WLAN-Antenna-Obscurities 7590 AX

It is a 15mm wire monopole which is a quarter wave 5GHz antenna
It is connected to the 2.4GHz (!?!) WLAN SoC, so it may also be a 15.5mm 1/8 wave 2.4GHz antenna
So far AVM never used 1/8 wave antennas, they would use a L-form folded quarter wave if space is an issue
It is NOT driven by a WLAN frontend like all other antennas, so the transmit power is likely low
In the FRITZ!Box 7590 AX v2 it is connected through a Murata test socket
Murata sockets are used for in-factory calibration of transmit power

Guesses[edit]

My first guess was it could be a sensor antenna for 5GHz Radar-Scan without disconnecting clients, but then the Murata socket would not be required, which only makes sense to calibrate transmit power.

A second thought was it may be 5 RX and 4 TX streams in 5GHz band, but then it's connected to the wrong SoC and MIMO usually can not work across multiple SoCs.

Maybe it is connected to the 5GHz SoC in an inner PCB layer, unlikely, since this would be unusual for AVM. They would typically use an IPEX-Cable to pass RF on a PCB across longer distances.

Another guess was it may be for short distance IoT usage, but there is no point in limiting the distance by not using a WLAN frontend and there's no 5GHz Smarthome stuff.

And finally - maybe the most propable guess - it may be a security check - a way to establish or detect a short distance WLAN connection for Mesh-registration and 2FA,

If you have further ideas please get in touch!

Gallery[edit]

Sample images of the 5th WLAN antenna:
If you want to extend the gallery with own work then please get in touch. See also the Photography-Inspiration article.