theres probably more info about the gainmaster on their website than any other cb antenna out there, the internal layout is shown in the user manual,
http://www.gain-master.it/Id-406%20Gain%20master.pdf
it claims to be a centerfed 5/8wave dipole which does need the matching stub it uses or some other form of matching,
its nothing at all like an imax, more like a supercharged big-stick,
sirio know how to make great performing antennas,
when they hit the market we can test the veracity of their low angle gain claims
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Hmm,
i think its a centre fed halfwave dipole,
as shockwave has posted about the i max in the better antenna thread,the i max has a capacitor in series with the radiator which electrically shortens it,therefore you need to make the radiator longer to compensate,which begs the question is the i max a 5/8 wave with a longer than normal radiator to compensate for the series capacitance rather than a .64 wave like some people claim?
anyway getting back to the sirio,now we find it also has a capacitor in series with the radiator,now if the right value capacitance was chosen you could make the radiator to appear like the top half of a centre fed 5/8 wave,very shrewd or very cunning ? i'll let others judge that,i have my own opinion.
they say a picture says more than a thousand words,in this case two pictures may well tell a lot more truth than sirios hype,for me the givaway in the gain master pdf is the current distribution and the radiation pattern.
the radiation pattern is typical half wave dipole mounted in free space when the antenna is balanced,funnily enough the rf current distribution is also typical of a 1/2 wave dipole,how can that be if its a 5/8 wave centre fed dipole?
have sirio rewrote physics ? or just cunningly bettered on shakespeares design (the same way they did on avanti's sigma 4 design) by including a choke to ensure balance,cut down on common mode current and no doubt give a much cleaner radiation pattern than a bigstick.at the same time giving the impression that it is a 5/8 wave centrefed dipole,with the keyword being 5/8 wave,everyone knows 5/8 waves are ultimately more desireable than halfwaves.
i think its a very clever manipulation by sirio to improve sales on what looks like a very well thought out centre fed halfwave dipole,i may be wrong but those radiation pattern/rf current distribution pics tell a story.if it truly was a centrefed 5/8 wave dipole,current maxima would not be in the centre.
