I tested signal strength by a somewhat unscientific method --using a Web-based Internet connection speed tester from McAfee, the PC security software company. McAfee claims the tester measures connection speed, but since it uses an ftp download test, it may also be partly testing throughput of the receiving device. It was the best we could find for testing a PocketPC unit on short notice. The Internet connection is a cable-modem service from Rogers Communications Inc., a Canadian cable TV company, with top speeds of 1.5Mbps download.

I tested four devices: the iPaq with the SanDisk card; my main PC, a Dell Dimension 4300, which is wired to the Netgear router; a Toshiba laptop with a two-year-old Actiontec 802.11b card; and a 600MHz HP desktop PC located one floor away and connected via an ActionTec Wi-Fi PCI card.

The results were all over the map, but there were some interesting patterns. The wired Dell PC scored highest, naturally, with speeds from 678 to 980Kbps. The wireless Toshiba laptop and the downstairs HP desktop scored slightly less -- 370 to 428Kbps.

In each case, I tested the iPaq with the SanDisk card at the same time as the other devices and at the same distance from the router. It always scored significantly lower than the other Wi-Fi devices -- from about 170Kbps in the downstairs location to a high of 240Kbps upstairs.

Although I could not do a similarly comparative test of the SD card's range, I did test it by moving progressively away from the router. At about 30 feet through a door and one wall, it measured 200Kbps on the McAfee connection test. At 45 feet it was down to 109Kbps, and at 60 feet 63Kbps.

The bottom line is that the SanDisk SD card appears to perform poorly compared to standard PC and PCI card Wi-Fi cards. It's not clear if this is a result of some necessary engineering compromises related to the SD form factor, or just the expected inferior performance of a first-generation product.

I have one other concern about the SanDisk card. It sticks up above the top of the iPaq unit by almost an inch. The light plastic casing is not a problem with SD flash memory cards that insert all the way into the slot, but with this extension for the antenna, I would be concerned about damage even in normal-use environments.

Plus, the iPaq won't fit in any standard protective case with the card installed.

That said, the SanDisk product appears to be the only game in town at this point for those with just an SD slot (and pity the poor Sony CLIE owners that have only a Memory Stick). SanDisk is also promising an even more attractive version some time in Q4 -- a Wi-Fi card with 256MB of flash memory in the same form factor. No price yet on that product.

This article originally appeared on Wi-Fi Planet.