Fixes

I bought a sketchy 25dBi Yagi-Uda antenna from China which did not perform great out-of-the-box. It had a hard time detecting access points just a few meters away, and my 5dBi Dipole antenna outperformed it in every way (even the range!). I did a bit of reading to learn about how the Yagi-Uda antenna works, and what I should expect from it. I noticed quite a few things from the one I got: It had a 2m coax cable, a "Balun", a misaligned driven element, and a screw that was too long, which causes the driven element to ground with the boom and parasitic elements. The first fix was to reduce the length of the coax cable from 2m to 15cm (about 6 inches), because even low-loss coax cables can reduce the received signals by as much as -10dB. Second was to open up the plastic case from where the driven element of the Yagi is mounted to check for sketchy soldering connections. From there I noticed that it had a "Balun", which is a wire extention connected with the driven element, to "Stabilize" the received signals. However, for UHF antennas (such as WiFi antennas, which are 2.4GHz and 5GHz) this is unnecessary, and may even introduce unnecessary loss in signal strength if done incorrectly; so I removed it. Third was to fix the misaligned driven element as it was a couple centimeters off the center of the folded dipole. I only needed to rotate its axis on the antenna's boom. Finally, I snipped the screw to make it a few millimeters shorter.

I should have tested each fix to see which of those affected the poor performance overall, but all of the fixes ended up making this cheap Chinese Yagi-Uda antenna to be an effective one. It is now able to pick up more access points at a greater range. Basically, it's working how it's supposed to.

Power Supply

Making the portable power supply consisted of an adjustable DC-DC step-up converter, a Li-poly Cell, and a micro USB Li-ion charger. I had to cut the JST connector off off the Li-poly cell since the charger I got didn't have a JST connector. The step-up converter is wired in series with a slide switch, then the li-poly and charger are wired in parallel to the converter.

Future Upgrades

I'm thinking about using a cheap airsoft's plastic body instead of making one out of wood, but I really like the weight and sturdiness, and look of a wooden stock. Ruining a good airsoft may also cost more. I would get a better Li-ion charger with an onboard switch, JST connector, and proper output pins to connect the DC step-up converter to. I also plan on using a single-board computer (*cough* Raspberry Pi *cough*) to do all the processing.