Antenna Design for SDR Hobbyists

Explore Software Defined Radio — by Wolfram Donat (17 / 30)

👈 How Antennas Receive | TOC | Chapter 4 Digital Speech Decoding 👉

So how does all of this theory affect us SDR hobbyists? The answer, of course, depends on how far down the rabbit hole you wish to go and what sort of results you’re expecting. If you’ve already experimented with the projects in Chapter 2 and Chapter 3, you’ve most likely been successful with the simple whip antenna that connects to your SDR dongle. You may have also noticed that some of those basic monopoles are built with a small coil in the middle of the antenna. This is simply a way of making the antenna’s effective length a bit longer without making it too unwieldy. Luckily, it doesn’t affect the antenna’s effectiveness (though I have seen some advertisements attempt to market the coil as a reception enhancer — make of that what you will).

Those simple whip antennas will work fine for the digital signal decoding in Chapter 5, as well, but you’ll have to switch it up a bit to get a hold of the NOAA satellite signals in Chapter 6. That’s because they, like most satellites, broadcast using a circular polarity — a right-hand circular polarity, in their case. Ideally, you should use a right-hand circular polarized antenna to pick up their signals, but luckily some genius in the SDR world discovered some time ago that a pair of rabbit ear antennas could also be used, given that they were spread apart this far and oriented just like that…