Watch Justin McAllister’s presentation on simple antennas suitable for a zombie apocalypse and two things will happen: you’ll be reminded that everything antennas do is amazing, and their reputation for being a black magic art will fade dramatically. Justin really knows his stuff; there is no dangle-a-wire-and-hope-for-the-best in his examples. He demonstrates that it’s possible to communicate over remarkable distances with nothing more than an off-the-shelf radio, battery pack, and an antenna of simple design.
A Hacker-Friendly Presentation
What’s great is that his talk presents information in a hacker-friendly way. Justin knows perfectly well that hackers will go out and dig up information on whatever interests them all on their own, so he focuses on showing what’s possible, what’s out there, and what stuff is called so the audience understands what to look for when they seek out more detail. After all, it can be hard to research something when one doesn’t know the right terms, or lacks an overall understanding.
The “surviving a zombie apocalypse” angle provides a useful context for the kind of antennas and wireless communications Justin dives into. Post-disaster survival depends in part on knowing one’s environment and communicating with (and watching out for) other humans. It will be important to hear news and be able to communicate with other people. Even if talking with other humans isn’t a factor, he reminds us that things like weather satellites will still be transmitting useful data regardless of what has happened on the ground.
Radio communications can operate without a wider infrastructure to support them, but using it effectively requires antennas, and antennas require their own kind of knowledge. Justin covers the basics of radios, cabling, and connectors in a concise way but focuses mostly on DIY antenna designs, all of which he has personally built and tested. Most of them are perfectly accessible to hobbyists with hardware store parts.
Simple, Effective Designs
Examples begin with simple wire dipole antennas (easily capable of cross-country communications with the right setup) and progress to more complex designs like a magnetic loop antenna, which was able to pick up stations all the way out in Japan from Justin’s kitchen table. Other examples include a dual-band VHF/UHF antenna that can be built with simple hardware, and a three-element Hex Beam antenna made with about $20 of hardware store parts. The last antenna shown is a multiband Vivaldi antenna on a PCB, which can’t really be done with basic hardware, but is nevertheless of simple design.
Wrapping up the talk (at 22:58), Justin shares useful resources for further learning, and warns that “[there are] a lot of opinions about antennas in the world, and a lot of them are wrong.” He suggests sticking to sites and resources that focus on hard data and experimentation.
If you’ve ever wondered what makes antennas work, or how the cable connecting a radio to the antenna (the feedline) doesn’t become part of the antenna, take twenty or so minutes to watch Justin’s presentation and come away with a much clearer idea of how even a self-contained, battery-operated radio can communicate cross-country with the right antenna.