Results of the spiral antenna are good, as can be seen on the following plot. UAV was on the ground, among trees, until 00:35. From there you can see it clear right up. BeiDou Geo satellites (C01-C04) are now tracked properly and are useful for processing, whereas before they were a cycle-slip mess. There is still directionality evident in the SNR, but is not enough to matter.
Thank you @VanavaraDigital for your antenna recommendation. I have better tracking and saved about 15g weight. I appreciate your participation in the forum.
As for antenna shopping, I just go to ali express and search for ‘bt-560d’, and buy the cheapest one. That’s how I’ll get my next one. I will convert the second unit as soon as I can based on my test.
As for mounting, I bought some 25x25x1.5mm L-shape aluminium extrusion, cut a small piece, drilled a 6.5mm hole for the antenna, drilled 2x2mm holes for mounting to the timber mast, and strengthened the mount with 2-part epoxy.
Looks like the helix antenna can be used with or without ground plane.
Helix antennas can be designed for use with or
without ground plane. If a helix antenna is
designed without ground plane it can be tuned
into such to show a more omni-directional
radiation pattern as shown in Figure 22.
Although we can determine an axial ratio close to
9 dB between zero degree and 90 degrees
elevation, which compares to the patch antenna,
the back lobe of the helix generally degrades
much smoother and does not show any
sensitivity at the –180 degree direction. In
contrast, the back lobe of a patch antenna
depends very much on the size and shape of the
The antenna vibration is supposed to be mitigated by the antenna mast being pressed into a 3mm piece of sorbothane stuck to the side of the P4. It is the material that kept coming up when i was searching for ‘best shock absorbing material’
Sorry to ruin the party but aren`t you introducing a flexed vibration ( like a tuning fork) ? Or you might have solved it some how, but hard to tell from the picture
Edit: Your wooden pole might be stiff enough to counteract that, of course