sUAS Antenna questions, nerds needed!!

James331

James331

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Hey guys,

Got antenna placement question, since according to the feds its a aircraft, I think its fare game to ask here ;)

I've recently been doing a little more flying and getting a little more trusting in the automation on this thing, but I do occasionally get some so so video performance, this rig should be able to reach out about 2mi while maintaining full ground control contact (of course I always fly IAW FARs).

The on board radios are

5.8Ghz video (white mushroom antenna)

2.4 control with telemetry (V antenna)

900mhz telemetry and mission upload/download (single black antenna)

and the large black saucer antenna is the GPS.

image.jpg


image.jpg




I'm wondering if the placement/direction of the antennas might be less than ideal, I can go out a decent ways, but Ill get some glitches on the video feed, nothing too bad but it seems to be under preforming a bit.

Thoughts??


Thanks
 
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Does that thing have a flux capacitor ? That is quite the set up you got there! I am no help in this area but my father would "get a nut" if you asked him about antennas ! He loves that stuff. They visited a couple months ago and we didn't have an antenna hooked up to the tv and he wanted to watch the Vikings game, simple solution, he built one. Then on his next visit he brought more do-dads to make it better and/or better looking. Interesting fella my dad is.
 
I had good luck with IBCrazy's stuff. What power tx are you running on the 5.8?
 
James331 said:
Hey guys,

Got antenna placement question, since according to the feds its a aircraft, I think its fare game to ask here ;)

I've recently been doing a little more flying and getting a little more trusting in the automation on this thing, but I do occasionally get some so so video performance, this rig should be able to reach out about 2mi while maintaining full ground control contact (of course I always fly IAW FARs).

The on board radios are

5.8Ghz video (white mushroom antenna)

2.4 control with telemetry (V antenna)

900mhz telemetry and mission upload/download (single black antenna)

and the large black saucer antenna is the GPS.

image.jpg


image.jpg




I'm wondering if the placement/direction of the antennas might be less than ideal, I can go out a decent ways, but Ill get some glitches on the video feed, nothing too bad but it seems to be under preforming a bit.

Thoughts??


Thanks
Click to expand...

Maybe move the video antenna to the bottom? I don't know the directional characteristics of that antenna but I'm guessing that it radiates mostly out the sides of the "mushroom" and not much up or down. If there are wires, circuit boards, batteries etc. between you and the antenna the signal might not be getting back to you very well, especially at certain angles. If you could place it on the bottom there wouldn't be much to block the signal. It could also be a faulty antenna or poor connection somewhere including in the coax connections. Do you have a buddy with an extra 5.8ghz antenna you can borrow to troubleshoot?
 
topgun260 said:
Maybe move the video antenna to the bottom? I don't know the directional characteristics of that antenna but I'm guessing that it radiates mostly out the sides of the "mushroom" and not much up or down. If there are wires, circuit boards, batteries etc. between you and the antenna the signal might not be getting back to you very well, especially at certain angles. If you could place it on the bottom there wouldn't be much to block the signal. It could also be a faulty antenna or poor connection somewhere including in the coax connections. Do you have a buddy with an extra 5.8ghz antenna you can borrow to troubleshoot?
Click to expand...

I'm going to agree. If the drone is airborne, a direct path to the receiver is "down". If the antenna is above the drone it has the possibility of being blocked by the drone body. Put the antennas on the bottom, if possible.
 
James331 said:
600mw
Click to expand...
600mW should be rock solid. Make sure you put the tx antenna on the tx and the rx antenna on the rx, as they have different numbers of lobes, for reasons that are magical to me.

Ghery said:
I'm going to agree. If the drone is airborne, a direct path to the receiver is "down". If the antenna is above the drone it has the possibility of being blocked by the drone body. Put the antennas on the bottom, if possible.
Click to expand...

Pardon my ignorance because I'm not an RF guy, but these are circularly-polarized antennas; will it make a difference if one is pointing up and the other down?
 
Ghery said:
I'm going to agree. If the drone is airborne, a direct path to the receiver is "down". If the antenna is above the drone it has the possibility of being blocked by the drone body. Put the antennas on the bottom, if possible.
Click to expand...

I remember someone saying the antennas also had to be in the same orintation, like if the airborn one was pointing up, the ground one also had to?

The UAS also lacks the clearance for a belly mout, perhaps if I put some tall gear on it, but that would also be a bit of drag and weight....
 
GeorgeC said:
600mW should be rock solid. Make sure you put the tx antenna on the tx and the rx antenna on the rx, as they have different numbers of lobes, for reasons that are magical to me.



Pardon my ignorance because I'm not an RF guy, but these are circularly-polarized antennas; will it make a difference if one is pointing up and the other down?
Click to expand...

The issue isn't that the antenna is pointing up or down. It appears that the location of the antenna creates the possibility that the signal can/would be blocked in certain orientations relative to the receive antenna. A test that you could run would be to fly until you start to see degradation of the video signal, stop and hover, then do a slow 360. Are there times when you are rotating that the video signal seems to fluctuate? Is the video signal worse when you are flying directly away and better when you are flying back? At 5.8Ghz it doesn't take much to reflect or block a signal. I'm sure everyone has heard of "line of sight" propagation meaning that if the transmitting and receiving antennas can "see" each other they should be able to communicate. But just because you can see your sUAS doesn't mean that the transmit and receive antennas have perfect line of sight or an unobstructed path. For a little more information about vertical, horizontal and circular polarized antennas check out this link. https://rcexplorer.se/projects/2011/08/circular-polarization-explained/
 
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