to provide frequency agility or beamforming.

The prototype is a circular patch antenna made with 3D printing. If you want to read the actual paper, you can find it on Nature Communications.

A compliant mechanism is one that achieves force and motion through elastic body deformation. Think of a binder clip. There’s no hinge or bearing. Yet the part moves in a useful way, using its own deformation to open up or grip papers tightly. That’s an example of a compliant mechanism. This isn’t a new idea — the bow and arrow are another example. However, because 3D printing offers many opportunities to build and refine devices like this, interest in them have increased in recent years.

We couldn’t help but notice that the antenna is a variation of a “compliant iris” like the one in the video below. You can find designs for these online for 3D printing, so if you wanted to experiment, you might think about starting there.

We’ve looked at compliant mechanisms before. Why would you want better chip-scale antennas? Why, indeed.

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Tiny11 Makes Windows 11 Small

February 21, 2023 by Al Williams 81 Comments

If you often spin up a virtual machine just to run Windows, you might be sad that you have to allocate so much space for it. The Tiny11 project provides a Windows 11 installer that strips and compresses a bare minimum system do under 8GB of space. We aren’t sure what the licensing aspects of it all mean, but there are a few things you need to know. You can see a video about the project below.

The installer requires you to activate Windows, so that’s probably a good thing from a legal standpoint. Besides being compressed, the installer, based on Window 11 Pro 22H2, removes sponsored applications and Teams. It does, however, have the component installer and the Microsoft store, so you can add back things you want that aren’t in the default install.

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Retro Gadgets: Make Your Scope Dual Channel

February 21, 2023 by Al Williams 32 Comments

We live in a time when having an oscilloscope is only a minor luxury. But for many decades, a good scope was a major expense, and almost no hobbyist had a brand new one unless it was of very poor quality. Scopes were big and heavy and, at the price most people were willing to pay, only had a single channel. Granted, having one channel is better than having nothing. But if the relative benefit of having a single channel scope is 10 points, the benefit of having two channels is easily at least 100 points. So what was a poor hacker to do when a dual-trace or higher scope cost too much? Why, hack, of course. There were many designs that would convert a single trace scope into a poor-quality multichannel scope. Heathkit made several of these over the years like the ID-22, the ID-101, and the ID-4101. They called them “electronic switches.” The S-2 and S-3 were even earlier models, but the idea wasn’t unique to Heathkit and had been around for some time.

For $25, you could change your scope to dual trace!

There were two common approaches. With alternative or alt mode, you could trigger a sync pulse and draw one trace. Then trigger again and draw the second trace with a fixed voltage offset. If you do this fast enough, it looks like there are two traces on the screen at one time. The other way is to rapidly switch between voltages during the sweep and use the scope’s Z input to blank the trace when it is between signals. This requires a Z input, of course, and a fast switching clock. This is sometimes called “chopper mode” or, simply, chop. This wasn’t just the realm of adapters, though. Even “real” analog scopes that did dual channels used the same methods, although generally with the benefit of being integrated with the scope’s electronics.

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3D Printing Antennas With Dielectric Resin

February 21, 2023 by Al Williams 14 Comments

[Machining and Microwaves] has long wanted to use a 3D printer to print RF components for antennas and microwave lenses. He heard that Rogers — the company known for making PCB substrates, among other things — had a dielectric resin available and asked them if he could try some. They agreed, with some stipulations, including that he had to visit their facility and show his designs in a video. Because of that, the video seems a little bit like a commercial, but we think he is genuinely excited about the possibility of the resin.

Since he was in their facility, he was able to interview several of the people behind the resin, and they had some interesting observations about keeping resin consistent during printing and how the moonbounce feed he wanted to print would work.

Some of the exotic RF test equipment was interesting to see, too. The microwave lenses look like some kind of modern art. According to the Roger’s website:

Radix Printable Dielectric materials are a ceramic-filled, UV-curable polymer designed for use with photopolymer 3D-printing processes like sterolithography (SLA) and digital light processing (DLP) printing. These materials and printing processes enable the use of high-resolution, scalable 3D-printing for complex RF dielectric components such as gradient index (GRIN) lenses or three-dimensional circuits. The 2.8Dk printable dielectric is designed to have low loss characteristics through millimeter wave (mmWave) frequencies and low moisture absorption for end-use applications.

It isn’t clear to us that you could use this resin in your own printers, but they did look pretty similar to what we have hanging around except, perhaps, for the continuous circulation of the resin pool. We figured the resin wasn’t inexpensive. In fact, we found a liter online for $1,863. We don’t know if that’s the suggested retail price or not, but we also suppose if you need this material, you won’t be that surprised at the cost.

If you don’t need microwave frequencies, you might be able to get by with some easier techniques. Or, you can even do something slightly more difficult but probably a lot cheaper.

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Digital Library Of Amateur Radio And Communications Is A Treasure Trove

February 20, 2023 by Al Williams 24 Comments

Having a big bookshelf of ham radio books and magazines used to be a point of bragging right for hams. These days, you are more likely to just browse the internet for information. But you can still have, virtually, that big shelf of old ham books, thanks to the DLARC — the digital library of Amateur Radio and Communications.

A grant from a private foundation has enable the Internet Archive to scan and index a trove of ham radio publications, including the old Callbooks, 73 Magazine, several ham radio group’s newsletters from around the globe, Radio Craft, and manuals from Icom, Kenwood, Yaesu, and others.

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Clear PLA Diffuses LEDs

February 20, 2023 by Al Williams 11 Comments

[Chuck] often prints up interesting 3D prints. But we enjoyed his enhancement to a cheap LED Christmas tree kit. The original kit was simply a few green PCBs in the shape of a tree. Cute, but not really something a non-nerd would appreciate. What [Chuck] did, though, is printed a clear PLA overcoat for it and it came out great. You can see how great in the video below.

You might think transparent PLA would be really clear, but because of the layers, it is more translucent than transparent. For an LED diffuser, though, it works great. There are a few things to consider when printing for this purpose. First, you’d think vase mode would be perfect for this, but he found out it didn’t work well — possibly due to something in the model, which was a download from Thingiverse.

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Quantum Interconnects Get Faster

February 17, 2023 by Al Williams 2 Comments

If you are a retrocomputer fan, you might remember when serial ports were a few hundred baud and busses ran at a few megahertz at the most. Today, of course, we have buses and fabric that can run at tremendous speeds. Quantum computing, though, has to start from scratch. One major problem is that jockeying quantum states around for any distance is difficult and slow. Part of it is that qubits decay rapidly, so you don’t have much time. They are also generally susceptible to noise and perturbation by outside forces. So many quantum machines today are limited by how much they can cram on one chip since there isn’t a good way to connect to another chip. The University of Sussex thinks it has improved the outlook for quantum interconnects with a technique they claim can move qubits around at nearly 2,500 links per second.

The technique, called UQ Connect, uses electric field links to connect multiple chips using trapped ions for qubits. If you want to read the actual paper, you can find it in Nature Communications.

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