An L-shaped band elimination filter on the T-shaped joint part is also used for restricting the resonance of the frequency multiplication of the first resonance frequency.

Band-pass filter often used in anti-jamming devices, in order to receive a valid signal within the band, while the elimination of high frequency and low frequency interference and noise.

Harmonic analysis and elimination system based on hybrid active power filter is proposed in this article to solve the serious problem oi harmonic pollution in power grid.