Antenas wifi

http://www.usbwifi.orcon.net.nz/

USB adaptors & DIY antenna = "Poor Man's WiFi" ?

Make 2.4GHz parabolic mesh dishes from cheap but sturdy Chinese cookware scoops & a USB WiFi adaptor ! The largest (300mm diam)shows 15-18dB gain (enough for a LOS range extension to 3-5km), costs ~US$5 & comes with a user friendly bamboo handle that suits WLAN fieldwork- if you can handle the curious stares!DIY antenna details best followed from these pix -click on a thumbnail for full size 800 x 600 images

Note -the phrase "Poor Man" is not usually considered insulting, but indicates (possibly with a degree of DIY pride) a desire to "make it do, use it up, wear it out" while laterally solving a problem. New Zealand Kiwi's are champions of such #8 wire ingenuity, with electric fences a typicalappropriate technology example. Guess our project even has East meets West cross cultural aspectsin the style of Kiwi Fruit evolving from Chinese Gooseberries !? Lab note jottings below pix rather blog style,but arose during an educational WiFi workout & are intended to stimulate others into similar DIY investigation. The author- who first wrangled antenna as a radio ham in the 1960s- is a careereducator with a flair for innovation,& has had extensive hands on DIY WiFi experiences - www.manuka.orcon.net.nz has insights into "his" Sardine Can Biquad antenna. LAB NOTES text below intended to document rather than entertain- suggest you stay with images for the latter!

http://www.usbwifi.orcon.net.nz/ (1 de 5)14/09/2005 23:40:31

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21 April 2004: The longawaited NetStumber 0.4 ( + PDA MiniStumb.) is just out ! ( www.netstumbler.com~1.2MB). Of course we've been trying all sorts of Wi-Fi cards to hand! Originally NS only favoured Orinoco PCMCIA, but the latest flavour IS talking to such cheapies as the popular NZ Dick Smith Electronics (DSE) NZ$69 USB thumb dongle adaptor (cat XH6822). This DSE sweetie is based on a ZyDAS chipset,& seems to performalmost as well as esteemed Orinocos under XP. Yah! Can't say things look bullet proof with NS 0.4 yet, but it's certainly a tempting way to go, since USB cables & active extenders are dirt cheap,& being just digital are lossless compared with COSTLY microwave coax cable & connectors. Will maybe do a roof top "sweet spot" trial from here in central Wellington, New Zealand & perhaps upload a NSfile,but picked up a AP ~500m LOS away OK. 25th April 2004: Well - ANZAC day dawned fine here in Wellington (NZ), so in best military tradition we ran a few LOS(Line Of Sight) scouting trials,supporting the USB device on a broom handle tied to the roof,fed by ~5m of regular el cheapo USB cable from an XP laptop running the new NS 0.4 inside. As always LOS means just that at 2.4GHz, & assorted in linetrees & buildings caused massive signal losses, so ~100m was all we managed while walking around the house/yard/street with a Dell Axim PDA & a Socket low power CF WiFi card. We'll give it a further trial tomorrow across the inner city Basin Reserve to Mt.Vic, where a standby Orinoco Sardine can biquad easily handles the 2km from work ( Massey University). Experiences however indicate already thatsuch simple food can reflectors at each end look only good for ~2km LOS, & this USB receiver doesn't seem as sensitive as an esteemed PCMCIA Orinoco. Sniff ! That USB adaptors ceramic antenna may be the culprit - anyone fancy a "hack" & installation of say a Biquad ?! THOUGHT - fit this thumb at the focal point of a directive antenna? Quick trials with NS 0.4 showed useful gain with even a baremetal plate behind it. Perhaps the classic "Sardine can" biquad reflector? Simple metallic plates behind the unit gave significant weak signal boost, espec. when spacings were ~32mm ( which of course is 1/4 wavelength at 2.4GHz). With DIY dishes (each 1520dB ?) then range increases to say 5-10km may result - dB maths says each 6dB gain will double the range. The real attraction with USB of course...