Linksys releases legal antenna add-ons for several of its Wi-Fi gateways: We've said it in this space before, and we'll say it again: in the U.S., you cannot legally mix and match antennas with Wi-Fi gateways. The FCC's Part 15 rules require that you only use antennas that were certified with the gateway that they were designed for. In response to a recent query made by a colleague of mine, the FCC wrote back a very clear response:

When using Part 15 (2.4GHz) devices, mixing and matching components is a violation of the rules. Only systems can be certified. Please see http://wireless.fcc.gov/outreach/2004broadbandforum/comments/ YDI_externalamps.pdf.

There you go. Oddly, it is perfectly legal to sell antennas separately from gateways without violating any laws. It's only deploying them that is technically illegal. We haven't heard of any letters or prosecutions, however.

Linksys isn't getting around this, but has rather taken several antennas and several gateways and paid the fees to get each of the combinations certified in a matrix. This cost them at least a few hundred thousand dollars in fees and associated expenses entirely separate from the development costs of the antennas themselves.

Linksys has two kinds of antennas and matching stands for each. One add-on, the TNC Connector Antenna, is designed for two-antenna systems: WRT54GS, WRT54G, WAP54G, BEFW11S4, and WAP11. The one-antenna device, the SMA Connector Antenna, works with more specialized equipment: WRV54G, WMP54GS, WMP54G, and WET54G.

Both antenna types cost $60 each (suggested retail), while the respective antenna stands are another $30. The stands allow mounting the antennas to a wall or ceiling.

D-Link meanwhile introduced two antennas, Tom's Networking reports, that appear to be freestanding: they don't discuss them being tested with systems, and thus are illegal to use as they suggest unless I'm missing the fine print. The D-LInk specs says, The D-Link ANT24-0400 Omni-Directional Indoor Antenna connects to a variety of D-Link Wireless PCI Adapters, Routers, and Access Points. A footnote reads, Works with any 802.11b/802.11g compliant devices with a SMA or TNC connector only.