By using a spectrum analyzer, electromagnetic signals which are present at the moment of measurement can be analyzed in a fast and accurate manner. All frequency components of electrical signals are displayed in magnitude as a function of frequency in a spectrum plot. Typical applications are unknown signals which contribute to distortion, intermodulation and interferences and affect the field strengths. Using the spectral representation disturbing signals can be identified as either a pulsed or continuous disturber. Often they do not conform to the existing norms and are not allowable. Main application domain of the spectrum analyzer is the microwave area, wireless communication systems, radio and television broadcasting, and broadband applications like digital microwave radio relays or radar. In these domains the spectrum analyzer is used for research, design, production, installation and maintenance.
For EMC emission measurements the spectrum analyzer is the most important measurement device. Visible signals can be assessed with respect to the existing norms. The capture of signals in the 2.4 GHz band of Wi-Fi is accomplished in a fast and easy way by attaching an appropriate antenna and the corresponding cable. The frequency range to display is configured by entering start and stop frequency or the frequency span and the center frequency. The amplitude at different frequencies can differ by several orders of magnitudes. The intermediate frequency filter has to be adapted to the bandwidth of the signal under test, in order to be captured in the correct way. In order to represent the frequency range under investigation with sufficient detail, the measurement needs sufficient time. Disturbing signals of small bandwidth occurring in EMC measurements can be better brought out using a quasi-peak detector.