Improving signal for embedded cellular modem in laptop
What laptop do you have? Some actually have external antenna connectors for this purpose. If your doesnt your best bet would be to get a cellular band RF wireless bidirectional amplifier. This detects the weak signal, amplifies it then rebroadcasts the stronger signal. Since these amplifiers typically have a much better receiver sensitivity than most celullar radios they are able to detect signals that are even below other radios noise floors. They also provide a higher transmit power but more importantly tower-packet-controlled transmit power control which makes them far superior than passive high gain antennas.
Here are in-building cellular amplifiers/repeaters:
http://www.rfwel.com/shop/home.php?cat=60 depending on how wide of an area that you wish to cater to and how weak your signal you can select the amount of gain that best suits your situation. A really nice low cost version for SOHO applications is the
Wilson Electronics SIGNALBOOST™ Mobile and Home/Office Cellular/PCS Amplifier. You would attach the velcro as close to the laptop antenna region as possible. For an entire room you would use
In-Building Wireless Dual-Band SOHO Cellular/PCS Amplifier. We recommend the latter.
Note that both of the above are dualband so they can work with Verizon or AT&T networks on both 800Mhz or 1900MHz. With the second one you would need a
high gain directional Yagi antenna (usually single band although we do have some dual band yagis
here or
omnidirectional antenna and an internal
dome antenna.
I have attached some pdf's that give a generic overview of how these amplifer could be connected. In these pdf's we show a cellular router w/ a PCMCIA/Express/USB modem but this would be replaced with a laptop in your situation. Of course if you are mounting these "outdoor" antennas inside your building you would not need the lightning surge protectors (or if you already have appropriate lightning discharge devices).
Hope this helps.