Has anyone tried using a GPS antenna as used on the Traquito just on leg of 1" that works very well on a U4B?
This type of antenna is a monopole antenna, like a 1/4-wave vertical. And like a 1/4-wave vertical, it also needs a groundplane (radials etc). Firstly 1" would?be 25.4mm which would not be the right length; at 1575 MHz L1 GPS a 1/4-wave antenna would need to be about 45mm (something like). The groundplane is formed by the groundplane of the tracker (Traquito in that case).?
However:?Traquito is a much larger tracker than U4B. Approximately 3x the weight?and 3x the board area. Therefore U4B would be an even less effective groundplane than Traquito.?
The antenna Dave VE3KCL used on the test flights, and I also used successfully, consists of a full-size dipole made from the same 0.33mm wire used in all the QRP Labs kits. Each arm of the dipole is 45mm long. Then make a "feedline" (and balun) by tightly twisting the wire for a distance of about 3-4cm (not critical). The result looks like a T with a shorter trunk than its arms; the vertical section is the twisted wire part, soldered to the U4B (ground and GPS Ant pins) at the bottom end, with the two horizontal arms of the dipole pointing left and right at the top.?
Furthermore Dave found that the performance is further improved by bending the dipole arms towards each other so that they are at 90-degrees. Now the antenna looks like a Y. Presumably improves the impedance match.?
I think this kind of dipole antenna outperforms most other types of passive antenna system. You see a lot of GPS ceramic "chip" antennas. These are a compromise, designed for when very little space is available. Your smartphone is a good example. That poor thing has to have a GPS antenna, WiFi, Bluetooth, Cellular, NFC, who knows what else... all crammed into a tiny case alongside a relatively huge screen, relatively huge battery, and tons of electronics. Having the space for a full-size dipole is a very nice luxury to have.
