I always assumed that the 5.0 GHz band for WiFi was some kind of recent improvement over the 2.4 GHz.

It turns out that the original specification was 802.11a, and called for 5.0 GHz. That was hard to implement or something, so they pushed out 802.11b, using 2.4 - apparently in the same frequency band allotted to microwave ovens. Anyway, that proliferated and now those channels are super noisy, hence the renewed push for WiFi on 5.0 GHz.

SOURCE:

Felt the sudden urge to fiddle with my home network configuration.

Here’s a p good article: http://www.wired.com/2010/09/wireless-explainer/