Design of a Resonant Microwave Absorber

The microwave absorbers are extensively applied in many military and civilian applications for stealth, camouflage, radar cross section (RCS) reduction, and improvement purpose of the inroom EM wave environment in anechoic chambers and indoor wireless LAN area. Although the absorbers can be categorized to many types, it is well known that more useful device in those areas is the resonant type microwave absorber such as Salisbury screen [1]. Salisbury screen, which represents one of the simplest planar types of resonant absorbers, consists of a resistive screen located a quarter-wavelength above a conducting surface, separated by a dielectric spacer. Hence, it is thick. Several practical structures for enhancing the main disadvantage of Salisbury screen have been proposed [2]-[3]. The method is to utilize periodic structures such as Frequency Selective Surface (FSS) [4] or EBG (Electromagnetic Bandgap) [5]-[6]. In this paper, we propose new designs of broadband resonant microwave absorber using a periodic structure. The simulated and measured results for the absorber structure are presented to verify the function as a broadband absorber, and based on the examination, more improved absorber structure is also proposed below.