Interestingly, virtually all of the 2-element commercial HF Yagis I've seen
successfully designed and marketed by manufacturers during my time as a ham
have been of the Reflector + DE variety. On just 40 meters, for instance,
Mosley, Hy-Gain, Cushcraft, M2, and Wilson all come to mind.
Q: Why do you think that might be?
A: Dave has hit on most of the reasons below. It's certainly not because the
manufacturers prefer to have their beams weigh more or cost more due to the
greater length of a typical reflector.
On May 18, 2012, at 1:26 PM, David Gilbert wrote:
> From what I understand of the theory, a director is capable of slightly
> (on the order of a tenth of a db) higher gain, but the tuning (spacing
> and director length) is considerably more critical in order to achieve
> that. I'd have to check, but it might even be that case that in order
> to get it optimized you'd need to adjust the driven element length as
> well. A reflector, on the other hand, gives its best gain at wider
> spacing and generally has a broader SWR curve, and also results in a
> higher feedpont impedance for the driven element. I have no doubt that
> the combination of those effects could make a reflector give higher gain
> in practice.
> Unless space (or boom length on a yagi) is absolutely critical, I'd vote
> for the reflector.
> Dave AB7E
TowerTalk mailing list