Tag Archives: Antenna

Touch Anything And Everything

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Powering IoT devices is often a question of batteries or mains power, but in rare exceptions to this rule there is no power supply (PDF Warning). At the University of Wisconsin-Madison and the University of California, San Diego, researchers have gone the extra mile to make advanced backscatter devices, and these new tags don’t need the discrete components we have seen in previous versions. They are calling it LiveTag, and it doesn’t need anything aside from a layer of foil printed or etched on a flexible ceramic-PTEF laminate. PTEF is mostly seen in the RF sector as a substrate for …read more

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Radar in Space: The Gemini Rendezvous Radar

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In families with three kids, the middle child always seems to get the short end of the stick. The first child gets all the attention for reaching every milestone first, and the third child will forever be the baby of the family, and the middle child gets lost in-between. Something similar happened with the U.S. manned space program in the 60s. The Mercury program got massive attention when America finally got their efforts safely off the ground, and Apollo naturally seized all the attention by making good on President Kennedy’s promise to land a man on the moon.

In between …read more

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Harley-Hardened Wire Helps High-Gain Antenna Hack

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What does a Harley-Davidson motorcycle have to do with building antennas? Absolutely nothing, unless you happen to have one and need to work-harden copper wire to build a collinear antenna for LoRa.

We’ll explain. Never being one to settle, [Andreas Spiess] needed a better antenna for his LoRa experiments. Looking for high gain and an omnidirectional pattern, he bought a commercial colinear antenna, which is a wire with precisely spaced loops that acts like a stack of dipoles. Sadly, in a head-to-head test [Andreas] found that the commercial antenna was no better than lower gain antennas in terms of range, …read more

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The Biggest Corner Antenna We’ve Ever Seen

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Radio waves are received on antennas, for which when the signal in question comes over a long distance a big reflector is needed. When the reception distance is literally astronomical, the reflector has to be pretty darn big. [The Thought Emporium] wants to pick up signals from distant satellites, the moon, and hopefully a pulsar. On the scale of home-built amateur radio, this will be a monstrous antenna. The video also follows the break.

In hacker fashion, the project is built on a budget, so all the parts are direct from a hardware store, and the tools are already in …read more

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Bandpass Filters from the CNC Mill

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A bandpass allows a certain electrical signal to pass while filtering out undesirable frequencies. In a speaker bandpass, the mid-range speaker doesn’t receive tones meant for the tweeter or woofer. Most of the time, this filtering is done with capacitors to remove low frequencies and inductors to remove high frequencies. In radio, the same concept applies except the frequencies are usually much higher. [The Thought Emporium] is concerned with signals above 300MHz and in this range, a unique type of filter becomes an option. The microstrip filter ignores the typical installation of passive components and uses the copper planes of …read more

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Using An AI And WiFi To See Through Walls

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It’s now possible to not only see people through walls but to see how they’re moving and if they’re walking, to tell who they are. We finally have the body scanner which Schwarzenegger walked behind in the original Total Recall movie.

This is the work of a group at the MIT Computer Science and Artificial Intelligence Laboratory (CSAIL). The seeing-through-the-wall part is done using an RF transmitter and receiving antennas, which isn’t very new. Our own [Gregory L. Charvat] built an impressive phased array radar in his garage which clearly showed movement of complex shapes behind a wall. What is …read more

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A Cleverly Concealed Magnetic Loop Antenna

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We’re sure all radio amateurs must have encountered the problem faced by [Alexandre Grimberg PY1AHD] frequently enough that they nod their heads sagely. There you are, relaxing in the sun on the lounger next to the crystal-blue pool, and you fancy working a bit of DX. But the sheer horror of it all, a tower, rotator, and HF Yagi would ruin the aesthetic, so what can be done?

[Alexandre]’s solution is simple and elegant: conceal a circular magnetic loop antenna beneath the rim of a circular plastic poolside table. Construction is the usual copper pipe with a co-axial coupling loop …read more

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Desktop Radio Telescope Images The WiFi Universe

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It’s been a project filled with fits and starts, and it very nearly ended up as a “Fail of the Week” feature, but we’re happy to report that the [Thought Emporium]’s desktop WiFi radio telescope finally works. And it’s pretty darn cool.

If you’ve been following along with the build like we have, you’ll know that this stems from a previous, much larger radio telescope that [Justin] used to visualize the constellation of geosynchronous digital TV satellites. This time, he set his sights closer to home and built a system to visualize the 2.4-GHz WiFi band. A simple helical antenna …read more

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Teardown Locates Fractal Antenna

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[IMSAI Guy] tore apart a device with a wireless network card and decided to investigate what was under the metal can. You can see the video of his examination below. Overall, it was fairly unremarkable, but one thing that was interesting was its use of an antenna on the PCB that uses a fractal design.

You probably know fractals are “self-similar” in that they are patterns made of smaller identical patterns. The old joke is that the B. in Benoit B. Mandelbrot (the guy who coined the term fractal) stands for Benoit B. Mandelbrot. You can think of it as …read more

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Tracking CubeSats for $25

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CubeSats are tiny satellites which tag along as secondary payloads during launches. They have to weigh in at under 1.33 kg, and are often built at low cost. There’s even open source designs for these little spacecrafts. Over 800 CubeSats have been launched over the last few years, with many more launches scheduled in the near future.

[Thomas Cholakov] coupled a homemade cloverleaf antenna to a software-defined radio to track some of these satellites. The antenna is built out of copper-clad wire cut to the correct length to receive 437 MHz signals. Four loops are connected together and terminated to …read more

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