Very practical, that's how some backhaul works(and why you see giant microwave dishes on mountain towers).

This Ars[1] article does a great job covering what goes into it. I know of more than a few WISP out there in WA state. They can't do the same data rate as fiber but getting a connection is pretty straightforward if there's any large mountains nearby.

[1] https://arstechnica.com/information-technology/2015/11/how-a...

This is kind of starting to happen with 60Ghz radios becoming more available. I think the problem with 'ultra-directional' radio antennas is that they're actually pretty difficult to build and even when they can be built they're very large. But with 60Ghz there is a lot of oxygen absorption, meaning that the signal dies off really quickly in all directions meaning that it won't interfere as much with other nearby installations. The equipment is just barely coming on to the market, though.

60 GHz PTP bridges have been around for 8 years or so, at 1GbE line rate. They're not rocket science, exactly, but knowing how to properly engineer a network with them is something that not every ISP can figure out.

Are you thinking of the siklu ones or someone else? I'm not aware of any that have been around that long (not arguing just curious) I was thinking of the IgniteNet and MiktoTik versions which I think are both more recent as well as PtMP applications which (I think?) Aren't really generally available yet.

True on knowing how to properly use them! Although to be fair I think most of the ISPs using them don't have a lot of use for really short, high capacity backhauls they're often looking for distance in rural areas.

Bridgewave shipped 60 GHz products 6 years before Siklu... Ignore the Ignitenet, it's a USB 802.11ad dongle glued into a radome. It's a toy. The Mikrotik doesn't have the reach to be a serious product. You can use "real" 60 GHz PTP stuff at five nines at 500-600 meters distance in a moderate rain zone, the mikrotik is good for maybe 90 meters.

Ah yes I forgot about Bridgewave. Agreed on all points for infrastructure needs. I would only add that when I read the OP (of this thread)'s comment I imagined using very very short/inexpensive 60Ghz links from neighbor to neighbor to create a kind of mesh. Possibly not what OP had in mind but it's the way I interpreted it. For that use the MikroTiks might actually make a lot of sense. (Very cheap and low range.)

Edit: Also since you're obviously knowledgeable about this stuff and I don't see a way to contact you on your profile - I've been running a matrix chat room around some of this stuff and would love to have you join! https://riot.im/app/#/room/#startyourownisp:matrix.org

I am a radio and network engineer, we use 71-86 GHz band FDD point to point 1 Gbps to 10 Gbps radio products extensively. One good example of a commercial ISP user that has publicized their use of such is Webpass (since acquired by Google) with their rooftop sites in the SF bay area.