Antiresonant

Antiresonant refers to a condition in a physical system where the response to an input at certain frequencies is greatly reduced or canceled, in contrast to resonance, where the response is amplified at natural frequencies. Antiresonances arise from destructive interference between oscillatory pathways or modes, or from a system’s topology creating a zero in its transfer function. They are often characterized by a trough in the amplitude spectrum and a rapid phase change near the antiresonant frequency.

In mechanical systems, antiresonances occur between resonant peaks in multi-degree-of-freedom structures and can reduce transmitted vibration at specific frequencies. In electrical engineering, antiresonant or notch behavior is used in filters to suppress a narrow band of frequencies, producing deep nulls in the output. In optics, antiresonant effects appear in structures designed to confine light via destructive interference, such as antiresonant reflecting optical waveguides (ARROWs), which use antiresonant layers to keep light in a core.

Antiresonance also appears in acoustics, where metamaterial panels or layered media exhibit frequency ranges with very low transmission, and in quantum mechanics, where destructive interference between pathways can yield zero transmission or scattering cross sections at certain energies.

Overall, antiresonant phenomena are the counterpart to resonance in specific frequency ranges, often exploited to suppress unwanted responses, shape frequency spectra, or tailor energy transmission in varied physical systems.