I call this antenna the MRA (Minimal Reactance
Antenna). It works on 160 through 10 Meters. It is a top-loaded
monopole. I don't think there has EVER been a top-loaded monopole
as loaded as this MRA. The mast is a 6-inch cylinder, 6-feet long,
that is surrounded by a 6-foot diameter octagonal group of panels
of aluminum sheet. The metal conductivity is optimum, and every
scrap of efficiency is gotten from how it is put together.
be with a remote-tuned LC network (on order from Bliss in Colorado). At the present, I match it with
a standard MJF pi-network tuner in the shack. Yes, a high vswr
exists, because the structure behaves like a 7-foot length of
180-ohm air dielectric coax cable (the 6-inch conductor in the
6-foot cylinder). The "trampoline" base is 18 feet in
diameter (essentially a 12-foot radial torus, which is connected
to the shield side of the feedline). Longer radials are not required.
When you look
at the network analyzer plot of the antenna from 1.6 - 30 MHz,
you see an absolutely
plot, with self-resonance at 6.89 MHz, 5 ohms real, and no
75 feet of coax
goes from the antenna to the shack. The coax is laying
on the ground. Moving the coax around does not affect the impedance
plot on the network analyzer, nor does connecting wires to the
antenna tuner ground.
the antenna is not being tuned by nearby conductive objects.
you would like a sked to hear the antenna, contact me at wb4ene
@ bellsouth net (delete spaces, add .)
- Ken WB4ENE –