ARLA/CLUSTER: FLOWA Yagi - Uma inovação no desenho de antenas direcionais

[João Costa > CT1FBF]

FLOWA Yagi

Derek Hilleard G4CQM unveils his new yagi innovation, the FLOWA, which
is an Ultra Compact design using unconventional element spacing. They
deliver true OWA wide bandwidth and stability.

Derek says:
I had the idea ten years ago when working on a research project into
Fractal Antennas, but that's another story.

These next generation yagis use unconventional parasitic element
spacing as a means of manipulating the yagis characteristics. The
problem is that software optimisers tend to move elements into
conventional positions.

I tried unconventional element spacing many times before without
success. However, over the last couple of years the amount of time I
have spent on yagi design has given me an insight into some very deep
aspects of their working and so I've come up with some 'tricks of the
trade' to make life easier and quicker.

When I got the initial spacing right, the optimiser enhanced what I
was doing as opposed to degrading it, but I had to find the biting
point!

Advantages of G4CQM's FLOWA's...

* No need for expensive NEC4 in design or analysis as there are no
tapered elements or bent wires present

* Absolutely no matching required or incorporated, true 50-Ohm feed

* Easily constructed, no pipe bending or cumbersome structures

* Highly stable design

* Amazing characteristics, for example polar pattern (F/R) holds tight
across the entire operational bandwidth in both E and H-Planes and
very wide bandwidths are possible

* The very latest yagi design concept...

Examples for the VHF bands can be seen at:
http://www.antennadesigner.co.uk/
and
http://www.powabeamantennas.co.uk/