There’s an update for LimeSDR Mini 2.0 orders placed before the 19th of October and forming part of the current production run: hardware will be reaching customers by early December.

“All the PCBs and components for the next manufacturing run have been delivered to the assembly house. However, there was a delay in scheduling assembly. It was originally planned for this week, but is now scheduled for the second week in November,” Andrew Back writes in the latest campaign update.

“Because of this schedule change, the updated timeline for shipping all orders placed before today to Mouser is the end of November. This means shipment to customers with those orders is expected in early December. Thank you once again for your support and patience.”

The LimeSDR Mini 2.0 is the next-generation replacement for the original LimeSDR Mini, updating the design to move to a more powerful field-programmable gate array (FPGA) while retaining the open-source nature and functionality of the original. More information is available on the device’s Crowd Supply campaign page.

Pseudonymous security researcher “Investigator515” and colleagues have branched out into the world of software-defined radio, launching a dedicated new Medium publication dubbed Radio Hackers.

“In our multi part series SDR & Radio Hacking, we’ve explored the usage of the radio frequency spectrum in signals intelligence and non traditional cyber security roles. What has started as a short multi part series has sparked off some interest so we’ve decided to change course slightly,” Investigator515 explains.

“This course change means we’ve launched a new Medium Publication called Radio Hackers. We’d like to centralize our articles around this topic in one easy place to keep them accessible for easy reference as well as stimulate discussion around exploring and securing vulnerabilities within RF based infrastructure. We’ve also extended the number of articles we intend to launch. This allows us to be able to explore additional topics, like Drone Down links & Bluetooth protocols as well as infrastructure like satellites, NFC, and various angles around playing with GPS.”

The team behind the publication has also pledged to cover topics including, but not limited to, amateur radio, the Internet of Things (IoT), various wireless protocols including Wi-Fi, Bluetooth, and Zigbee, signal identification and decoding, and hardware manipulation.

The new publication is available on Medium now.

KrakenRF is preparing to launch a compact yet performant satellite dish and feed for reception of weather satellites on suitable software-defined radio platforms – using a folding “petal” design to make it easier to ship and transport.

“Discovery Dish is a 65-cm diameter aluminium satellite dish and active filtered feed designed for receiving GOES HRIT, GK-2A LRIT, FengYun LRIT, NOAA HRPT, Metop HRPT, Meteor M2 HRPT, and other weather satellites that operate around 1.69GHz,” the company writes of its upcoming device.

“The dish is designed to weigh under one kilogram, and it splits into three petals, making it easier to ship worldwide. The 1.69GHz feed contains a built-in LNA right at the feed point, as well as filtering, which means that there is almost no noise figure loss from cables or connectors.”

The dish is to be sold bundled with a mount, a feed optimised for 1.69GHz reception with a Qorvo QPL9547 low-noise amplifier, and 5m of RG58 cabling, KrakenRF has confirmed. Add-on options include a 1.42GHz feed designed for hydrogen line observation and radio astronomy and a pole-mount weatherproof electronics enclosure which doubles as a heatsink for devices like a Raspberry Pi and software-defined radio.

More information is available on the Discovery Dish Crowd Supply page, though the pictured prototype is a one-piece model without the three petals of the final design.

Researchers at the Hong Kong University of Science and Technology, meanwhile, have turned to something different for a recent experiment in measuring galactic neutral hydrogen: a wok from the kitchen.

“Astronomy observation is difficult in urban environments due to the background noise generated by human activities,” explains lead author Leo W. H. Fung of the problem the team set out to solve for as little capital outlay as possible. “Consequently, promoting astronomy in metropolitan areas is challenging.

“In this work, we propose a low-cost, educational experiment called Wok the Hydrogen (WTH) that offers opportunities for scientific observation in urban environments, specifically the observation of the 21 cm (f₂₁=1420.4 MHz) emission from neutral hydrogen in the Milky Way. We demonstrate how to construct a radio telescope using kitchenware, along with additional electronic equipment that can be easily purchased online.”

The team’s observation station reuses a round-bottomed Chinese wok, designed for commercial cooking, as a reflector for a 2mm copper wire dipole antenna connected to a folded quarter-wave balun, a low-cost commercial low-noise amplifier, and from there to a software-defined radio connected to a laptop, with everything grounded and the electronics fitted to a shielding box to reduce noise from terrestrial sources.

A preprint of the team’s paper on the project is available on Cornell’s arXiv server.

Radio ham Ben “VE6SFX” Eadie is also turning to less-common materials for his latest antenna, turning copper foil and gaffer tape into a surprisingly high-performance J-pole antenna.

“I was making [antennas] out of copper tubing, and it was getting heavier and larger and bigger and uglier – and it was driving me crazy,” Ben writes of his reason for seeking out a different approach, inspired by the work of John Portune. “After watching one of John’s videos I started thinking, ‘wait a minute, if I can use copper foil tape all I need is some sort of substrate to hold it, and will that work as an antenna?’ This will require the handyman’s secret weapon: Duck tape.

“I’ve made ladder line antennas and I’ve cut them too short,” Ben continues of the benefits to a gaffer tape antenna. “Because it’s really hard to add on pieces, you have have to solder them on, it’s a pain. Here’s the thing about foil tape is that the sticky stuff doesn’t seem to impede or stop any of the [electrical] flow so if you end up having something that’s too short lay another piece of copper foil tape over top of the first one until you get that tune that you want – and you can cut it down but you can [also] lengthen this out infinitely by just adding chunks of foil.”

Ben’s full video is available on his YouTube channel, Ham Radio Rookie.

Pepijn de Vos, meanwhile, has documented yet another approach to building an antenna, using a PCB to create a patch antenna for a GPS receiver.

“At MCH [the May Contain Hackers conference] I met up with a few maps people and worked on a GPS app for the badge,” Pepijn writes, referring to an Espressif ESP32-powered electronic badge given to attendees at the event. “After that I decided I should make my own add-on with a GPS antenna, and that I wanted to design and print the antenna on a PCB.

“I decided the best way to prototype these things was to use the CNC [mill] at Tkkrlab to mill a double sided PCB blank into an antenna and solder some SMA connectors to it. First I drew the antenna in KiCAD using SMD pads as the patch, there is even an option to make chamfered pads. I also added a stripline to calibrate the width. Then I exported the PCB design to Gerber, loaded it into FlatCAM to convert it to a toolpath, and used bCNC to execute it.”

Pepijn’s full project write-up, which includes simulation and measurement, is available on the maker’s blog.

If that weren’t enough antenna examples, physics researchers at the University of Otago have come up with what they says is an entirely new form of antenna altogether: a vapour-filled glass bulb dubbed a “passive Rydberg-atomic transducer.”

“We combine a rubidium vapour cell with a corner-cube prism reflector to form a passive RF transducer, allowing the detection of microwave signals at a location distant from the active components required for atomic sensing,” the team, lead by Susi Otto, PhD, explains. “This compact transducer has no electrical components and is optically linked to an active base station by a pair of free-space laser beams that establish an electromagnetically induced transparency scenario.”

The device is claimed to offer superior performance to existing antenna technologies with improved sensitivity, broad tunability, and a highly compact physical size — and are being positioned as a solution to improving battlefield communications by allowing a single antenna to cover an entire spectrum of frequencies, something which could also prove useful in satellite communication.

In testing, the team’s prototype was used in-the-field to measure microwave fields outside the lab at a distance of 30m using a free-space laser link. “[We] foresee significant future prospects of achieving a much larger separation between the transducer and the base station,” the team notes.

The device is detailed in Applied Physics Letters, under open-access terms.

The Tech Minds YouTube channel has published a video demonstrating how to use a software-defined radio and a low-cost commercial mesh antenna for radio telescope observations of the hydrogen line.

“Generally, radio telescopes consist of a parabolic reflector which in some cases can be as large as 100m in diameter – with the largest in China measuring around 500m across,” the host of the channel notes. “Obviously most of us don’t have that kind of space or even money to have such a large dish for radio astronomy, but what we can do is something like this.

“This is a satellite mesh antenna from from Nooelec,” the host continues. “Due to its Center frequency being close to 1.7GHz and it [having] a wide bandwidth we can use this antenna to detect the hydrogen line – or, in other words, the 21cm spectral line. This originates from the Milky Way and, without getting too technical, is created by a change in the energy of solitary neutral hydrogen atoms. It is produced by a spin flip transition and the result of this is electromagnetic radiation at a frequency of 1.42GHz which can be detected from Earth.”

While hydrogen line signals are weak, the channel was able to pick it up using the mesh antenna, a low-cost software defined radio, and a filter and low-noise amplifier tuned for 1.52GHz.

Full details are available on the Tech Minds YouTube channel.

The European Telecommunications Standards Institute (ETSI) has stated that it may be willing to open the cryptography algorithms behind the Terrestrial Trunked Radio (TETRA) protocol – following backlash surrounding the discovery of serious vulnerabilities.

“The ETSI Technical Committee in charge of TETRA algorithms is discussing whether to make them public,” ETSI spokesperson Claire Boyer told The Register in a statement this month, confirming that the issue is being discussed and may be put to a vote if a consensus can’t be reached.

The cryptographic algorithms behind TETRA were the source of much interest earlier this year when, as reported in July’s OTA, reserachers discovered a family of five serious security vulnerabilities dubbed TETRA:BURST.

These, the researchers claimed, included a “backdoor” in the TEA1 encryption algorithm which made it “trivially brute-forceable on consumer hardware in minutes” – though ETSI denied this constituted a backdoor.

More information is available in The Register’s coverage.

Finally, the US National Radio Astronomy Observatory (NRAO) has shown off an antenna prototype for what will become the next-generation Very Large Array (ngVLA) radio telescope.

“[The antenna’s] design allows the surface of the dish to withstand whatever the environment throws at it – extreme temperature, wind, gravity – the reflector will maintain its precise shape within several microns, the equivalent of three human hairs,” claims Lutz Stenvers, whose company was called upon to build the prototype — an 18m dish made of 76 aluminium panels arranged in an octagonal shape and weighing an impressive 43 tons.

The finished ngVLA interferometric radio telescope will be made up of 244 dishes, including a “core array” in New Mexico and the American southwest plus a baseline through the US, Mexico, and Canada. It is designed to bridge the gap between the existing ALMA and future SKA1 systems, promising what its creators say will be “ultra-sensitive imaging of thermal line and continuum emission down to milliarcsecond resolution.”

More information on the ngVLA project is available on the official website.