Why and when did the FCC decide to allocate the 2.5 and 2.45 GHz part of the EM spectrum to be used by things such as; cordless phones, microwaves, cellular phones, wireless netoworks, etc… Why this number and not 2.6, 2.3, 2.9, etc… Was this chosen because it’s a good frequency for cordless phones or perhaps a good frequency for microwaves to operate at and so they gave that frequency to it and everything else just followed suit because it was there?
To my knowledge, nothing except microwave ovens operate at 2.45 GHz. Cordless phones and other wireless devices operate in the 2.4 GHz range, which is slightly lower. 2.5 GHz is allocated to Instructional Television Fixed Service (ITFS), which is used to deliver educational programming to schools and such. It may be reallocated to prove 3G (third generation) wireless communications, if it hasn’t already.
It’s generally a matter of allocation of bandwidth and making sure that there will be little or no inteference between unlike devices. It’s unlikely there was any technical reason that there was a technical reason for not choosing a nearby band but there was instead a logistical one.
Have you ever seen a chart of the allocations of the EM spectrum? It’s jam packed. Every band is allocated for something or another. I would presume that it’s largely arbitrary which uses got allocated which frequencies, although guided by things like range and reasonable antenna size.