Dielectric loss is the energy that is dissipated as heat when a dielectric material is exposed to a varying electric field.
Dielectric loss describes the inefficiency that occurs within an insulating material when it is subjected to alternating voltage or rapidly changing electric fields. Although a dielectric is intended to resist electrical conduction, molecular polarization within the material causes a small portion of electrical energy to be absorbed and converted into heat. This energy loss can influence electrical performance, thermal behavior, and long-term material stability.
In wire and cable construction, dielectric loss is a key factor in determining how effectively a cable supports signal transmission, particularly at higher frequencies. Insulation materials with low dielectric loss allow signals to travel with less attenuation and distortion, which is critical for coaxial, data, AV, and control cables used in commercial and industrial systems. Higher dielectric loss can contribute to reduced signal strength, increased attenuation, and thermal buildup within the cable.
The level of dielectric loss depends on the dielectric’s molecular structure, chemical composition, and density. Engineered polymers, fluoropolymers, and foamed insulation materials are often selected for their low-loss characteristics, while more basic insulation compounds may exhibit greater loss as frequency increases. Manufacturing consistency also plays a role in maintaining stable electrical properties over the cable’s service life.
Dielectric loss is commonly quantified using the dissipation factor or loss tangent, which compares the amount of energy lost as heat to the amount of energy stored in the material. Lower values indicate more efficient insulation performance and improved signal retention.
Dielectric loss characteristics are referenced in insulation testing and material performance standards published by organizations such as IEEE and IEC.
Dielectric loss was identified during early studies of alternating current behavior and capacitive materials. As communication technologies evolved and higher-frequency systems became common, reducing dielectric loss became a central focus in the development of advanced insulation materials.