Topband: Inverted L

K9AY k9ay at k9ay.com
Wed Feb 6 09:49:06 EST 2008


from Ron, 4S7RO:

> Any recommendations re adding 80m to an existing 160m inverted L? Would it 
> be better to:
>
>  1)  insert a coax trap
>  2)  Tue the antenna at the base (LC network)?

Ron,

It is possible to install a separate 80M 1/4-wave wire at the same feedpoint 
to make a "parallel" or "fan" vertical. To make it work properly, the two 
wires should be separated by at least 24 to 30 inches (60-75 cm). It also 
helps if both are configured as an inverted-L, with the 80M top wire pulled 
away in a different direction. With these construction techniques, coupling 
between the wires is reduced -- otherwise, you will likely have trouble with 
80M matching and bandwidth.

I've done this myself in the past, and for a couple DXpedition antennas. I 
think VK6VZ has a similar 2-band setup.

73, Gary
K9AY





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