Directional RF Chamber for 5.8Ghz receivers

[zwirek2201]

Hi guys!

After watching LTT's RF chamber video I had an idea for a project. 

I'm one of the organizers and race directors in the Polish FPV micro drone racing league and I've been struggling with our lap timer solution for quite some time.

To quickly describe our setup:

Our laptimer (the device that measures our lap times) is based on multiple RX5808 5.8Ghz receivers. Each receiver is set up to a specific channel and when multiple drones are racing, it gets the RSSI data from all of them and looks for signal peaks. Laptimer is set up next to our start gate and when a drone flies through the gate, laptimer catches that. 

The problem with the system is that often (especially on smaller tracks) drones will fly behind the laptimer or even above the laptimer and will get picked up. We managed to limit the issue by putting the lap timer inside of a metal ammo box and directing the open side of the box towards the start gate. It works much better, but it's still not great. When a drone files behind the ammo box, the signal peaks. The peak is lower than when the drone is in front of the box, but it's still high enough that it makes marshalling races very fiddly. 

I'm determined to make a better solution, but I'm not sure what the best way would be. I know from our community that some people made enclosures using copper mesh and even with grounding the mesh, the situation is still not great. 

I've seen in the LTT video how fiddly the process of eliminating RF is and I'm pretty sure we're making some dumb mistakes in our enclosures

Any help will be greatly appreciated!

[TylerD321]

Would putting aluminum foil around the box and/or on the inside of the box except for the opening help?

[zwirek2201]

1 hour ago, TylerD321 said:

Would putting aluminum foil around the box and/or on the inside of the box except for the opening help?

I assume that copper mesh works better than aluminum since copper is much more conductive so it would probably make a small difference, but not enough to actually fix the issue.

[samygiy]

Are you using a directional antenna /  What kind of antenna are you using?

[Heats with Nvidia]

That actually sounds like a job for a directional antenna like a horn antenna. I have, for example some microwave experimentation sets for schools that work at a little over 4GHz and those have horn antennas, so they should also work at a little higher frequencies. Really funny is, that these sets were actually made in Poland...