I spent the whole weekend building this... Err... "Portable" directional 2m #hamradio antenna with @Jen Blight, and it was pretty great.

(It's portable in the sense that it only weighs about 2lbs, and can be taken apart to fit in a backpack. I hope to make substantially more portable ones in the future).

The elements are made from 0.5" PEX irrigation tubing (think hula hoop material), wrapped in copper-coated fabric and copper tape, with a layer of clear "repair" tape to prevent tarnishing, while preserving the mad wizard staff vibes.

Each tube is connected to itself using Anderson powerpole connectors, so they can be easily unplugged, and twisted into a smaller footprint for travel.

The boom is a fiberglass driveway marker, and the mast is a telescoping fiberglass pole.

I don't yet know how well the antenna performs, and as you might be able to see from the VNA, it needs a little tuning. But my radio didn't emit any smoke when I transmitted using it! And the signal made it clearly to its intended target (who was about 30ft away).

I'm currently using my 64-core Linux desktop to run a genetic algorithm to optimize my design for an emergency #hamradio antenna. About an hour ago I submitted a patch to the (Haskell) codebase of the optimizer to allow it to support curved wires, which I needed because my design is made of four circular hoops. Despite being a fairly low activity project, the PR was merged within about 10 minutes, which felt awesome.

Am I cool yet? How many more layers of nerd do I have to add before I'm cool?

Trying a couple different materials for my "emergency kit highly directional #hamradio antenna":

1. Stainless steel spring-crafting wire (idea credit: @flammifer@superstimul.us) isn't the best choice of antenna material or diameter, but it is extremely portable: I'd add connectors so I could unplug the ends and twist the wire up, to have it fit in about one square foot.
2. PEX tubing is much lighter than it looks, is much sturdier and harder to accidentally deform, and covering it in copper foil tape should produce an excellent antenna. But it would be much harder to fold a PEX antenna down into an emergency kit sized package.

I think I'm just going to make both and compare them.

Another cool #hamradio fact is that, since right now we're near a maximum in the solar cycle, around dusk and dawn you can basically communicate directly with any place on the planet. To communicate with daytime places, you use the 10m band, and to communicate with nighttime places, you use the 40m band. The pink speech bubbles on this map show people who reported hearing my 10m signal in the last hour. If I switched to transmitting on 40m, you'd see a similar set of speech bubbles but going east instead of west.

When the solar cycle is in a trough, only the nighttime signals get through.

A slightly horrifying / cool thing I learned from doing #hamradio and in particular the FT8 mode:

Every 15 seconds, thousands of computers let out a wavering, wailing tone into the void. Then there's 2 seconds of silence. And then they do it again. Since they're doing this by sort-of "pretending" to be sending audio signals, you can listen to it: soundcloud.com/vartchcodpiece/…

It sounds kinda like a mashup of whalesong and digital ghostly wailing. Wailsong, I guess.

What are they saying to each other, you ask? They're basically having the same conversation over and over again. I'll tell you how it goes:

"Hi, anybody there? I'm Alice and I live in Appalachia."
"Hi Alice, I'm Bob and I live in Bermuda."
"Hi Bob, I'm Alice and I hear you really clearly."
"Hi Alice, I'm Bob and I hear you not-so-clearly."
"Hi Bob, I'm Alice and goodbye!"
"Hi Alice, I'm Bob and goodbye!"

FT8 - 3.573 Khz - 80m

FT8 or Franke & Taylor 8 is a form of digital communication used primarily by amateur radio operators to communicate on amateur radio bands with a majority of traffic occurring on the HF amateur bands

^SoundCloud

Some #hamradio updates:

1. Because US amateur radio licenses are public and include addresses, you can see a map of everyone with a license. It's way denser than I would have expected in Berkeley:
   

   

   And hey, there's @Daniel Filan with his fancy Extra-class license a bit further down on the map!

2. Today I managed to hear my first trans-pacific signal, from Nauru (a tiny island country 5,000 miles from here). Apparently it's what's called a "DXpedition", where a group of radio amateurs go on holiday in order to help other amateurs check "rare" countries off their lists. Unfortunately from their website, it looks like they're transmitting with more than ten times as much power as I have (or at least they brought equipment for broadcasting at that power level), so this isn't much evidence about whether I'll be able to have a full conversation with them or not.

About two years ago I got a ham radio license. I haven't done anything with it so far, but I just ordered my first HF radio transceiver, and materials for a ~100ft temporary antenna in my back yard (I'm extremely lucky in that my new house has a 120ft tree in the back that I can lift a wire into).

We're approaching a peak in the solar cycle, which means that over the next year or so it will be unusually possible to communicate over extremely long distances. You can look at dxmaps.com/spots/mapg.php (especially the "10m" and "40m" tabs) to see real-time examples of the kind of distances I'm talking about: In the evenings, if my setup works well, I'm expecting I'll be able to have conversations with people in Japan, Australia, and New Zealand, without any intermediate infrastructure at all. This is such a wild thing to be able to do; I'm really excited.