Re: Dish reflector

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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