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gareth wrote:
Ignoring, for the moment, travelling wave antenna, and restricting discussion to standing wave antennae ... An antenna is an antenna. A wave is launched, and radiates SOME of the power, and suffers both I2R losses and dielectric and permeability losses associated with creating and collapsing the near field. Nope, voltage is applied to an antenna causing currents to be created which in turn cause an electromagnetic field to be created. As antennas are made of real materials they have a resistance and the current through that resistance leads to losses. However, in the real world most antennas have an impedance in the tens of Ohms while the resistance is in milliohms, so normally the losses are trivial compared to the radiation. At first, there is no standing wave, until the wave reaches the point of reflection in the antenna and heads back the way it has come (because not all has been radiated*****) On the way back, it againn suffers the losses described above, as well as radiating a bit more. Pure nonsense. It then reaches the other end and suffers further reflections ad infinitum. Pure nonsense. An interesting conclusion is, therefore, that the I2R losses are repeated, each tiome with a smaller loss, as the wave decrements. A nonsense conclusion based on a nonsense assumption. ***** Without the remnants of non-radiated power, there could NOT be a standing wave! Sigh. -- Jim Pennino |
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