To answer the question, I don't. Look at it this way. The AC supply to your house, for example, is a low impedance; it can supply hundreds of amps (the transmitter). The 100 watt lamp (antenna/load) in your house is a relatively high impedance compared to the supply. There is no impedance match between supply and load, not even close. SWR is very high. Do we care? No, we're not trying to transfer the maximum amount of power here as we do in an antenna system, only the amount of power required by the lamp.
Hope that helps. Laryn K8TVZ