On Wed, 8 Jan 1997, MARK TOUSSAINT wrote:
>
> Remember that adding length to the inverted L will help, but most
> important is that the vertical portion be as long as possible. All you'll be
> doing by adding length to the horizontal portion is making a bigger cap.
> hat. Good luck, Mark AJ1X
>
Not completely true - by adding horizontal length *beyond a quarter-wave*,
the current maximum is moved "up" the vertical section. If the wire was
one-half wavelength long, for example, the current maximum would be at the
wire's midpoint. If the L is exactly one-quarter wavelength long, the
current point is at ground level. Raising the current maximum away from
the ground should reduce ground losses and improve low-angle radiation.
How far the current maximum should be raised depends on how long the
vertical section is. I would model the L with different horizontal
lengths and see how the pattern changes - expecting that adding length
would first improve low-angle radiation and then start to fill in the
high-angle pattern as more current begins to flow in the horizontal
section. I would also expect that there would be a fairly large range of
vertical/horizontal ratios for which the
pattern changes very little.
73, Ward N0AX
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