Statistical Analysis of Fabrication Discrepancy Effects on Periodic Circuit Analog Electromagnetic Absorbers

Periodic circuit analog absorbers (PCAAs) are widely used to reduce electromagnetic (EM) scattering fields in various applications. Their performances are sensitive to various geometric parameters. Thus, the stability and sensitivity of the EM absorbing characteristics of PCAAs during a fabrication discrepancy due to the manufacturing uncertainty were investigated. These discrepancies are large in terms of the wavelengths at high frequencies. This article considered randomly produced nonuniform thicknesses of a conductive ink to fabricate the array structure of a PCAA and its two sandwiching dielectric substrate layers on both sides. To examine the discrepancies in fabrication, the thicknesses of the conductive ink were generated from random numbers with a desired mean value and a reasonable standard deviation of the normal distribution. To indicate the EM-field absorbing capability, we studied characteristics, such as S-parameters (reflection and transmission coefficients) and the resulting power efficiency, using numerical high frequency structure simulator (HFSS) full-wave simulations at a frequency band of 10 GHz. They were further validated by conducting experiments on prototype samples. We observed that the resonant frequencies were considerably affected by the thickness of the conductive ink in the PCAA structures. A fabrication accuracy of less than 10(-4)lambda was required to attain a stable performance.