Pros and Cons of the Dual Band Inverted L Antenna
A dual band/single antenna approach introduces complexity by adding a
trap. In fact, some have warned against attempting the antenna due to the
trap alone. Having a single wire to cover the lowbands is tempting,
but may not be worth the increase in complexity and probability of failure.
Evolution of the dual band 160/80 meter inverted L using MMANA
The popular inverted L
be a good choice for ease of installation, low cost, and design
Having driven my ham radio budget into the red
with the tower project, I have resorted to using a freeware antenna
The modeling package is based on MININEC which has a number of limitations.
I started with a simple base fed, quarter wave,
inverted L for 160 meters. Wanting to make this a dual band antenna, I
decided to put a trap at the top of the vertical section. Given the lack of
tall supports for the horizontal wire, I am forced to have a sloped L.
The resulting design is a vertical wire parallel to my tower (hopefully
about 3 ft away), 18.5m up to the trap and 19m sloping down.
The feedpoint is a 300 pF series cap an UNUN to
match the low impedance. The trap in the LC is at 2.9 MHz and
consists of a 25.1 ÁH inductor and 120 pF cap.
Modeled Performance and SWR Plots: 80 meters
Modeled Performance and SWR Plots: 160 meters
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