Post by leviw on Mar 18, 2017 8:38:22 GMT -7
Has anyone tried using directional antennas for the ubiquity payload?
I'll lay out what I think I know to get a discussion started. Now, I'll be the first to admit I'm not a radio guru, so what I think I know might be wrong. However, I do have some small amount of experience with dipole, circular polarized, and patch antennas from researching and using them with analog fpv systems on hobby drones.
Dipole antennas (like the fatshark stick antennas with the default ubiquity payload) should emit a donut shaped signal centered around the antenna. Pointing the two antennas at different angles means the two donuts overlap and we get good coverage in any pretty much any direction. The downside is that a lot of our signal strength is being wasted into the sky or along the horizon, only a tiny fraction actually makes it to the ground.
Patch antennas may be a better choice because they are much more directional. They produce a signal shape more like a pacifier. The beam width varies but can be around 65 degrees, which means the ground station would need to be relatively close to the balloon's position on the ground. (Within 10-20 miles, by my estimate.)
Yagi antennas have an even smaller directional beam width. They would be even better but I think you would need to implement a pointing system on the payload. That sounds hard.
Has anyone tried using a patch antenna on the payload? Or something else?
Has anyone looked into this and what have you learned?
edit: full source
I'll lay out what I think I know to get a discussion started. Now, I'll be the first to admit I'm not a radio guru, so what I think I know might be wrong. However, I do have some small amount of experience with dipole, circular polarized, and patch antennas from researching and using them with analog fpv systems on hobby drones.
Dipole antennas (like the fatshark stick antennas with the default ubiquity payload) should emit a donut shaped signal centered around the antenna. Pointing the two antennas at different angles means the two donuts overlap and we get good coverage in any pretty much any direction. The downside is that a lot of our signal strength is being wasted into the sky or along the horizon, only a tiny fraction actually makes it to the ground.
Patch antennas may be a better choice because they are much more directional. They produce a signal shape more like a pacifier. The beam width varies but can be around 65 degrees, which means the ground station would need to be relatively close to the balloon's position on the ground. (Within 10-20 miles, by my estimate.)
Yagi antennas have an even smaller directional beam width. They would be even better but I think you would need to implement a pointing system on the payload. That sounds hard.
Has anyone tried using a patch antenna on the payload? Or something else?
Has anyone looked into this and what have you learned?
edit: full source