ANTENTOP- 01- 2017, # 021

The Three L-Antennas

Conclusions:

-The Wide L-antenna is a shortened horizontal dipole that can come close to having the gain and efficiency of a conventional horizontal, center-fed dipole

-The Tall L-antenna performs much like a vertical but with some gain towards the side arm.

-The Equal L- antenna is part- vertical and part- dipole and can favor either type by changing the angle of the side arm.

 All three forms are suitable for limited space environments and have a degree vertical and horizontal polarization which helps in both local and long distance communication.

 Wire Antenna Modeling Software

 This study answers the questions of what happens when you bend a dipole at different angles and feed it at different points.

 It is unlikely an average amateur radio operator would have the time and resources to do this study by building prototypes even if he had the desire. With modeling software a ham can do in a few hours or days what would otherwise take weeks or months, if ever.

 The results by way of software reveal how the changes in an antenna affect frequency, impedance, radiation pattern and other characteristics. Through optimization, modeling predicts the dimensions and angles that will give the best SWR, Gain or Efficiency.

There is a catch. Modeling software lives in its own perfect little world inside the computer. It works with the information given. The more sophisticated the program and the user, the better the results. In the real world we take guidance from the results but understand there will be differences in materials, design, construction, support structures and effects from near by things.

 Modeling eliminates dead-ends, gives ideas and guides us to a working antenna.

 References:

  1.     McCoy, Lewis G., W1ICP,"A Limited-Space Antenna." QST Oct. 1960: pp. 23-25

2.    "The ARRL Antenna Book." 1974- 1997. 225 Main St., Newington, CT 06111

3.     Cebik, L. B., W4RNL,"Whips, Tubes and Wires: Building a 10-Meter L Antenna." QST Dec. 1999

4.     Cebik, L. B., W4RNL,"The L-Antenna." www.antennex.com/preview/Folder01/lant/lant.htm

5.     LaBarge, Craig, WB3GCK,"The Up and Outer Antenna" www.qst.net/wb3gck/up_and_outer.htm

6.     Buddipole, Inc. 3028 SE 59th Ct. #600, Hillsboro, OR 97123

7.     MFJ Enterprises, Inc., 300 Industrial Park Road, Starkville, MS 39759

8.     SteppIR Antennas,2112 116^th Ave. NE, #1-5, Bellevue, WA 98004

9. "The ARRL Antenna Book", 22^nd edition, pg. 4.2.14

10.   Free antenna modeling program by Arie Voors. www.qsl.net/4nec2/

73! de Dick Reid, KK4OBI

From Dick: If you are interested in what happens to a radiation pattern if you bend a dipole into an L, or a V, U... side-to-side, up-or-down...  zig-zag, meander, off-center, elevated radials, etc... my QSL website about Bent Dipoles is the place to go. www/qsl.net/kk4obi

There are over thirty variations on ways to put up a dipole in limited space along with color 3D radiation patterns and details about the change in radiation characteristics, gain/SWR/impedance/efficiency/resonant length, etc. 

For modelers the 4NEC2 software models are provided for each type of bent antenna.  This allows an antenna model to be adjusted to represent your specific situation.

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