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The collinear antenna was historically used by base station sites, stacking various 1/2 wave dipole elements on top of each other for increased gain connected by some equipment to correct for phase error between the elements of the array. The higher in frequency the better in gain you can achieve in a relatively small assembly. The eight element array built here will yield 6dBi gain (reference: By Brian Oblivion and Capt.Kaboom, modified by Richard A Wenner). http://www.nodomainname.co.uk/Omnicolinear/2-4collinear.htm I used some old "Ethernet" thicknet coax, it's just well shielded RG8U. Fed by a small 1 or so watt "linear" that also includes a preamp on receive, connected in turn to the WRT54G box running HSMM-MESH. It should get out pretty well, but nobody else is in the area... I do see a lot of wifi routers in the neighborhood.
 I used a halfwave groundplane a quarter wavelength below the bottom 1/2 wave segment. Here it is in a crawl space closet just under the house roof.
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