Why HF rocks

When I first got my amateur radio licence, it was a class-B licence because I hadn't taken my Morse code test. This meant I could only use bands over 30MHz.
Now, there's a lot of cool stuff that you can do above 30MHz, but it was the bands below 30MHz that interested me - the HF bands.
So my interest in amateur radio died a death for decade or so.

Luckily for me, fellow ham and Open Source advocate Bruce Perens (K6BP) lobbied for the removal of the Morse code requirement for below 30MHz, and in July 2003, the UK removed the requirement.
I went out and bought a Yaesu FT-857D, some antennas, and started making contacts. Also, because I didn't have to learn Morse code, I started to learn it. It's hard though.

So why does HF rock?

HF (3MHz to 30MHz) has some interesting capabilities that make it very interesting. Our neighbourhood star, the Sun, emits vast amounts of radiation in all directions, sometimes more, sometimes less. These photons hit molecules or atoms of gas in the ionosphere, knocking an electron off, leaving a positively charged ion. This is great news for radio hams, as these ions causes the ionosphere to "reflect" radio waves.

Around midday on Boxing Day, 2016, I drove to some high ground near the Mendip Hills, south of Bristol, UK, and put my rather large antenna on my car.
With nothing more than my car, the diesel in it, my transceiver and antenna, I transmitted 100W (which is about as much power as a bright lightbulb). Most of that signal went in the wrong direction, or went up, or down. A very tiny fraction of that signal travelled to the horizon, and carried on until it hit the ionised ionosphere, where it was reflected back to Earth a couple of thousand miles away. An even smaller amount bounced back off the Earth, and up again to the ionosphere, and again a few more times. Eventually, roughly a fourteenth of a second after I sent it, a tiniest fraction of the original signal happened to hit the antenna of VK5ZM 10000 miles away in Adelaide who happened to be on the same frequency as me. The tiny radio signal induced a tiny current in his antenna, which his receiver amplified, and converted back into my voice.
We could hear each other well enough to have a quick five minute chat with each other.

I find that amazing. With nothing more than 12 volts, my transceiver, antenna and some favourable solar weather, I can bounce signals between the Earth's surface and the ionosphere around the entire planet. Look Mum, no wires. Also no fibre optics, no repeaters, no satellites, no Internet. Just pure physics.

Compare that with your phone which can barely reach the cell tower a mile or two away, and which uses cables underground and under the sea, along with billions of pounds worth of infrastructure to get your voice from a to b.

That's why HF rocks.