heterodyndetectors
Heterodyne detectors are devices that detect signals by mixing an incoming signal with a reference oscillator, called the local oscillator. The mixing produces a beat note at a difference frequency that can be amplified and processed, enabling detection of signals with frequencies that would be difficult to handle directly. Heterodyne detection is used in radio receivers, optical systems, spectroscopy, and metrology.
Principle: A nonlinear element such as a diode mixer combines the input signal frequency f_sig with the
Applications: In radio technology, heterodyne receivers downconvert wideband RF to a fixed IF for amplification and
Variants and equipment: Common realizations include diode or transistor mixers, balanced detectors to suppress LO leakage