Scalar network analyzers measure the amplitude portion of scattering or S-parameters, reflection and transmission coefficients between the incident and reflection waves that describe a device’s behavior under linear conditions at the microwave frequency range. Most scalar network analyzers are used to measure transmission gain, transmission loss, return loss, and standing wave ratio (SWR). Traditional devices use diode detectors to convert a radio frequency (RF) input signal to a proportional DC level. This method is less expensive than the tuned-receiver approach, but inherently scalar in nature. Some scalar network analyzers include a 5 ¼” floppy drive or a 3 ½” disc drive. Others include a compact disc (CD) drive for loading programs or storing data. Tape drivers and display options are also available. For example, analog meters display S-parameter values with a simple visual indicator such as a needle. Digital readouts use numeric or application-specific display. With video displays, data is presented via a cathode ray tube (CRT), liquid crystal display (LCD) or multi-line form.