Below is a graphic using NEC4.2 to show the effect of adding a vertical "ground wire" of varying lengths to the MW transmit system described there. The 90 mW of power shown in the graphic includes the power lost as heat in the r-f resistances of the loading coil, and the buried ground rod. Increasing the length of that ground wire increases both the radiation resistance of the antenna system, and the field intensity it produces at a given distance (other things equal). Clearly, that ground wire is not a low-impedance path between the transmitter chassis/r-f ground terminal, and where it attaches to the top of the buried ground rod. Instead, it is one of the radiating conductors of that antenna system.