Grounding
Steve Rabinowitz
get my tabletop. Where the radio will be there are no pipes etc, what is the
best way to ground, can I use the center screw of the electric outlet. Been
using protables now & a set top with a whip built in antenna (RS394).
David
Only if your mains wiring is in metallic pipe or raceways. Otherwise
I'd run a discrete wire.
Steve Rabinowitz
ground. Would rather not run the wire outside,
"David" <ric...@knac.com> wrote in message
news:qhhgp1dr3e1bg5ie4...@4ax.com...
RHF
Vice using the questionable the Ground {Green Wire} of your
Household AC Power System.
Why not consider a simple Around-the-Room {Ceiling Level}
Horizontal [Flat] Loop Antenna. The Loop Antenna is consider
a 'blanced' Antenna that does not require a Ground and is
Horizontally Polarized so it generally pick-up less man made noise.
The "In-Door" Horizontal [Flat] Loop Antenna is easy to build;
usually is relatively long 40-60 Feet for an In-Door Antenna;
and relatively lower noise pick-up to an in-door vertical antenna
or long wire antenna.
The Radio or Receiver can be run off of AC with an AC Ground
connection via the AC Power Plug or DC without any Ground
connection at all.
something to consider - iane ~ RHF
.
.
. .
.
David
<ste...@earthlink.net> wrote:
>Is there any where in the house or must I attch to a metal stake in the
>ground. Would rather not run the wire outside,
>"David" <ric...@knac.com> wrote in message
>news:qhhgp1dr3e1bg5ie4...@4ax.com...
>> On Thu, 08 Dec 2005 13:02:01 GMT, "Steve Rabinowitz"
>> <ste...@earthlink.net> wrote:
>>
>>>Will be using a long wire strung around inside of the house for now when I
>>>get my tabletop. Where the radio will be there are no pipes etc, what is
>>>the
>>>best way to ground, can I use the center screw of the electric outlet.
>>>Been
>>>using protables now & a set top with a whip built in antenna (RS394).
>>>
>>>
>> Only if your mains wiring is in metallic pipe or raceways. Otherwise
>> I'd run a discrete wire.
>>
>
>
A fuse or breaker box that is ''served'' by metal conduit or raceway,
or a metal (for sure) cold water pipe that has metallic continuity
(for sure) into the ground.
bpnjensen
Horizontal [Flat] Loop Antenna. The Loop Antenna is consider
a 'blanced' Antenna that does not require a Ground and is
Horizontally Polarized so it generally pick-up less man made noise. <
IIRC, the impedance for this type of antenna is about 100 ohms. I
would suggest that, if this type of antenna is used, for best match it
be mated to the low-Z input of the radio (50 ohms rather than 500),
although an appropriate transformer could easily resolve this (probably
minor) problem regardless of the input.
Bruce Jensen
Joe Analssandrini
If you run any kind of wire in your house, you probably will not need
any grounding at all. Just to check, however, try the radio without
grounding at first and then try hooking up a ground and see if there is
any improvement or any difference at all. (The ground on your
electrical outlet is fine for this experiment.)
RHF and BPNJensen's posts are also correct. A loop antenna used inside
a house may give better performance than just plain wire run randomly
and loops generally need no grounding.
As a matter of fact, in my personal experience, a loop antenna, indoors
or outdoors, will afford much better reception quality (S/N ratio) than
long wires in areas where there is a great deal of local electrical
interference as loops tend to "reject" such interference.
You might want to try to make (or buy) a loop antenna and mount it in a
window. There are several sources on the web for instructions and a
very good book is Joe Carr's LOOP ANTENNA HANDBOOK.
Do try a good antenna on your Satellit 800. I think you'll be very
pleased.
Best,
Joe
Sanjaya
"RHF" <rhf-new...@pacbell.net> wrote in message
news:1134063478.3...@z14g2000cwz.googlegroups.com...
RHF,
This is the first time I recall you *not* posting a link to materials/instructions for
building the antenna you recommended in your reply.
It seems like one I've seen you refer to previously, but darned if I can find it in my saved
newsgroup messages.
mi...@sushi.com
solution is to buy the Wellbrook ALA100.
At 40ft of wire, I find two BCB stations about 20 miles away force my
7030 to switch on the attenuator. I have maybe 10db before the s-meter
is pegged, so I wouldn't go much beyond 60ft if you get the wellbrook.
Bob Miller
<ste...@earthlink.net> wrote:
You probably won't hear any differently with a ground.
And be careful where you attach one: I know a ham who lost his whole
station -- lightning hit and came up through the ground wire and fried
his equipment.
Unless you can hear a difference, I wouldn't bother.
Bob
k5qwg
Steve Rabinowitz
plate of the electric outlet won't be any good then. I could have swore my
father years ago used that for grounding.news:eg2hp1t2e5g7gre99...@4ax.com...
w_tom
alternative path to earth. Your building does that just fine.
But be better advised to earth using a lightning rod located
above the roof.
Safety ground system and earthing system share many
components. Different systems for different purposes with
some common parts. AC wall receptacle is not an earth
ground. An antenna is earthed so that lightning will not take
a more destructive path via the receiver. Ac receptacle
ground means lightning would spread out inside the building to
damage other electronics.
Connect things to the wall receptacle grounded screw to
protect human life. This is not same as earthing lightning.
To earth lightning, install Ben Franklin's well proven
solution above the roof. Earth incoming transients on utility
wires using either 'whole house' protector or a ground block -
all connected to a common earth ground that remains outside
the building.
RHF
If the Loop were free standing in open Air; then yes what you say
would be generally true. However, the Wire Antenna Element is
usually laying against the surface of the House's Interior Walls
and therefore may not be as theoretical as expected.
TIP - Try the Loop Antenna with both Antenna Inputs the LO-Z 50
Ohms and the HI-Z 500 Ohms on Several Shortwave Bands :
120M - 90M - 75M - 60M - 49M - 41M - 31M - 25M - 22M
- 19M - 16M - 13M - 11M
YMMV - On some the LO-Z may be the best connection and
on others the HI-Z may be the best connection.
BALUN - As you stated a simple Matching Transformer may
provide the necessary Broad Banded 'match' to be able to use
a single In-Door Loop Antenna Input for All Bands.
TWIN LEAD DOUBLE LOOP - Another 'Trick' is to make the
Loop a Double Loop using 300 Ohm TV type Twin Lead wired
in Series with a piece of the same 300 Ohm TV type Twin Lead
from the Ceiling Loop to the Radio/Receiver. In this instance
the HI-Z 500 Ohm Terminals usually work the best and it goes
without saying that the Double Loop is Twice as Long as a
Single Loop :o) This does not seem to work as well with
the narrower and closer together common Speaker Wire.
FWIW - Some Claim that the Double Ceiling Loop Antenna
provides more signal and less noise then a Single Ceiling
Loop Antenna. I have yet to do a side-by-side of the One
or the Two around the same Ceiling at the same time.
Note - I would thing that it would take at least 6" or may
be closer to a Foot between the Single and Double Loops
to give each one a reasonable independent test in the same
room.
Some Food-for-Thought and an Invitation to Experiment
with In-Door Horizontal [Flat] Ceiling Loop Antennas.
[ Surprise Yourself :<]
RHF
Wire Wire Everywhere . . . Pick a Wire - Any Wire !
Ninty Feet (90-Ft.) of 22 AWG Stranded Hook-Up Wire
RadioShack Catalog # 278-1218
http://www.radioshack.com/product/index.jsp?productId=2036275
Fifty-Five Feet (55-Ft.) of 18 AWG Stranded Hook-Up Wire
RadioShack Catalog # 278-1220
http://www.radioshack.com/product/index.jsp?productId=2049741
Fifty-Five Feet (55-Ft.) of 18 AWG Stranded Hook-Up Wire
RadioShack Catalog # 278-1220
http://www.radioshack.com/product/index.jsp?productId=2049741
Fifty Feet (50-Ft.) of 24 AWG Clear Insulation Stranded Speaker Wire
RadioShack Catalog # 278-1301
http://www.radioshack.com/product/index.jsp?productId=2102499
[ For That "Instant" Dipole Antenna ]
- In-Door In-the-Attic In-the-Room -
For that "No-See-Um" [Hidden] Ceiling Loop Antenna . . .
http://groups.google.com/group/rec.radio.shortwave/msg/a4a4ff8558eb78c8
Fifty Feet (50-Ft.) of White 30 AWG Single Strand
Kynar Insulated Wire Wraping Wire
RadioShack Catalog # 278-502
http://www.radioshack.com/product/index.jsp?productId=2062641
.
.
READ - Indoor Antenna & Lead-In = Hook-Up Wire / TV Twin Lead
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/75
.
READ - Try "In-Door" {Inside-the-House} Antennas First before . . .
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1036
.
READ - Two InDoor "Hidden" SWL Antenna Ideas
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/209
.
READ - The Carpet Loop Antenna
[ Sizing the Loop and Choosing the Cable ]
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/292
.
.
iane ~ RHF
.
.
. .
.
RHF
Please Educate me as to Why the Loop Antenna
would be Un-Balance without using a Balun ?
i want to know - cause -iane ~ RHF
nm...@wt.net
....................................................................................................
You don't need a ground. I wouldn't bother. Being the antenna is in
the
house, I see no real reason or advantage to use one. Any long wire
you run to a ground, will act more like part of the antenna, than a
ground.
MK
Sanjaya
> Sanjaya,
>
> Wire Wire Everywhere . . . Pick a Wire - Any Wire !
>
Thank you!
Smokey
One should NEVER use the metal screw or electrical conduit for an earth
ground. Not only is this contrary to the NEC code but it allows ground loop
currents to exist along the single ground path due to inconsistent bonding
between conduit, flanges, flange screws and...eventually...the ground rod.
Lightning will follow the path of least resistance. You will often see a
coil (even a single turn) of taped of professional communications atenna
systems at the point of entry into the building. This is to provide, however
slight, a small impedance to discourage lightning current from taking THAT
path and, instead chosing a separate direct ground path.
Do this little experiment: Install a good ground at the entry to your house
and run a wire to it for your shortwave receiver. Once done, take an
ohmmeter and measure the resistance between that ground wire and the screw
on your wall outlet. I have often been surprised at how much resistance
exists between the wall outlet and a "real ground." Well, that resistance is
probably more than enough to divert a lightning current to a shorter path to
your receiver such as through its antenna. Good luck.
Vern Weiss W9STB
"w_tom" <w_t...@hotmail.com> wrote in message
news:43990DA5...@hotmail.com...
Robert11
Question re the "loop"
Would you connect the end of the loop to the beginning, thus making a "true
loop" up there, or just leave it
open at the end ? Why ?
What is the effect of the vertical run down to the receiver ?
Would you suggest coax for this vertical section, or usually not necessary ?
Bob
--------------------------
"RHF" <rhf-new...@pacbell.net> wrote in message
news:1134063478.3...@z14g2000cwz.googlegroups.com...
RHF
THE LOOP ANTENNA ELEMENT :
The Loop being a Square/Rectangular Shaped Loop completes the
Circling of the Room around the Four Walls. Both Ends of the Loop
come together at some point on the Wall or at a Corner of the Walls
near the Ceiling and are connected to a Pair {Two} Parallel Wire
Feed-in-Line that goes down to the Radio's Antenna Input.
THE FEED-IN-LINE :
The short vertical Feed-in-Line for this type of In-Door {In-the-Room}
Loop Antenna is usually a Pair {Two} Parallel Wires.
* 300 Ohm TV type Twin Lead works well as a Feed-in-Line
for this type of Loop Antenna.
* Speaker Wire also can be used; either flat or twisted will work.
* The basic wire used to make the Wire Loop Antenna Element
can be continued as a single piece from the Radio up the Wall;
around the Four Walls; and down back to the Radio. If this is
done then it is recommended that the short vertical parallel run
has the two Wires Twisted together.
* A piece of Audio Coax Cable can also be used; especially if
the Radio uses an 1/8" Mono Jack for the External Antenna Input.
WANT A BIGGER LOOP ANTENNA - PUT IT IN THE ATTIC :
[ When an Out-Side / Out-Doors Antenna is NOT Permitted. ]
KISAP: I recommend using TV type Antenna Parts for most
"In-the-Attic" Antenna installations.
* 75 Ohm Coax Cable for the Feed-in-Line for Household
'man-made' Noise RFI/EMF Reduction.
* TV 75 Ohm to 300 Ohm Matching Transformer (Balun) for
Noise RFI/EMF Reduction and AM/MW Band Signal Reduction.
* TV 300 Ohm Twin Lead for the Wire Antenna Element
50-100 Feet -or- 90 Feet of Insulated Hook-Up Wire.
* "F" Jack to 1/8" Plug (1/8" Mono-Jack Adapter)
RadioShack Catalog # 278-257
READ - For Shortwave Listening (SWL) here is a "Simpler" Horizontal
Loop Antenna in the Attic using common TV type Parts.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/6656
http://groups.google.com/group/rec.radio.shortwave/msg/a759a36c32f5ecd7
READ - Shortwave Listeners (SWL) Horizontal Loop Antenna
built with common and cheap TV Parts
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/6135
http://groups.google.com/group/rec.radio.shortwave/msg/b88323867b8b44a3
ADDITIONAL READING LIST - Here are several Messages
to Read about In-the-Attic Antennas:
* Things-to-Think-About: Using Attic Antenna with the your
'portable' AM/FM/Shortwave Radio.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1658
* A Compilation of "In-the-ATTIC" Antennas
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/426
* Low Cost SWL Antenna (Made From TV Parts)
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/17
* ATTIC - Receiving Antenna Question - Think Loop made from TV Parts
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1635
* Ground Required At Balun ? {Getting "Grounded" in your Attic}
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/287
* Snake-in-the-Attic SWL Antenna {Simplest Low Noise Attic Antenna}
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/313
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/317
* AM/MW Band Signal Reduction using TV Type Coax Cable Parts
for better Shortwave Listener Antenna
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/930
* Simple SW Antenna = Improved Random Wire Antenna
using TV Antenna Parts
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/740
.
.
hope this helps - iane ~ RHF
.
All are WELCOME and "Invited to Join" the
Shortwave Listener (SWL) Antenna eGroup on YAHOO !
<http://groups.yahoo.com/group/Shortwave-SWL-Antenna/>
SWL ANTENNAS GROUP => http://tinyurl.com/an6tw
.
Some Say: On A Clear Day You Can See Forever.
I Believe : On A Clear Night You Can Hear Forever
. . . and Beyond , , , The BEYOND ! ! !
With a Shortwave Listening Antenna of your own making.
"If You Build It {SWL Antenna} You Will Hear Them !"
<http://groups.yahoo.com/group/Shortwave-SWL-Antenna/>
SWL ANTENNAS GROUP => http://tinyurl.com/an6tw
RHF
Do the same simple experiment in a 50+ Year Old House
and you may be 'shocked' at the results ;-) ~ RHF
Robert11
Thanks so much for reply and info.
I guess what you are suggesting is the "right" way of doing it.
I will try your suggestion once it warms up enough in attic to get up there
without frostbite !
Just trying to learn and understand thing a bit more -
a. Would coax work (meaningfully) better than the 300 ohm TV wire for the
feed line ? Would I need a Balun also ?
b. What are the major performance differences, therefore, between the
apparently 3 different ways of doing it:
- your suggestion of a balanced twin line to receiver
- what I now have, a single wire forming a sort of loop, with the
end open
- a modification to what I now have where the end would be
connected back to the beginning, thus forming a true
loop.
(the second and third config's both having a single, unshielded, wire
running down to the receiver)
Thanks,
Bob
---------------------
"RHF" <rhf-new...@pacbell.net> wrote in message
news:1134149698.6...@g14g2000cwa.googlegroups.com...
mi...@sushi.com
loop to inductively couple to the signal loop. This leaves the signal
loop balanced.
mi...@sushi.com
unbalance it. Clearly if one side of the radio input is at ground,
then one side of the loop will be at ground.
Telamon
"Smokey" <teleg...@hotmail.com> wrote:
> I'm with Tom...
< Snip >
Then you would be the "thunder" to the nut case lightning Troll.
In any event into the kill file with you.
< Plonk >
--
Telamon
Ventura, California
Telamon
"RHF" <rhf-new...@pacbell.net> wrote:
Any time you connect a transmission line directly to a antenna the coax
shield can affect the antenna unless you decouple it.
You can:
1. Run the coax at a right angle from the antenna elements.
2. Use a choke of some type on the coax.
Otherwise the coax shield become part of the antenna.
--
Telamon
Ventura, California
RHF
My assumtions were that he said he was getting ready for a Table Top
Receiver; and that it would have both a LO-Z 50 Ohm {SO-239 Jack}
and HI-Z 500 Ohm {Pair of Terminals} as the External Antenna Inputs.
But in re-reading the original post; I see that it is a RadioShack
DX-394 which only has the one SO-239 Jack as it's External
Antenna Input.
My general preference with a Ceiling Loop Antenna is to use 300 Ohm
Twin Lead as the Feed-in-Line from the Wire Loop Element to the
Receiver's HI-Z 500 Ohm {Pair of Terminals} for the External Antenna
Input. The exception being if the Radio uses an 1/8" Mono-Jack as
the External Antenna Input. Then a short piece of simple Audio Coax
Cable with an 1/8" Mono-Plug can be the better choice for a
Feed-in-Line from the Loop Antenna to the Radio.
Note - Horizontal Wire Loop Antenna Element directly connected to a
Vertical Feed-in-Line.
Telamon
"RHF" <rhf-new...@pacbell.net> wrote:
You would be better off using 50 ohm coax for the loop antenna and also
the lead-in using the radios low Z input.
If you are in a low noise area then use an unbalanced coax loop for more
pickup. If local noise is a problem then use a voltage balanced loop.
--
Telamon
Ventura, California
leansto...@democrat.com
an antenna, but not aimed with the rest of the loop. For instance, a
horizontal loop connected to vertical coax would fit your description,
but I would still say the coax unbalanced the loop.
FWIW, I get better results with vertical loops than horizontal.
Telamon
leansto...@democrat.com wrote:
> I agree on the choke, but it seems to me the right angle coax would be
> an antenna, but not aimed with the rest of the loop. For instance, a
> horizontal loop connected to vertical coax would fit your description,
> but I would still say the coax unbalanced the loop.
The electrical fields on the coax lead-in with be decoupled from the
same on the antenna elements when it is at right angles to it.
> FWIW, I get better results with vertical loops than horizontal.
I've seen the same thing generally.
One advantage to making a loop antenna out of coax is that it is about
a third larger in electrical length than the single wire due to the
dielectric in the coax causing the velocity factor to be .6 to .7 of
air in most cases.
> Telamon wrote:
> > In article <1134116506....@g47g2000cwa.googlegroups.com>,
> > "RHF" <rhf-new...@pacbell.net> wrote:
> >
> > > M... - " The loop will be unbalanced if you don't use a balun. "
> > >
> > > Please Educate me as to Why the Loop Antenna
> > > would be Un-Balance without using a Balun ?
> > >
> > > i want to know - cause -iane ~ RHF
> >
> > Any time you connect a transmission line directly to a antenna the coax
> > shield can affect the antenna unless you decouple it.
> >
> > You can:
> > 1. Run the coax at a right angle from the antenna elements.
> > 2. Use a choke of some type on the coax.
> >
> > Otherwise the coax shield become part of the antenna.
> >
> > --
> > Telamon
> > Ventura, California
--
Telamon
Ventura, California
RHF
Yes - A 'smaller' Vertical Coax Cable Loop Antenna
is another opinion to consider for an In-Door Antenna.
The "TRICK" to TV 'type' Coax Cable [Shielded] SWL Loop Antennas {RHF}
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1626
http://groups.google.com/group/rec.radio.shortwave/msg/3ba0aadd03af7bc7
The basic design of the "GreerTech" Coax Cable [Shielded] Loop
Antenna is good and very practical.
GREERTECH => http://www.greertech.com/hfloop/mymagloop.html
LOOP=> http://www.greertech.com/hfloop/mymagloop.html
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1625
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1730
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1539
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1008
http://groups.google.com/group/rec.radio.shortwave/msg/008005ce8c7f5c9c
"Build - Your - Own" Coax Cable Loop Antenna
http://groups.google.com/group/rec.radio.shortwave/msg/9adc49a6c156fa2b
A GreerTech RG8 Coax Cable Loop Antenna used with an Active
Pre-Selector could be a low cost 'better radio reception' answer
instead of the with AOR and WellBrook WideBand Active Loop
Antennas.
Try an In-Door Antenna 'designed' for Shortwave Listeners
with RFI and EMF Noise Problems . . . The Loop Antenna !
http://groups.google.com/group/rec.radio.shortwave/msg/a76e2b951e35abd9
RG8 AND RG58 'type' Coax Cable "In-Door" Loop Antennas
Loop Antenna Questions : Paired ? -or- A Pair ?
http://groups.google.com/group/rec.radio.shortwave/msg/7052a8e37790a367
Hula Hoop Loop Antenna and more . . .
http://groups.google.com/group/rec.radio.shortwave/msg/84fc1c535a7e8169
"Loop Antenna" Forum {Group} on YAHOO !
LOOP => http://groups.yahoo.com/group/loopantennas/
Discussion of Loop Antennas on all bands including ferrite loops,
air core, all types. All bands SHF, VLF, LF, MF, HF, VHF, UHF, etc.
Shortwave, longwave, receivers, transmitters, all fair game here.
So... is there a Loop Antenna in your Radio Listening Future ?
hope i have you going in circles (thinking of loops) - iane ~ RHF
RHF
Here are two messges to read that may answer your questions
and point you in the right direction concerning Horizontal
[Flat] Attic Loop Antennas :
For Shortwave Listening (SWL) here is a "Simpler" Horizontal
[Flat] Loop Antenna in the Attic using common TV type Parts.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/6656
http://groups.google.com/group/rec.radio.shortwave/msg/a759a36c32f5ecd7
Shortwave Listeners (SWL) Horizontal Loop Antenna
built with common and cheap TV Parts
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/6135
http://groups.google.com/group/rec.radio.shortwave/msg/b88323867b8b44a3
Using these common TV type Parts these Attic Loop Antennas
are Easy to Visualize, Lay-Out, Build and Use. They are a
good choice for an In-Door Antenna when an Out-Side Antenna
is not practical or possible.
* 300 Ohm TV Twin Lead for a Double Loop Antenna Element
* 300 Ohm to 75 Ohm TV Matching Transformer
* 75 Ohm RG6 Coax Cable for a Feed-in-Line
Connected to your Radio/Receiver and the Shack's Ground
be what that ground may be.
hope this helps - iane ~ RHF
.
.
. .
.
leansto...@democrat.com
the coax is still another antenna.
Telamon
"RHF" <rhf-new...@pacbell.net> wrote:
> Telamon,
>
> Yes - A 'smaller' Vertical Coax Cable Loop Antenna
> is another opinion to consider for an In-Door Antenna.
>
> The "TRICK" to TV 'type' Coax Cable [Shielded] SWL Loop Antennas {RHF}
> http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1626
> http://groups.google.com/group/rec.radio.shortwave/msg/3ba0aadd03af7bc7
Yes the 75 ohm TV stuff will work OK if that is what you have around.
The only problem there is the cable size does not match up with the 50
ohm connectors. Usually you can hack that well enough to connect things
together. If you are going to buy the coax you might as well but the 50
ohm cable.
--
Telamon
Ventura, California
Telamon
leansto...@democrat.com wrote:
> Yes, the field that the coax sees is not the same as the antenna, but
> the coax is still another antenna.
You prevent the coax lead-in from becoming another antenna by
terminating it in its characteristic impedance on both ends.
If the coax lead-in is terminated by the loop on one end and the radio
on the other end it will not behave as an antenna. Most people do not
understand this termination requirement and that is just one reason a
impedance matching UNUN is important on a single wire antenna for
example.
--
Telamon
Ventura, California
RHF
Thank You for remind me of this simple fact
about a properly Terminated Coax Cable and
the need to have it Matched on both ends.
[ Making It an Effective Signal Conduit. ]
to live is to learn - cause - iane ~ RHF
RHF
FWIW - Most of my better performing "GreerTech" Coax Cable
Veritcal Loop Antennas are made using full size RG8 Coax Cable.
Yes - Sometimes Bigger (Thicker) is Better.
The basic design of the "GreerTech" Coax Cable [Shielded] Loop
Antenna is good and very practical.
GREERTECH => http://www.greertech.com/hfloop/mymagloop.html
LOOP=> http://www.greertech.com/hfloop/mymagloop.html
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1625
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1730
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1539
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1008
http://groups.google.com/group/rec.radio.shortwave/msg/008005ce8c7f5c9c
~ RHF
SeeingEyeDog
"bpnjensen" <bpnj...@yahoo.com> wrote
>
> the impedance for this type of antenna is about 100 ohms.
At what frequency?
A large horizontal loop of about 40 feet or larger circumference will
exhibit different impedance across the bands as will any single wire antenna
or dipole. Except that a large horizontal loop will exhibit a significantly
less impedence variation.
> would suggest that, if this type of antenna is used, for best match it
> be mated to the low-Z input of the radio (50 ohms rather than 500),
> although an appropriate transformer could easily resolve this (probably
> minor) problem regardless of the input.
I wouldn't be too concerned about the impedance for receiving purposes. The
broadband nature of a large horizontal loop will offset any loss from
impedance mismatch compared to any other type of single wire antenna or
dipole at the same height.
As a once famous person said, "It's all relative." Or better, "If you build
it 'RF' will come."
Just do it and experiment.
SeeingEyeDog
"Robert11" <rgs...@notme.com> wrote
>
> a. Would coax work (meaningfully) better than the 300 ohm TV wire for the
> feed line ? Would I need a Balun also ?
Using 300 ohm line gently twisted (don't kink it) in a spiral (any
direction - L or R) once about every 12-18 inches or so is generally a
better "match" than coax for the broadband large horizontal loop.
>
> b. What are the major performance differences, therefore, between the
> apparently 3 different ways of doing it:
>
> - your suggestion of a balanced twin line to receiver
Don't be concerned about impedence mismatch using a large horizontal loop
for reception purposes. It is superior to any other single wire antenna or
dipole. The large horizontal loop will perform equally to your random wire
on your random wires resonant frequency or multiple but will out perform it
over all other bands. Assuming they are compared at the same height.
My horizontal loop is about 80 meters in circumference in the shape of a fat
"L" using a 450ohm ladderline feed. It is about 15 meters in height - not
ideal, but so what. I can transmit on any HF amateur frequency without
using any balun or matching device. Reception exhibits the same
characteristics, as it should.
> - what I now have, a single wire forming a sort of loop, with
the
> end open
This is a random wire regardless of the configuration. It is NOT a loop.
Creating a loop would make it far more "broadbanded" than a random wire or
dipole.
Just try it and experiment.
nm...@wt.net
>or outdoors, will afford much better reception quality (S/N ratio) than
>long wires in areas where there is a great deal of local electrical
>interference as loops tend to "reject" such interference.
Only because they have good nulls though...They have no
magic anti noise properties otherwise.
MK
RHF
You bring up an interesting point, about using the existing
"Available Space" i.e. THE-ATTIC and the three Antennas
that are often time mentioned :
1. The simple Random Wire (Longwire) Antenna run between any
two far-points in the Attic : With a 'limited' Signal Capture Area
{Aperture} along the longitudinal lay of the Wire Antenna Element.
[ A Wire within single plane of existence having one axis. ]
2. The basic Dipole Antenna run between the same two far-points
in the Attic : Again with a 'limited' Signal Capture Area {Aperture}
along the longitudinal lay of the two adjacent Wire Antenna Elements.
[ Two Wires within single plane of existence having one axis. ]
3. The common Horizontal [Flat] Loop Antenna run between any
four-or-more far-points (corners) in the Attic : With a 'expanded'
Signal Capture Area {Aperture} between the parallel lays of the
Wire Antenna Elements : Front-to-Back and Side-to-Side.
[ A Wire Folded within single plane of existence having two sets
of perpendicular axis's each composed of two parallel elements
separated by a significant amount of space. ]
Conclusion - Having stated the three above sets of parameters
for the above three types / shapes of Antennas that are often
used as In-the-Attic Antenna : It now becomes apparent to me
that the Loop Antenna is the better choice with a potential for :
* Higher Signal Levels due to the fact for the available space
there is simply more Wire in the Air.
* Equally as low Noise due to the natural properties of a Loop.
* Greater Antenna Aperture {Signal Capture Area} due to the
natural shape and size of a Loop in any given space; with less
apparent signal fading.
Going One Step Farther : A Vertical [Tall] Loop Antenna
In-the-Attic could offer almost as many advantages over the
Random Wire Antenna and Dipole Antenna; as does the
Horizontal [Flat] Loop Antenna. A Vertical [Tall] Loop
Antenna can like the Horizontal Loop Antenna add all the
things a Horizontal Loop Antenna can except in the Vertical
Dimension. The Vertical Loop Antenna may take other forms
then the common Square or low-aspect-ratio Rectangle that is
associated with the Horizontal Loop. The Vertical Loop may be
a Triangle or Delta Loop or a Rectangle with high-aspect-ratio
being many times longer then it is high. Intuitively I would
think that for a Vertical Loop Antenna to perform up to its
potential the maximum Length-to-Height (Aspect) Ratio
would be about 4:1 or 5:1 .
Note - Horizontal Squares being 1:1 and Horizontal Rectangles
being in the range of 1:1.5 to 1:3 .
hope this helps - iane ~ RHF
.
.
. .
.
nm...@wt.net
for the above three types / shapes of Antennas that are often
used as In-the-Attic Antenna : It now becomes apparent to me
that the Loop Antenna is the better choice with a potential for :
* Higher Signal Levels due to the fact for the available space
This can vary though. Would depend on the bands used, etc..
Just having more wire in the air doesn't mean much in itself.
It's quite possible and common for a smaller footprint antenna
to trounce the larger one. IE: my coax fed dipoles have a total
of 440 ft of wire in the air. Yes, it works well on any HF band,
but my yagi would eat it for lunch on the bands the yagi is designed
for. And the yagi uses a total of appx 90 ft of element/s to do it.
>* Equally as low Noise due to the natural properties of a Loop.
And what would these properties be? The only "noise" property a
loop has that differs from any other wire antenna is the reduction
of corona, or static buildup, etc. And only in locations where that
could help, would it be any advantage. Here in Houston, it would
mean nada. At HCJB, with the large amounts of element eating
corona up in those high mountains, it can help. Other than that,
the loops behave no different than any other antenna.
>* Greater Antenna Aperture {Signal Capture Area} due to the
natural shape and size of a Loop in any given space; with less
apparent signal fading.
This means little in general.. I can run a full wave loop on 80m
for NVIS, and compare it to a dipole, and they are almost exactly
the same in the real world. If you model a 80 dipole at 40 ft and
compare it with a 80 horizontal loop at 40 ft, the loop has the small
advantage of 1 db. In the real world, this is basically unnoticable
on HF. It's not the aperture you would want to worry about.
It would be the pattern of the antenna on the various bands, vs
whatever you would compare it to. This can easily be modeled.
>Going One Step Farther : A Vertical [Tall] Loop Antenna
In-the-Attic could offer almost as many advantages over the
Random Wire Antenna and Dipole Antenna; as does the
Horizontal [Flat] Loop Antenna.
You say? What would these advantages be? Have you tried modeling
it? You might be surprised...
A full wave loop has no advantage over a dipole, except in differences
in
pattern. They are both about equally efficient.
What would that mean? On some bands, the dipole could be better.
On others, the loop... Basically, it's a crap shoot.
Here, I have enough room to run either full wave loops, or dipoles.
I run the dipoles. Why? Same appx performance, with less work
involved. On the higher bands, I'd generally prefer the dipoles, vs
a horizontal loop due to current distribution concerns.
Vertical loop vs dipole? About 2 db or so, and barely worth the
trouble.
I'd rather run an extended double zepp, vs the vertical fed loop.
Has about 1 db more gain on it's design freq.
Intuitively I would
think that for a Vertical Loop Antenna to perform up to its
potential the maximum Length-to-Height (Aspect) Ratio
>would be about 4:1 or 5:1 .
Nope. The maximum performing loop is a perfect circle.
A square would be better than a tall narrow loop. Whatever
covers the largest area is best as far as gain.
If you want horizontal, you feed at the top or bottom.
Vertical, from either side.. A loop is a loop no matter
the orientation. Same properties will apply to both.
Anyway, there is no real advantage to a loop vs dipole, unless
the pattern of the loop is more favorable for a certain
band and direction, etc, in use at the time. This will vary.
As far as s/n ratio, you could run either one with little or no
difference on most the bands, assuming both are properly
decoupled from the feedline..
MK
RHF
In-the-Attic = Limited Space and Antenna Size
In-the-Attic = Usually means that the Wire Antenna Element
is 12 Feet to 18 Feet High above AGL for a single story house.
Maybe twice that for a two story house or split-level condo.
NOTE - For a Shortwave Listener's (SWL) "Receive Only" Antenna
that is designed to "Fill" the Available Space : Whether these
Antennas are : a Random Wire; a Dipole, or a Loop they are
not "Cut' for any specific Wave Length and Frequency; they
are simply Random Wire Antennas
IN-THE-ATTIC AND ATTIC SIZE :
In a 30 Foot by 40 Foot size Attic a basic straight Random
Wire Antenna can be 30 Feet along the short side; 40 Feet
along a the long side; or 50 Feet across a the diagonal.
In a 30 Foot by 40 Foot size Attic a simple straight Wire
Dipole Antenna can be 30 Feet along the short side; 40 Feet
along a the long side; or 50 Feet across a the diagonal.
In a 30 Foot by 40 Foot size Attic a common Wire Loop
Antenna would be : 30 Feet along one short side; 40 Feet
along one the long side; 30 Feet along the other short side;
40 Feet along the other long side; for a total of 140 Feet
around the Attic [.]
MK - It should be self-evident that " there is simply more
Wire in the Air. " and that is all I said and meant to say.
RELATIVE ANTENNA NOISE :
" Equally as low Noise due to the natural properties of a Loop. "
The usual ascertion is that a Dipole Antenna has a Lower Noise
Factor (Property) then the same Length Random Wire at the
same Height; all other things being equal : Balun / No Balun;
Coax Cable / Twin Lead / Ladder Line; ETC.
The Horizontal [Flat] Loop Antenna has the same Lower Noise
Factor (Property) then the Dipole Antenna has in the same
relative Available "In-the-Attic" Space : All other things being equal
:
Balun / No Balun; Coax Cable / Twin Lead / Ladder Line; ETC.
There is Nothing to be gained or lost by using the Dipole or Loop
Antenna in the Attic Noise Wise : But with the Loop Antenna more
Wire is in the Air which can result in more Signal from the Antenna.
ANTENNA APERTURE :
RHF Said - " Greater Antenna Aperture {Signal Capture Area}
due to the natural shape and size of a Loop in any given space;
with less apparent signal fading. "
MK - You model two 80 Meter Band Antennas; a Half-Wave Dipole
Antenna and a Full-Wave Horizontal Loop Antenna and say that they
are the same with little measurable difference between the two. "OK"
Again here my beginning point is "In-the-Attic" were both the Dipole
Antenna and the Horizontal [Flat] Loop Antenna are using the same
Available Space and are in fact simply two 'random wire' antennas
that happen to be laid-out in the confines of the Attic. Here the 50
Foot long Dipole Antenna with lets say 50 Square Foot of Signal
Capture Area has less potential as an Antenna : Then the 140 Foot
long Horizontal [Flat] Loop Antenna with lets say 120 Square Foot
of Signal Capture Area that has more potential as an Antenna.
To my simple way of thinking relative size and area does matter.
? Now is this Theoretically or Machine Measurable - Most Likely.
? Now is this Discernable by the Shortwave Listener (SWL) - Maybe.
THE CRAP SHOOT :
MK you say : "Basically, it's a crap shoot." "I run the dipoles."
RHF says : For an In-the-Attic Antenna "Crap Shoot" I prefer
the Horizontal [Flat] Loop Antenna - It's a matter of choice.
MY INTUITIVE STATEMENT ABOUT VERTICAL LOOP ANTENNAS :
RHF Said - " Intuitively I would think that for a Vertical Loop Antenna
to perform up to its potential the maximum Length-to-Height (Aspect)
Ratio would be about 4:1 or 5:1 ."
Again here my beginning point is "In-the-Attic" most every Attics
that I have been in is Longer and Wider then they are High {Tall}.
So 'if' we are trying to Maximizing the Size of the Vertical Loop
Antenna then a simple Circle or Square would not produce as much
Wire Length and Combined Area as a Rectangle or Triangle using
up the Available Space inside the Attic. The added comment about
the Length-to-Height (Aspect) Ratio being about 4:1 or 5:1 was to
not have the Vertical Loop become to flat compressed and effectively
become a fat Folded Dipole Antenna of sorts.
RESTATING MY CONCLUSIONS {NON-TECHNICAL OPINIONS} :
For a "Receiver Only" Antenna being used by a Shortwave Listener (SWL)
The Horizontal [Flat] Loop Antenna used In-the-Attic may/could/should
perform better then the simple Dipole Antenna with potentially Higher
Signal Levels; the same relative Noise Level; and less apparent Fading.
STAYING ON MESSAGE - THIS CONVERSATION :
MK - You appear to be a "Technical Person" and that is well and good.
However, I am for the most part a non-technical person who simply tries
to Keep It Simple And Practical [KISAP]. For me these Conversations
can be an interesting exercise in restating my simple minded opinions :
But for you these Conversations may turn out to be an exercise in
futility
- a Fools Errant so to speak.
MK - Part of my 'iane' signature { I Ain't No Elmer }
Means : I Don't Get Techincal - Because - I simply am not smart
enough to try and WOW anyone with the all that math or science.
MK - I Am Glad We Had This Talk :o)
kisap - keeping it simple and practical ~ iane ~ RHF
.
All are WELCOME and "Invited to Join" the
Shortwave Listener (SWL) Antenna eGroup on YAHOO !
<http://groups.yahoo.com/group/Shortwave-SWL-Antenna/>
SWL ANTENNAS GROUP => http://tinyurl.com/an6tw
.
Some Say: On A Clear Day You Can See Forever.
I Believe : On A Clear Night You Can Hear Forever
. . . and Beyond , , , The BEYOND ! ! !
With a Shortwave Listening Antenna of your own making.
"If You Build It {SWL Antenna} You Will Hear Them !"
<http://groups.yahoo.com/group/Shortwave-SWL-Antenna/>
SWL ANTENNAS GROUP => http://tinyurl.com/an6tw
SeeingEyeDog
types; dipoles, longwires, yagi's. etc. These are all "tuned" antennas
(even a random longwire) and their maximum gain is only evident in a single
band. While a large horizontal loop of "one wave" in length (example: 80
meters circumference = one wavelength at 3.5MHz) will perform equally to a
"half wave" dipole (i.e. 40 meters long) AT THE SAME HEIGHT.
Where the large horizontal loop shines is at all frequencies about its "one
wave" length. The large horizontal loop of a theoretical length of 80
meters in circumference will exhibit the characteristics of a dipole at ANY
frequency above 3.5MHz. Whereas a halfwave dipole will only exhibit equal
performance at 3.5MHz and its multiples (i.e. 7MHz, 14MHz, 21MHz).
Everywhere else the dipole will exhibit a loss compared to a large
horizontal loop.
The characteristics of our theoretical 80 meter large horizontal loop are
"relatively" flat all through the spectrum with much less peaks or valleys
compared to a dipole all the way up to at least 30MHz.
It is the ideal antenna for general SWL and HF utility monitoring because
its performance is equal all across the shortwave spectrum. Consider its
performance similar to a UHF/VHF discone antenna. It exhibits a flat
response, no gain or loss (relative to a half-wave vertical), from
50-900MHz! That is about 1000MHz! - that is very "broadbanded."
"RHF" <rhf-new...@pacbell.net> wrote in message
news:1134493027....@z14g2000cwz.googlegroups.com...
RHF
Thank You for the Reply and Sharing this Info concerning the
characteristics of the Dipole Antenna verses the Loop Antenna.
May we all Learn something new each day; and re-learn
something anew all over again everyday :o) - iane ~ RHF