Ian White, G3SEK wrote:
I want you to stop and think a moment, about how an IDEAL INDUCTANCE
behaves in an antenna. (Sorry to shout, but every time I type "ideal
inductance" quietly, you seem to read something else :-)

Ian, please take your own advice. It's pretty obvious that you are
thinking about an IDEAL INDUCTANCE in terms of a lumped circuit analysis
which is invalid when analyzing a STANDING-WAVE ANTENNA. The equations
governing the behavior of a standing-wave antenna are similar to the
equations governing the behavior of a lossy transmission line with
reflections. In fact, just by looking at the equations, you cannot tell
whether they apply to a transmission line with reflections or to a
standing-wave antenna.

Hint1: Write the equation for the total current on a standing-wave
antenna that includes forward and reflected currents and "loss" due
to radiation.

Hint2: A real-world mobile loading coil acts like a section of transmission
line where Z0=SQRT(L*C). It does NOT act like a lumped circuit inductance.

Hint3: An IDEAL INDUCTANCE doesn't exist in reality. Lumped circuit
inductances are a shortcut that doesn't exist in reality and surely
does NOT apply to distributed networks like a standing-wave antenna.

Hopefully you will agree that an IDEAL INDUCTANCE does not ever have
different currents at its two terminals, and does not radiate either.

Can't agree to that at all. In fact, here's a repeat from another
posting that proves that the superposed forward and reflected
currents at each end of a lossless inductance *cannot* be equal.
Please don't use the copout excuse that an ideal lumped inductance
doesn't have any phase shift through it. *ALL* real-world loading
coils have a phase shift that can easily be measured. If it has
any phase shift at all, the current magnitudes at each end of the
coil *cannot* be equal unless a current min/max occurs in the middle
of the coil which doesn't happen in a typical mobile antenna.

P.S. How about discussing the technical issues instead of the
personalities involved?

There doesn't need to be a current drop through a coil for the
total current to be different at each end. Assume a base-loaded
mobile system. Assume the forward current through the coil is
constant at 1.1 amp. Assume the reflected current through the coil
is constant at 1.0 amp. Assume the phase shift through the coil is
45 degrees.

If the forward current and reflected current are in phase at the
base of the coil (feedpoint) the total current will be

1.1+1.0 = 2.1 amps of total current at the base of the coil.

The total current at the top of the coil will be

1.1 amps at -45 degrees superposed with 1.0 amps at +45 degrees.

1.1*cos(-45) + 1.0*cos(45) = 1.48 amps.

The coil is lossless and the component currents are absolutely
constant through the coil yet the superposed total current at
the top of the coil is only about 71% of the superposed total
current at the bottom of the coil. No "technical jargon" involved.

Using circuit analysis on a distributed network problem simply
demonstrates ignorance of the problem. It's an easy mistake to
make and a hard mistake to admit (especially for gurus :-).
--
73, Cecil http://www.qsl.net/w5dxp


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---