Before Dale Manquen analyzed how the TMCC signal propagates and is received by the locomotives, Lionel's patent (5,441,223 dated 15 Aug 1994) was the go-to reference for TMCC. The patent's diagrams show two RF signals - the CAB1<->Base1 communication, and a signal radiating from the track. The "Earth ground" signal component from the house wiring is not illustrated in patent diagrams. The patent states:
The controller transmits control signals between a rail of the track and earth ground, generating an electromagnetic field which extends for several inches around the track. A receiver in the locomotive can then pick up signals from this electromagnetic field.
Myth Number 1 on how the locomotive receives the TMCC signal.
The patent statement, along with the patent's diagrams illustrating the field radiating from the track, led me to believe the locomotive's antennas were picking up the radiated track signal. Additional explanations from Lionel techs did not correct my misunderstanding. Myth Number 1 was firmly in my mind.
I was challenged to solve TMCC signal issues on a multi-level layout and Lionel's videos on TMCC at the time - especially the one describing a TMCC Force Field - were not helpful. This thread questions Lionel's explanation of the TMCC signal. (Thankfully, the link to the referenced TMCC Force Field video now returns "It looks like you are heading the wrong way.")
Dale's explanation on TMCC signal propagation produced an AHA! moment that guided me to a solution that used strategically placed Earth ground wires. The signal field radiated by the house Earth ground wiring is critical for TMCC reception in the locomotives. The signal portion received from the track common via the wheels and frame of the loco can be assumed to be strong. But the signal portion received from the house wiring is much weaker and depends on the proximity of house ground wires. Obstructions and metal objects on the layout connected to track common will weaken the ground signal. Strengthening the house ground signal on the layout has solved all of my TMCC signal challenges. The forum has numerous threads (search TMCC ground plane) on how to accomplish this.
So if you are having TMCC signal issues after doing basic troubleshooting (i.e. the third pin of the power brick is connected to the DC barrel plug and the outlet itself is grounded), a review of Dale's TMCC Signal Basics is recommended. Imagine how the house ground signal is propagating to the locomotive trouble spots on the layout and find a way to provide the TMCC ground plane to that area.