Any router which supports 802.11b should work and most of them do. We have successfully used:

• Apple Airport Express
• TP-Link WR700n
• TP-Link TL-MR3040 (battery powered)
• Verizon MiFi 4510
• Linksys E2000 (* had to turn off WiFi Protected Setup on the router in order to get reliable connections – with WiFi Protected Setup turned on the WiFi Link (in router mode) would sometimes not associate with the Linksys router.
• Linksys WRT54G2 (was set to Manual Setup – not WiFi Protected).
• Linksys AC1900 (works well in commercial buildings – can be used along with TP-Link TL-MR3040 routers (or Airport Express) to create large network for multi-fan testing).