WM0041801 TELLO Test Report Shenzhen RYZE Tech.
TELLO Test Report details for FCC ID 2AOOE-WM0041801 made by Shenzhen RYZE Tech Co.,Ltd.. Document Includes Test Report Test Report
Tello PCB and antenna reference, to help fellow crazy modders ;)
- Thread starter ph2t
- Start date
zaldy
Member
I've been working on a few mods that have required me to gut my poor tello several times over. I have put together a couple of pictures that have helped me with my modding. Motor and antenna pinouts, etc.
I'm doing some more research into the tello antenna configuration and will post on that here as well. Write-ups take time, especially when you want to lay a lot of information out in a way that helps others. Please be patient with me as I add my thoughts and results to this thread.
Tello printed circuit board (PCB) layout - viewed from the underside.
View attachment 2605
Notes on the above picture:
- The antenna is approx. 10mm in length, at 2.4GHz this puts it at less 1/10th of the wavelength of the Wi-Fi signal. An antennas length is guided by wavelength of the signal it is carrying. Wavelength is to do with frequency. I won't go into it here, google "wavelength and antennas" to get the gist. The diagram above quotes 1/4 wavelength, this is incorrect.
Tello antenna PCB - located in the two rear motor mounts.
View attachment 2606
Notes on the above picture:
- The tello has two independent antennas that are not directly connected
- According to other forum posts here it is a smart antenna array (two antennas located in each rear motor mount) that dynamically changes between each antenna depending on which one has the better signal connection to the smartphone controlling it.
- The antennas are patch antennas, a flat antenna that is etched onto a PCB. Usually the ground plane is located on the other side of the PCB - in case of the tello the circular coil located above the antenna is the ground plane.
- The antenna is approx. 10mm in length, at 2.4GHz this puts it at less 1/10th of the wavelength of the Wi-Fi signal. An antennas length is guided by wavelength of the signal it is carrying. Wavelength is to do with frequency. I won't go into it here, google "wavelength and antennas" to get the gist.
- Antennas under a 1/2 wavelength generally perform better when provided with a ground plane (old engineering degree notes here, I might be wrong). The coil shaped wire in the above picture is providing the ground plane for the small antenna that is on the PCB.
- All the transmitting and receiving for the tello is done through its two rear feet, not the arms nor the chassis.
More to come... Just getting this up for the moment and I'll edit/contribute more as a test and confirm my theories.
cheers,
ph2t.
So, i just read this.. interesting..
Quick Google on "wavelength and antennas" reveal that ideal antenna length for Wifi frequency (2,4 Ghz) is around 30 mm (3cm) - About quarterlength of Wifi frequency itself..
(The Fundamentals of Wi-Fi Antennas - Technical Articles)
Based on your photos, Tello PCB antenna is 10mm,, well below ideal length (maybe?) also, Tello antenna could be Monopole Antenna (which explain why there is Groundplane above PC antenna itself) (
Why Antennas Need a Ground Plane
In this post we discuss what the purpose of a ground plane is, how it works with an antenna, and why some antennas require a ground plane while others do not.
arsiconsultants.com
maybe there is way to mod the antenna to 30mm length? i dont know.. or create a Dipole antenna on top Tello? maybe?
Disclaimer: i'm not antenna or radio expert.. just some IT guy, but this post really triggers my curiosity about antenna lenght, radio wavelength, and related stuff.. so, thank you for made my brain itch for some reading and information.. nice
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