The infamous TMCC "Force Field" video surfaces again. Mike's description of TMCC track signal and interference is very wrong. Lionel's original TMCC patent illustrations showed the TMCC signal "halo" broadcasted from the outside rails to the engine antenna, thus creating a myth of how the track signal RF works that still persists. Dale Manquen, an Electrical Engineer with extensive HAM radio experience, published (Trainfacts.com, August 2011) his "TMCC Signal Basics" article that describes how the TMCC track signal really works. Dale's description in short:
The ouside rails carry half of the RF signal component via the engine's wheels and chassis to the receiver.
The engine's antenna(s) carry the other half of the RF signal to the receiver. The voltage difference between the two sources is the received track signal.
The Command base transmits a track signal component out the common wire post to the outside rails.
The Command base transmits the other half of the signal, via the power supply's ground pin, to the electrical ground wires of the house/building's 120V wiring. The track signal radiates from the house wiring and is picked up by the engine's antenna.
Mike's description of where to add a ground plane wire is OK even though he confuses the issue with force fields and the like. Dale's article sent me in the right direction; I approach weak TMCC track signal problems by asking "what is keeping the house wiring's signal from reaching the engine's antenna?" Typical culprits are overhead or adjacent tracks that overwhelm the house signal (this is an unwanted "halo" broadcast from the outside rails), metal bridges that block the signal, and metal accessories that are connected to the common rails. Adding a ground plane wire resolves the problem.
I have never needed to add capacitors to improve the track signal.