The frequency range needed for a spectrum analyzer will depend on the application, meaning the frequencies to be investigated for both wanted and unwanted signals, and the purpose of the signal detection. For spectrum monitoring, for example, the frequency range only needs to include the frequencies to be monitored. For device development and EMI investigations, many standards require measurements of spurious emissions at the third harmonic of the fundamental frequency; for a device operating in the 2.4 GHz ISM band, such as a Wi-Fi or Bluetooth device, a frequency range of at least 7.2 GHz is required. For compliance to standards, in some cases spurious emissions to the 5th harmonic are required; for the 2.4 GHz device a frequency range of 12 GHz is required. For 5G devices operating in the n258 band from 24.25 to 27.50 GHz, there are very few spectrum analyzers available with the necessary maximum frequency of 82.5 GHz. Many standards from organizations such as ETSI, ANSI or 3GPP specify limits for out-of-bands emissions, much closer to the fundamental frequency. In every case, check the standards that apply to the device to test and, as a rule of thumb, aim for a maximum frequency that exceeds the maximum anticipated by 20%.