DAVE,

AHhhh, We Now Have More Information.

An ATTIC Location and a Target Broadcaster Frequency (VOK).

If your House/Building (The Attic) is positioned properly; and you
have a specific band of Frequencies that you want to Receive.
The you may wish to consider a simple Dipole Antenna for
Directivity and relative Gain for a designed Frequency.

"Using a 'SLINKY' as an Antenna ?" read Message #64
http://groups.yahoo.com/group/SWL-AM...nna/message/64

* Single SLINKY Vertical "Mono-Pole"
( The INVISABLE BroomStick Antenna )

* Dual SLINKY Horizontal "Dipole"

http://groups.yahoo.com/group/SWL-AM...nna/message/66


Consider a commercial SLINKY Dipole Antenna in the Attic.
http://groups.yahoo.com/group/SWL-AM...na/message/216
http://groups.yahoo.com/group/SWL-AM...na/message/254


iane ~ RHF
..
..
= = = "Dave"
= = = wrote in message ...

- - - S N I P - - -


Okay, so here's the problem. The fence is metal, and the house
is covered with steel siding. My DX-402 does pick up BBC on 5975
pretty well with just the whip (next to a window), but VOK is
extremely weak to vanishing. (This last one is what I want the
broomstick antenna for.) If I do go with the broomstick, should
I stick with the five-foot piece that I already have cut, or go
with a longer eight-foot piece which will still fit nicely in the
corner I have in mind. Or should I go all out with a ten-foot
piece (or even multiples maybe) and put it in the attic? Also,
what type of ground should I use? I could run a ground wire out
the window to a ground rod that is as old as the house, but that's
about my only option (the house predates three-prong plugs with
a real ground.)

I really appreciate your thoughts on these things. You obviously
know a lot more about this stuff than I do.

Thanks,

Dave

..

AV & DAVE,

FIRST: These are NOT Transmitting Antennas so the Metal
Fence does NOT represent a 'potential' Hazard to your
Transmitter. (Possible Direct Short Circuit to Ground.)

"AV" - It's Not the Fence...
Its the 200 Feet of Wire that makes up your Antenna Element.

NOTE: With Metal Fences "Insulated" Wire seems to work better )

Two Points of View for 'shorter' (20Ft-50Ft) Insulated Wire
Antenna Elements that are mount "ON" or "THRU" Metal Fences:

* Some people may tell you to run/route the Insulated Wire
alone the "Top" of the Metal Fence.
The Reasoning Being: The Wire is Higher in the Air
and Off the Ground.
(The Metal Fence will have less effect on the RF Signals
being Received.)

* Other people may tell you to run/route the Insulated Wire
alone the "Middle" of the Metal Fence.
(Half-Way between the Top and Bottom of the Fence.)
The Reasoning Being: The Wire is in the Air and Off the Ground.
(The Wire is being 'coupled' to the Metal Fence and the "Whole"
Metal Fence has become the Antenna with a greater capture are
to Receive RF Signals.)


THIRD OPTION: "Above-the-Fence" Field SWL Antenna for a Field Radio.

Recently I had the need to build a 'temporary' Low Noise SWL
Antenna that was going to be 'mounted' ABOVE a Cyclone Fence.
NOTE: The Fence was down the Hill about 75 Feet from the Deck
of a Cabin. The Fence ran between a small Lake and a Cabin
overlooking the Lake.
* The Antenna Element was 100 Feet of Landscape Lighting Cable
(Heavy Duty Outdoors Zip Cord).
* The Fence was a Six Feet (6Ft) Tall Chain Line Fence.
* I walked-off the fence with a note book and pencil.
The Fence Sections (Poles) were 20 Ft apart.
* When down to the hardware store and bought Six 10 Ft
pieces of 1" PVC Pipe.
* Also bought some plastic Locking Wire Ties.
* Drilled a hole in one end of each of the PVC Pipes and
installed a Wire Tie with a 2"-3" Open Loop.
* Placed a piece of PVC Pipe next to each of the Metal
Fence Poles.
* * Attached a Guide Rope to the two end pieces of PVC Pipe.
* Ran/Routed the Antenna Element through the Open Wire Tie Loops.
* Affixed the two Feed-End wires of the Antenna Element
across a TV 300 Ohm Matching Transformer (MT) and connected
100Ft of 75 Ohm Coax Cable to the other end of the MT.
* * Attached a 12 Ft Ground Wire to the 75 Ohm Side of the MT.
* At the Far-End of the Antenna Element; stripped and twisted
together the two wires and covered them with electrical tape.
* Place the Far-End PVC Pipe in the Vertical Position and
used two Wire Ties to one at the Bottom of the fence and one
at the top of the fence to hold it in place. Plus used the
Guide Rope to Counter the Force of the Antenna Element.
* Next placed the four middle pieces of PVC Pipe in the
Vertical Position and used two Wire Ties to one at the Bottom
of the fence and one at the top of the fence to hold it in place.
* Then the Feed-End PVC Pipe in the Vertical Position and
used two Wire Ties to one at the Bottom of the fence and one
at the top of the fence to hold it in place. Plus used the
Guide Rope to Counter the Force of the Antenna Element.
* Attached the other end of the Ground Wire to the Metal
Fence Post with a Large Hose Clamp at ground level; at the
base of the Metal Fence Post and the in-the-ground Cement
Anchor (2Ft-3Ft).
* Ran/routed the Coax Cable from the the Antenna Element
to the Receivers location on a Deck. Used a second grounding
point directly under the deck at one of the Metal Pier Anchors.
* Terminate the Coax Cable with an "F" Connector to PL-259
Plug Adapter for connection to the Receivers LO-Z (50 Ohm)
SO-239 Jack. Or, use a second MT and Connect the 300 Ohm
Output Leads to the Receiver's HI-Z (500 Ohm) Terminals.

TBL: The Antenna Element is a "Flat-Thin-Loop" that is
Physically 100 Ft Long and Electrically 200 Ft Out-and-Back.


iane ~ RHF
..
..
= = = AV
= = = wrote in message ...

Dave wrote:

It is a metal fence. Chain-link.
I didn't think that was a very likely answer to my problems.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

I'd be curious as to why running a wire along a metal fence would
be such a problem. I just ran about 200 feet of wire along the top
of a wire fence (2 inch square openings), albeit the type that is
covered with some green vinyl. And I have noticed CONSIDERABLE
improvement in reception. Wouldn't attaching to so much metal just
help to expand the range of the antenna ?

Also, related to the metal fence thing: what would happen were
I to attach a wire to my metal roof?

And as long as we're on the subject of random wire, what's the
deal with needing "stranded" wire. I had about 100 feet of that
first, and then when I went to buy some more all they had was
single strand, so I bought that and just added that to the end
of the stranded. what's the importance/need of using stranded?

av

..

In article ,
"Dave" wrote:

"Telamon" wrote in message
...
In article ,
"Dale Parfitt" wrote:

"donutbandit" wrote in message
...
"Dave" wrote in
:

I just got through picking up a ton of discontinued wire from my
local Home Depot, and was planning on building a "broomstick"
antenna like some I found described on the net.

I built one. I was quite disappointed after reading all the hype.

I get better reception from a wire run around the corners of my
bedroom ceiling.

I would not anticipate the broomstick antenna to be any different than
a metal tube or rod of similar dimensions.

Good comparison. A tightly wound broomstick would resemble a rod for
receiving purposes.

--
Telamon
Ventura, California

Still true, even if each turn of wire is insulated from those adjacent to
it? How could that be?


At RF frequencies the coils are shorted electrically because there is a
lot of capacitance between them. It won't work much better than a piece
of metal the same size. Coils can be useful as part of an antenna if the
turns are farther apart but as an element to pick up RF energy from the
air medium it will work poorly.

--
Telamon
Ventura, California

Still true, even if each turn of wire is insulated from those adjacent to
it? How could that be?

Thanks,

Dave


Telamon's explaination is spot on. The end of an antenna is high
impedance- coils at the far end do not behave as inductors, rather as
capacitors- thus the analogy to a solid tube. If the coil is placed, at a
current point of an antenna (eg. near the center of a half wave) then it
behaves as a pure inductor.

Dale W4OP

TELAMON,

"Tri-Band BroomStick Antenna" Read Message #410
GoTo= http://groups.yahoo.com/group/SWL-AM...na/message/410

* Eight Foot piece of 1.25" ID (1.5" OD) PVC Pipe

* Seventy Feet (70 Ft) of #14 AWG Insulated Wire (19 Strands)

* Top Hat ("9-12" Pie Pan)

* Separator Stub 4"

* Top Coil: 32 Turns @ 1/8" Spacing

* Separator Stub 18"

* Middle Coil: 52 Turns @ 1/4" Spacing

* Separator Stub 11"

* Bottom Coil: 82 Turns @ 1/2" Spacing

* Separator Stub 6"

* Lead-In-Line Connection


"Image of Tri-Band 'BroomStick' Antenna"
GoTo= http://groups.yahoo.com/group/SWL-AM...na/message/412


PHOTOS Section: Image "BroomStick Antenna Tri-Band"
GoTo= http://photos.groups.yahoo.com/group...FM-Antenna/lst


iane ~ RHF
..
..
= = = Telamon
= = = wrote in message ...

- - - S N I P - - -

At RF frequencies the coils are shorted electrically because
there is a lot of capacitance between them. It won't work much
better than a piece of metal the same size. Coils can be useful
as part of an antenna if the turns are farther apart but as an
element to pick up RF energy from the air medium it will work
poorly.

..

"Telamon" wrote in message
...


At RF frequencies the coils are shorted electrically because there is a
lot of capacitance between them. It won't work much better than a piece
of metal the same size. Coils can be useful as part of an antenna if the
turns are farther apart but as an element to pick up RF energy from the
air medium it will work poorly.

--
Telamon
Ventura, California

I have a little trouble with this statement.

If there is so much capacitance between turns that you have an effective
short, then things like IF transformers and AM loopstick antennas can't
possibly work. A loading coil at the base of a whip antenna is no more
useful than a chunk of metal? It just doesn't make sense.

Coils are added to antennas to increase their effective length. If they just
acted like a solid piece of metal they couldn't do that.

craigm

In article ,
(RHF) wrote:

TELAMON,

"Tri-Band BroomStick Antenna" Read Message #410
GoTo= http://groups.yahoo.com/group/SWL-AM...na/message/410

snip

I don't Yahoo.

--
Telamon
Ventura, California

CraigM,

1. If you look at many Transmitter Loading Coils.
They are often Bare Wire with Insulated "Spacers" that
provide an Air Gap. One of the "Features" of this 'design'
is to Allow for HEAT (Power) Dispensation.


2. Many Up-In-The-Air Antennas use "Loading Coils" that
are simply made of the same Insulated Wire or Bare Wire
used in the Antenna. Frequently there is a 'small' Air
Gap (about one to two wire diameters) in these Loading
Coils. Sometimes when Insulated Wire is used these
Loading Coils are simply wound with NO Air Gap.
But remember, there is the Gap (Spacing) that is created
by the Covering Insulation on both sides of the inner wire.

Loading Coil Looks Like: iWiiWiiWiiWiiWiiWiiWiiWiiWiiWi
"W" = Wire (Inner)
"i" = Insultation (Outer)


3. For Shortwave "SWL" Antennas that are Receive ONLY.
It is Simplier and Easier to use Insulated Wire and wrap
the Loading Coils using the Side-By-Side wire wrapping
method.

NOTE: An 'alternative method' is to use a "De-Wired
Insulated Wire" as a Spacer to create a Uniform Gap
between the Loading Coil's wire coils.

HOW TO: Estimate the length of the Wire required for
the Loading Coil; and "Cut" a second piece of Insulated
Wire to 'act' as a Spacer. Remove the 'inner wire'
from the Insulation and use the Hollow Insulation (Tube)
as a Spacer.


4. Cheap-and-Dirty "Loading Coil Form" = Simple and
Easy to Make. Basically use common PVC Pipe:

* 3/4" ID = 1" OD = Circumference 3.14"
+ Plus Factor in One #14 Insulated Wire Diameter (0.10")
= Length of One-Turn-of-the-Coil would be 3.46"

* 1.25" ID = 1.5" OD = Circumference 4.71" (Per Turn)
+ Plus Factor in One #14 Insualated Wire Diameter (0.10")
= Length of One-Turn-of-the-Coil would be 5.02"

HOW TO: Estimate the Lenght of your Loading Coil Winding Area.
Add Two Inches (3/4" PVC Pipe) or Three Inches (1.25" PVC Pipe)
to this for both PVC "End Caps" that will be used in the Form.
* Cut the PVC Pipe to Length.
* Glue on the End-Caps.
* Drill a 1/4" Hole in the Ends of each of the End-Caps.
[The End-Cap-Hole]
* Drill a 1/4" Hole at the PVC Pipe right next to the Edge
of each of the End-Caps. (Directly opposite each other.)
[The Side-Hole]

Use Black 1/4" Drip Irrigation Tubing (DIT) as a Strain
Relief for the Antenna Wire / Loading Coil Wire.
* Cut the DIT in to 4" pieces:
* Use two pieces of DIT per Loading Coil.

HOW TO: Building the Antenna "Loading Coil".
* Feed the Antenna Wire through one piece of DIT.
* Feed the Antenna Wire & DIT through the End-Cap-Hole
and around to the Side-Hole.
(About 2" out the End and 1/4" out the Side.)
* Jam about 1" of the Hollow Insulation (Tube) that is
being used as a Spacer into the Side-Hole.
* Wrap the Loading Coil using the Antenna Wire and the
Spacer as a Wire Pair.
* Use Electrical Tape to 'temporarily' hold the Antenna
Wire and Spacer in place on the PVC Pipe.
* Feed the Antenna Wire through the other piece of DIT.
* Feed the Antenna Wire & DIT through the other Side-Hole
and around to the End-Cap-Hole.
(About 2" out the End and 1/4" out the Side.)
* Trim the Hollow Insulation (Tube) Spacer Free-End
down to 1" and JAM that End into the other Side-Hole.
* Use RTV Silicone to Seal the Side-Holes and End-Cap-Holes.
NOTE: The "Remaining" Antenna Wire is routed to the Antenna's
Far End (Terminating Insulator) -or- the next Loading Coil.


OBTW: A copy of this Message has been posted to the YAHOO eGroup
"SWL Antennas and AM & FM Antennas" - Read Message #421:
* HOW-TO-BUILD: SWL Antenna Loading Coils - One Method
http://groups.yahoo.com/group/SWL-AM...na/message/421


iane ~ RHF
..
..
= = = "craigm"
= = = wrote in message ...
"Telamon"
wrote in message news:telamon_spamshield-
...


At RF frequencies the coils are shorted electrically
because there is a lot of capacitance between them.
It won't work much better than a piece of metal the
same size. Coils can be useful as part of an antenna
if the turns are farther apart but as an element to
pick up RF energy from the air medium it will work poorly.

--
Telamon
Ventura, California

- - - - - - - - - - - - - - - - - - - - - - - - - - - - -

I have a little trouble with this statement.

If there is so much capacitance between turns that you
have an effective short, then things like IF transformers
and AM loopstick antennas can't possibly work. A loading
coil at the base of a whip antenna is no more useful than
a chunk of metal? It just doesn't make sense.

Coils are added to antennas to increase their effective
length. If they just acted like a solid piece of metal
they couldn't do that.

craigm

..

In article ,
(RHF) wrote:

CraigM,

1. If you look at many Transmitter Loading Coils. They are often
Bare Wire with Insulated "Spacers" that provide an Air Gap. One of
the "Features" of this 'design' is to Allow for HEAT (Power)
Dispensation.

The space between the wires does help heat dissipation but the reason
for it is to reduce parasitic capacitance. The wire size has more to do
with how much power will go through it.

2. Many Up-In-The-Air Antennas use "Loading Coils" that are simply
made of the same Insulated Wire or Bare Wire used in the Antenna.
Frequently there is a 'small' Air Gap (about one to two wire
diameters) in these Loading Coils. Sometimes when Insulated Wire is
used these Loading Coils are simply wound with NO Air Gap. But
remember, there is the Gap (Spacing) that is created by the Covering
Insulation on both sides of the inner wire.

Loading Coil Looks Like: iWiiWiiWiiWiiWiiWiiWiiWiiWiiWi "W" = Wire
(Inner) "i" = Insultation (Outer)

Any type of electrical component exhibits all the other electrical
properties. Inductors and transformers have some self-capacitance and
resistance. Capacitors have some inductance and resistance. Inductors
of any type have a tendency to have longer electrical paths than
comparable capacitors or resistors so parasitics are more of a problem.
Most of the time care must be taken to have self-resonant behavior
occur above the frequency of operation.

Keep in mind the need to have windings apart from each other in order
to reduce the parasitic capacitance between them. Air has a constant of
one and any other solid plastic insulation will have a higher constant
so placing insulated wire in contact will still create significant
capacitance. Air is the best insulator to use.

--
Telamon
Ventura, California