At 08:37 AM 4/6/03 -0500, you wrote:
>Hi Pete,
>18 feet is closer to .14 wavelength. Dr. Lawson says with that boom length
>gain is around 7 dBi with around 11 dB f/b
Yeah, I did the math wrong by half. The physical dimension is correct, but
you're right -- it's .137 wl.
Thanks to everyone who provided info -- It seems as if there are some
conflicting numbers in the W2PV book. Per K4JA, he calculates on page 1-22
that a 2-element NBS yagi with a boomlength of .2 wl will have a modeled
gain of 6.7 dBi. NBS's own calculations indicated 4.8, while two other
methods he used (realizing this is a while ago) gave 6.7 and 7.5.
K8IA says that in Chapter 8 "Practical Designs," he shows a 2 el DE-Ref
yagi on a 232" boom (19'-4"). Its gain appears to be 7.02 dBi, with F/B of
10.8 db. WW3S confirms this reading.
On the other hand, per K1SR, it looks like 6.41 dBi, presumably from
elsewhere in the book.
Looks like I'm in the ballpark, anyway -- so far my model with an 18-foot
boom and 38-foot elements roughly center-loaded shows 6.43 dBi and a peak
F/B of 13 dB.
Thanks again!
73, Pete N4ZR
The World HF Contest Station Database was updated 2 April 03.
Are you current? www.pvrc.org/wcsd/wcsdsearch.htm
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