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Jim Kelley wrote:
Cecil Moore wrote: The other 10% is the traveling wave that gets radiated of course (neglecting losses). Absurd. Current does not "get radiated". It's *energy* in the traveling wave that gets radiated. Less energy indeed lowers the current amplitude. The Method Of Moments used by NEC assumes the radiated fields originate from the current in each segment of the antenna. Current is certainly attenuated by radiation as it is by dissipation in lossy transmission lines. In fact, the same attenuation factor is applied to the current equation as is applied to the voltage equation. The difference in the forward current vs the reflected current on the standing-wave antenna at the antenna feedpoint is due to energy lost to radiation. Radiation from an antenna indeed does lower the current on the antenna. The conservation of energy principle strikes again. You can prove it for yourself by modeling a terminated rhombic using EZNEC. The current amplitude in the traveling wave antenna slowly falls as the energy is radiated. Or put in one amp of 70cm current at one end of 200 feet of RG-58 and see how much current you get out at the other end. You don't really think that lumped circuit model assumptions apply to distributed networks, do you? You claim that W7EL measured the phase shift of standing wave current. He of course made no such claim. So yes, I need you to explain how it is possible for someone do measure a "current" that does not flow. This should be good. My point exactly. w7el "measured" the phase shift in current that doesn't flow. That was his entire problem. One cannot measure phase shift in current that doesn't flow, yet that's exactly what w7el and w8ji reported doing. -- 73, Cecil, IEEE, OOTC, http://www.w5dxp.com |
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