> >
> > There are plenty of reasons why they are different, when you add them
> up,
> > there is enough reasons for serious operator to choose quad or Quad-Yagi
> > configurations. This is based on real 2m modeling and measurements.
>
>
> //The "Quagi" designed by N6NB 25 years ago as a hybrid quad-yagi was
> derived exactly that way: Modeling on 2m, using loop elements and linear
> elements and combinations thereof until the best results were achieved.
> Those studies indicated that beyond the reflector and DE, additional loop
> elements provided no better results by any measurement than linear
> elements did, which is why the final Quagi design used loops for the REF &
> DE, and linear elements for all directors. Interestingly, the original
> research as reported reveals that the real reason for the loop DE was
> simply a highly efficient way to transfer energy without the use of any
> matching devices. In the Quagi design, the loop terminates in an SO-239
> connector soldered directly to the copper wire comprising the loop, and
> the transmission line is directly attached to that. The REF spacing is
> adjusted to provide a good match to 50 Ohm coax and adjusted in length for
> best F/B. When Overbeck originally developed this antenna, he modified a
> few commercial aluminum Yagi products for 2 meters by replacing only their
> DE and REF elements with loops, and leaving all else as-is, and was able
> to improve performance of the popular (e.g., Cushcraft) designs
> immediately by doing only that, at the antenna range set up at the Central
> States VHF Conference. The popular thinking was that the improvement was
> largely the result of eliminating the lossy "Redi-Match" used by Cushcraft
> in their design and replacing it with something having no loss, like a
> copper wire loop. -WB2WIK/6
>
> >
> > 73 Yuri
>
>
>
|