When your homebrew Yagi antenna only sort-of works, or when your WiFi cantenna seems moody on rainy days, we can assure you: it is not only you. You can stop doubting yourself once and for all after you’ve watched the Tech 101: Antennas webinar by [Dr. Jonathan Chisum].
[Jonathan] breaks it all down in a way that makes you want to rip out your old antenna and start fresh. It goes further than textbook theory; it’s the kind of knowledge defense techs use for real electronic warfare. And since it’s out there in bite-sized chunks, we hackers can easily put it to good use.
The key takeaway is that antenna size matters. Basically, it’s all about wavelength, and [Jonathan] hammers home how tuning antenna dimensions to your target frequency makes or breaks your signal. Whether you’re into omnis (for example, for 360-degree drone control) or laser-focused directional antennas for secret backyard links, this is juicy stuff.
If you’re serious about getting into RF hacking, watch this webinar. Then dig up that Yagi build, and be sure to send us your best antenna hacks.
It’s due to antennas & propagation (primarily) that we say, “All RF is FM (fantastic magic).”
I was on IRC once and said (very obviously joking) that RF is black magic. some RF wizard took it personally and started saying that people are ignorant, RF is just maths etc.
I wonder if this person was in puts on sunglasses the spectrum.
Ha! Proper response would be this:
https://www.youtube.com/watch?v=iN-aXzpQUdw&t=45s
I don’t mind it at all being linked to black magic” been casting bolts of RF since the tender age of 15. :)
years ago i bought a wifi yagi cantenna from ebay but couldn’t receive anything with it. then later i bought a usb wifi peripheral for 1/4 the price with a rubber duck on it. I had success with that. I think part of the problem was the cantenna had 6 feet of coaxial cable on it and there was far too much signal loss in the cable.
tldr, don’t assume you need to shell out for best results.
I’m struggling trying to visualize wtf a “yagi cantenna” would look like. They seem mutually incompatible.
IIRC, it’s a length of all-thread with washers at specific intervals.
Something like this: https://youtu.be/Thpdfw2b9uM?si=VRKSy9ODSjAT1dI9
Seriously. Sticking a yagi inside a metal can. I’d love to see the rationale behind that, and the modeling too.
You can’t just wrap a can around an already-tuned Yagi-Uda antenna and hope it performs better. The ends of the yagi elements are high voltage nodes and will couple strongly with the conducting can, altering their tuning significantly. So the can forms an integral, tuned component of the antenna, and the whole assembly must be tuned as a unit.
Also, that steel can will absorb a lot of the RF power, functioning as a dummy load, due to its magnetic permeability and poor conductivity.
If would be interesting to see proper lab measurements of its gain compared to a similar size unshielded yagi, or even a plain dipole.