Bandwidth Specification WiFi/WiMax

I know that wifi and wimax use frequencies around 2.3 to 5 GHz, and that several specific bands are used (2.3,2.4,3.5,5). But,

Are there specific requirements for an antenna to use wifi/wimax? Like, is there a specific 10 dB return loss bandwidth required to be considered suitable for wifi/wimax certificaiton?

Thanks.

Typically WiFi could be in every ISM or non bands where are enough space. WiFi usually needs 20MHz bandwidth for speed up to
65MB/s . For instance can work @ 915MHz, 2450MHz, 5-6GHz, 10,25GHz 24.125GHz 56GHz? and so on. Could be variations, it depends from country.
For highest speed 40, 80, 160 MHz bandwidth and chains up to three for 1GB/s.