All The Answers

Buenos Dias! The last time I apologized for a short post, it didn't end up being a short post at all, but this time I honestly don't have too much to add. Even so, I feel like I accomplished a lot this week. Since practice presentations begin next week, this week I really had to bear down (ha) and finish up my powerpoint. It's one thing to do a ton of reading and research, but it's a totally different thing to sit down and try to figure out what is worth presenting to you guys, and most importantly, what the answers were to my original research questions. Just to recap for everyone, my primary research question was if the tracking system currently used to track sea otters in Monterey can be improved, and if so, how. After hours of reflection, making charts, and flipping coins (kidding), I can finally say that I have an answer to that question. If you want to know what my answer is... well, I won't spill the beans until my presentation, so you'll have to come and find out!

As for the secondary research question (that isn't really a research question), which was whether or not I like engineering, I can safely say that I do indeed enjoy engineering. Learning about and going through the engineering process was a lot of fun, but it also stretched me in a lot of ways that high school never had, which was really good for me. As a math guy, I thought that engineering was just a bunch of math, but I was actually totally wrong! The only calculations and equations I had to use in my entire research project were when I was making and analyzing antennas. There were a couple other equations that I would've had to use if I had the money, time and resources to actually build a tracking system, but my engineering project was mostly math-less. Some of you who know me well are wondering how I could possibly be okay with not using very much math, but the best parts of engineering (and my project) are when groups of people who know their subject get together and brainstorm ideas furiously. After months of research on tracking systems, I was able to join in these amazing discussions and get a lot of of them. I'm so glad even before I continue on to my undergraduate education I've had the opportunity to get a taste of what engineering is all about.

P.S. Engineers get free laser-pointer pens sometimes, and they are the best things in the world!

Dual Frequency PIFA

Well, judging from my fellow students' blogs, SRPs are finally slowing down and beginning to become more focused on presentations and final products. My project is no exception, as I've been rather busy this week trying to plan out my presentation. It's kind of funny, because when I began attending BASIS in 9th grade I was convinced that I was going to graduate early so that I could avoid the 20-minute presentation that was required for Senior Research Projects. Even though in this school year alone I've already given six or seven presentations that long, and presenting doesn't freak me out as much as it used to, it's still pretty surreal to actually be working on my SRP presentation.

Anyhow, this week I went back to the workshop (mostly for fun), and found a PIFA that had an L-shaped cut through the top plane. I was curious, so I decided to make one of my own to see what it does! Here's a picture of the one I made:

My dual frequency PIFA

As many of you are probably guessing because of what it probably my least creative blog-post title to date, this antenna resonates at two distinct frequencies! I painstakingly cut and measured the copper material exactly like I would to make a 1.575 GHz GPS PIFA, but I wasn't too careful with the L-cut that I made. That is to say, I didn't know that it would resonate at two frequencies, so I didn't place special care in the dimensions of the L-shaped cut I made. Take a look at the network analyzer readings I got from my antenna.

Remember that in order to get good transmission at a certain frequency, the network analyzer should have a reading of -10 dB or lower at that frequency, so this antenna resonates well at approximately 1.408 GHz (marker 1) and very well at approximately 2.131 GHz (marker 2). I put marker 3 at exactly 1.575 GHz, because I was curious about what it would look like since the dimensions of the PIFA without the cut would have led to a 1.575 GHz antenna, and interestingly enough there is a little blip at that frequency, but it's only about -4 dB. 

Something that I didn't know until Marcos taught me was that the 2-D area of each part of the dual antenna has a lot to do with the frequencies that they resonate at. I had thought that the piece with the longer perimeter would correspond to the longer wavelength (lower frequency), but it turns out that the piece with the larger area will correspond to the longer wavelength, even if it has a shorter perimeter. 

If PIFAs were to be used in tracking devices for larger animals, where they could be more easily integrated into the circuitry, and there were two frequencies that the device needed to transmit at, then a dual PIFA would be a great option. For instance, if the device had GPS capability, but it also needed to communicate with the receivers in a MURS frequency, one antenna would be able to facilitate both frequencies. That's pretty convenient!

As always, thanks for reading, and have a nice weekend!

Maybe We Can Have Nice Things!

Hello again readers! It's been a pretty crazy week, but that's not terribly uncommon these days, with both high school and the college choosing process coming down to the finish line, so it's always nice to just sit down and write a blog post where I can share with you guys and reflect on what I've learned so far. It's a little scary to think about it, but even this project is getting pretty close to finishing up, so I'm beginning to focus less and less on researching and learning new things and more on working towards writing my research paper and my final presentation. But that doesn't mean that I can't spend a little time messing around with antennas still!

Now that I've set my system requirements with a little table fairly similar to the example that I showed last week, my next important step is to solidify the possible systems that I will be proposing and analyzing in my final products. Soon, maybe even today, I'm going to email a man who is probably currently the premier California sea otter researcher to ask him if he thinks my idea for putting a collar-like device at the base of an otter's tail is viable. If so, then suddenly both GPS and multilateration systems become much more attractive options, but as I already mentioned, both systems require that we worry about battery-life significantly more because they use much more power than a triangulation system's device.

Fortunately, I have a couple of ideas to extend battery life! I know that I'm not reinventing the wheel here with my project, because I don't know enough about electrical engineering to create a brilliant new tracking system, but perhaps I can synthesize our current technology with the older technology still in use in animal tracking devices to make a system that is better overall. That's why it's not particularly novel for me to suggest that we use solar-rechargeable batteries in tracking devices, but as far as I can tell it hasn't been done much. Although solar-powered devices could be very useful in devices for tracking other animals, I'm not too optimistic about the prospect of using it on a sea otter transmitter. Putting a tiny solar panel on the ankle or the base of the tail of a sea otter may not capture very much of the sun's energy. On top of that, from the videos of sea otters swimming that I've seen, it appears that the most of the sea otter's body is underwater most of the time, including the base of the tail and the ankles.

What I am more excited about is the possibility of using kinetically-rechargeable batteries in the devices to prolong their lives. No external attachment would have to me made to accommodate these batteries; in fact, utilizing them would be as simple as purchasing the batteries and plugging them in. As a bonus, the batteries themselves aren't even that expensive, at less than $25 a pop. Certainly if a transmitting device was attached to an otter's ankle the battery would be constantly recharged by the sea otter swimming and foraging for food, and I believe that a device at the base of the tail would get a fair amount of kinetic energy.

Please forgive the following scientific digression... this is the stuff that I get excited about. If you've taken college physics in the area of electricity and magnetism, this explanation of how rechargeable batteries work will be almost trivially simple. If you have a solenoid (the helically shaped wire below), you can move a magnet back and forth inside it to create a changing magnetic field, which in turn "inducts" an electrical current in the solenoid wire. If the solenoid wire is hooked up to a capacitor, the energy can be stored and used to recharge the battery and supply current. This system seems to me a remarkably simple yet subtly elegant way to prolong the life of any battery to the point where the battery is so effective that it may last longer than the device itself!

Passing a magnet through this solenoid is an easy way to generate an electric current. 

Well, that's all I have for this week. As always, thanks for reading!

Pictures: http://www.wildnatureimages.com/images%203/080505-003..jpg
http://www.school-for-champions.com/science/images/electromagnetic_solenoid__wire.jpg