How is spectrum analyzer operated?

A spectrum analyzer or spectral analyzer is a device used to examine the spectral composition of some electrical, acoustic, or optical waveform. It may also measure the power spectrum. There are analog and digital spectrum analyzers: * An analog spectrum analyzer uses either a variable band-pass filter whose mid-frequency is automatically tuned (shifted, swept) through the range of frequencies of which the spectrum is to be measured or a superheterodyne receiver where the local oscillator is swept through a range of frequencies. * A digitalspectrum analyzer computes the discrete Fourier transform (DFT), a mathematical process that transforms a waveform into the components of its frequency spectrum. http://en.wikipedia.org/wiki/Spectrum_analyzer

rf microwave spectrum analyzer provides a direct display

yes

spectrum analyser is single channel and cannot find ratio of phase and magnitude