I won't debate the differences in patterns, as I have no data on the
patterns for the NBS designs. In the ones I've built, gains measured
were pretty close to what they claimed and the claimed gains of the K1FO
style antennas from Directive Systems
http://www.directivesystems.com/antenna4.htm (for the same number of
elements) is usually within a quarter to a half of a dB of the claimed
gains of the NBS designs. I didn't notice a high sensitivity to build
errors. I used the design lengths and diameters of the elements on a
wood boom. On my 222 version, I used the T match (same thing as the
K1FO designs) and all I had to do was shorten the driven element to get
zero reflected power (which was expected since you need to make the
driven capacitive to tune out the inductance of the matching rods). Not
sure what you mean by horrid bandwidth...are the NBS designs too narrow
or too wide? Again, I've never noticed that as being a problem because
I only use my (222 for example) antenna from about 222.100 to 222.150.

Scott
N0EDV

Tom Ring wrote:
Scott wrote:

If you don't mind having a little less gain than is ultimately
possible by using an antenna modeling program, the NBS (Nation Bureau
of Standards) designs are pretty straight-forward.


NBS yagis were quite horrible actually. Not good gain, horrid
bandwidth, high sensitivity to build errors , crummy patterns compared
to anything since the early 90's. Don't bother.

tom
K0TAR