Re: [IRCA] Some help with "large" loops?

[Russ Edmunds <wb2bjh@xxxxxxxxx>]

For our DXpeditions at Long Beach Island NJ, we use a 16' x 36'
arrangement, using two collapsible fiberglass fishing poles from Cabela's
Outdoor Stores ( also available on line ). I forget what they cost but I
don't think it's that much. For 8' of height, you might do better at 18-20'
of length.

Height isn't critical, nor is sag. What seems to be most critical is the
ratio of height to length. The size we've used seems to be close to
optimal. Ours has the bottom wire on the ground. For using these types of
supports, you can use moderately lightweight wire - strong enough not to
break easily, but not enough to create wind resistance.

As we split the antenna amongst 6 to 10 DX'ers, we use 2 preamps, either
Wellbrook or another brand which is a bit less expensive although the brand
name escapes me right now. You might get by with only one.



On Tue, Nov 18, 2014 at 11:50 AM, Nick Hall-Patch <nhp@xxxxxxxx> wrote:

> Nobody's jumped in yet Brian, so some quick opinions.
>
> - How important is the shape and symmetry of the loop; e.g. wire sag,
> sloping ground, differing heights of the two vertical components?
>
> You can get away with some variation (I know I've discovered after the
> fact that one vertical leg wasn't as tall as I thought it was) and sag, but
> it doesn't hurt to aim for symmetry.
>
> - How important is the height above ground for the bottom wire?
>
> I have a Flag that is about 10 feet above the ground for the bottom wire,
> and found not a lot of difference from one that is a foot or so above the
> ground, at least so far as nulls are concerned.  The higher antenna may be
> a bit quieter when dealing with local noise.
>
> - Does the type of wire matter much (within reason)?
>
> not that I'm aware of
>
> - If I want something reasonably sturdy and with the possibility of going
> up to 20-25' height, am I looking at $100 or more for a suitable pair of
> telescopic fiberglass poles?  I don't plan on deploying this if it's windy.
>
> I wouldn't go for height to start with, so keep it simple.  A properly
> tensioned 1x2 x 10 or 12 feet can be sturdier than a telescoping pole.
> Poles are great for portability or instant antennas however.
>
>  An amplifier can help if you think it's a bit deaf.  I really like the
> Wellbrook FLG100, but it's pricey.
>
>
> It sounds like your antenna has to be close to the house by necessity, so
> you might be losing some of the characteristics (and getting additional
> noise).   If you think that might be an issue, you could look into Mark
> Connelly's Micro Super Loop:  http://www.qsl.net/wa1ion/
> loop/car_roof_loop.htm   I don't think it has to be attached to a car,
> hi.  (amplifier necessary)
>
> A remotely adjustable termination can help at least when you are getting a
> feel for the antenna.   Again, Mark Connelly has suggestions.  I still have
> mine remotely adjustable, as sometimes that extra couple of dB less on the
> splash can bring out the DX.
>
>
> best wishes,
>
> Nick
>
>
>
> At 07:25 18-11-14, you wrote:
>
>> I'm hoping to pick the brains of those of you who have experimented with
>> various "modern" loop designs.  With limited room, poor ground
>> conductivity, and not being able to set up something permanent, I've been
>> a
>> bit discouraged by the sizes of antennas that people are using to get
>> nulling patterns other than a figure-eight.  However, after looking at
>> Bruce Conti's page on the "Super Loop" (corner-terminated, corner-fed), I
>> realized that this was something I could try after all.
>>
>> This weekend, I threw together a "portable" 8' x 25' loop using PVC pipe
>> and wood for the two end supports.  I still need to do the termination and
>> impedance matching right, but my "close enough" beta version was promising
>> as far as signal strength across the BCB and noise levels, although the
>> quality of the backside nulling wasn't as clear (the whole point of this
>> experiment is to null out SoCal and/or northern Baja California).  This
>> was
>> squeezed in between the house and carport, the only practical corridor I
>> have for something this size.  I would like the ability to have a support
>> 20-25' high, mainly to get the loop more clear of structures.
>>
>
>
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-- 
Russ Edmunds
15 mi NW Phila
Grid FN20id
<wb2bjh@xxxxxxxxx>

AM: Modified Sony ICF2010's (2) barefoot w/whip
FM: Yamaha T-80 & T-85, each w/ Conrad RDS Decoder;
Onkyo T-450RDS; Tecsun PL-310 ( 2);
modified Sony ICF2010 w/APS9B @ 15';
Grundig G8 w/whip; modified Sony ICF2010 w/whip
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