[TowerTalk] Log Periodics

[Ken Hirschberg]

Hi Pete and all -
The exception is the case of 2 elements, where 2 driven elements outperform
either the reflector-driven or the driven-director parasitic.  See the
comparison of 2-driven and 3-el Yagi on Array solutions' web site:
arraysolutions.com. Products, antennas for hams, cal-av, 2D-40.
73, Ken K6HPX,
President,  CAL-AV Labs.

Pete Smith wrote:

> At 11:35 AM 12/8/00 -0000, Tim Makins,  EI8IC wrote:
> ...
> I would thus
> >be interested to hear comments on single-band log periodics versus single
> >band yagis, with the same number of elements.
>
> This isn't directly apposite, in that it deals with so-called log-cell
> driven yagis, where in addition to the log cell a parasitic reflector and
> director are used.  However, after an exhaustive review of the literature
> and his typical careful modeling, LB Cebik concluded:
>
> "As a gain enhancement, the log-cell driver technique has very limited
> utility amid current yagi technology.  Its chief merits involve operating
> bandwidth and front-to-back ratio.  However, even here, its utility may be
> limited when the complexity and weight of the array are factored into
> antenna design and construction decisions."
>        --- NCJ, May/June 2000
>
> Extrapolating only slightly, I think there is even less of a case to be
> made for a single-band LPDA without parasitic elements, since such an
> antenna offers the worst of both worlds -- less gain, less F/B, greater
> weight and complexity, and no better useful SWR bandwidth than an
> equivalent-boomlength OWA yagi or other modern design.
>
> 73, Pete N4ZR
>
> Contesting is ... Extreme Radio
>
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>
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