Radio Hacks

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Ham Radio May Speed Up Soon

October 29, 2023 by 14 Comments

The FCC is circulating a proposal for new rules pertaining to amateur radio in the United States. In particular, they want to remove certain baud rate restrictions that have been in place since 1980. It appears the relaxed rules would apply only to some bands, notably some VHF and UHF bands along with the 630 meter and 2200 meter bands, which — we think — are lightly used so far. We’ll save you from grabbing the calculator. That’s around 475 kHz and 136 kHz.

Ham radio operators have long used digital modes like radio teletype and with restrictions on antennas and increasing interference from wireless networking to solar panels and more, digital has become even more popular than in the past. Besides that, cheap computer soundcards make it easier than ever and sophisticated digital modulation techniques have long left the old, clunky TeleType in the dust.

However, the FCC currently limits the baud rate to 300 baud or less, ostensibly to restrict signal bandwidth. No one wants to have an entire band consumed by a 10 Gb RF network. However, modern techniques often squeeze more into less and the FCC will finally recognize that by converting the limit to signal bandwidth, not baud rate.

What’s the bandwidth? For the common bands, it sounds like 2.8 kHz is the answer. For the VLF bands, they are asking for suggestions. The 2200 meter band isn’t even 2.8 kHz wide to start with!

All this talk makes us want to build something for the 2200 meter band. We better start winding the coil now. Then again, maybe we should go piezo. You know, just in case Thomas Dolby tells us that one of our submarines is missing.

A Quick And Stealthy Mobile Slot Antenna From Copper Tape

October 25, 2023 by 41 Comments

[Ben Eadie (VE6SFX)] is at it again with the foil tape, and this time he’s whipped up a stealthy mobile sunroof antenna for the amateur radio operator with the on-the-go lifestyle.

You may recall [Ben]’s recent duck tape antenna for the 70-cm ham band, an ultra-lightweight design that lends itself to easy packing for portable operation. The conductors in that antenna were made from copper foil tape, a material that’s perfect for all sorts of specialized applications, like the slot antenna that he builds in the video below. In the ham world, slot antennas are most frequently seen cut into the main reflector of a direct satellite dish, often in hopes of avoiding the homeowner association’s antenna police. Even in the weird world of RF, it’s a strange beast because it relies on the absence of material in a large planar (or planar-ish) conductive surface.

Rather than grabbing an angle grinder to make a slot in the roof of his car, [Ben] created a “virtual” slot with copper tape on the inside of his car’s sunroof. His design called for a 39″ (0.99-m) slot, so he laid out a U-shaped slot to fit the window and outlined it with copper foil tape. His method was a little complex; he applied the copper tape to a transparent transfer film first, then stuck the whole thing to the underside of the glass in one go. It didn’t quite go as planned, but as he learned in the duck tape antenna, the copper tape makes it easy to repair mistakes. A BNC connector with pigtails is attached across the slot about 4″ (10 cm) up from the end of one of the short legs of the slot; yes, this looks like a dead short, but such are the oddities of radio.

Is it a great antenna? By the numbers on [Ben]’s NanoVNA, not really. But any antenna that gets you heard is a good antenna, and this one was more than capable in that regard. We’ll have to keep this in mind for impromptu antennas and for those times when secrecy is a good idea.

Continue reading “A Quick And Stealthy Mobile Slot Antenna From Copper Tape” →

Atomic Antenna Uses Lasers

October 21, 2023 by 12 Comments

If you think about it, an antenna is nothing more than a radio frequency energy sensor, or — more precisely — a transducer. So, it shouldn’t be a surprise that there could be different ways to sense RF that would work as an antenna. A recent paper in Applied Physics Letters explains an atomic antenna comprised of a rubidium vapor cell.

The interesting thing is that the antenna has no electrical components in the antenna, and can be located far away from the actual receiver. Instead of coax cables, the signal is read with a laser.

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Junk Bin Cyberdish Turns You Into The Satellite Tracker

October 21, 2023 by 3 Comments

The good thing about listening in on satellites is that they tend to beam down all kinds of juicy information from their lofty perches. The bad thing about satellites is that to stay in those orbits, they’ve got to be moving really fast, and that means that you’ve got to track them if you want to keep a nice consistent signal during a pass. And that can lead to all sorts of complexity, with motorized two-axis mounts and fancy tracking software.

Or does it? Not if you’re willing to act as the antenna mount, which is the boat [Gabe] from the saveitforparts channel on YouTube recently found himself in when searching for L-band signals from the GOES satellite. His GOES setup uses a 30″ (0.8 m) dish repurposed from a long-range wireless networking rig. Unfortunately, the old security camera pan-tilt unit it was mounted on wasn’t quite up to satellite tracking duty, so [Gabe] pulled the dish off and converted it to manual tracking.

With a freshly wound helical antenna and a SAWbird LNA at the focal point, the dish proved to be pretty easy to keep on track manually, while providing quite the isometric workout. Aiming was aided by an app called Stellarium which uses augmented reality to point out objects in the night sky, and a cheap tablet computer was tasked with running SDR++ and capturing data. Sadly, neither of these additions brought much to the party, with the latter quickly breaking and the former geared more toward stargazing than satellite snooping. But with some patience — and some upper-body strength — [Gabe] was able to track GOES well enough with the all-in-one “cyberdish” to get some usable images. The whole saga is documented in the video after the break.

Kudos to [Gabe] for showing us what can be accomplished with a little bit of junk and a lot of sticktoitiveness. He promises that a legit two-axis mount is in the works, so we’ll be on the lookout for that. We’ve seen a few of those before, and [Chris Lott] did a great overview of satellite tracking gear a while back, too.

Continue reading “Junk Bin Cyberdish Turns You Into The Satellite Tracker” →

This Packable Ham Radio Antenna Is Made From Nothing But Tape

October 13, 2023 by 47 Comments

On today’s episode of “Will It Antenna?”, [Ben Eadie (VE6SFX)] designs and tests an antenna made entirely of tape, and spoiler alert — it works pretty well.

By way of background, the basic design [Ben] uses here is known as a J-pole, a popular “my first antenna” design for amateur radio operators looking to go beyond the stock whip antenna that comes with that cheap handy-talkie you just can’t resist buying as soon as you get your license. Usually, though, hams will build their J-poles from rigid materials, copper water pipe being a typical choice. Copper has the advantage of being easily sourced, and also results in a self-supporting, weather-resistant antenna that’s easy to mount outdoors. However, copper is getting to be egregiously expensive, and a couple of meters of water pipe isn’t exactly amenable to portable operation, if that’s your jam.

To solve those problems, [Ben] decided to keep his copper use to a minimum with a roll of copper foil tape. He doesn’t provide any specs on the tape, but it looks like it’s about 6 mm (1/4″) wide and judging by a quick Amazon search, probably goes for about $10 a roll. He starts the build with a couple of strips of plain old duck tape — we’ve already had the “duck vs. duct” argument — laid out with the sticky sides together. The copper foil is applied to the duck tape backing using dimensions from any of the J-pole calculators available online. Dimensions are critical to getting good performance from a J-pole, and this is where [Ben]’s tape design shines. Element too long? No problem, just peel up a bit and tear some off. Did you go too far and make an element too short? Easy — just stick on an extension piece of foil. Tuning the location of the feedline connection was a snap, too, with movable terminals held in place with magnets.

Once everything was tuned up, [Ben] soldered down the feed points and covered the foil with a protective layer of duck tape. The antenna performed swimmingly, and aside from costing almost nothing to build, it weighs very little, rolls up to fit in a pack for field operations, and can easily be hoisted into a tree for better coverage. Looks like we’ll be putting in an order for some copper tape and building one of these too. Continue reading “This Packable Ham Radio Antenna Is Made From Nothing But Tape” →

National Research Council laboratories in Ottawa

Canada Abruptly Ends Official Time Signal

October 13, 2023 by 47 Comments

In a sudden move that was noted not only by Canadian media, but also international media channels, the National Research Council Time Signal that was broadcast by Canadian Broadcasting Corporation (CBC) on CBC Radio One since November 5 1939 was turned off on October 9th, after eighty-four years, one world war, countless generations, and the rise of modern technology. Although perhaps obsolete by today’s standards, this 15 to 60 second long broadcast at 13:00 Eastern Time every single day has been a constant in the life of Canadians, whether they tuned into local radio, or (increasingly) via Internet radio.

The NRC Time Signal consisted out of a series of 800 Hz sinewave ‘beeps’ followed by a second-long signal to indicate the top of the hour. Back in the day this was extremely useful to sync one’s clocks, watches and other time-keeping devices to. Yet between the transmission delays caused by Internet radio and the increased availability of NTP and other time sources on modern-day devices, the signal’s main use appears to have become a nostalgic reminder of what once was a constant of each and every day.

In this regard the public response to the rather unceremonious decommissioning without prior announcement was rather predictable. After all, even if it wasn’t that useful, why throw out something that is more recognizable than any other radio jingle for generations of Canadians?

Top image: National Research Council laboratories in Ottawa.

Antennas Can Be A Total Mystery

October 10, 2023 by 14 Comments

The real action in the world of ham radio is generally in the high frequency bands. Despite the name, these are relatively low-frequency bands by modern standards and the antenna sizes can get a little extreme. After all, not everyone can put up an 80-meter dipole, but ham radio operators have come up with a number of interesting ways of getting on the air anyway. The only problem is that a lot of these antennas don’t seem as though they should work half as well as they do, and [MIKROWAVE1] takes a look back on some of the more exotic radiators.

He does note that for a new ham radio operator it’s best to keep it simple, beginning work with a dipole, but there are still a number of options to keep the size down. A few examples are given using helically-wound vertical antennas or antennas with tuned sections of coaxial cable. From there the more esoteric antennas are explored, such as underground antennas, complex loops and other ways of making a long wire fit in a small space, and even simpler designs like throwing a weight with a piece of wire attached out the window of an apartment building.

While antenna theory is certainly a good start for building antennas, a lot of the design of antennas strays into artistry and even folklore as various hams will have successes with certain types and others won’t. It’s not a one-size-fits-all situation so the important thing is to keep experimenting and try anything that comes to mind as long as it helps get on the air. A good starting point is [Dan Maloney]’s $50 Ham Guide series, and one piece specifically dealing with HF antennas.

Continue reading “Antennas Can Be A Total Mystery” →