[Lowfer] Renamed as Loop Antenna Possibilities

[Bill Ashlock]

Hi Stan,

I still haven't decided on an outside material for the house up here. If a log exterior it would have to be 'log facing' because of the 15" of wall thickness needed but I'm concerned with the maintenance expense required to keep this looking good. One of my resent ideas is to use concrete siding. Has an authentic wood grain look and feel and the paint is supposed to last 20 years.

A few thoughts on your "loop possibilities":

1. The use of large diameter cable to lower the Rac requires a lot of copper which is very expensive and also very heavy. The Skin Effect at these frequencies causes most of the loop current to flow in the very outermost portion of the cable, so in essence, you are throwing a lot of copper. Suggest the use of good quality RG-8, RG-9, or 3/8s to 1/2" copper tubing.

2. Wind does not usually cause a tuning problem with single-turn loops of this size. It definitely IS a problem with multi-turn loops.

3. My experiments have shown that a ground screen is not needed for loops at low to mid frequencies unless the ground has very low conductivity... but in this case the screen would have to be extremely large..... maybe multiple wave lengths in size.

4. Recommend doing all your loop testing right at the loop terminals. Too many variables are inserted into the test results when a transmission line is introduced.

Have fun...

Bill A

> Date: Sun, 10 Oct 2010 09:07:10 -0400
> From: stanw1le at verizon.net
> To: lowfer at mailman.qth.net
> Subject: Re: [Lowfer] Renamed as Loop Antenna Possibilities
> 
>   Hello Bill,
> 
> Sorry for the confusion. I still am impressed with your R50 at the cabin.
> 
> Are they round logs or squared logs in the walls ?
> 
> Your comments are welcome.
> 
> Standing by on Cape Cod      Stan, W1LE
> 
> 
> 
> 
> 
> On 10/9/2010 11:21 PM, Bill Ashlock wrote:
> > Hey Stan,
> >
> > Which "Bill" are you addressing this to? I don't see the original post. I have some comments on your loop ideas (below) if you are interested.
> >
> > Bill A
> >
> >> Date: Sat, 9 Oct 2010 15:58:35 -0400
> >> From: stanw1le at verizon.net
> >> To: lowfer at mailman.qth.net
> >> Subject: [Lowfer] Renamed as Loop Antenna Possibilities
> >>
> >>    Hello Bill,   Thanks for the details.
> >>
> >> One plan is to use 4 each, 50' lengths of #2AWG welding cable in a 200'
> >> rectangular loop.
> >> Maybe not square, but maybe 70' wide X 30' high, like yours about 10'
> >> above ground
> >> so I do not hang myself looking for nigh crawlers (fishing bait).
> >> I am thinking more of permanent structural supports like ROHN 25 towers
> >> to support everything.
> >> The welding cables have  some weight, so I may support them on a
> >> horizontal non metallic catenary.
> >> Original plan was for 2 each tower, suspending the single loop between
> >> then at an opportune LOB.
> >> Definite merit to 3 towers and 2 orthogonal loops.
> >>
> >> I cut most of the trees down on that side of the yard and they were
> >> rather short<  50'.
> >> They would really whip around in the wind. Towers would be reasonably rigid.
> >>
> >> The ground screen I originally envisioned was 6' wide galvi chain link
> >> fence material,
> >> either laid on top of or buried under the loop. Maybe on the grass may
> >> be better
> >> because the acidic soil with acid rain will eat up the galvi/steel in a
> >> couple of years.
> >> At least on the grass I can easily inspect it.
> >>
> >> I inspected the fencing materials I can salvage and they are buried in
> >> over growth.
> >> Will be quite a job removing them. The dog kennel panels may be easily
> >> salvaged,
> >> but the dogs will get that material. And should be able to mow over it.
> >>
> >> The welding cable insulation is orange in color and probably goodly
> >> rugged for the intended service.
> >> May have to paint it to tone it down.
> >>
> >> Originally was planning to do all RF testing outside at the antenna feed
> >> but
> >> I am thinking now of just bringing the feeds to the house, any
> >> combining/switching inside.
> >> The shorter ISO shipping containers 8'W x 20' long x 8' high have merit and
> >> are by far cheaper that any shed for the floor space. And a shielded
> >> room....
> >> Easy to deliver, but would take some work making pretty for the neighbors.
> >> Larger military shelters are a possibility, then I could argue to the
> >> taxman they are
> >> not a permanent ground based shelter, but rather a vehicle accessory.
> >>
> >> Stan, W1LE     Cape Cod
> >>
> >>
> >> ZZZZz
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