A filter media for an active field polarized media air cleaner comprises two layers of dielectric material, and a high-impedance permeable net is sandwiched in the low-impedance dielectric layer.

The paper discusses high frequency discharge with dielectric electrode, emphasizing on the basic issues relating to the influence of frequency, dielectric constant on discharge and impedance match.

A novel horn feed composed of metallic ridged horn and dielectric impedance wall which has small dimension and weight is introduced.