[TowerTalk] B&W Broadband Folded Dipoles

[spelunk.sueno]

I've been using a full-wave 75 meter horizontal loop for about 6 years now.
It works well on all HF bands from 80 to 10; on 160 it's a little finicky
but I managed a cw contact or two.

It's strung through the trees around my 1/3 acre residential lot, about 25
feet above ground (the trees were too fragile for me to climb higher.)  I
feed it with about 33 feet of 250 ohm (?) twin lead through a current balun
to coax, then to a MFJ 969 tuner.  (I agree: a tuner's unavoidable with
these wire-type antennas.)

Barry, if you have enough room to put one up (270 feet circumference divided
by four sides = about 70 feet per side) it would be worth playing around
with it, especially for its low cost.


-Gene Smar  AD3F
-----Original Message-----
From: Lowell, Mark <mlowell@noclant.navy.mil>
To: towertalk@contesting.com <towertalk@contesting.com>
Date: Wednesday, September 30, 1998 9:46 AM
Subject: Re: [TowerTalk] B&W Broadband Folded Dipoles


>
>
>> >What would you suggest in it's place given:
>> >
>> >1. Less than 100 feet long.
>> >2. Covers 1.8 - 30 Mhz.
>> >3. No antenna tuner.
>> >4. Feed it with coax.
>> >5. Put it up in an afternoon with a couple of poles.
>> >6. $200 or less.
>> >
>> >Thanks,
>> >Barry
>>
>> I'd eliminate requirement #3. Then, I'd put up a 100' doublet, and feed
>> it with open wire or 450 ohm transmitting twin-lead. Run the open wire
>> right to the house, then use a balun before going inside. Use the
>> shortest possible run of solid dielectric RG-8 / RG-213 to get to the
>> tuner. Some transceiver auto-tuners can handle this antenna directly.
>>
>> 100 feet is a bit too short to cover 1.8 MHz. But, as long as it is high
>> enough, this antenna will do OK for the other bands.
>> Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@radio.org
>
>>   I like AA4LR's solution, though I'd try it without the balun at the
>>house first, and I'd droop and/or dogleg as much wire as possible off the
>>ends and give that tuner a fighting chance on 160m!
>>73, DavidC  AA1FA
>
>I can contribute a suggestion. Bill and Dave are right about a multiband
>doublet. They can and do work well.
>
>Make a doublet and feed it in the center with ladder line. Transition the
>ladder line to shielded-parallel lines where it enters the shack (2 pieces
>of rg-58 - connect per ARRL antenna book). Connect to an inexpensive tuner
>with internal balun similar to MFJ 949. Sorry, but you've got to have a
>tuner!
>
>Now, here's the neat part. No ground radials will be required. Also, you
>can greatly extend the doublet's low frequency resonance by capacitively
>end-loading it, the most efficient way of loading an antenna.
>
> Connect 25 foot or so 'tails' to each end of the doublet and let them hang
>down. Attach another cross piece, as long as you have room for, to the
>bottom of each tail, such that the composite, end-load attachment looks
>like an upside-down "Y". Attach and tie off tag lines to spread and secure
>the tails. This way, your tag lines extend and become part of the
>capacitive end-load. Terminate the copper and switch to rope at least 8
>feet above the ground for safety.
>
>You will be amazed at how much loading you can achieve.
>You will have many lobes of covereage with good gain on the higher bands,
>and even have some coverage off of the ends, thanks to the tails. On 160,
>it will be almost omnidirectional, and good for close-in contacts ('cloud
>warmer').
>
>An attempt at an ASCII art illustration follows:
>
>
>   **************||****************
>   *             ||               *
>   *             ||               *
>   *             ||               *
>  * *            ||              * *
> *   *           ||             *   *
>*     *                        *     *
>
>I have a friend, Mickey, KU4KW, who simply added coils, wound on PVC forms,
>to the very end of his short doublet, and can load it in many places on
>160M.
>
>Have fun!
>
>--...MARK_N1LO...--
>
>--
>FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
>Submissions:              towertalk@contesting.com
>Administrative requests:  towertalk-REQUEST@contesting.com
>Problems:                 owner-towertalk@contesting.com
>Search:                   http://www.contesting.com/km9p/search.htm
>


--
FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm