Fractenna wrote:
I'm not taking credit. This is a minor adjustment of a Cebik design.
Seems to fit the OP's rqmts, however: no folded-dopole feed, 50 ohm
matched BW of 156-162 MHz and 5-6 elements.

Regards,

Wes


This looks like a modofied approach to an NBS Yagi-Uda.

The only special feature of the NBS designs (other than the prestigious
mailing address) was a self-imposed restriction to equal spacings
between directors. That turned out to be an evolutionary dead-end, and
you won't find it in any modern optimized yagi design.

The design proposed by Wes doesn't have that feature - fortunately - and
is actually one of the OWA (Optimized Wideband Array) family. One of the
special features of that family of yagis is a very close spacing between
the driven element and the first director, which raises the feedpoint
impedance to 50 ohms and allows a simple split-dipole driven element.

Even this feature is not original to the OWA family. I don't know when
(or indeed how often) it might have been invented, but it was first
systematically used by DL6WU some 25 years ago. With additional help
from computer analysis and optimization, the OWA family continued the
development.

Modern Y-U design allows for a higher feedpoint SWR. Matching loss is offset by
higher gain and better consistency of F/B. If no matching, then a shaped,
folded dipole is used. Typically a F/B better than 22 dB (sim) is acheived with
a 10% bandwidth.

We're now in the excellent position of having several alternative ways
to design a yagi to meet each user's specific combination of
requirements. That approach is certainly one of them.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek