Comment by gus_massa

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.