Depending on how your Bond-villain vacuum tunnels and repeaters are set up, it's possible, i surmise, to create a tunnel way that can repeat without adding an interminable delay node or nodes. Imagine the One Way Valve Nikola Tesla patented, except with microwave repeaters shelled and pocketed into the sides of the tunnel passage instead of water-holding empty pockets.

Although I think that this is very nice, I always like to go to the "ultimate level" and consider what we would do if there was a way to send informative electrical signals using the earth as a resonator, and that idea chiefly brings me back to Wardenclyffe.

Did you know that the magnetic field of mars is weirdly shaped? It is only magnetic on the "Southern Half" of the ball that is Mars and has a slight gradient. So, assuming we can create some sort of information share that could function on the dynamic magnetic shielding of the earth, we'd have to rethink it for Mars, and any planet with a non uniform magnetic field from pole to pole.

Thanks a lot for your creativity. Keep writing, together we got this!