which wireless protocols is limited to operating in the 5GHz range only
The wireless protocol that is limited to operating in the 5GHz range only is called "802.11a". This protocol is one of several defined by the Institute of Electrical and Electronics Engineers (IEEE) for wireless local area networks (WLANs).
To find this answer, you can start by researching different wireless protocols commonly used in WLANs. One helpful resource is the IEEE's official website, which provides detailed information about various wireless standards. By exploring the different IEEE 802.11 protocols, you can identify the one that operates exclusively in the 5GHz frequency band.