Frequency Spectra and Frequency Response in the Complex Plane

By plotting and with the aid of the digital computer, the imaginary versus real components of Fourier frequency spectra and frequency response on the complex plane, a far greater insight into system behavior is obtained than is otherwise possible. The effects of varying the position, length, and height of a single rectangular pulse on its Fourier frequency spectrum are demonstrated clearly. The frequency response of a system is graphed on the complex plane as the ratio of output to input frequency spectra.