Although the design had been known earlier, the monoband log-cell Yagi array was briefly popular in amateur literature in the late 1970s and early 1980s, largely through the work of Rhodes, K4EWG, Painter, W4BBP, and Zimmer, K4JZB. The purpose of this series is to contribute a little toward the re-evaluation of the log-cell Yagi, using NEC-4 as a means of analyzing various aspects of the design.
In Part 1, I shall look briefly at a superior log-cell Yagi design, and then look at the performance characteristics of some pure Yagi designs that we might use as standards of comparison. In this way, we can begin to see more clearly where the log-cell Yagi fits into the amateur arsenal of antennas.
In Part 2, we shall examine some basic principles behind the log cell itself, with especial attention to element phasing. One might also use LPDA principles to show how a log-cell works, but the basics of element phasing can make a number of facets of both Yagi and log-cell Yagi design somewhat clearer.
In Part 3, we shall look at several (at least 4) practical 10-meter log-cell Yagi designs. I shall claim no great originality for any of the designs, although each has required considerable effort to optimize all of the operating characteristics, including gain, front-to-back ratio, and SWR bandwidth. All of the antenna designs will feature direct 50-Ohm feedpoint impedances.
In the final section, Part 4, we shall examine the V-element question. Does bending half-wavelength elements forward contribute anything useful to the performance of the log-cell Yagi? This question, of course, will involve us in a broader question of V-ing any half-wavelength element.
Part 1: An Introduction to the Log-Cell Yagi and Some Standards of Comparison
Part 2: Element Phasing and Log-Cell Design
Updated 3-5-2000. © L. B. Cebik, W4RNL. A version of these items appeared in The National Contest Journal. Data may be used for personal purposes, but may not be reproduced for publication in print or any other medium without permission of the author.
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