For the last week or so I have been working on building my own antennas. It was a ton of fun, even if it took me a couple of days to properly solder anything, and it took a whole day to tweak them after they were built. The type of antenna I was working with is called a PIFA antenna, and below is a picture of the two that I built. They don't look fantastically different from the model PIFA that I took a picture of last week, but that's a good thing I suppose.
My two 1.575 GHz PIFAs |
The peak resonance for this PIFA is practically exactly 1.575 GHz |
For those really interested in the workings of the PIFA, the length of the top plane plus the length of the distance between the two plates is supposed to be equal two a quarter-wavelength of the radiowave, but the antenna will also pick up the frequency that corresponds to a half-wavelength of another radiowave, which is why there is another return loss peak at about 3 GHz.
This tidbit probably relates to more of you out there: PIFAs are actually in use in many smartphones! Obviously they don't look too much like the clunky things that I've been making out of copper, but they are there, and oftentimes the ground plane (the larger of the two planes) is actually the back of the phone, and the top plate is concealed inside the phones and integrated very efficiently with the help of remarkable electronics packaging. If you don't believe me, check out the picture below of a Samsung Galaxy S. The six individual plates on the diagram on the right each serve as the top plate for a PIFA at different frequencies, and they all share the same ground plate. If you're anything like me, you've always wondered how the heck smartphones don't have antennas sticking out of them, and this is pretty fascinating and exciting.
Samsung Galaxy S and its fabulous PIFAs |
I'll stop raving about antennas for now. Now that my PIFA mission has been completed, I will be reading all about the last three years of Golden Lion Tamarin collar research in order to get a 30,000 feet view of the entire problem so that I can start researching solutions and applications for otters. Plus, I have an entire 200-page book about otters, which I'm very excited to read. Because otters are adorable. I promise I'll find good pictures of otters for the next blog post, because frankly I don't think the otters would feel comfortable among a bunch of technology pictures. Until next week!
Source: http://www.antenna-theory.com/antennas/patches/samsungantennas.jpg
They must think you're pretty awesome if they're willing to spend the money for you to build stuff out of solid copper. Ain't cheap.
ReplyDeleteA technical question: Why is your dB axis scaled by 20 rather than by 10 as is the case for most log scales?
Well, they were actually just copper plates with a dielectric between them, but still!
ReplyDeleteDang it, you're right. I had a misconception about decibels, and the axis is actually scaled by 10. I'll go change it. Thanks!
Wow Luke, you're so amazing. You're helping otters and your explanations are very clear.
ReplyDelete