The propose of this paper is to design the circularly polarized antenna for mobile base station, using a curved strip dipole associated with U-shaped reflector and multi-layer metallic rod elec-tromagnetic band gap (E...The propose of this paper is to design the circularly polarized antenna for mobile base station, using a curved strip dipole associated with U-shaped reflector and multi-layer metallic rod elec-tromagnetic band gap (EBG). It can be used to simplify the single feed system of an antenna. The advantages of this proposed antenna are easy fabrication and installation, high gain and light weight. Moreover, it provides a sectoral radiation pattern, a main beam having a narrow beam width in the vertical direction and wider beamwidth in the horizontal direction, which are appro-priate for mobile phone base station. The half-power beam in the H-plane and E-plane are 60 and 14.4 degrees, respectively. The antenna is designed and analyzed by using a computer simulation technology (CST). In addition, S11, axial ratio, radiation pattern and gain are displayed. The designed technique could be confirmed by a measurement resulting from prototype antenna corresponding to simulation results. The proposed antenna has a bandwidth covering the frequency range of 1870 - 2170 MHz, and the gain of the antenna increases up to 15.11 dBi.展开更多
Concave surfaces focus sound while convex surfaces disperse sound. It is therefore interesting to know if it is possible to make use of these two opposite characteristics to enhance the band gap performance of periodi...Concave surfaces focus sound while convex surfaces disperse sound. It is therefore interesting to know if it is possible to make use of these two opposite characteristics to enhance the band gap performance of periodic arrays of solid cylinders in air. In this paper, the band gap characteristics of a 2-D square array of semi-hollow circular cylinders embedded in air are investigated, both experimentally and theoretically. In comparison with the types of inclusion studied by previous researchers, a semi-hollow circular cylinder is unique in the sense that it has concave inner surfaces and convex outer surfaces. The finite difference time domain (FDTD) method is employed to study the propagation behavior of sound across the new phononic crystal of finite extent, and the influences of sample size and inclusion orientation on band gap characteristics are quantified in order to obtain the maximum band gap. For reference, the band gap behaviors of solid circular cylinder/air and hollow circular cylinder/air systems are considered and compared with those of semi-hollow circular cylinder/air systems. In addition to semi-hollow circular cylinders, other inclusion topologies such as semi-hollow triangular and square cylinders are also investigated. To validate the theoretical predictions, experimental measurements on square arrays of hollow Al cylinders in air and semi-hollow Al cylinders in air are carried out. The results demonstrate that the semi-hollow circular cylinder/air system has the best overall band gap performance.展开更多
文摘The propose of this paper is to design the circularly polarized antenna for mobile base station, using a curved strip dipole associated with U-shaped reflector and multi-layer metallic rod elec-tromagnetic band gap (EBG). It can be used to simplify the single feed system of an antenna. The advantages of this proposed antenna are easy fabrication and installation, high gain and light weight. Moreover, it provides a sectoral radiation pattern, a main beam having a narrow beam width in the vertical direction and wider beamwidth in the horizontal direction, which are appro-priate for mobile phone base station. The half-power beam in the H-plane and E-plane are 60 and 14.4 degrees, respectively. The antenna is designed and analyzed by using a computer simulation technology (CST). In addition, S11, axial ratio, radiation pattern and gain are displayed. The designed technique could be confirmed by a measurement resulting from prototype antenna corresponding to simulation results. The proposed antenna has a bandwidth covering the frequency range of 1870 - 2170 MHz, and the gain of the antenna increases up to 15.11 dBi.
基金Supported by the National Basic Research Program of China ("973" Project) (Grant Nos.2006CB601202,2006CB601204)the National Natural Science Foundation of China (Grant Nos.50676075,10572111,10632060)+1 种基金the National 111 Project of China (Grant No.B06024)the National High Technology Research and Development Program of China ("863" Project) (Grant No.2006AA03Z519)
文摘Concave surfaces focus sound while convex surfaces disperse sound. It is therefore interesting to know if it is possible to make use of these two opposite characteristics to enhance the band gap performance of periodic arrays of solid cylinders in air. In this paper, the band gap characteristics of a 2-D square array of semi-hollow circular cylinders embedded in air are investigated, both experimentally and theoretically. In comparison with the types of inclusion studied by previous researchers, a semi-hollow circular cylinder is unique in the sense that it has concave inner surfaces and convex outer surfaces. The finite difference time domain (FDTD) method is employed to study the propagation behavior of sound across the new phononic crystal of finite extent, and the influences of sample size and inclusion orientation on band gap characteristics are quantified in order to obtain the maximum band gap. For reference, the band gap behaviors of solid circular cylinder/air and hollow circular cylinder/air systems are considered and compared with those of semi-hollow circular cylinder/air systems. In addition to semi-hollow circular cylinders, other inclusion topologies such as semi-hollow triangular and square cylinders are also investigated. To validate the theoretical predictions, experimental measurements on square arrays of hollow Al cylinders in air and semi-hollow Al cylinders in air are carried out. The results demonstrate that the semi-hollow circular cylinder/air system has the best overall band gap performance.
