SteppIR uses a Driven and Director in their 2 ele design.
W0MU-1 CC Cluster w0mu.net:23 or w0mu-1.dnsdynamic.com
On 5/18/2012 12:22 PM, W2RU - Bud Hippisley wrote:
> 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.
> Bud, W2RU
> 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
TowerTalk mailing list