I don't mind calling the connector an RJ45, but calling this thing an "RJ45 dongle" makes my eye twitch. It's an Ethernet dongle - RJ45 can be used for a lot of other things. For example I've seen "RJ45 dongles" that convert USB to RS232 serial for the console ports on a lot of networking equipment.
I did wired WiFi for CES one year. Made having our iot devices on WiFi on the floor much better than other vendors. It’s a long boring story but it was a fun hack.
I’m actually really interested: I have a piece of stage lighting, that has a 2.4 GHz Wi-Fi controller. I’d love to convert this to wired Wi-Fi. Can you share what is necessary to achieve this hack? Can I “just” run antenna cable between router and controller? Or what kind of radio physics needs to be understood?
Truly wired WiFi is easy with the devices that have threaded SMA connectors for antennas, e.g. the motherboards or the mini-PCs that allow the use of external antennas.
With those you just need coaxial cables of appropriate lengths, also with SMA connectors, for making point-to-point connections.
If you want a network where each device can talk with any other devices, you also need a splitter, also with SMA connectors.
Many WiFi M.2 2230 cards have MMCX coaxial connectors on them, which allow the connection of internal antennas attached somewhere on the case of the laptop or mini-PC.
For these, there are MMCX to SMA adapters, which you can use together with SMA cables.
Some M.2 cards have even smaller U.FL coaxial connectors. For these there are U.FL to SMA adapters.
For devices that do not have any standard antenna connectors, one may need to modify them, to solder some RF connectors, which is hard to do without greatly lowering the quality of the WiFi links, due to additional attenuation and reflections.
I would imagine that the stage lightning microcontroller is running a variant of ESP8266 or something similar where the "antenna" are actually thick traces on a circuit board (https://www.electronicwings.com/storage/PlatformSection/Topi...). This is obviously good enough for regular WiFi, but I would imagine this would complicate an attempt for wired WiFi tenfold.
Unfortunately, I no longer have the opportunity to do this.
Some years ago, I have been working in designing certain kinds of WiFi devices.
For their testing in a laboratory, a wired setup was used, exactly as described, i.e. with SMA coaxial cables replacing the antennas in the units under test, together with splitters and/or directional couplers to implement multi-point networks, and together with attenuators to simulate a greater distance between the units under test.
The majority of the tests concerning hardware and software were done using the wired setup, which allowed the simultaneous testing of a great number of units in a small space, without interference between their different tests. Only a much smaller number of tests was done with antennas, on the units that had already passed all hardware and software tests, so only the behavior of the antennas remained to be checked.
Such tests in wired setups were done both for the production units, for quality control, and for prototypes, where new versions of hardware and/or software were developed, and it made no sense to waste time with wireless testing until the new hardware and/or software was proven to be completely functional in the wired setup.
In a testing laboratory, there would be a huge amount of coaxial cables and adapters, attenuators, splitters and directional couplers, and of WiFi interfaces, so demonstrating a complex setup would be easy. Otherwise, collecting enough devices and accessories to make an impressive demonstration would be costly when you do not actually have a need for those devices.
In a home where you have an Internet router/gateway that has external WiFi antennas and you have a desktop using one of the many motherboards that include a WiFi interface with connectors for external antennas, you could use an SMA coaxial cable between your desktop and the router/gateway, instead of using an Ethernet cable.
This would be the simplest example of wired WiFi. There are cases when this would be a good idea, e.g. when the router/gateway has only few Ethernet ports for local devices and those are already occupied by other computers. In this case buying an SMA cable may be preferable to buying an additional Ethernet switch and also preferable to a wireless connection, if your home has many neighbors who also use WiFi, creating a congestion that slows down the wireless communication.
Anecdote time (but in a more simple case): Like 15 years ago, I got tired of too many wires at home and I bought a wifi pci for my desktop computer. The problem was that the antenna was in the back, so the computer was blockink the signal. I bough a SMA extension to be able to put the antena on top of the computer and it worked like a charm. Best $5 ever.
TIL. After maybe 25 years of using this connector, I've never heard it called 8P8C. I knew Ethernet has used other physical layers including coax, which I used to run between Amigas way back in the day. But, today I finally learned about 8P8C.
RJ45 isn't even actually the same connector, at least not in the original FCC naming. That was an 8P8C keyed modular connector. RJ45 connectors had only two of the positions connected to wires (one phone line) an internal resistor between two of the other positions, and a keying bar that stuck out of the plug so they wouldn't even go into the unkeyed 8P8C jacks we use for Ethernet.
So I'll still call them RJ45 connectors. Because nobody has time to say "8P8C unkeyed modular connector" every time!
Yes, and RJ45. It used to be defined by the US FCC[1] in 47 CFR Part 68 Subpart F. Along with others, like RJ31X, RJ38, etc. The "RJxxy" numbers were the Universal Service Order Codes (USOCs), the `y` value described the use (e.g. W for wall-mounted jacks). Pages 143 & 144 of the PDF (403 & 404 of the print version) have the electrical connection diagram and the USOCs, pages 125-129 (385 -389 print) have the mechanical drawings. The unkeyed 8p8c connector we use today is also in there (pdf pgs 103-113), but the RJ45 series used the keyed connector! It's RJ31X & RJ38X that used the unkeyed 8-position series jack & 8-position plug we call RJ45 today (pdf pages 137-138).
Though the pinout was influenced by the phone standards, that’s why the first two pairs are nested into each other in the center, which you obviously wouldn’t do for a high-speed digital interface.
Yep, and these days ribbon cables are rare, instead we have Flexible Flat Cables or Flexible Printed Circuits. Ribbon cables are the old cables like IDE hard drives used, with insulation displacement connectors, while FFCs and FPCs are much thinner and use integral connection schemes (tinned pads on the cable itself get clamped by some sort of connector on a PCB).
I’ll show myself out