I've had a number of inquiries about the N4XX coaxial inverted "L"
antenna. For those of you who haven't seen the article, the antenna is
basically half of a double bazooka antenna. It is roughly 1/4 wave long
(allowing for the velocity factor of the foam RG-8X mini cable). It is
made up of (according to the article) 124 feet of coaxial cable shorted
at the 104 foot point. This means that the inner conductor and shield
of the cable are soldered together. From that point, add another twenty
feet of cable (according to the article) shorted at BOTH ends. The
bottom of the 104 foot portion is fed. The center conductor of the
feedline goes to the shield of the 104 foot portion and the shield of
the feedline goes to the center conductor of the 104 foot piece of
cable.
I found it necessary to make the tip portion of cable 23 1/2 feet long
rather than 20 feet to achieve resonance at 1.850 KHz. Add all the
radials which can fit on your property and have at it.
In an effort to have as little wear on the coaxial cable at the 90
degree bend, I ran mine through a solid-brass pulley attached to a large
insulator with a short piece of nylon rope. This allows the antenna to
ride the wind more easily and eliminates a sharp bend and chafing of the
coaxial cable.
No matching network is needed so there is nothing which can arc or
corrode. The antenna takes the full U.S. limit with ease. I don't know
what will happen when I add additional radials but with ten radials, I
can cover almost the entire 200 KHz of the band.
Dave Heil K8MN
Cameron, WV
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