HAMNET Report 5th December 2021


Here’s a situation in a quantum computer lab, where a Ph.D might not have been as useful as a qualification in lock-picking!

The South China Morning Post reported last weekend that water leaking through the ceiling of a Chinese national research facility might have destroyed a new-generation quantum computer under construction if not for the quick action of students working late.

The incident has brought attention to the fragility of the hi-tech machines, but also the vulnerability of the humans who design and operate them.

Around 2am on Sunday morning, 26-year-old doctoral student Zhong Hansen was working at the Hefei National Laboratory for Physical Sciences at the Microscale in Anhui province when he noticed water spilling into his lab, according to an official investigation.

The lab was filled with expensive equipment, some of which was unique. More than 180 superconducting detectors cooled by liquid nitrogen alone cost more than 24 million yuan (US$3.7 million). They were part of Jiuzhang 3, China’s next world-leading quantum computer based on light, and Zhong was working late writing code for an experiment.

He found the water was coming from a locked laboratory. After calling for help, other students also still at work joined him in the rescue bid. With the help of security guards they forced the door open and stemmed the leak.

The authorities rewarded Zhong and four other students with 120,000 yuan (US$19,000) between them. In a statement on Thursday, the national research centre said much equipment might have been destroyed and the Jiuzhang 3 project “delayed by over a year”.

Perhaps lock-picking should be included as a module in your Ph.D course!

I have posted previously my concerns over the huge constellation of Starlink satellites being placed in low earth orbit, and the effect their presence and RF signals might have on visible light and radio-astronomy. I continue to be worried, and note that telemetry is becoming trackable from them now. Southgate Amateur Radio News reports from Hackaday.com that often, mere curiosity is sufficient to do something. This is also the case with people trying to analyse the communication setup and protocol which SpaceX is using with their Ku-band based Starlink satellites.

One of these fine folk is Christian Hahn, who has recently posted some early findings to r/StarlinkEngineering over at Reddit. Some of the captured data seems to include the satellite ID system that ground-based user stations would presumably use to keep track of overhead Starlink satellites.

For the capturing itself, Christian is using a second-hand dish for capture and a DIY SDR using KC705 FPGA-based hardware – which may have begun its life as crypto mining hardware – along with the usual assortment of filters and other common components with this kind of capture.

Even at this early time, some features of the Starlink protocol seem quite obvious, such as the division into channels and the use of guard periods. Nothing too earth-shattering, but as a fun SDR hobby it definitely checks all the boxes.

Christian has also announced that at some point he’ll set up a website and publish the findings and code that should make Starlink signal analysis easy for anyone with a readily available SDR receiver.

It remains for the radio-astronomy body to determine what degree of interference the satellites will cause to the astronomers!

And several sites have posted about the real threat two astronauts aboard the ISS would have faced had they done their planned space-walk on Tuesday the 30th, because of risks to their spacesuits caused by space debris after a Russian satellite was destroyed earlier in an experiment by the Russians.

All aboard the ISS were obliged to take cover in their respective “lifeboats” until the immediate threat was over. The debris spread out over the next few orbits, and was calculated no longer to pose a threat, and the spacewalk to replace a defective 20 year old S-band antenna took place successfully on Thursday the 2nd December.

A report from India says that solid, metal antennae have been the standard in a wide range of technologies for decades, including a wide variety of radio communications and scanning such as radar. However, research into the concept of liquid antennae was discussed in the 1990s. A liquid antenna would comprise a lightweight and perhaps collapsible container that could be erected into the appropriate shape and filled with a suitable liquid. Water, saltwater, ionic liquids, and other substances have been investigated over the years.

New work in the International Journal of Ultra Wideband Communications and Systems offers a novel design of a conical structure for a liquid antenna that can operate effectively across a wide frequency range. The antenna is compact and cost effective the team reports as well as offering a simple way to reconfigure it for different applications, something that is not easy with a solid metal antenna. Conical antennae are usually the form required for radio-frequency broadcast.

Roopa and E. Kiran Kumar of the Siddaganga Institute of Technology Tumakuru, in Karnataka, India, have demonstrated proof of principle for their new type of liquid antenna using pure water, seawater, and glycerine as the liquid component. The device can achieve voltage standing wave ratio of 1 to 2 over a frequency range of 300 to 850 megahertz, the team reports. They add that the gain achieved in experimental results was 2 dBi, which is comparable with their simulations in which the gain is around 1.9 dBi. The operating frequency is adjusted by changing the height of liquid within the cone.

The team concludes that their proposed antenna is simple, low cost, and covers a wide range of frequencies, which can be tuned easily. The radio emission from the antenna is omnidirectional and the fact that it is transparent gives it an additional attractive design feature for the development of wireless applications. In addition, the antenna is 30 to 40 percent shorter than its equivalent metal antenna.

Thanks to techxplore for that report.

I don’t know about you, but I can see this technology very rapidly catching on in amateur radio. Just imagine – with a few minor adjustments to the chosen additives to the liquid inside the antenna, one might not be at all disappointed if the bands seemed closed. One would be obliged to sit back in a comfortable camping chair, to drink the contents of the antenna, and watch the smoke curl over the coals as you grill your steak to perfection! Now that is the very essence of amateur radio! Who needs sunspots anyway?

This is Dave Reece ZS1DFR reporting for HAMNET in South Africa.