Jim Kelley wrote:
Gene Fuller wrote:

Antenna books point out that the current in a short antenna decreases
in a straight line, not a sine curve, from the feed point to the tip.
(E.g. Kraus, 2nd Ed. page 216)


Isn't that simply because the slope of a sine wave near the zero
crossing closely approximates that of a straight line?

73, Jim AC6XG


Actually, no one really knows whether it's really a sine curve
or not because no one has ever been able to solve the integral
equation that would give an exact answer. The sine approximation
works o.k. because the far field is relatively insensitive to
changes in the shape of the current curve back at the antenna.
The best thing to do is to approximate the curve with a
moment method program on a computer. That's what the moment
method does best.
73,
Tom Donaly, KA6RUH