Keith Dysart wrote:
On Dec 14, 11:17 am, Cecil Moore wrote:
Cecil Moore wrote:
Stubs like this one are easily modeled with EZNEC.
In fact, here it is:

http://www.w5dxp.com/stub_dip.EZ

So how much energy is stored in the stub?

Compared to the 100 J dissipated each second?

You are still comparing apples and oranges.

Why not compare it to the 6000 joules dissipated
each minute? Or the 360,000 joules dissipated each
hour? Or the 8+ megajoules dissipated each day?

The length of time that we need to use for a fair
comparison is the length of time it takes the forward
energy to propagate from one end of the stub to the
other. That time is about 62.63 ns for a 4 MHz 1/4WL
stub, or 6.263E-8 seconds.

100 joules/sec times 6.263E-8 seconds is
6.263E-6 joules or 6.263 microjoules lost to
radiation. That's 6.263 microjoules per 62.63 ns
so the power remains the same.

The forward power is about 31 microjoules per
62.63 ns. The reflected power is about 25
microjoules per 62.63 ns.

The forward energy is about five time the radiated
energy. The reflected energy is about four times
the radiated energy. That's why the standing-wave
current completely swamps the traveling-wave current
such that it is extremely difficult to use that
current for phase measurements.

Make the lossless stub one second long plus 1/4WL
and then recalculate the energy stored in the stub.
--
73, Cecil http://www.w5dxp.com