Telemetry transmission antenna?

[Steve Carr]

There is no antenna only for telemetry.

Okay, got that. I dug out an old drawing and added the notes in yellow. Does this look correct now?

 

[h-elsner]

Yes, this is my understanding. Perfect.

 

[PatR]

Using that photo for reference it appears it’s quite possible to occlude the ST-16’s GPS antenna with our body. I wonder how many GPS warnings might have been induced because of that?

 

[Steve Carr]

I wonder how many GPS warnings might have been induced because of that?

Indeed. I didn't realize that was the location until I had to remove that board for a repair recently. I found the antenna under the wires for the Mic.
I'm not certain you would get a warning if only the ST16 has GPS loss.

 

[DCH]

Using that photo for reference it appears it’s quite possible to occlude the ST-16’s GPS antenna with our body. I wonder how many GPS warnings might have been induced because of that?

This is a valid concern. I have wondered that very thing myself. I'm a skinny guy, but I would imagine a beer belly might obscure the antenna.

Also that photo is showing an ST16 with two external antennas, not an ST16+ with 3. That might cause some confusion of antenna ID for people new to this subject, like the OP. Just sayin...

 

[jandjfrench]

There is no antenna only for telemetry.
Both 2.4GHz RC (ZigBee) antennas are bidirectional. There are two for antenna diversity. The receiver checks what antenna has the best signal and takes this. Antenna diversity is made to overcome interferences and gaps in the radiation pattern of the antenna.
The minimum radiation (as well as receiveing signal strenght) is on top of the rod antenna. This is the reason why the two antennas should have 90° to each other, i.e. one horizontal and one vertical. Where the ones minimum there the others maximum.

At the two antenna ST16 the internal is horizontal --> the external should be vertical. For the 3 antenna ST16 it's up to you. 90° to each other no matter in which direction is optimal.

There is only one 5GHz antenna for the video downlink and command uplink which is also used for "Dual Band Control Redundancy".

Internal we have another two antennas: One GPS antenna und one 2.4GHz WLAN antenna for the pad mode.

br HE

I was intrigued by the idea of using the same antennas for simultaneous transmission and reception so I did a bit of research and found this: https://www.eetimes.com/document.asp?doc_id=1296042#
At only $2.29 in lots of 10K this comes across as something as close to magic as I can imagine.

 

[Steve Carr]

There are far more two antenna models out there I believe. The pic does demonstrate how easy it is to relocate that antenna.

 

[Phaedrus]

Okay, got that. I dug out an old drawing and added the notes in yellow. Does this look correct now?

View attachment 14537

Interestingly enough, some RC brands are starting to place the transmitter antenna inside the case. 2.4GHz has no trouble with plastic, so no reason not to do it. The only issue would be like the ST16 photo above where the second antenna can be more easily blanked by the electronics in the case. I suspect that's why they moved them both outside.

 

[Phaedrus]

Indeed. I didn't realize that was the location until I had to remove that board for a repair recently. I found the antenna under the wires for the Mic.
I'm not certain you would get a warning if only the ST16 has GPS loss.

View attachment 14542

Makes sense. GPS has a little easier time compared to 2.4 and 5.8 since it is down around 1.2 to 1.5 GHz.

 

[Steve Carr]

I suspect that's why they moved them both outside.

Possibly. Or perhaps, as I discovered, there were times when the telemetry dropped out but not the control signal. Maintaining telemetry is critical to determining warranty issues. It's also critical in locating a downed bird. If that signal is interrupted the file stops recording.

 

[RPR]

Hello Steve, sorry to bump this post. I stumbled on this thread via search.. Thanks for posting the photo, just wondering did you happen to take a photo or noted the markings on the antenna? I've used zigbee antennas in the past, and I believe they have replaced those version with paddle antennas. I am attempting to upgrade all of my internal antennas to new versions.

 

[Steve Carr]

did you happen to take a photo or noted the markings on the antenna?

The little internal dipole or the stick antenna? As long as they are 2.4 GHz antennas, I don't think it matters. Also, there is not point in replacing the internal wifi antenna because it's only used for connecting to your home wifi for updates.

 

[RPR]

The little internal dipole or the stick antenna? As long as they are 2.4 GHz antennas, I don't think it matters. Also, there is not point in replacing the internal wifi antenna because it's only used for connecting to your home wifi for updates.

I’m looking at the dipole whip antenna than runs from the RC board. The bottom antenna (thanks for documenting that as well) is not needed.

Thanks a bunch Steve.