We’ve known a few people over the years that have some secret insight into antennas. To most of us, though, it is somewhat of a black art (which explains all the quasi-science antennas made out of improbable elements you can find on the web). There was a time when only the hams and the RF nerds cared about antennas, but these days wireless is everywhere: cell phones, WiFi, Bluetooth, and even RF remote controls all live and die based on their antennas.
You can find a lot of high-powered math discussions about antennas full of Maxwell’s equations, spherical integration and other high-power calculus, and lots of arcane diagrams. [Mark Hughes] recently posted a two-part introduction to antennas that has less math and more animated images, which is fine with us (when you are done with the first part, check out part two). He’s also included a video which you can find below.
The first part is fairly simple with a discussion of history and electromagnetics. However, it also talks about superposition, reflection, and standing wave ratio. Part two, though, goes into radiation patterns and gain. Overall, it is a great gateway to a relatively arcane art.
We’ve talked about Smith charts before, which are probably the next logical step for the apprentice antenna wizard. We also covered PCB antenna design.
What a coincidence! This weekend I’ve been working on getting my 40m dipole up. Still have some work to do on it, but I’ve been agonizing over antennae and baluns and other mysterious things for a while, trying to get myself and a friend on the air. I wrote about it on my blog if anyone cares to read it: http://miscdotgeek.com/bitx40-ssb-tranciever-project/
I still have to get a pole up (it’s not going very high) and measure out the wire and get it hung up. I am hoping to get it done this week, as my BITX40 should be here soon!
You have two typos in one word – it is Transceiver not Tranciever.
On this post?
I’m guessing the URL from geocrasher.
F.M.
Whoa, that graphic is quite-intuitive. Gonna have to check this out.
I remember having that realization about why half wave was magic and then you understand stubs too…that was pre Wikipedia though.
It seems to me that the if the blue waves represent current, that they are not correct. If going above the wire = positive current (sucking electrons away), then when one side is positive, the other should be negative of equal magnitude (for this geometry). Naturally, the same applies throughout the cycle.
they are already wired opposite, so flow indicators in the same directions will actually flow in opposite directions.
The whole thing is half wave so when the centre is at zero volts the edges are at max magnitude but different signs. When center is max or min the edges are at zero.
For all the German readers there is the “Rothammel Antennenbuch”, which one of the books recommended to every HAM radio operator.
Ah, and if you search a little you find the PDF of an older version of the book. The basics of antenna technology didn’t change much over time, so this should be fine.
I imagine material science has though.
Seeing things like this and being able to provide an intuitive understanding is of such great value. I dare say more than the math-loaded PhD level understanding when it comes to being able to get systems functional.
I love the way the math can be easily rendered into waveforms these days. Amazing how you can simulate and get an accurate picture.
I was just reading about another attempt at using the EM equations: Ch00ftech’s. He wasn’t trying to make an antenna, but trying to magnetically levitate a tiny wooden car for a toy car race. He wasn’t successful, but research simulations he did were very informative of why it wouldn’t:
“Lorenz Forces and losing the Pinewood Derby”
http://ch00ftech.com/2016/11/20/lorentz-forces-and-losing-the-pinewood-derby/