Spectrum analyzer antenna

I was looking into renting a spectrum analyzer to test one of my zigbee boards and am quite confused with the antenna options out there and was hoping someone could shed some light on this :

So there are quite a few models of analyzers out there which look at a farily high spectrum, 7Khz to 8GHz etc but most/all the antennas only seem to have bandwidths of upto 1Ghz or at the max 2 Ghz.

Any of the other antennas which have higher bandwidths go upto 18Ghz and are HUGE horn antennas which need a wooden tripod and an additional preamplifier (i.e. lots of $$$)

any idea what people typically use for looking at the 2.4 Ghz range interms of an antenna which has a well documented (maybe caliberated) gain??