Sirrio's new vector 4000 design claims 2DBD gain listed on their website, now it is getting some where, a true test result over the regular standard di pole, a full wave loop has 3dbd over a dipole, and it is just a wire.
Did some more research and found this blurb on another site, pretty well sums it up all in one.
*****5/8 Wave Vertical
There's nothing magical about the 5/8 proportion of a wavelength (62.5%), a whip this long has no special properties - a coil is needed to bring the antenna into resonance. It just happens to be close to the limit (0.64 of a wavelength) to which you can extend a single element (1/4 wave style) antenna before the radiation pattern breaks up in undesirable ways. By making the whip as long as possible compared to a 1/4 wave, we get a lower angle of radiation and a squashed radiation pattern (less signal goes upwards) and so a higher effective gain (3dB) than a 1/4 wave. Popular for mobile use, but they can lead to worse results in hilly areas as less signal gets up into the hills. If used on a handheld, you'll need to keep it vertical - which is why manufacturers usually provide 1/4 waves instead. 7/8 waves are slightly different, they are collinears - a 1/4 wave (2/8) combined with a 5/8 section, yielding a dB or so more than a 5/8 on it's own. ****End of quote
Except the Sigma is not a collinear antenna it is a shunt feed vertical.
So theory states the Sigma IV will have a whole 1DB gain
( maybe)over a 5/8 wave,1DB, do not know if I can hear that difference in my recieve.
So the real world comparision I posted of the 5/8 and the Sigma IV can be summed up to time of day, conditions, sun spots, etc. etc. as I heard the 5/8 stronger then the Sigma IV.
Great topic and really enjoyed the replies, comments, thanks to all.
