Ask HN: What's with the DIY state of the art long-range Wi-Fi?

An upside of highly directive, P2P links is that they can provide some protection against EW, simply by nature of having a constrained field of view. Also I'll note most consumer devices (laptops, cell phones) have pretty bad antennas, they're assuming you have a router right nearby. You might get much better coverage if you're also able to provide the user with a simple USB dongle that can attach to an external antenna (e.g. a 10dBi yagi-uda)

If there is need for any input on the antennas side, I'm more than happy to help (EM PhD, design antennas for a living). 2.4GHz is relatively forgiving, you can literally hand make antennas, with some attention to detail. If you have access to shipping (I really don't know the situation) they can be mass produced on PCB.

For short range coverage you may want to consider repurposing commercial hardware (routers, access points etc) that supports OpenWRT, those should be easier to find, also used, and way cheaper than specialized hardware. https://openwrt.org/toh/start

Long range communications will require directional antennas, which implies mostly fixed and point to point. Also to achieve line of sight and avoid the fresnel zone obstruction the antennas need to be mounted higher than the highest obstacle in between. Solar power is viable, but battery backup should also be provided. Antenna masts and solar panels would make them visible from distance, and of course although the traffic can be encrypted, they scream all around the air that there is a station operating there; hidden SSID does not make their operation invisible to a spectrum analyzer or any specialized electronic warfare gear - of which the enemy has plenty - that should be taken into consideration.

Anyway, Mikrotik makes some interesting powerful wireless routers like the Metal 52 ac which can operate at over 1W both on 2.4GHz and 5GHz. They're conveniently bullet-shaped and can be supplied by PoE, so that you can connect them just behind the antenna (either directional or omni) to achieve minimum losses. I've bought some good WiFi hardware, cables and antennas at netek.eu (now wifimarket.eu) and batna24.com. Mikrotik is Latvian, Batna and Wifimarket are in Poland, you shouldn't have problems shopping from them. Wifimarket today seems to have a very reduced product line compared to a few years ago when I shopped there. They had really good antennas and cheap really good quality parts to build antennas (dipoles to make patch antennas by adding a reflector etc.) that would come very handy on the field. You may ask them if they still sell them elsewhere. (btw. no affiliation here, just a happy customer)

Think about using fiber optics at least for longer fixed paths: a couple routers with SFP can provide a gigabit connection over several kilometers, and the fiber cable can be easily buried so that it's not easy to notice and doesn't hint the enemy that a transmitter is operating nearby like WiFi would certainly do.

For very slow and long distance communication, namely text messages, LoRa can be an option to which encryption can be added externally. All other considerations about radio transmission remain valid for LoRa too, however. You may find these links interesting:

https://disaster.radio/ https://meshtastic.org/

Also worth of mentioning for different purposes: https://github.com/ExpressLRS/ExpressLRS

Best luck with everything. слава україні!

A cantenna is cheap and can easily bridge around 2-5km if there's not much noise on the spectrum.

If you want to create a meshnet, you should look for OpenWRT compatible hardware in terms of routers and clients.

There's lots of ralink or RTL based USB wifi dongles that also have support for gnuradio so you could also switch frequency bandwidths if they got a tuner on them.

An easy and stealthy low-bandwidth meshnet can easily be created with old DVB-T usb sticks because the RTLSDR allows flexible channel hopping and key rotations, if necessary.

There's also lots of RTLSDR projects that use the LoRa spectrums, and they might work if you are looking for a text based communications network. That's why I mentioned it. There's also the OsmocomBB project which also has support for RTLSDR in case you want to create your own DIY GSM network with IMSI catchers and the like :)

Wi-Fi usually has the problem that the 2.4Ghz and 5Ghz frequencies are overloaded with noise, so they are hard to tweak into a long range mesh network.

[1] https://osmocom.org/projects/rtl-sdr/wiki

[2] https://openwrt.org/toh/buyerguide