Troubleshooting WiFi Connection Problems with Radio Spectrum Analyzers
Spectrum analyzers are devices capable of detecting radio emissions across a given frequency range. They can be used to troubleshoot problems with wireless WiFi connection caused by other electronic devices.
Scanning for available WiFi access points will list available hotspots and their signal quality as well as the WiFi channel they occupy. They won't show actual radio emission happening at those frequencies. It can happen that a radio device working on similar frequency will interfere with the WiFi signal causing hard to find problems. Spectrum analyzer would show radio emission which could be traced to for example broken microwave or wireless mouse, keyboard or a bad Bluetooth device.
There is a lot of professional grade equipment on the market. Among more affordable ones we can mention RF Explorer, which covers both 2.4 as well as 5GHz WiFi ranges. RF Explorer is a portable device that can be used without any laptop or phone connected to it. Collected data can be saved and analyzed in desktop or mobile applications.
If you need extremely wide frequency range not only for WiFi then HackRF One could be a good choice. It's a software defined radio meaning you have to connect it to a computer and then program it to do given task.
To troubleshoot WiFi problems just check the frequency range used by your access point. If there are other radio emissions you will be able to see them on the frequency scan graph. If you get closer to the source the signal will get stronger so you may try to find it that way. Odd cases like microwaves don't happen to often, but out of spec radio devices like wireless mouses or keyboards are more often. If they emit strong enough signal, they might interfere with your WiFi, causing connection problems.