F35 could have an ADSB radar transponder (digital, returns a packet of digital data when receiving a radar ping). In fact I'm sure it's required by latest aviation regs. But they are military, they can turn it off or on anytime as dictated by mission profile.
My opinion.
Method of propagation unknown.
If "free space" EM wave then speed of light, which I used in the calc. If propagation through earth's mass, propagation speed unknown.
Personally I believe it might have been an longitudinal wave rather than a conventional transverse one; therefore wavelength calc does not apply or should be done in a different manner.
Just provided wavelength calc to refute the silliness that said it was VHF.
According to Q's crumb on it, it was some kind of NEW technology turned on, to replace the demolition/decomissioning of certain satellite tech. That's how I interpreted it. I won't speculate further without more data.
I perceive it too – continually. However you and I don't know the source or purpose. Your statement implies knowledge of the source. Examine your assumptions & reconcile.
I don't think the new signal is "imaging" purpose. It may be comms, it may be weaponish, in purpose.
Reason I can't speculate is because distracted, need to watch Barr hearing right now.
I do not accept the conventional interpretation that the signal originated at Mayotte. Maybe it did, or maybe as you say, "entry point" where the signal was focused or picked up. We do not have enough info. Longitudinal waves also have to be considered before eliminating that as a possibility.