The super-hyper singular integrals in the EFIE of the second form in Eq. (1) were prohibitive and there was no direct way to evaluate them. But we have developed a novel technique to efficiently handle such singularities based on the series representation of the Green's function and a constant current approximation. The approach allows us to solve the EFIE of the second form directly. It has locality in its unknown association with space, and hence is easy to incorporate with FMA. The derived closed-form formulas can be used to calculate both selfinteraction and near-interaction terms in the impedance matrix very accurately and conveniently. The numerical errors in the scheme mainly come from the lower-order approximation for current and geometry. We can easily implement the higherorder approximation of current in the scheme because the introduction of higher-order terms only weakens the degree of singularity. We will incorporate the higher-order representation of geometry for the scheme in the future and improve the overall accuracy further. ABSTRACT: A method of measurement of the real and imaginary parts of high dielectric constant materials at THz frequencies is described. The method is based on application of double-layer sample with variable distance between slabs. The recorded power transmittance inerferogram is employed for reconstructing complex permittivity of a material under test. Reconstructing algorithm and its realization are presented. Example of measurements of the alumina sample in 0.8 -1.1 THz has demonstrated a good agreement with independent data obtained from the time-domain terahertz spectroscopy method. ABSTRACT: Negative-permeability sub-wavelength particles, namely split-ring resonators and spiral resonators, are compared and their performances analyzed for a different number of concentric rings and spiral turns, respectively. Left-handed lines are designed, fabricated, and measured that use multiple complementary split-ring and spiral resonators. More compact structures are obtained, with improved characteristics.