007, im sure toll free modelled a 27ft sigma as thats what he was using a while back and thats what he referes to in his post,
according to the arrl the central monopole can be extended to about 3.2 x the sleeve length, after that higher angle lobes start rearing their ugly head, ( explains why i lost signal performance as i went too long with the central monopole )
i cant explain why you had the 5/8wave in front, thats not how it pans out here,
i still have not seen a pic of the fabled larry lw150 antenna,
cebik had something interesting to say about ground conductivity that he felt needed to be further investigated, it may or may not help explain why some folk just dont see what they expect,
5/8waves at moderate heights over anything but very poor soil dont provide their highest gain at low angles like they do in the free space plots,
in the real world over average to very good soils the 5/8waves major lobe is up at 35 degrees with a smaller lower lobe down towards the horizon giving only a fraction of a db improvement in gain at desireable angles over a 1/4wave when mounted at the same base height,
that more than likely explains why my low mounted i10k works superbly for short hop skip but not as good as the sigma style over distance locally or in longer hop skip,
another thing cebik notes is that a 90 degree radial 5/8wave provides its highest gain and lowest angle of radiation when mounted over very poor conductivity soil,
over very poor soil the 5/8waves lower lobe becomes the major lobe,
over better conductivity soils the 5/8 waves secondary upper lobe is dominant with less energy going into the more desirable lower angles,
it seems not everybody will get the same results depending on your soil conductivity all else been equal,
im sure the same antenna will not work best at all locations
