Radio Frequency (RF) & Wireless Design

This article describes the intricacies of the dilemma with 5G being to close to the Airplane Ground Altimeter frequency band :

https://www.brookings.edu/blog/techtank/2022/01/21/did-the-faa-cry-wolf-on-5g/

The stop bands or guard bands should be or have been in place to help block interference, but that alone is not enough of a solution since the specification on the Airplane Ground Altimeters did not take into account the proximity of the RF traffic when it was drafted and released.

Now that this situation has arisen all aspects of RF traffic must be reexamined carefully to understand the situations where RF interference is possible. This is not simply local to just landing, but is also an issue wherein the 5G RF traffic inside the passenger compartment can actually be stronger, especially when mixing with other 5G frequencies creating 'images' that are inside the Ground Altimeter frequency band.

This video gives a detailed explanation of how this can happen :

https://www.youtube.com/watch?v=_ya7Z6yWbJY