WHY - The simple Random Wire Antenna is better than the Dipole Antenna for the Shortwave Listener (SWL)
RHF
Dipole Antenna for the Shortwave Listener (SWL)
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/4854
JP,
* "proper elevation and orientation"
There is the thing that makes the properly built Amateur
Dipole Antenna the better Transmitting anf Receiving Antenna
for it's designed Frequency and Target Signal Area.
AMATEUR DIPOLE ANTENNA :
The Amateur Radio Operator who knows his craft will take
the time and spend the money to Build and erect the Dipole
Antenna in the right place and at the right height for it
to perform optimaly for it's designed operating Frequencies.
OOPS - The Shortwave Listener will often simple 'hang-up'
the Dipole Antenna between two relatively low supports
and expect miracles.
RANDOM WIRE ANTENNA [LOW NOISE INVERTED "L" ANTENNA] :
NOTE - This is why the simple Random Wire Antenna configured
as an Inverted "L" Antenna is usually the better "Throw-It-Up"
Antenna for the Shortwave Listener who wants an All Band
(AM/MW and Shortwave) that is an Omni-Directional Antenna
to Hear Them All . . .
TIP - The lay-out of the Inverted "L" Antenna lend itself to
the design concepts of the so called Low Noise Shortwave
Listener's (SWL) Antenna that were popularized by John Doty.
READING LIST - Low Noise Shortwave Listener's (SWL) Antenna :
* Building an Inverted "L" Antenna using the PAR Electronics
EF-SWL (End Fed - Shortwave Listener) Antennna
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/3089
* Low Noise Shortwave Listener's (SWL) Antenna - by Design
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/3015
* The Shortwave Listener's (SWLs) Antenna a simple practical
Devise for Better Radio Rececption.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2471
* Three "Must" Links to Read -wrt- Low Noise Shortwave
Listener (SWL) Antenna
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2016
* The Inverted "L" Antenna
- It's 'basic' Lay-Out and Structure {Why It Works}
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1969
* The 'simple' Answer (in most cases) is the Low Noise
Inverted "L" Antenna
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1785
* Converting a Random Wire Antenna to a 'Low Noise'
Inverted "L" Antenna
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1766
* Par EF-SWL End-Fed Shortwave Antenna configured
as an Inverted "L" Antenna
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1562
* Antennas - Five Things to Consider : Antenna, Balun,
Ground, Coax and Planning
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1544
iane ~ RHF
.
.
. .
= = = In Shortwave-...@yahoogroups.com,
= = = "Jack Painter" <223bthp@c...> wrote:
C.E.,
I didn't mean to imply that an HF antenna would normally
transmit farther than it can receive, only that a random
wire can sometimes outperform it on the receive-end.
This can happen even when listening on the transmitting
antenna's resonant frequency.
Under average circumstances, a dipole at proper elevation
and orientation will outperform a random wire (tx or rx).
- - S N I P - - -
Jack
.
.
. .
.
.
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.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/502
.
I BELIEVE: On A Clear Night . . .
You Can Hear Forever and Beyond, The BEYOND !
With a Shortwave Listener SWL Antenna of your own making.
"If You Build It {SWL Antenna} You Will Hear Them !"
.
.
. .
bpnjensen
and one for the radio is worthwhile to reduce noise? And if so, how
far apart? Random readings on this group the last year or so suggest
that this is a recipe for voltage differences that can cause problems
for the receiver...with wider spacing of the rods resulting in greater
potential differences.
Thanks for all your information!
Bruce Jensen
Michael Lawson
"bpnjensen" <bpnj...@yahoo.com> wrote in message
news:1126104588.0...@g44g2000cwa.googlegroups.com...
I'm going to have to dig this up again, but I thought that I
read somewhere in my internet searching on antennas
that you'd want something like at least 10 feet between
the two so you don't have to worry about electrical issues
for lightning. In my personal case, I have two grounds in
my backyard because not that I wanted two, but because
I moved my antenna, so I needed a ground at another
location. I ended up using both grounds anyway, the
first one at the 9:1 transformer, and the second at the
entrance to the house with the zap trapper.
--Mike L.
RHF
.
A Second Look : The WellBrook lay-out for a Low Noise Antenna
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/4856
.
This webpage by WellBrook shows what I think is the best
way of using a 9:1 Matching Transformer at the 'remote'
Antenna Feed-Point and then using a 1:1 Line Isolation
(Coupler) at the ground level (rod) entry to the House.
http://www.wellbrook.uk.com/longwire.html
.
Note - How the Feed-Point of the Antenna is moved to the
Far-End of the Antenna vice the normal way of simply using
the Nearest-End as the Feed-Point.
http://www.wellbrook.uk.com/longwire.html
.
TIP - Burying the Coax Cable under the Ground directly
under the elevated Antenna Wire can also improve the
overall properties of Antenna.
(Making the Coax Cable a Unifying Ground Radial)
.
IMHO - Even if a 1:1 Line Isolation (Coupler) is not used
with the above lay-out of a Far-End-Fed Inverted "L"
Antenna. Since the Horizontal Arm of the Antenna would
be at least 30 Feet (10 Meters) the distance would still
make the use of an Antenna Feed-Point Ground and a
Shack Ground the better Noise Reduction Set-Up.
http://www.wellbrook.uk.com/longwire.html
PLUS AGAIN - Burying the Coax Cable under the Ground
directly under the elevated Antenna Wire can also improve
the overall properties of Antenna.
(Making the Coax Cable a Unifying Ground Radial
between the Antenna Ground and the Shack Ground.)
.
.
iane ~ RHF
.
.
Telamon
"RHF" <rhf-new...@pacbell.net> wrote:
< Snip >
> = = = In Shortwave-...@yahoogroups.com,
> = = = "Jack Painter" <223bthp@c...> wrote:
>
> C.E.,
>
> I didn't mean to imply that an HF antenna would normally
> transmit farther than it can receive, only that a random
> wire can sometimes outperform it on the receive-end.
>
> This can happen even when listening on the transmitting
> antenna's resonant frequency.
< Snip >
Highly unlikely on receive for the same reason as on transmit.
--
Telamon
Ventura, California
bpnjensen
--
Telamon
Ventura, California <
I agree in general, except for the fact that a dipole has a
characteristic directionality, whereas a random wire significantly
shorter than the wavelength will be omnidirectional. I suspect that
there will be occasional times when this factor matters.
When it doesn't matter, a random wire is still a more versatile antenna
than a single-lambda dipole, even when untuned.
I have an Alpha-Delta DXUltra, which is basically a multi-lambda
dipole, and a 60-foot random wire through a transformer at 20 feet
elevation above ground. Noise levels aside, there is little I can hear
on the DXUltra that doesn't appear on the wire, and quite a bit on the
wire, especially at freqs < 6 MHz, that is inaudible on the DXUltra
(even though the DXUltra supposedly is good down to 120 meters - this
loss of signal may be a function of inadequate height, since the
antenna center is only 27 feet sloping to 7 feet at either end).
Bruce Jensen
David
I find a random wire superior overall to just about any ''tailor
made'' SWL antenna I've tried.
bpnjensen
made'' SWL antenna I've tried. <
I do find that the dipole is wonderful on 7 MHz, and 11 MHz and up. On
9 and 6 it's about a toss-up, and on down through the tropicals the
wire is better.
My big problem is noise, especially on the lower bands. I have an MFJ
noise cancelling unit that works with the two antennas, but I think two
simpel wires phased would work rather better. If I can arrange such an
array that can be set up on my smallish property, I will let folks
know. Meanwhile, I still have a large horizontal loop to build around
my fence...
Bruce Jensen
David
I've used the MFJ Noise Canceller with an MFJ-1024 Remote Active
antenna for the noise sense with decent results. Since then I ditched
my Linksys router and 90% of the noise went away.
Telamon
"bpnjensen" <bpnj...@yahoo.com> wrote:
The assertion that RHF made was that resonance on an antenna is not
important on receive and only important on transmit. It is a tried and
true technique to cut a dipole for a certain receive frequency. When an
dipole antenna is at resonance it will generate a larger voltage from a
distant signal on that frequency than other frequencies above and below
it for the same reason more power will be radiated from it on transmit.
Depending on a number of other factors this alone may or may not allow
you to hear a distant station at a level better than the random wire.
The random wire is not omnidirectional and a direction it can pick up a
signal well will depend on frequency, its length, distance from the
ground and a few other things.
That's just the physics of the statements in question. Now if you want
to qualify it with other criteria such as "I can hear the same stuff on
a random wire" that is a different story.
Resonance is an important quality in any antenna. The random wire is
just called random because you are NOT building it with a particular
resonant frequency in mind. A random wire is resonant at some frequency
and will perform better at that point just as a dipole or nearly any
other antenna as a general rule. There are exceptions of course such as
very electrically short antennas designed to be amplified due to the low
efficiency. There resonance is not a factor considered in its operation.
A random wire antenna is half an antenna where the other half is ground.
For it to work well generally means you need a good outdoor RF ground.
This can be a problem itself depending on where you live. A dipole is a
full antenna that does not need an RF ground to work properly.
A random wire is a common mode antenna that will do a good job of
picking up local electrical noise so the criteria is that you need a
good RF ground or radials in its place and you need to live in an
electrically quiet area.
If the Alpha-Delta DXUltra is worth the money you paid for it it should
work better then a "random wire" at some frequencies. Sometimes the
behavior of antennas or circuits is not apparent by only looking at a
small selection of frequencies.
--
Telamon
Ventura, California
Telamon
David <ric...@knac.com> wrote:
An antenna "tailored" for a frequency will pick up more signal energy on
that frequency than an antenna of the same type that is not resonant at
that frequency.
--
Telamon
Ventura, California
RHF
.
But lets say your perfect Antenna is laying on the ground
or still in the box. (Absurd I Know - But Imagine It.)
.
Then my Slinky Antenna hanging from a tree limb and clipped
to the Radios Whip Antenna would work as good or better.
.
>From my original posting :
OOPS - The Shortwave Listener will often simple 'hang-up'
the Dipole Antenna between two relatively low supports
and expect miracles.
Question - When is a Dipole not really a Dipole ?
.
Answer - When the Dipole is not properly set-up and installed [.]
.
Note - Often Shortwave Listeners (SWLs) spend a lot of
Money for very expensive Shortwave (SWL) Antennas and do
not set them up right and/or do not install them correctly.
.
Tip - This is the Magic of the Random Wire Antenna and more
specifically the Inverted "L" Antenna using Low Noise
Antenna 'concepts' that were popularized by John Doty.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/3015
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2471
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2016
{ Hey I am Back-on-Theme Again ! }
.
- - - - - [ { ( RANT - O N ) } ] - - - - -
.
ONCE AGAIN - HERE IS MY MESSAGE (MISSION) :
The Low Noise Shortwave Listener (SWL) Antenna is basically
a "Random Wire" Antenna Element that is 'configured'
(laid-out) in the Shape of an Inverted "L" :
- Having a 'remotely located' Ground Rod installed
at the base of the Vertical-Up-Leg
- Shorter Vertical-Up-Leg going from ground level up to the
- Longer Horizontal-Out-Arm going to it's Far-End Support
- Using a 9:1 Matching Transformer mounted directly
on a Ground Rod.
- Using a Coax Cable Feed-in-Line from the Matching
Transformer to the Radio/Receiver.
NOTE - This is the basic Shortwave Listener's (SWL)
Antenna that uses the "Low Noise Antenna" 'design
concepts' that were popularized by John Doty.
.
Can We All Say - Random Wire Antenna !
.
Can We All Say - Configured as an Inverted "L" !
.
Can We All Say - 9:1 Matching Transformer !
.
Can We All Say - Remotely Located Ground Rod !
.
Can We All Say - Coax Cable Feed-in-Line !
.
Can We Al Say - Low Signal-to-Noise Ratio !
.
Brothers & Sisters - Are We Of One Accord - Amen & Hallelujah !
.
NEXT - Factor-in-the-Reality : That not everyone has the
necessary 'Space' and means to Set-Up a properly 'Cut'
Dipole Antenna at the right Height in their average size
(small) city/urban Single Family Home Building Lots.
[ A Mans Got To Know His Limits -and- His Wife's Limits Too ! ]
.
SOoooo... Enter the Inverted "L" Antenna ! ! !
* Locate a good spot for your 'remote' Ground Rod.
Be it 12Ft > 24Ft > 36Ft > 48 Ft > 60 Ft or more
from the House and sources of RFI / EMF Noise.
* Figure out how high "Vertically" you can go up.
Be it 10 Ft > 15 Ft > 20 Ft > 25 Ft > 30 Ft or more high.
* Figure out how long "Horizontally" you can go across.
Be it 20 Ft > 30 Ft > 40 Ft > 50 Ft > 60 Ft or more high.
* Buy your Eight Foot (8') Ground Rod.
* Buy enough Wire for your Antenna Element.
* Buy / Build your 9:1 Matching Transformer.
* Buy enough Coax Cable to go from the Ground Rod
and al the way into your Radios.
* Buy enough Rigging Rope and Insulator for your Antenna.
BUILD YOUR VERY OWN INVERTED "L" ANTENNA ! ! !
http://www.wellbrook.uk.com/longwire.html
{ Just Do It Right The First Time ! }
.
The Message is Simple - The Object is Clear.
.
If You Built It - You Will Hear Them ! and I Dipole You Not !
.
.
iane ~ RHF
.
RHF
antenna is not important on receive and only important on transmit. "
Telamon - Did I in-fact say that ? ? ?
[ Please re-read my original posting again. ]
.
AMATEUR (HAM) RADIO VIEW POINT :
If... I were into the Amateur (Ham) Radio process of Two-Way
Communications that requires an Antenna for both Transmitting
and Receiving : Then a Dipole would be one of the first Antennas
that I would consider using. Because as you so ably point out
it is a very good antenna to use to Operate on a specific band
of frequencies like the Ham Radio Bands. Plus when a Dipole
Antenna is properly set-up it is a very good directional antenna
for Amateur Radio use.
.
SHORTWAVE LISTENER (SWL) VIEW POINT :
[ The Average Joe Shortwave Listener (SWL) - I have a Radio and
want an (One) Antenna to improve what I can Hear without any other
gadgets that get-in-the-way of simply Listening to the Radio. ]
However, since I am only a Shortwave [Program] Listener (SWL)
and I do not listen to a single band of Shortwave Frequencies.
My Focus is on Receive "ONLY" Antennas [.]
* I want to Listen {Hear} to the Entire Shortwave Band and
the AM {Medium Wave} Broadcast Band (BCB).
Note - So my Antenna needs are not necessarily well served by
a Dipole Antenna.
* My need is to "Listen" {Hear} Everyone; on All Frequencies;
in All Directions.
Note - My need is not to Talk and Listen to one individual;
on one frequency; in one direction.
* I want a Single (One) Antenna to cover the Entire Shortwave Band
and the AM {Medium Wave} Broadcast Band (BCB). A very broad
banded Antenna that 'by-design' will be generally good on all
frequencies; but very poor on any specific frequency.
* I want a Single (One) Antenna to receive from All Directions
across Shortwave Bands and the AM {Medium Wave} Broadcast Band (BCB).
A very Omni-Directional Antenna that 'by-design' will be generally
good in all directions; but very poor on any one direction.
* I want a Single (1) Antenna to reduce all the Man Made Noise (RFI
/ EMF) that I can Hear all over the AM/MW and Shortwave Radio Bands.
.
MY CHOICE IS - The Inverted "L" Antenna that uses the Low Noise
Antenna 'design concepts' that were popularized by John Doty.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/3015
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2471
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2016
.
FWIW - Generally these Shortwave Listener (SWL) Inverted "L" Antenna
have a 'Shorter' Vertical-Up-Leg and a 'Longer' Horizontal-Out-Arm :
The Vertical-to-Horizontal (Up-to-Out) Ratio of the Wire Antenna
Element is usually 1V:2H or 1V:3H and even 1V:4H.
Note - This Up-to-Out Radio and Numbers are really not important :
But some people need a Set-of-Numbers to "Built-To" to make things
work just right in their minds, when they start a project.
.
Lastly Telamon - For the Shortwave Listener (SWL) seeking that
One Single Antenna that is : Broad-Band and Omni-Directional
and Low Noise - yes, Yes. YES ! Resonance Is Not Important.
.
.
as always and respectfully 'iane' ~ RHF
.
.
bpnjensen
>That's just the physics of the statements in question. Now if you want
to qualify it with other criteria such as "I can hear the same stuff on
a random wire" that is a different story. <
I understand your statement - and I recognize that my earlier blurb
about hearing things on the wire vs. the dipole is not strictly
speaking a physics statement. It is true, however, and a good deal of
that has to do with the frequencies in question and the resonance of
the dipole vs. the general coverage capabilities of the wire.
>A random wire is a common mode antenna that will do a good job of
picking up local electrical noise so the criteria is that you need a
good RF ground or radials in its place and you need to live in an
electrically quiet area. <
Absolutely - my problem exactly (at least the second one). I have what
I believe to be an excellent ground, in soft moist soil not far from
salt water...and it makes a BIG difference to have it hooked up...but
it's plenty noisy around these parts.
>If the Alpha-Delta DXUltra is worth the money you paid for it it should
work better then a "random wire" at some frequencies. Sometimes the
behavior of antennas or circuits is not apparent by only looking at a
small selection of frequencies. <
Right - This is exactly what I see, but also the reverse is true - the
random wire does better at some freqs - hence my additional quickie
discussion about the effective frequency ranges of each antenna. The
DXUltra is cut for SW bands, and is theoretically designed to grab most
everything down to 2 MHz, but in practical terms it falls off
dramatically below about 5 MHz. Again, it may not be high enough, but
additional height at this locale would be supremely impractical.
What I truly want to accomplish is to get the noise down at 60m and
higher wavelengths - at higher frequencies life is generally quiet
enough already.
Bruce Jensen
Telamon
"RHF" <rhf-new...@pacbell.net> wrote:
> Telamon - " The assertion that RHF made was that resonance on an
> antenna is not important on receive and only important on transmit. "
> .
> Telamon - Did I in-fact say that ? ? ?
> [ Please re-read my original posting again. ]
< Snip >
Your original post contained the reply below that you re-posted without
comment, which I can only assume means that you are in agreement with it.
Your posts are kind of long and rambling so maybe I'm mistaken.
= = = In Shortwave-...@yahoogroups.com,
= = = "Jack Painter" <223bthp@c...> wrote:
C.E.,
I didn't mean to imply that an HF antenna would normally
transmit farther than it can receive, only that a random
wire can sometimes outperform it on the receive-end.
This can happen even when listening on the transmitting
antenna's resonant frequency.
Under average circumstances, a dipole at proper elevation
and orientation will outperform a random wire (tx or rx).
- - S N I P - - -
Jack
--
Telamon
Ventura, California
RHF
.
That was the Post (at the Bottom)
That I Posted To (at the Top)
That was Posted Else Where.
.
~ RHF
. . . . .
RHF
.
FLAT FOLDED "Z" DIPOLE [ F 2 Z D ] ANTENNA Flat { Bent Horizontal "Z" }
:
F2ZD =>
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/5058
When a Shortwave Listener (SWL) says that they are going to install
a Dipole Antenna; and it is apparent that they have a very long dipole
that will be mounted very low. I suggest that the SWL install the
Dipole in the Shape of a Flat {Horizontal} Folded {Bent} "Z" with the
Arms Bent using four supports. Use four pieces of 21 Foot Top Rail at
the Corners of a 25 Foot Square. With 3 Feet in the Ground the Top of
the Top-Rail will produce an 18 Feet Antenna Rigging Height.
.
An 85 Foot Flat Folded "Z" Dipole Antenna that is Rigged on the
diagonal
between two opposite corners and the Remaining Wire is then Rigged
Clock-Wise {To the Right} to the adjacent corners.
.
This still gives the Shortwave Listener (SWL) :
1. A 'balanced' Antenna
2. A relatively 'longer' Antenna Wire
3. An Omni-Directional Antenna
.
TIP - Adding a 4:1 Balun and Coax Cable completes the F2ZD Antenna
for the Shortwave Listener (SWL).
.
NOTE - The Shortwave Listener (SWL) "Shack" Ground is the only required
Ground for the F2ZD Antenna.
.
OBTW - A Ground Rod can be installed in the Concrete base of one
or all of the Top-Rail Supports for future used.
.
FWIW - These same Four Corner Top-Rail Supports can be used to
Rig a Horizontal Loop Antenna about 100 Foot around.
.
F2ZD ANTENNA SIZING - Sizing the Square :
* 68 Feet F2ZD Antenna = 6.9MHz > 13.8 MHz > 27.6 MHz
20 Foot Square = 28' Diagonal = 80' Around
* 85 Feet F2ZD Antenna = 5.5 MHz > 11 MHz > 22 MHz
25 Foot Square = 35' Diagonal = 100' Around
* 102 Feet F2ZD Antenna = 4.6 MHz > 9.2 MHz > 18.4 Mhz
30 Foot Square = 42' Diagonal = 120' Around
Note - Standard Dipole Antenna Formula : 468 / Frequency MHz
.
.
iane ~ RHF
.
.
Telamon
"RHF" <rhf-new...@pacbell.net> wrote:
I don't Yahoo and I can't even view the message link at the top because
Yahoo wants cookies enabled, which I'm not willing to do either so with
that I don't quite get the Z shape idea other than to fit the antenna in
less space lengthwise but that shape will make it less effective.
The 4:1 BALUN is a good idea but they are not all made equal and the
response on some will fall off on the low end so watch out for that.
--
Telamon
Ventura, California
RHF
.
Yes as you indicated, when the standard Dipole Antenna is Folded
into a "Z" and mounted lower to the Ground : Then it is really no
longer an 'effective' Dipole Antenna for a single band and direction.
.
But for the Shortwave Listener (SWL) who have be told that they
have to use a Dipole Antenna; or that the Dipole Antenna is the
best Antenna; or who already bought a Dipole Antenna; or was given
a Dipole Antenna; and insists on using a Dipole Antenna. Then my
recommendation is the Flat Folded "Z" Dipole (F2ZD) Antenna.
.
The Flat Folded "Z" Dipole (F2ZD) Antenna can be a reasonably good
Broad Banded and Omni-Directional Shortwave Listener (SWL) Antenna.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/5058
.
NOTE - If only two pieces of Top-Rail can be installed as Supports
for the F2ZD Antenna; then the Wire-Ends can be Sloped to the
Adjacent Corners.
.
ALTERNATIVE - If however, the only place you can run/route the
Wire-Ends is under the Top Wires of the Dipole. Then try Sloping
the Wire-Ends back down to near the Ground at the Center-Point of
the Dipole. From the Side this looks like a squashed Inverted
Triangle (Delta). Note - Do not join the Ends of the Dipole
together to from a Loop Antenna.
.
Once Again, the 4:1 Balun and Coax Cable Feed-in-Line increases
the F2ZD Antenna's utility for the Shortwave Listener (SWL).
.
iane ~ RHF
.
.