late to the party...
I realize you mentioned "on the go" and portability so this may or may not be of interest. But the following three items are a a real bargain to extend your range and signal strength 10x at home or on the road. I've used them all among many other wifi gadets over the years.
3.53 shipped free from ebay
Product Feature:
Chipset:Realtek 8188CU
Peak throughtput: 150Mbps
Antenna: 2dBi antenna
en/UploadFiles/SL-1501N.jpg wireless transmission speeds up to 150Mbps
Built-in smart antenna
In line with IEEE802.11b, IEEE802.11g, IEEE802.11n standard
WPS security settings with one-click button, to simplify the process of the wireless security settings
Type A USB interface provides
Provides two operating modes: centralized control type (infrastructure) and equation (Ad-Hoc)
CCA technology automatically avoids channel conflicts using its channel selection feature, be sure to use the wireless network will not affect the neighbors
Supports WEP encryption, WPA/WPA2, WPA-PSK/WPA2-PSK and other advanced encryption and security mechanism
Supports PSP connection mode
Provide easy configuration, monitoring program
Support wireless roaming (roaming) technology to ensure efficient wireless connections
and this...
15.29 shipped free from ebay
*this is actually pretty small antenna dimensionally and I would doubt its Dbi rating. There are better looking panel antennas on the web for not much more.
and this.....
either 12ft ($1.46) or 15ft ($1.95) usb male/female extension from monoprice
Barely over 20 dollars in all. Leaves plenty of room for upgrading the usb wifi (many of them now sport std sma external antenna connnections) to a more powerful one. Remember though, an overpowered usb card with a 14db external antenna can be overkill if the card's sensitivity is no better than the cheaper usb card. Wifi has to broadcast AND receive.
For portablility when away from home if carrying your laptop in a protective bag you simply remove the weather protective front cover of the panel antenna, making it much slimmer and slide it into a pocket of the laptop bag. Then you can run the cable innocuously to your laptop bag and point it whereever you find strong signals. Hotspots and cafes and hotels galore in downtown areas whereever you're sitting.