Following the Frozen Grand Central and the Trafalgar Square Freeze and another in Rome (let me know if you know of any more), San Francisco has had one too, despite the pouring rain, today in the rain at the cable-car turn around at Powel and Market. (best movie on YouTube I have found, let me know if you have found a better one)
Here are a few more movies of the Powel Street Freeze:
Youtube 2
Youtube 3
Youtube 4
LiveJournal
http://improveverywhere.ning.com/
[this is a work in progress, it is not complete yet, please leave comments at the bottom, thanks.]
I have been reading about Cantennas and the like, home made directional hi-gain wireless antennas. I fancy making one but I don’t like the internal wi-fi card approach; the losses and complications from using long coaxial cable at these frequencies seems unnecessary to me. I searched about on eBay for a while and found a nice Netgear USB wireless adapter.
Netgear USB adapter in its case.
Netgear USB adapter with its case removed.
Closeup of Netgear USB adapter’s dipole antenna.
With the old antenna removed.
A short length of coax soldered into place (very tricky).
I am going to use it to with various configurations of antennas, dishes, cantennas, yagis, waveguides and so on to see what results i get. Initially i have it attached to an old laptop’s antenna (see picture above) and it is sat in my window to check I have not damaged the card or messed up the soldering (indeed I am using it now to upload this).
My initial experiments ended in disaster, I cut off the USB Dongle’s antenna and soldered on come coax from a laptop (see the pictures) but i was getting better results through the coax than through the antenna on its end. So I dropped the coax bit and soldered the antenna on directly but it kept braking off and repeated attempts to solder it back on ended when there was nothing left to solder to! Other people seem to have manged it, but I can’t and it is not like I am so unskilled with a soldering iron either!
Instead I have bought an older USB non-dongle-type wifi adapter from eBay, a NetGear MA101, which I have attached a very short pigtail to, so I have a long USB lead and a short pigtail, which gets over the problem of a long coax being very lossy. Basically i am copying one of these designs, more specifically this one.
So far, still not much of a result………. The whole apparatus works fine but seems to be somwhere between very slightly directional and not be directional at all. As you can see from the photos, I have tried to extend the can with card and tin-foil, and shield the card’s on-board antenna with some foil, but this made no difference.
Next I am going to upgrade is to ditch the tin can (which is almost 100mm diameter, incidentally) and make a nice smooth-sided, flat-ended and long tube.
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Software
I like the look of this http://www.netstumbler.com/downloads/
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Cantenna:
This website seems to be one of the best from my point of view, a nice simple explanation of the maths and dimensions for a 100mm can which is what I happen to have here. So the can i have is a lot less than ideal, it is not smooth or the ideal size, but it will do for my first experiment.
Great site which includes lots of good info on Cantennas and the Pringles Cantenna Myth. If you take the time to work it out and not just read the crap others have written you will find the Pringles tube is too narrow and would need to be impossibly long at this frequency.
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Some links and other bits and bats for later:
This is exactly what I am thinking of off - http://www.usbwifi.orcon.net.nz/
http://www.rahul.net/dold/clarence/usb-can/im000742-800×600.jpg
http://www.qsl.net/n9zia/wireless/pics/tincanant.jpg
http://flakey.info/antenna/waveguide/
http://www.usbwifi.orcon.net.nz/
802.11b Homebrew WiFi Antenna Shootout
http://www.oreillynet.com/cs/weblog/view/wlg/448
Antenna on the Cheap (er, Chip)
“Cantenna” - yagi design for 802.11b wireless application
Pringles Cantenna - will not work!
DX Zone list of WiFi antennas - all sorts of designs
Pantenna
http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=12612
http://flakey.info/antenna/waveguide/
http://www.unwiredadventures.com/unwire/2005/12/defcon_wifi_sho.html
http://www.engadget.com/2005/11/15/how-to-build-a-wifi-biquad-dish-antenna/
http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=12611
Common Wireless Antenna Connectors
Waveguide on Wikipedia
Feedhorn on Wikipedia
Back in sunny San Francisco for a while. Weather has been fantastic. Been keeping myself busy cycling all over the city, trying to do 2 hours a day for 5 days a week! On Saturday Amanda and I cycled over the Golden Gate to Sausalito and caught the ferry back.
I usually forget to take my camera but I cycle all over the city on my own with no real sense of where I am going, which is fine for me. I make decisions as whether to turn or go straight on based on the traffic and the lights and the hills ahead.
Today i found myself climbing the highest peak in San Francisco by acident; I made the decision to climb to the top when i found myself about half the way up it already - at the top i was disappointed to find a car park and a wide road circumnavigating the Twin Peaks, typical. Still, the view was amazing with no fog and no clouds in the sky.
Panorama of San Francisco from Twin Peaks:
We have also spent a weekend in wine country, less than two hours north of SF, in the NapaValley. We hired an “economy” from a rental downtown, they did the usual “free upgrade”, expecting us to be pleased with the monster Mustang they gave us; “it is a lot of fun to drive” they said.
We drove to Calistoga and got a cheap-ish motel there. Next morning Amanda had arranged a surprise for me, turned out to be a mud bath! This is one way of getting me to do something I would not do, call it a surprise and don’t tell me until it is too late for me to back out.
After the mud-bath (which, in truth, i enjoyed rather a lot) we went for a drive, visited the Petrified Forest (three-million year old redwoods turned to stone, “discovered” in 1871 which i suspect means discovered by white-man) and on to an Old Faithful, an artificial geyser which we did not bother paying the $8 each to see. On to the mega-rich St Helena where they sell Burritos for twice what they cost in SF (bugger that!) and then to a wine tasting for $5 for 6 which seemed much more reasonable, especially since the guy serving us did not seem able to count.
Over night in Santa Rosa and a night in a very crappy motel, but it was only $60 for the room. On to The Jelly Belly factory and Berkeley Hat Co. where I bought a nice leather pork-pie/trilby/fedora type thing. Another fantastic weekend!
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