http://www.boulder.nist.gov/timefreq...al/pdf/451.pdf

Can someone please comment on the following statements and questions?
Thanks.

1 The reflector and director element lengths and spacings of Table 1 are
good for a yagis where d/lambda is 0.0085 and boom is non conducting.

2 You make a correction to the lengths when d/lambda of your reflector
and director element diameters are other than 0.0085.

3 When you use a metallic boom, you have to make corrections to the
element lengths as per Table 10.

4 I take it that whatever you put in place for DE, all spacing and
reflector and director elements continue to remain correct. So you can place
whatever you want for DE, hertz dipole, folded dipole, gamma match, T
match, DE with 1/"4 dia tube or 1.2" dia tube -it does not matter,
parasitic element lengths once calculated need not be changed whatever you
DE you place in the design. Spacing always remain the same.

5 How do you go about designing for DE?

6 Do the element length corrections due to use of a metalic boom assume a
particular element fixing method? Such as through the boom or on top of the
boom?

7 The designs are maximised for gain.

8 What is the bandwidth of a NBS designed antenna?

9 Has anyone written a program specifically for an NBS antenna so you can
calculate the element lengths without relying on tables and graphs?

10 Once designed the NBS design will probably work very close to
parameters. But strictly speaking the antenna will only work very close to
parameters if the antenna is 3 wavelenghts above ground. But for reception
purposes on VHF, you can probably ignore effect of ground and no further
design is probably necessary. (Lets face it with most bought antennas for
receivimng, you just put them up. You don't start altering element spacings
etc.)