Block LD2410B radar by direction

So I created my own sensor using this guide and it works well, but I realized the sensor go crazy after my ceiling fan is on. My objective is to turn the ceiling fan on/off depending if my kids are in the room or not.

I saw this post and understand how the gates works, but in my case the distance of the ceiling fan is the same as the beds.

Top view of the room, where the cross is the ceiling fan. Red box is where I place my DIY sensor.

I am hoping to “block” the radar horizontally anything above the sensor. Tried using aluminium foil and other objects but it doesn’t seem to work.

To illustrate, this is the side view mock up of the same room. Idea is to block any movement above the red dotted line.

Does anyone have this problem and managed to find a solution? Thanks.

Note: Cross post on reddit