why so many different type of 5G ?

See the link from SravankrA; there are 3 different 5G frequency ranges, each with different features and speeds. (I’ve been studying it for a while). The high band, which can reach gigabit speeds, hasn’t really been deployed anywhere except for a few test sites, and isn’t available at all outside of the US.

Phil0124 wrote:

Would not consider frequency ranges different 5G concepts. Just frequencies. That would be like saying there’s 3 different ethernets.

They are different in many respects, not just frequencies, from the modulation techniques, range, interference rejection and speed. And also where they are deployed. (that’s with my microwave engineering hat on).

There’s only one 5G. What are you referring to exactly?

You may find your answer here --> Understanding 5G Spectrum Frequency Bands - Telit

There are at least that many.

Original Ethernet used coaxial cable.

See this;

The Ethernet physical layer evolved over a considerable time span and encompasses coaxial, twisted pair and fiber-optic physical media interfaces, with speeds from 1 Mbit/s to 400 Gbit/s.[47] The first introduction of twisted-pair CSMA/CD was StarLAN, standardized as 802.3 1BASE5.[48] While 1BASE5 had little market penetration, it defined the physical apparatus (wire, plug/jack, pin-out, and wiring plan) that would be carried over to 10BASE-T through 10GBASE-T.

The most common forms used are 10BASE-T, 100BASE-TX, and 1000BASE-T. All three use twisted-pair cables and 8P8C modular connectors. They run at 10 Mbit/s, 100 Mbit/s, and 1 Gbit/s, respectively.[49][50][51]

https://en.m.wikipedia.org/wiki/Ethernet

Would not consider frequency ranges different 5G concepts. Just frequencies. That would be like saying there’s 3 different ethernets.

Also, I doubt that’s what the OP is referring to.

You left out token ring 😁

And don't forget that 4Mb Token Ring and 16 Mb Token Ring handled things in completely different ways...

Vampire clamps freak me out, man!