Inverted L Receive Antenna
Robert11
First, thanks everyone for answering my previous posts on antennas, and
providing all those great links. Have been reading on, but it certainly is
a confusing subject, at least to me, with apparently lots of contradictory
opinions.
So again, thanks very much for help; really appreciate it.
Have finally convinced the wife to go along with an outside antenna as
everyone has been suggesting to me, rather than living with the wire strung
around the 4 corners of my attic which I now have. Took some doing.
Do listening only, most anywhere from 30 on down to 0.5 MHz.
Have pretty much decided on purchasing the PAR EF-SWL (45 feet overall L,
end fed), and
configuring it close to the house as an Inverted L.
a. Is there an "optimum" ratio between the lengths of the horiz and vert.
legs ?
What does it depend on ?
b. I saw some radiation plots for the antenna, and although I don't
understand these plots fully, they don't seem to be perfectly omni. When I
string it up, I might as well try to optimize it for my preferred listening
directions.
Would this be perpendicular to the horizontal axis (e.g., if I want E-W
optimized, should the horiz wire be strung N-S, or,... ?
Or, it is so close to omni, that it really doesn't matter ? Would the
answer be (very) freq. dependent ?
c. Think there would be any meaningful losses is I run the vertical length
fastened to the house ?
d. I guess that "the higher, the better" applies here also. True ?
If so, any problem with end of the vertical also being raised from
close to ground level as a result of trying to bring everything up ?
Thanks,
Bob
Telamon
"Robert11" <rgs...@notme.com> wrote:
> Hello:
>
>
>
> First, thanks everyone for answering my previous posts on antennas, and
> providing all those great links. Have been reading on, but it certainly is
> a confusing subject, at least to me, with apparently lots of contradictory
> opinions.
>
> So again, thanks very much for help; really appreciate it.
>
>
>
> Have finally convinced the wife to go along with an outside antenna as
> everyone has been suggesting to me, rather than living with the wire strung
> around the 4 corners of my attic which I now have. Took some doing.
>
>
>
> Do listening only, most anywhere from 30 on down to 0.5 MHz.
>
>
>
> Have pretty much decided on purchasing the PAR EF-SWL (45 feet overall L,
> end fed), and
>
> configuring it close to the house as an Inverted L.
>
>
>
> a. Is there an "optimum" ratio between the lengths of the horiz and vert.
> legs ?
Not really.
> What does it depend on ?
The idea is to be sensitive to vertical and horizontal voltage polarized
waves so something around 50%.
> b. I saw some radiation plots for the antenna, and although I don't
> understand these plots fully, they don't seem to be perfectly omni. When I
> string it up, I might as well try to optimize it for my preferred listening
> directions.
This is not important as you are not going to get the antenna high
enough off the ground to worry about it.
> Would this be perpendicular to the horizontal axis (e.g., if I want E-W
> optimized, should the horiz wire be strung N-S, or,... ?
Generally you want to run the horizontal part north - south for
reception east - west. The horizontal part of the antenna will still
receive north and south just not as well.
> Or, it is so close to omni, that it really doesn't matter ? Would the
> answer be (very) freq. dependent ?
You would have to invest in expensive towers to get the antenna high
enough for the patterns to matter.
> c. Think there would be any meaningful losses is I run the vertical length
> fastened to the house ?
Yes keep it away from the house. The house is a source of noise in
addition to weakening the signals the vertical part can receive.
> d. I guess that "the higher, the better" applies here also. True ?
Higher is better.
> If so, any problem with end of the vertical also being raised from
> close to ground level as a result of trying to bring everything up ?
Yes. For a single wire antenna the other half of the antenna needs a
good RF ground, which means you don't want the coax and radio connection
to the mains ground to be the return. You want to use a UNUN from coax
to to wire near the ground level and run the vertical part of the
antenna from that point. You should have a ground rod at that same point
for the antenna/UNUN RF return.
--
Telamon
Ventura, California
RHF
Concerning the building of an Inverted "L" Antenna
for Shortwave Listening using the Par Electronics
End-Fed Shortwave Listener (EF-SWL) Antenna
READ THESE MESSAGES :
QUESTION - Is 'it' a Longwire {Random Wire} Antenna -or-
an Inverted "L" Antenna ?
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/6300
http://groups.google.com/group/rec.radio.shortwave/msg/85364956151adbba
WHY - The simple Random Wire Antenna is better than the
Dipole Antenna for the Shortwave Listener (SWL)
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/4854
http://groups.google.com/group/rec.radio.shortwave/msg/bb023dcbd76abc37
http://groups.google.com/group/rec.radio.shortwave/msg/e1d43c05075de087
http://groups.google.com/group/rec.radio.shortwave/msg/4ced7dc5f3aadadc
A SECOND LOOK - The WellBrook lay-out for a Low Noise Antenna
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/4856
http://groups.google.com/group/rec.radio.shortwave/msg/83ecfc2f91fe5c7e
BY DESIGN - The Low Noise Shortwave Listener's (SWL) Antenna
http://groups.google.com/group/rec.radio.shortwave/msg/17ab857189fec531
http://groups.google.com/group/rec.radio.shortwave/msg/481fa55268969cfd
QUESTIONS - On the Inverted "L" Antenna
http://groups.google.com/group/rec.radio.shortwave/msg/e0b3ddbed819958d
http://groups.google.com/group/rec.radio.shortwave/msg/c890a154db93a89a
http://groups.google.com/group/rec.radio.shortwave/msg/c14b09ea224f4434
WHAT ABOUT - An End-Fed Inverted "L" Antenna ?
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1971
http://groups.google.com/group/rec.radio.shortwave/msg/f6f7b5506cc942e2
http://groups.google.com/group/rec.radio.shortwave/msg/776c390272c6c91f
FLIPPING - The Inverted "L" Antenna 'Back-to-Front'
= Better Shortwave Listening (SWL) Performance
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2013
http://groups.google.com/group/rec.radio.shortwave/msg/6079890656d94af1
ANTENNAS - Five Things to Consider : Wire Antenna Element
+ Matching Transformer + Ground + Coax Cable and Planning
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1544
http://groups.google.com/group/rec.radio.shortwave/msg/103fe02cad4e5650
HOW HIGH - Should a Shortwave Listener (SWL) Inverted "L" Antenna be...
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/6585
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/6586
http://groups.google.com/group/rec.radio.shortwave/msg/61e83483a4e9ac59
LETS THINK - Out-of-the-Box {Ready-Made} Shortwave Listener (SWL)
Antennas
http://groups.google.com/group/rec.radio.shortwave/msg/a91e9554b3d7d7ee
IMHO - Your simplest and lowest coat 'ready-made' Shortwave
Listener's Antenna (Best Bang for the Buck) providing very
good results is the Par Electronics EF-SWL [End-Fed Short
Wave Listener} Antenna Configured as an Inverted "L" Antenna
with a 15 Foot Vertical-Up-Leg and a 30 Foot Horizontal-Out-Arm
[45 Feet Total] Plus a Ground Rod and Coax Cable Feed-in-Line.
http://www.universal-radio.com/catalog/sw_ant/2205.html
.
PAR EF-SWL ANTENNA READING LIST :
- Par Electronics EF-SWL Antenna configured as a
Low Noise Inverted "L" Antenna
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2593
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2603
- Why the Low Noise Inverted "L" Antenna is a Good Choice
for a Shortwave Listener
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/2002
- The 'simple' Answer (in most cases) is the
Low Noise Inverted "L" Antenna
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1785
- Make your 'basic' Inverted "L" Antenna a
LOW NOISE Inverted "L" Antenna
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1717
- What "Shape" is your End-Fed Shortwave Antenna ?
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1711
.
PAR Electronics EF-SWL" End-Fed Shortwave Antenna
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/277
http://groups.google.com/group/rec.radio.shortwave/msg/672c697b586250c4
PAR Electronics EF-SWL Antenna - Setting-Up the Ground Connection
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/1666
http://groups.google.com/group/rec.radio.shortwave/msg/ee85739bddf54cc3
http://groups.google.com/group/rec.radio.shortwave/msg/9db0c1f933b5e495
No CounterPoise - Portable Antenna System for QRP and QRO
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/6596
http://groups.google.com/group/rec.radio.shortwave/msg/1eeda92918fd7b70
.
.
as always more than you wanted to know - 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
.
.
. .
.
tyer
Generally speaking "higher is better." But so is "not too close to the
house. Keeping the antenna at least 15-20 feet from your dwelling will
reduce the rfi your antenna will pick up.
All best,
tyer