Harold,

Building a 'simple' Attic Loop Antenna = Not So Simple !
http://groups.yahoo.com/group/Shortw...a/message/6653

ATTIC "CONICAL" LOOP ANTENNA :
The general ideas in the Drawing of the Attic Conical Loop
Antenna is to try an approximate a single turn SkyWire Loop
Antenna that is located OutSide. Not a Great SkyLoop design
but better than most for Wide Band Use considering that it
is after all "stuck-in-an-attic'.

Caution - Winding the Loops too close together can effectly
make them one loop or a very narrowly tuned loop.

Tip - The Pictured Attic Conical Loop Antenna can be
Lengthen and Shorten at the Feed-Point Corner by Tapping
Each of the Corner Turns there.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/

SAFETY - The Advantage of using TV type Stand-Offs on the
UnderSide of the Roof's Surface Keeps them away from your
Feet and Body so that you are less likely to Trip-and-Fall
and Injure yourself while Walking-About the Attic.

3 1/2" Wood Screw Stand-Offs with Insulators [4-Pack]
RadioShack Catalog # 15-853
http://www.radioshack.com/product/in...ductId=2104003

BUILDING THE RIGGING BOARDS FOR THE LOOP ANTENNA ELEMENT :
All-That-Being-Said :
* You can buy two pieces of 1"x4"x8' Wood Boards.
* Place-Clamp the Two Boards Together and Measure of 46"
* Draw a 45* Line from the 46" Mark across the 4" Flat
Side of the Boards. From the other end of the Broads to
the other end of the 46" 45* Line should also Measure
about 46". Saw the Boards in Two (4 pieces) Un-Clamp
the Boards.
* Now take all Four (4) pieces with the Square-Flat-Ends
and 45*-Sloping-Ends Matching-Up and Clamp them together
laying Horizontal to work on them. The Short Edge of the
Broads should be Up with the 45* Angle Surface Sloping Down.
* You are now going to Cut a Series of 1/2" to 3/4" Cuts
for the Wire Antenna Elements to be Held-in. These can be
simple Vertical Down Cut or a 45* Cut towards the Square
Flat End. First Measure in 2" from the Square-Flat-End
and make your First Cut. The next Series of Cuts is based
on what you want you Wire Spacing to be or the Number of
Turns you are trying to get into the available space.

Three Inch (3") Spacing with 13 Turns Possible
Cuts = 2" 5" 8" 11" 14" 17" 20" 23" 26" 29" 32" 35" 38"
- Note - Can be used for Six Inch (6") Spacing with 7 Turns
using every Second Cut to Wrap the Wire Antenna Element.
- Note - Can be used for Nine Inch (9") Spacing with 5 Turns
using every Third Cut to Wrap the Wire Antenna Element.
- Note - Can be used for Twelve Inch (12") Spacing with
4 Turns using every Fourth Cut to Wrap the Wire Antenna Element.

Four Inch (4") Spacing with 10 Turns Possible
Cuts = 2" 6" 10" 14" 18" 22" 26" 30" 34" 38"
- Note - Can be used for Eight Inch (8") Spacing with 5 Turns
using every Second Cut to Wrap the Wire Antenna Element.
- Note - Can be used for Twelve Inch (12") Spacing with
4 Turns using every Third Cut to Wrap the Wire Antenna Element.

Five Inch (5") Spacing with 8 Turns Possible
Cuts = 2" 7" 12" 17" 22" 27" 32" 37"
- Note - Can be used for Ten Inch (10") Spacing with 4 Turns
using every Second Cut to Wrap the Wire Antenna Element.

* * * My Choice for Spacing and Turns * * *
Twelve Inch (12") Spacing with 4 Turns Possible
Cuts = 2" 14" 26" 38"

ATTIC SIZE = LOOP SIZE & WORKING HEIGHT :
With a Waist to Shoulder Working Heigth in an Attic and
an Average Size 25' by 40' Attic the the Loop Size would
be about 15' by 30' or about 90 Feet around one time.
With Six Inch (6") Spacing and up to 7 Turns Possible
- Loop # 1 = 90 Feet
- - Loop # 2 = 180 Feet
- - - Loop # 3 = 270 Feet
- - - - Loop # 4 = 360 Feet

Or you may want to try Nine Inch (9") Spacing with
5 Turns Possible
Cuts = 2" 11" 20" 29' 38"
- Loop # 1 = 90 Feet
- - Loop # 2 = 180 Feet
- - - Loop # 3 = 270 Feet
- - - - Loop # 4 = 360 Feet
- - - - - Loop # 5 = 450 Feet

These both have you using up almost a Full Spool of #14 AWG
Stranded Insulated Wire (made with 19 Strands) and IMHO
that is enough Wire in the Attic to hear anything that
you can hear from there.

Now that you have made your "Spacing Cuts" keep all the
Boards Clamped Together and Drill a 1/2" Hole Center 2"
back from the Square-Flat-End. More about this latter.

Un-Clamp the Boards and I Recommend that you Paint them
with some White Paint so that they are Easier to see in
the Attic. Also if you want to after the Boards are Dry
from Painting; you can Lay the Boards Side-by-Side and
Number the "Spacing Cuts" so that you will know where
you are at with each Wrapping of the Turns. - It Helps.

MOUNTING THE RIGGING BOARDS :
The Four Square-Rectangular Rigging Boards at Waist to
Shoulder Height position the Rigging Boards; this is about
3-5 feet above the Attic Floor and all the Electrical Wiring
and most of the Things up there. Mount the Four Boards in
the Attic on Slanted Rafter that make-up the Under-Side of
the Roof. The Square-Flat-Ends are Facing-Out and the
45*-Sloping-Ends up along-side the Rafters; with the points
down. Nail or Screw (3-Each) the Boards in place so that
the 1"-Top-Edge with the Cuts in it is Facing "Up" and is Level.

Attach a 5-8 Foot Piece of Nylon-Poly Rope to the 1/2 Hole
at the Square-Flat-End of the Rigging Boards. Tie-it-Off
and let it hang for now.

RIGGING - THE WIRE ANTENNA ELEMENT :
Start from the First Cut nearest the Rafters and your
Feed Point Corner Wrap the First Turn. When you get back
to the Starting Point place the Wire in the Next Outer Cut
that meets you spacing requirements. Continue this Process
until you are Run Out of Wire or Cuts when you come by the
Starting Point. Now place a Nail or Hook directly above
the Square-Flat-Ends of the Rigging Boards to provide some
Upper-Support-Points for the Extended Rigging Boards.
Next take the Nylon-Poly Ropes and Tie them to the
Upper-Support-Points and Secure them so that Hold-Up
the Outer Tips of the Rigging Boards.

FEED-IN-LINE AND BALUN :
You can use a Balun between the Loop Antenna Element and
the Coax Cable or not; the Choice is yours. If you do
choose to use a Balun; then a 1:1 is usually used if this
is a Transmitting Loop Antenna; and a 4:1 is usually used
if this is a Receive Only Loop Antenna.

GROUNDING :
The Shack Ground is your System Ground and the Outer
Shield of the Coax Cable is the Ground Path from your
Radios and Shack's Equipment up to the Attic.
A separate Ground Wire can be used from the Shack up
into the Attic if you wish or use RG6 type 75 Ohm Coax
Cable with a Messenger Wire as an extra Ground Wire
to and from the Attic and Shack.

Good Luck with your Attic Loop Antenna Project.


iane ~ RHF