[Antennas] How To Build Multiband Dipole Like the Alpha Delta DX-EE?

Thu, 8 May 2003 08:24:00 -0500

 I'd like to build a multiband dipole just like the Alpha Delta DX-EE to
replace the homebrew coaxial trap dipole I currently have in my attic. Since
the antenna will be in the attic, it doesn't need to be nearly as tough as a
commercial antenna (I should be able to do it for a lot less than Alpha
Delta's 100ドル). Plus, I'd like to use my current antenna's balun on the new
antenna and Alpha Delta doesn't offer theirs with a balun.
 Based on Alpha Delta's Web site, the antenna is about 40ft long and covers
10/15/20/40m. The antenna is comprised of three parallel dipoles. 10m is
covered on one dipole, 15m on another, and 20/40m on the third.
 The third dipole appears to provide support for both 20m and 40m by
placing an inductor (not a trap, according to Alpha Delta, because their is
no capacitor) at the point which marks the end of the 20m section.
Supposedly, this inductor acts as a choke at 20m effectively terminating the
20m section and acts as an inductive load on 40m effectively decreasing the
length of the 40m section.
 Does anyone have plans for the design of such an antenna? I'm primarily
looking for information on the inductor in the 20/40m combination dipole;
what should the inductance be and how should I approach building such an
inductor using common (hardware store) components?
 Thanks, Michael N9BDF
PS The "Amateur Radio Emergency Communications Consistency Act" (HR 1417)
and the "Amateur Radio Spectrum Protection Act" (HR 713 & S. 537) have been
reintroduced in Congress. Please contact your Congressmen to ask for their
support of these bills! See the following ARRL link for details:
http://www.arrl.org/govrelations/