Roy Lewallen wrote:
[...]
modeling the particular situation would be a good idea before doing
any expensive and extensive tower lengthening. In all the cases I
looked at, however, the 5/8 wave vertical did show some gain over a
quarter wave vertical up to at least 14 degrees. Whether the difference
is worth the added height is up to the individual.

Another height-related factor that may be worth considering is the
effect of surrounding the lower part of the antenna by nearby buildings.
Inside a typical 2-floor home are 3-D grounded meshes of electrical
wiring and (in many countries) central heating pipes. The wiring mesh
typically extends up to 6m/20ft above ground, which may be a significant
fraction of the antenna height.

For example, in the suburban situation here, the lower part of my
vertical for 40m was almost completely surrounded by these "scattering
objects" at distances ranging from 0.5 to 2 wavelengths. I never got
around to modeling the effects of these objects... though someone could
easily try it.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek