1. ANTENNA MODELLING Or You can’t fall from a keyboard!

2. Modelling Techniques NEC-based Analysis Optimization techniques Empirical- and Equation-based methods Traps, Feedlines, Propagation, etc.

3. NEC Numerical Electro-magnetics Code Uses Method of Moments (MOM) NEC-2 (Public Domain) NEC-4 (License req’d, Export restrictions)

4. NEC-2 based software MININEC (several versions) EZNEC2 (dos), EZNEC3 (windows) NECWin Plus, NECWin Pro 4NEC2 and several other lesser known (?) programs

5. MININEC Initially in BASIC for small computers version 3.13 in public domain shortcomings and strengths commercial implementations available e.g. EM Scientific, Teri Software, Orion, etc

6. EZNEC By Roy Lewallen, W7EL DOS, windows, and Professional Versions Current windows version 3.0, Price US$89. Free demo version available downloadable Excellent documentation and support (Demonstration)

7. NECWin By Nittany Scientific DOS, Windows, and Professional versions NECWin Plus, Price US$ 150. User friendly 400+ page tutorial by L.B. Cebik US$ 50.

8. Other NEC-2 Based Software EZNEC and NECWin for serious Hams? Google search will find many others Try “Antenna Modelling” or “Unofficial NEC Archives” Some have demo versions

9. 4NEC2 Free “experimental version” continuing development (Arie Voors) Downloadable from Unofficial NEC Archives

10. Real and Possible Problem Areas Tapered elements Grounds Wires meeting at sharp angles Elevated radials Traps Number of segments (convergence test) Beverages

11. Traps Most programs allow modelling of traps Inserted as “Loads” EZNEC allows for R+jX form or Laplace transform polynomial But see cautions in Cebik and W8JI sites

12. Beverage modelling Exercise in frustration Ground problems low height must use S-N model Need R G for Mininec Gnd varies with depth ON4UN model ?? 2-media ground ?

13. Optimization software Yagi Optimizer - Dos? Yo - YO7 etc MultiNEC - can take EZNEC (or other) files, and run them, making changes to selected parameters between runs.

14. Demonstration of EZNEC 3.0 Using free demo version of EZNEC 3.0 Model of “Field Day Special” antenna Necessarily brief