sma

StarTech.com 10FT RP-SMA TO SMA WIRELESS ( RPSMASMA10MM )
$15.30
Do you need antenna cables for your wireless LAN? StarTech.com offers a variety of adapter cables to suit your specific needs.All StarTech.com cables are constructed with top-quality components.

WiFi RF Adapters for D-link, Linksys, Cisco and more
$19.95
I received this product very fast. Ordered on a Friday and received it on Monday. Everything was as described and worked fine.

+9dBi 15" 3x WiFi Booster Antenna (RP-SMA connectior) for Linksys WET11, WET54G, WMP11 PCI Card, WPS11, WMP54G, WMP54GS, WRT54GC
$8.56
... over the internal antenna in the Linksys WRT54GC, which did not come with an external one. The router always worked well at home as it was, but when I transplanted it to our office the signal didn't go very far. Adding this made a dramatic difference ... strong signal nearly everywhere in the building now. I don't know if replacing an existing external antenna would make a huge difference, but it's a terrific add-on for that router.

Hawking HWUG1 Wireless G USB Network Adapter with External SMA Jack
$59.00
So I'm looking for an Improvement in signal for a tough location at work surrounded with steel. I have a MacBook that has good WiFi and I have no complaint but I wanted a boost to get this tough signal. I installed the software at home with no issue and it worked fine. I was able to pick up a number of other wifi's in the area that I hadn't seen before with mixed strength (with my Mac or PC). All were WEP, WAP'ed and WOOP'ed looking for MAC daddies so I couldn't test them out for speed.
At my tough location at work I saw an improvement but not much. A co-worker had all sorts of USB wifi antennas that he had been testing at home with little to no results and let me try some of them. The cool part of the HWUG1 is I could just screw the cable in to the USB module .
The end result is none of his antennas gave me much of a boost although they were bigger and I could aim them where as the HWUG1 was limited. He told me that he had shopped around and had poor luck with getting much boost any of the ones he had bought (4). He even gave me the one that gave me the best results...wasn't doing him much good
I went to Kauai and the place I was staying had WIFI with a weaker signal. The MacBook did better than the HWUG1...I put the HWUG back in the bag for the rest of the stay.
I spent a lot of time reading up on the different ones. All claim to be the best... with the most Db.... Good luck
Would I buy it again...probably not. The software does let you see the signal strength which Mac does not. It is nice to be able to screw in other antennas....all-n-all not much reason to buy it. Good luck. If you find somthing better let me know