Al,
The DB-36 uses a wire parallel to and slightly above the boom. At each end,
the wire is connected to the center of one of the adjustable elements -
director 2 at one end and the reflector at the other end. These two
elements act as top hat capacitive loading to the 36' long dipole, and can
be adjusted based on frequency. This allows a good SWR match over the
entire 80M band. There is also a very small amount of inductance added on
either side of the feedpoint (it's on the order of 2.5 uH, but I don't
recall the exact amount) and the antenna is feed with a 4:1 balun (50:12.5
ohms). The pattern is broadside to the boom which is at right angles to the
pattern on 40M & up. The gain on 80M according to the NEC2 model is 1.44
dBi, which is about 0.7 dB less than a full sized dipole. The front-side
pattern will vary with height above ground and the angle of the incoming
signal, but will vary from about 6-10 dB.
73,
Clay W7CE
----- Original Message -----
From: "Al Williams" <alwilliams@olywa.net>
To: <towertalk@contesting.com>
Sent: Saturday, April 18, 2009 9:10 AM
Subject: [TowerTalk] db36 89m option
> Is there a diagram or explanation of the wire for the 80m antenna option
> on the db36? I wonder if it can be put on a crankup tower and also what
> the radiation pattern is like?
>
> k7puc
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