Local Electric Field Enhancements of Two Closely Spaced Subwavelength Spheres in Microwaves

The local electric field enhancement (LEFE) among powdered metals or dielectrics in microwaves has been widely applied in many fields, but it is still a challenge to describe the LEFE intuitively. This article presents a simple model to predict the LEFE in two closely spaced subwavelength spheres in microwaves, based on the quasistatic electric field approximation and the dipole–dipole interaction. The results show that this LEFE is related to the radius of spheres, the separation distance, and the permittivity of spheres. The proposed model is able to predict the LEFE accurately if the electric length of the two spheres is within one-tenth of a wavelength when put in free space or a waveguide. The proposed model can benefit in predicting the LEFE in subwavelength metals or dielectrics, which can benefit a wide range of applications.