Could one modify their wifi device, so it would work at a different frequency, like Like say, the 2,155mhz to 2,180MHz range?

This frequency range is almost certainly not supported by the chipset in your device, though the supported frequencies do vary by device.  Even if it did work, it would be vary illegal in almost any country.

P.S. Upon closer inspecting an Atheros based card that I have the lowest frequency that it supports is 2312 MHz, which is actually surprisingly low but still nowhere near your given range.

You can get cards which use the 802.11b protocol at 900Mhz.

Where can I find card  running 802.11b at 900Mhz?

http://www.embeddedworks.net/wlan/oem_m … 00MHz.html

I have no experience with any 900 Mhz equipment.

Great!!! Thanks.

If theres any commercial viability on the band ubiquiti might be able to help you (www.ubnt.com)... they're doing 11b/g @ 700 and 900 mhz, and 11a at 3.5, so they obviously have the technology.

I personally use both of their 900 products with great results.

Hi

oswave.com published firmware for Atheros chipset with extended range of frequencies:
# Available frequency range from 2312 MHz to 2732 MHz when operating in 802.11b/g mode (84 selectable channels).
# Available frequency range from 4920 MHz to 6100 MHz when operating in 802.11a mode (236 selectable channels).
# User selectable channel width - 40 MHz, 20 MHz, 10 MHz or 5 MHz for the whole supported frequency range.

But:
- this firmware is not free and this company seems to be in violation to GPL license conditions.
- use of non-standard frequencies is not really allowed, depending on your country, check ITU frequency chart. ( I think WiFi is classified as ISM )

regards.