Antenna Topics

Cost Effective Ferrite Chokes and Baluns — This is an expanded version of the May 2010 'In Practice' column by Ian White, GM3SEK, in Radcom magazine. This paper explains the ins and outs of the problems caused by common mode current and offers several cost effective choke and balun designs used to eliminate such problems. [Requires Adobe Reader]
Ground Systems as a Factor in Antenna Efficiency — This classic paper by Brown, Lewis and Epstein was originally presented in Proceedings of the Institute of Radio Engineers in 1937 and is, still today, the standard referenced by the FCC, text books and many amateur radio publications. Note: This is a rather large file (about 6 Megs). [Requires Adobe Reader] 
Ground Systems as a Factor in Antenna Efficiency (Abstract) — Walter Maxwell, W2DU's (SK) brief summary on Brown, Lewis & Epstein's landmark paper (above). This synopsis was originally posted on the recreation radio amateur antenna (rraa) news group and is repeated here with Walter's kind permission.
A Ham's Guide to RFI, Ferrites, Baluns, and Audio Interfacing — An excellent tutorial written by Jim Brown, K9YC, for understanding and fixing RFI problems. Includes an excellent explanation of balun operation. A must read for anyone designing and/or building baluns. [Requires Adobe Reader]
450Ω Ladder Line Attenuation — Measured data for four types of this popular transmission line.

Another Look at Reflections (Too Low an SWR Can Kill You) — This is a series of articles published in QST in the mid 1970s (reprint courtesy of the ARRL) discussing the various facets of the operation of rf transmission lines. This is an excellent series for those interested in gaining a further knowledge of the subject. [Requires Adobe Reader] 

The Broadband Double-Bazooka Antenna - How Broad Is It? — Yes, it is broader, but for the wrong reasons. Check this out. Written by Walter Maxwell, W2DU (SK), a true antenna guru. [Requires Adobe Reader] 
Easy Way Antenna Systems — Written by John M. Haerle, WB5IIR (SK). A must read for anyone considering building a good low cost HF multi-band antenna system.   [Requires Adobe Reader] 
J-Pole Construction Drawings — Complete plans for making a 2-meter J-Pole antenna. [Requires Adobe Reader]  
NEC Wire-grid Vehicle Models — These are models that were used in my CQ article on 5/8-wave whips mounted on vehicles. The models are for mid and full size passenger cars, small pickup, and a sport utility vehicle. They are geometry models only. You must add the wires sizes, sources, loads and etc.
FT_calc_1a — An Excel worksheet developed by Ron Sanders, VK2WB, to find the correct (linear) operating conditions for using ferrite toroid cores in broadband RF power applications. This worksheet's output provides limiting voltage calcluations as well as other useful data.

Antenna Modeling Tutorials — NEC modeling is an excellent tool of learning about and designing antenna systems. NEC software can be obtained for free or at relatively low cost. If you have not yet got your feet wet in this educational and interesting area of amateur radio these articles by L. B. Cebik, W4RNL (SK) are an excellent place to start. (reprints courtesy of the ARRL) [Requires Adobe Reader]   
Part 1: Getting settled and getting started
Part 2: The Ins and Outs of Modeling
Part 3: Sources, grounds and sweeps
Part 4: Loads, transmission lines, tests and limitations