On a spare Sunday afternoon I put it all together, and to my surprise, it works exceptionally well!

With the dongle plugged into my computer I rarely get a 3G service.  With this woktenna I get 4-5 bars of 3G.  The best I've got is number 13 or -87dBm, a workable connection with 5 bars solid.

Parts:

• One Mesh fruit bowl from Myers $30
• One Active USB cable (5m)  from Jaycar $14.95
• One Paper Towel Holder from a bargain shop $2
• One beer coaster
• An old speaker mounting bracket
• Scraps of aluminium, bike parts and a drink bottle lid.

The focal point of the dish is 190^2/(4*105) = 85.95mm.  This is just shy from the edge plane of the rim.

Here's a small ruby script that displays the signal strength directly from the Huawei E169.  It requires

sudo gem install ruby-serialport

#!/usr/bin/ruby

#puts "hi"

require 'rubygems'

require 'serialport'

require 'readline'

sp = SerialPort.new "/dev/tty.HUAWEIMobile-Modem", 38400

sp.read_timeout == 200

1000.times do

  sp.write "AT+CSQ\r\n"

  j1 = sp.readline

  t = Time.new.to_s

  puts "TIME: " + t + "SIGNAL: " + sp.readline

  sp.flush

  sleep(1)

end

#puts "ho"

Recipe

• 3G USB Modem with external antenna connector
• Pigtail cable from USB modem to external antenna
• DrayTek 2820n 3G/ADSL/Wifi Router
• G-Spotter Broadband Antenna
• Optional : Big Wifi Antenna

Commentary

I've used an Optus E169, and Telstra Sierra Wireless 301 USB modems in pre-paid mode to maintain great, permanent 3G connectivity in places where the service is unreliable via a 3G handset.

Both of these dongles have an external antenna connector.

I use an external antenna mounted on a tripod.

3G Long Range Antenna
http://www.broadbandantennas.com.au/

To share the 3G connection I use a Draytek Vigor2820n.  This ADSL/Wifi router also has a USB port and displays the 3G radio reception signal strength in the browser. It redials the 3G connection on demand, if required.

Draytek Vigor2820n
http://www.draytek.com.au/products/Vigor2820.php

This was my setup while travelling recently.  Using it I can scan the horizon for the strongest signal (much like peaking a satellite dish). In some remote places where there is no GSM service on phones I can at least get a GPRS service to the outside world.

If you can get a 3G service, adjusting the directional antenna can optimise it.

There's no webpage on either carrier showing you how much trafficyou've used with prepaid, you have to put the dongle in a laptop and (optus: send an SMS with their software, Telstra: use the connection app to query the balance).

The latency on both 3G services I used was fine for my use.  I conduced multi-party (8) videoconferences with US and EU endpoints. Skype video fine, YouTube fine. No sweat with the 4Mbps connection I'd usually get. As a test, I was watching the recent Broadband Futures event streamed live to my beachside cabin – it worked fine.

<BEWARE>Re-charging a Telstra prepaid connection takes (some time? - 48hrs).  If you use the service before the credit is made to your account, the usage on the re-charge you bought is billed at the maximum price. Only after <some time> does the billing rate adjust to what you've just paid for.</BEWARE>

See Also

Steve Jenkin's Page
http://lab-notes.blogspot.com/2009/12/wireless-broadband-plans.html