QuickerTek (http://www.quickertek.com) has extended its line of
ExpressCard MacBook Pro products to include a new version that comes
with an external antenna that increases speed and range. The new
ExpressCard with antenna is available for US$199.95.

It sports an external antenna with 5dBi of RF power. Because it’s
external to the MacBook Pro case, it can be placed for optimum signal
strength and speed, according to the folks at QuickerTek. The antenna
itself clips to the MacBook Pro case when open.

The stock MacBook Pro has 30 milliwatts of wireless RF power. This
ExpressCard has 300 milliwatts of RF power. Additional power is
needed to penetrate walls, office equipment and floors (upstairs and
downstairs) where 25 percent of signal strength is lost at each
barrier, says QuickertTek.

All QuickerTek ExpressCards work with all Apple AirPort Base
Stations, including the 802.11n AirPort Extreme. They support all
standard security protocols including WPA, WPA2-64bit Personal and
128bit WEP, so you can log-in anywhere you have password access. They
support Mac OS 10.4 and higher, including Sleep Mode.