On Thu, 09 Mar 2006 08:32:44 -0500, David Shrader
wrote:

wrote:

SNIPPED



If I have a 10 degree tall base loaded antenna it is a ten degree tall
antenna. It is NOT 90 degree resonant antenna with "80 degrees of
missing length" in the inductor, nor with that 80 degree long inductor
behave like 80 degrees of antenna length would.


I beg to differ.

If I have a 15 degree long physical antenna, center loaded at 10
degrees, with 5 degrees above the coil I do have a 15 degree physical
antenna. That does not mean the antenna is NOT 90 degrees elctrically
long! Resonance requires that the reactive components cancel both in
amplitude and phase! Each reactive component introduces phase shift into
the system. The antenna, without a loading coil, is composed of three
terms: resistance [radiation and loss], self capacitance, and self
inductance. In a shortened antenna the self capacitance dominates and
the resultant phase shift is NOT zero. It is required to add inductance
to achieve resonance [phase shift = 0]. If an antenna is electrically 15
degrees long and the self inducance does not reduce the reactive phase
shift to zero PHASE SHIFT MUST BE ADDED TO THE ANTENNA for resonance.
This phase shift is accomplished by the loading coil.

Now, when that antenna is fed with 1 ampere [Imax] at the base of the
antenna and the feed current follows a cosine distribution to the base
of the coil [I = Imax*cos(theta)][theta=10], you claim that the current
exiting the coil is also Imax*cos(theta), or 98.5% of max value.

Tom has quite adequately addressed this, however, if you go he

http://www.k6mhe.com/n7ws

and look at either Note 1 or 2 and then look at figures 1 and 2 this
might change your mind about the current distribution.

[snip]