Kevin Muenzler wrote:
>
> Gang,
> I've seen the inverted-L described a couple of times but haven't
> paid much attention. (sorry) Would someone please
> describe to me the inverted-L antenna.
Kevin
Simply put an inverted L is a vertical antenna in which some portion of
the upper end of the vertical is bent over 90 degreees parrallel with
the ground. They are most ofetn seen on 160 meters where the mechanical
challenges of putting up a free standing 130' structure are either
mechanically challenging or prohibitive expensive for most people's
budgets.
For exaample an inveretd L for 160 meters which is 50' high but 85'long
on the vertical leg will work within a db or so of full sized vertical.
Another trick with inverted L's is to make there total length about 3/8
of a wavelength, then tune out the inductive reactance with a simple
series capacitor. At this length the Inverted L the "real" portion of
the feed point impeadance is very close to 50 ohms. The radition pattern
is pretty much vertically polarized and omni-directional at low take-off
angles, At higher angles(above 30 degrees) there is a slight pattern skew
in favor of the direction of the end of the horizontal wire (not broadside!).
I have used this antenna on 160 meters for over 10 years (175 countries worked
so far), In fact in recent years I have used two of them in phase. One final
note
to be really effective as with any vertical antenna you need a really good
ground
system made up of tens of radials.
Dave
soon to be the ham "formerly known as N0DH"
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