“There’s no point in beaming episodes of EastEnders up into the sky and out into space”
@PaulOckenden
Thanks for the feedback so far on this short series of columns covering LoRa and LoRaWAN. It’s nice to hear that the idea of low-powered long-range radio is grabbing your interest.
I briefly mentioned antennas last month, but let’s take a look in a bit more detail now. Actually, I say “detail”, but antenna theory gets very complex and you’d need a thick book to cover it all, not just a few paragraphs in a magazine column, so as usual I’ll try my best to simplify things. Apologies in advance if you’re a radio nerd and my simplification goes a step too far!
There are many different types of antenna, but perhaps one of the first things to look at is whether they’re directional or not. Actually, to a degree, all antennas are directional. You’ll never get a truly 360° pattern, “isotropic” in antenna parlance, but that’s just being pedantic – certain antennas are designed to pick up signals from all around, while others are looking for a single point some distance away.
Think about TV aerials for a moment. In particular, think about those big transmitters you see. Some look like versions of the Eiffel Tower, with Crystal Palace an excellent example. Others are more like tall concrete poles; for instance, you might have spotted the Emley Moor transmitter if you’ve driven up the M1 through Yorkshire as it’s the tallest free-standing structure in the UK (there’s a taller mast in Cumbria up into the sky and out into space. These TV transmitters need to radiate out in a plane, and perhaps counterintuitively they’re called “omnidirectional“
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