ARRL

Forum Home - Rules - Help - Login - Forgot Password
Members can access, post and reply to the forums below. Before you do, please first read the RULES.

large Conductors for Dipole

Jul 15th 2013, 22:45

WB5EMX

Joined: Mar 15th 2013, 21:23
Total Topics: 0
Total Posts: 0
I am wondering if a dipole made from very wide (i.e. 1") aluminum straps would give a significant advantage over wires. Is there a better application for these materials than that in the amateur radio hobby? I believe they are 0.04" thick.
Thanks,
Bob WB5EMX
Jul 16th 2013, 01:22

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
That aluminum might have interesting applications at microwave frequencies--but nearly all of my microwave work has been with relatively narrow band antennas--a DC to daylight antenna is nearly useless on a mountaintop with over 150 transmitters (including an FM broadcast station).

At HF, the most popular technique seems to be the cage dipole, in which spreaders hold parallel wires apart. Hams are always interested in significantly cheaper alternatives that work well.

Zack Lau W1VT
ARRL Senior Lab Engineer
Jul 16th 2013, 04:10

WB5EMX

Joined: Mar 15th 2013, 21:23
Total Topics: 0
Total Posts: 0
Interesting comment, Zack. I'm wondering if this will buy me anything on, 17 meters. I guess I will build it and try it. From what I can reason, it will have lower resistance because there is so much more conductive surface than on a piece of 12 or 10 AWG wire. I do not know if there are other advantages or not.
Jul 16th 2013, 11:02

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Folks have used wide aluminum in building small transmitting loops--where the lower resistance is useful in reducing losses. But, many prefer copper, which can be easily soldered. Welding aluminum isn't one of my skills, though maybe I ought to do something about that?

The strap may be useful in building VHF folded dipoles.

Zack Lau W1VT
ARRL Senior Lab Engineer
Jul 17th 2013, 00:36

AA6E

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
If I understand the question, I don't think you'll see any significant advantage of large conductors in a 17M dipole. (There could even be a problem with overly fat conductors: wind cross-section. You don't want it to blow away!)

The main reason to use large conductors (or cages of conductors) is to get a broader resonance. It doesn't have anything (directly) to do with resistance. Note that the 17 M band is only .06% wide -- any kind of normal weight dipole would work fine. It only needs to be strong enough to support itself, and to carry the current without heating very much. (The heating tells you how inefficient the antenna is.) A broadband dipole is needed on the bands that are bigger in percentage terms. The worst HF band is 80M, which is about 13% wide and very hard to cover at low SWR with any single antenna (even a cage).

Wideband VHF/UHF dipole-style antennas benefit from fat conductors - like the bow-tie UHF TV antennas we used to see, or the discone.

73 Martin AA6E
Jul 17th 2013, 04:44

WB5EMX

Joined: Mar 15th 2013, 21:23
Total Topics: 0
Total Posts: 0
Martin: I suspect you are right.
Jul 17th 2013, 13:44

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0

An advantage of a folded dipole or loop driven element is the possibility of DC grounding the element opposite the feedpoint--allowing lightning to have a direct path to ground.

Zack Lau W1VT

Back to Top