A laptop-based spectrum analyzer with a directional antenna is the best solution for locating a non-802.11 device that is suspected of causing interference on the WLAN. A spectrum analyzer is a device or a software application that can measure and display the frequency spectrum of electromagnetic signals in a given range.
A spectrum analyzer can show the amplitude, frequency, bandwidth, modulation, and other characteristics of different signals in the spectrum, which can help identify their sources and types. A spectrum analyzer can also detect non-802.11 devices that may cause interference on the WLAN, such as microwave ovens, cordless phones, Bluetooth devices, or radar systems. A laptop-based spectrum analyzer is a software application that runs on a laptop computer and uses an external USB adapter as its RF interface. A laptop-based spectrum analyzer has the advantage of being portable, flexible, and cost-effective compared to a hardware-based spectrum analyzer. A directional antenna is an antenna that radiates or receives RF signals more strongly in one direction than in others. A directional antenna has a high gain and a narrow beamwidth, which means it can focus the RF energy in a specific direction and reduce the interference from other directions. A directional antenna can also increase the range and sensitivity of the RF signal detection. To locate a non-802.11 device that is causing interference on the WLAN, a laptop-based spectrum analyzer with a directional antenna can be used to perform a technique called RF hunting or triangulation. This technique involves pointing the directional antenna in different directions and observing the signal strength and characteristics of the interfering device on the spectrum analyzer. By moving around and changing the direction of the antenna, the location of the interfering device can be estimated based on where the signal strength is highest and most consistent. References: 1, Chapter 7, page 282; 2, Section 4.3