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Burr - Take a look at this Shortwave (HF) Antenna.
All-Band Sloping Inverted "L" Antenna -by- Rolf Brevig [LA1IC] http://www.hamuniverse.com/slopinginvl.html Put that 4:1 balun, a couple of insulators and some extra wire to good use! -source- Ham Universe - http://www.hamuniverse.com/ * The Inverted "L" Antenna : How It Works * "Magic" Wire Lengths * Non-Metric {Feet} and Metric {Metres} Calculations * Tuning Procedure for the Inverted Sloping "L" Antenna for Amateur Radio Operators. NOTE - This Sloping Inverted "L" Antenna design uses a a Ground Mounted Matching Transformer and Ground Rod at the Feed-Point with a Coax Cable feed-in-line. Implementing the Low Noise Design Concepts that were popularized -by- John Doty READ - SWL Longwire + Low Noise Antenna Connection + Grounding Is Key To Good Reception Three Messages to Read -by- John Doty http://groups.google.com/group/rec.r...bc6a2bf8acc12d Follow the Links/URLs provided in the Message ? Why ? Use the Sloping Inverted "L" Antenna : It only requires One above ground level Elevated Support Point. MOD - For the Shortwave Radio Listener (SWL) making one of these simple Wire Antennas the only "Modification" would be to use a 9:1 Matching Transformer {Balun, MLB} for Receive 'Only' : Instead of the Amateur Ham 4:1 Balun cited for used with a Transmitter. SIZING - The All-Band Sloping Inverted "L" Antenna for the Shortwave Radio Listener (SWL) Basic it is simply a "Random" Wire Length to cover the 'available' Space that you have in your Yard : Going from the ground* to the Apex {High-Point} of the Antenna and back to the gorund*. * Note - A Fence-Top may be used at one or both Ends instead of the ground for Safety or convenience. For Those Who - Have-to-Have "Numbers" : * SHORTY - Small Size Lot - Backyard : Short-Back-Leg = 17.1 Feet for 22m Long-Front-Leg = 24.5 Feet for 31m Total Length ~ 41.6 Feet Apex ~ 15 Feet** Ground Foot-Print ~ 30 Feet Tip-to-Tip * AVERAGE - Medium Size Lot - Backyard : Short-Back-Leg = 24.5 Feet for 31m Long-Front-Leg = 38.5 Feet for 49m Total Length ~ 63.0 Feet Apex ~ 22 Feet** Ground Foot-Print ~ 46 Feet Tip-to-Tip * BIGGIE - Large Size Lot - Backyard : Short-Back-Leg = 38.5 Feet for 49m Long-Front-Leg = 59.2 Feet for 75m Total Length ~ 97.7 Feet Apex ~ 34 Feet** Ground Foot-Print ~ 71 Feet Tip-to-Tip ** Note - If you are using a Fence-Top or other Supports : Instead of the surface of the ground : Then add their Average Height to the Apex to get the 'corrected' Height of the Apex. Doing-the-Angles of the Sloping Inverted "L" Antenna : http://www.lerc.nasa.gov/WWW/K-12/airplane/sincos.html The Angle of the Apex should be around 90 Degrees; with the Starting Angle of the Short-Back-Leg at Ground to the Apex about 60 Degrees; and the Ending Angle at Ground of the Long-Front-Leg from the Apex to Ground about 30 Degrees. FWIW - I call this Sloping Inverted "L" Antenna a Lazy Inverted "L" Antenna because the "L" is too 'Lazy' to Stand Up-Side-Down {Inverted} ![]() Be it Sloping or Lazy - It's sort of an 'L' - iane RHF {pomkia} |
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