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For One and All,
Question is 'it' a Longwire {Random Wire} Antenna -or- Inverted "L" Antenna ? http://groups.yahoo.com/group/Shortw...a/message/6300 AMATEUR [HAM] - INVERTED "L" ANTENNA : The traditional Amateur (Ham) Inverted "L" Antennas used as both a Transmitting and Receiving Antenna usually were Symmetric Dimensioned Vertical and Horizontal Antennas. Vertical - - - Horizontal - - - - Total "Up Leg" - - - "Out Arm" - - Length Half - - - - - - - Half - - - - - - - Full 1/8 WL = = = 1/8 WL = = = 1/4 WL for XX Meter Band 1/4 WL = = = 1/4 WL = = = 1/2 WL for XX Meter Band 1/2 WL = = = 1/2 WL = = = One WL for XX Meter Band SHORTWAVE LISTENER {SWL} - INVERTED "L" ANTENNA : However, the Shortwave Listener (SWL) Inverted "L" Antenna is usually an Asymmetrical Dimensioned Antenna with a 'shorter' Vertical "Up" Leg and a 'longer' Horizontal "Out" Arm. For the Shortwave Listener (SWL) the Inverted "L" Antenna is generally built as an "Available Space" Antenna for Receive 'Only'. It goes as HIGH as "I Got Something to Hang it From" and as Long as "I Got Something to Hang It Between". Most of the Time the "Up Part" is 10-15-20-25 Feet High. Most of the Time the "Out Part" is 20-30-40-50 Feet Long. Often the Horizontal Out-Arm is Two (2X) to Three Times (3X) the Length of the Vertical Up Leg. The Shortwave Listener (SWL) Inverted "L" Antenna is usually described as Vertical - - - Horizontal - - Total "Up Leg" - - - "Out Arm" - - Length ( 1/3 ) - - - - ( 2/3 )- - - - Full 10 Feet + + + + 20 Feet = = = 30 Foot Long Random Wire 15 Feet + + + + 30 Feet = = = 45 Foot Long Random Wire 20 Feet + + + + 40 Feet = = = 60 Foot Long Random Wire 25 Feet + + + + 50 Feet = = = 75 Foot Long Random Wire 30 Feet + + + + 60 Feet = = = 90 Foot Long Random Wire Vertical - - - Horizontal - - Total "Up Leg" - - - "Out Arm" - - Length ( 1/4 ) - - - - ( 3/4 )- - - Full 10 Feet + + + + 30 Feet = = = 40 Foot Long Random Wire 15 Feet + + + + 45 Feet = = = 60 Foot Long Random Wire 20 Feet + + + + 60 Feet = = = 80 Foot Long Random Wire 25 Feet + + + + 75 Feet = = = 100 Foot Long Random Wire 30 Feet + + + + 90 Feet = = = 120 Foot Long Random Wire The majority of these Shortwave Listener (SWL) Inverted "L" Antennas "Fit" into the Sizing Range of 12 to 24 Feet High by 24 to 72 Feet Long which is about 36 to 96 Feet in Total. KC7NOD refers to the Shortwave Listener's (SWL) Inverted "L" Antenna simply as an "Improved Random Wire Antenna" http://www.kc7nod.20m.com/improved_rw.htm Read his description he says it all very well and briefly. http://groups.yahoo.com/group/Shortw...na/message/466 - - - - - TO QUOTE A PRIOR MESSAGE BY ME - - - - - * * * EXTRACTED from Newsgroups: Rec.Radio.Shortwave = = = From: (RHF) = = = Date: 11 May 2004 01:22:51 -0700 = = = Local: Tues, May 11 2004 12:22 am = = = Subject: ABOUT - Inverted "L" antennas This is why a Receive ONLY Shortwave Listeners (SWL) Antenna one that is Omni-Directional generally works better then one that is intended to be directional. * The SWL Version of the Inverted "L" Antenna works well as an Omni-Directional Antenna. The SWL Inverted "L" Antenna usually has a Vertical 'Leg' that is 1/3 to 1/2 the Length of the Length of Horizontal 'Arm'. Plus the SWL Inverted "L" Antenna usually is lower to the Ground. This closeness to the Surface of the Ground results in the SWL Inverted "L" Antenna being a form of "Near Vertical Incident SkyWave" {NVIS} Antenna. NVIS= http://www.qsl.net/k5eph/nvis.htm * These SWL Versions of the Inverted "L" Antennas can be any size because they are in-fact simply Random Wire Antennas that are designed to fit the available space. http://groups.yahoo.com/group/Shortw...nna/message/54 * The Inverted "L" Antenna 'Shape' lends itself to the Design Concepts of a "Low Noise Antenna" that has been popularized by John Doty; consisting of: Antenna Element; Matching Transformer; Grounding Point; Coax Cable Feed-in-Line; Radio/Receiver. DOTY= http://www.anarc.org/naswa/badx/ante...e_antenna.html http://groups.yahoo.com/group/Shortw...enna/message/2 http://groups.yahoo.com/group/Shortw...na/message/374 - Two Reasons to use a Balun (Matching Transformer) with a Receive Only Antenna. DOTY= http://www.anarc.org/naswa/badx/ante..._longwire.html http://groups.yahoo.com/group/Shortw...na/message/150 - Magnetic Longwire Balun (MLB) - Build Your Own "DIY" http://groups.yahoo.com/group/Shortw...na/message/177 http://groups.yahoo.com/group/Shortw...na/message/466 http://groups.yahoo.com/group/Shortw...na/message/467 - Balun Reading List ( Long ) http://groups.yahoo.com/group/Shortw...na/message/337 - The "Grounding-Point" = Ground Rods and Ground Wires ETC. DOTY= http://www.anarc.org/naswa/badx/antennas/grounding.html http://groups.yahoo.com/group/Shortw...na/message/425 http://www.hard-core-dx.com/nordicdx/antenna/ground/ http://groups.yahoo.com/group/Shortw...na/message/470 http://groups.yahoo.com/group/Shortw...na/message/539 For those who want a 'Set of Numbers' to Build their SWL Inverted "L" Antenna here are a few 'Sets of Numbers' to consider for your available space: - 10Ft High Vertical 'Leg' with a 20-30Ft Horizontal Arm having a Total Length of 30-40 Feet. Also: 20x40-60 & 30x60-90 - 15Ft High Vertical 'Leg' with a 30-45Ft Horizontal Arm having a Total Length of 45-60 Feet. - 25Ft High Vertical 'Leg' with a 50-75Ft Horizontal Arm having a Total Length of 75-100 Feet. - 35Ft High Vertical 'Leg' with a 70-105Ft Horizontal Arm having a Total Length of 105-140 Feet. NOTE: The Amateur/HAM Inverted "L" Antenna is usually made-up of Two Equal Sections One Vertical 'Leg' and One Horizontal 'Arm'. These Two Equal Section can be: * 1/8th Wavelength = Quarter Wavelength Total * 1/4th Wavelength = Half Wavelength Total * 1/2th Wavelength = One Wavelength Total Because of the 'equal' proportionality, the Amateur/HAM Inverted "L" Antenna is most often Higher above the Ground then the SWL Version. Dr. Ace's [WH2T] Inverted L Antenna Info ACR= http://www.bloomington.in.us/~wh2t/invertedl.html http://groups.yahoo.com/group/Shortw...na/message/309 iane ~ RHF - - - - - Un-Quote - - - - - MORE MESSAGES TO READ : The 'Best Shape' (Configuration) Antenna that lends itself to the Low Noise Antenna Design is the Inverted "L" Antenna. http://groups.yahoo.com/group/SWL-AM...nna/message/10 Understanding the Random Wire Antenna . . . and Building a Better One ! http://groups.yahoo.com/group/Shortw...na/message/200 Inverted "L' Antenna Reading List http://groups.yahoo.com/group/Shortw...na/message/374 "LOW NOISE SWL ANTENNA" - by Mark Connelly [WA1ION] http://groups.yahoo.com/group/Shortw...na/message/119 "Another Look at Noise-Reducing Antenna Systems" Inverted "L" Antenna as an 'available space' SWL Antenna http://groups.yahoo.com/group/Shortw...nna/message/54 "LOW NOISE SWL ANTENNA" - popularized by John Doty. http://groups.yahoo.com/group/Shortw...enna/message/2 MORE LINKS TO READ : RRS = http://tinyurl.com/8wj86 RRS = http://tinyurl.com/aw7ox iane ~ RHF . . Tous Sont Bienvenus ! - - - Groupe par Radio d'auditeur d'onde courte pour des Antennes de SWL http://groups.yahoo.com/group/Shortwave-SWL-Antenna/ . Alle Sind Willkommen ! - - - Shortwave Radiozuhörer Gruppe für SWL Antennen http://groups.yahoo.com/group/Shortwave-SWL-Antenna/ . Tutti Sono Benvenuti ! - - - Gruppo Radiofonico dell'ascoltatore di onda corta per le Antenne di SWL http://groups.yahoo.com/group/Shortwave-SWL-Antenna/ . Todos São Bem-vindos ! - - - Grupo de Rádio do ouvinte do Shortwave para Antenas de SWL http://groups.yahoo.com/group/Shortwave-SWL-Antenna/ . Все *адушны ! - - - Группа оператора на приеме коротковолнового диапазона Radio для Aнтенн SWL http://groups.yahoo.com/group/Shortwave-SWL-Antenna/ . ¡Todos Son Agradables! - - - Grupo de Radio del oyente de la onda corta para las Antenas de SWL http://groups.yahoo.com/group/Shortwave-SWL-Antenna/ . = = = = = Translation = = = = = All are Welcome - - - To Join the Shortwave Listeners (SWL) Antenna Group on YAHOO ! http://groups.yahoo.com/group/Shortwave-SWL-Antenna/ . . .. . |
#2
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NOTE: The Amateur/HAM Inverted "L" Antenna is usually made-up
of Two Equal Sections One Vertical 'Leg' and One Horizontal 'Arm'. These Two Equal Section can be: * 1/8th Wavelength = Quarter Wavelength Total * 1/4th Wavelength = Half Wavelength Total * 1/2th Wavelength = One Wavelength Total Because of the 'equal' proportionality, the Amateur/HAM Inverted "L" Antenna is most often Higher above the Ground then the SWL Version. Actually most "ham" inv L's are also built to fit the lot, except that total length is more important if you want it resonant, or a certain length for performance. The stock inv L is a quarter wave long. No matter the up/out ratio. Few hams run 1/2 wave inv L's, unless they are using a tuner, etc. The extended inv L is pretty common, and is usually appx 3/8 or 5/8 wl long. It's often used to reduce ground losses at the base, as the maximum current point is moved upwards off the ground. It also will give more NVIS performance unless the vertical section is very tall. The 3/8 WL version can be matched with a cap. The 5/8 WL with a coil. The only band I've used an inv L on was 160m. I've used both the 1/4 wave, and 5/8 versions. The vertical section was 45 ft, and thrown up and over a tall tree branch. But I yanked it down this last summer as it was redundant. I already have a 160m Z dipole, and can feed my dipoles as a top loaded vertical for long haul, so the inv L wasn't really needed. The shorted coax dipoles that act as a top load vertical outperformed the L most of the time. It's 42 ft tall. About the same as the L, but it has much less radation at high angles being the top loading is balanced. Unless you *want* some horizontal componant for NVIS, etc, the T vertical actually has a cleaner vertical pattern. My Z dipole outperforms the L for horizontal NVIS. MK |
#3
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MK - "Z" Dipole ?
What makes your Dipole a "Z" Dipole ? What are the Advantages of the "Z" Dipole over a stabdard Dipole ? i want to know - iane ~ RHF |
#4
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What makes your Dipole a "Z" Dipole ?
Well, it's a dipole shaped into a Z shape in order to fit this lot. What are the Advantages of the "Z" Dipole over a stabdard Dipole ? None. It is slightly inferior to a "straight" dipole. But...It's more efficient than most any kind of loaded dipole. So...It's about the next best thing to a normal straight dipole. I use it on 160m for NVIS. When I go longer haul, I go to the vertical. MK |
#5
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MK,
So a "Z" Dipole would be Rigged Flat. And in a Square Backyard say 50'x50 you run it between two opposite Corners and then along two parallel Sides; using four support points. ~ RHF |
#6
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So a "Z" Dipole would be Rigged Flat.
And in a Square Backyard say 50'x50 you run it between two opposite Corners and then along two parallel Sides; using four support points. Yep. I can run an 80m dipole straight, but not 160m... The Z dipole works pretty well. Better than any loaded version I tried. MK |
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