GSM频段双频工作微带天线的数值模拟_英文_

GSM频段双频工作微带天线的数值模拟_英文_ 系 统 仿 真 学 报Vol. 16 No. 10 ?2266 ? JOURNAL OF SYSTEM SIMULATION Oct. 2004 Numerical Simulation of Dual-frequency Microstrip Antenna for GSM Band YU Wen-ge, ZHONG Xian-xin, WU Zheng-zhong (Key Lab for Optoelectronic Technology&Systems of Ministry of Education,Chongqing University, Chongqing 400044, China) Abstract: The novel MEMS microstrip antenna designed in this paper is very useful in cellular or PCS applications where two distinct frequency ranges exist for transmitting and receiving. The 10dB bandwidth and efficiency of the micromachined antenna are more than 8% and 78% respectively, the length is less than 1/16 wavelength. The Haar-Wavelet-Based multiresolution time domain (H-MRTD) is used for modeling and analyzing the antenna for the first time. In addition, the mathematical formulae are extended to an inhomogenous media. Numerical simulation results are compared to those using the conventional 3-D finite-difference time-domain (FDTD) method and measured. It has been demonstrated that, with this technique, space discretization with only a few cells per wavelength gives accurate results, leading to a reduction of both memory requirement and computation time. Keywords: H-MRTD method; FDTD method; microstrip antenna; MEMS; UPML absorbing boundary conditions GSM频段双频工作微带天线的数值模拟 余文革,钟先信,巫正中 (重庆大学光电技术及系统教育部重点实验室 213 室, 重庆 400044) 摘 要: 设计 领导形象设计圆作业设计ao工艺污水处理厂设计附属工程施工组织设计清扫机器人结构设计 了具有双频段工作特性的微机械微带天线,该天线适用于蜂窝通信及个人通信系统。其 10dB 带宽达到了 8%以上,辐射效率为 78%,天线长度小于1 /16 波长。首次将三维H -MRTD ,the Haar-Wavelet-Based multiresolution time domain,全波分析 方法 快递客服问题件处理详细方法山木方法pdf计算方法pdf华与华方法下载八字理论方法下载 应用于该天线的建模和分析,并将 H-MRTD 数值计算公式推广到了非均匀有耗媒质中。数值模拟 结果同传统 FDTD 方法及实验结果进行了比较,结果 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 明,每个波长只需取较少的空间离散网格,三维 H-MRTD 时 域全波分析方法便能较精确地模拟微机械微带天线,并能有效地减少 CPU 计算时间及节省计算机内存。 关键词:H-FDTD 方法,FDTD 方法,微带天线,微电子机械系统,UPML 吸收边界条件 文章编号:1004-731X (2004) 10-2266-04 中图分类号:TP391. 9 文献标识码:A staggered cell to analyze and simulate the dual frequency Introduction microstrip antenna. The major advantage of the MRTD algorithms is their capability to develop real-time time and Microstrip antennas are being used in communication space adaptive grids through the efficient thresholding of the systems due to their low profile. But main disadvantage of wavelet coefficients. with this technique, space discretization microstrip antenna is its narrow bandwidth. To make it more with only a few cells per wavelength gives accurate results, suitable for communication systems especially broadband leading to a reduction of both memory requirement and communication we should increase its bandwidth. However in computation time. Associated with practical model, an uniaxial some systems, such as two way wireless communications, in perfectly matched layer (UPML) absorbing boundary order to have simply one antenna to transmit and receive the [10]was developed, a three-dimensional formulation conditionsinformation, the antenna must be capable of operating in two of the discrete difference equations arising from the Maxwell’s distinct frequency ranges rather than just one so there is also [1-2]system is first extended to an inhomogenous medium, it is need for dual band antenna. In addition, due to the applied to the analysis of a novel dual-band microstrip antenna. miniaturization of portable communication devices, a small [3-5] Comparing with the full Si antenna, The antenna in this paper antennais desirable. [6] has more wider bandwidth and higher efficiency. The finite-difference time-domain (FDTD) method is widely used for solving problems related to electromagnetism. 1 Dual-frequency microstrip antenna However, there still exist many restrictive factors, such as memory shortage and CPU time, et al. we first adopted the The layout of the novel patch antenna for GSM band method of the Haar-Wavelet-Based multiresolution time designed in this paper is shown in Fig.1. The antenna with one [7-9] edge shorted and another edge connected to a strip of domain (H-MRTD)with compactly supported scaling transmission line is very useful in cellular or PCS applications function for a full three-dimensional (3-D) wave to Yee’s where two distinct frequency ranges exist for transmitting and receiving. The design method is based on using reactive [11] loadingto create an additional resonant frequency. 收稿日期:2003-09-27 修回日期:2004-01-20 基金项目:国家重点基础研究 发展规划 小学教师专业发展规划教师个人发展规划三年劳动实践场所建设地理教师发展规划教师三年成长专业规划 项目(G1999033105). The new antenna design follows a number of steps. First, a 作者简介: 余文革(1967-), 男, 四川渠县人, 博士生, 研究方向为 MEMS1/8 wavelength rectangular patch antenna that is shorted on 天线及电磁场数值分析。 v v ，mic rostripline HTE FL O N E , , , (1) , t v ,1 v v E Si 20 , , H , , ， ,E, t , 1 21 where , is permittivity, , is permeability, , is electric 22.5 patch ground conductivity. Each field component is expanded into scaling functions: shortw all ,(s) , , (s / s u)A u (2) and wavelets: top veiw sidev eiw , (s) , , (s / s u) u (3) Fig.1 The layout of dual-frequency microstrip antenna , (s) , 1, s (0,1) ， where, and . , (s) , , (2s) , (2s 1) one end has a resonant frequency fis created where the feed , r , (s) , 0, otherelse. ,point is selected to match the patch impedance to . Next, a 50, Expansion and testing is performed for each spatial coordinate transmission line is added to one edge of the patch (an edge not with corresponding discretization indices s , {x, y, z} parallel to the shorted end of the patch) to create two resonant , as well as for time with rectangular pulse . h(t) u , {k , l, m} n frequencies on either side of fwhile simultaneously removing r In compact notations, the x -directed electric field component the resonance at f. The reason for the dual resonance is that rin the staggered Yee’s grid of size is represented as x, y, z addition of the transmission line adds a capacitance below fr x ,,, which decreases the resonant frequency and conversely adds an E ( x, y, z, t ) , E x n k ，1 / 2,l ,minductance above fwhich increases the resonant frequency. A r klm ,,, n starting point “A” for the transmission line is selected at a ,, ( x),( y), ( z)h(t ) k ，1/ 2 l m n (4) distance from the shorted end of the patch in such that the two where x , k x, y , l y, z , m z, t , n t . created resonances are at the desired distance away from f. In rThe summation over includes eight terms ,,, addition, selecting the length of the transmission line to be a stemming from all the permutations of scaling functions and 1/8 wavelength causes the two resonant frequencies to be wavelets: symmetric about f. Since the transmission line has a smaller width r, ,,, , {,,, ,,,, ,,,, ,,,, ,,,, ,,,, ,,,, ,,,, } than the rectangular patch, its effective dielectric constant eff The representation of the other field components is easily is larger. Thus, the length of the transmission line is slightly derived through permutation of the indices and follows the longer than the length of the original rectangular patch. same rule as for standard FDTD scheme. Inserting the above The antenna using the new design method is tested and expressions into the difference equations and performing a computed by using FDTD and H-MRTD method. The [12] Galerkin test procedure leads to the following expressions dimensions (units: mm) used are shown in Figure 1. The for the electric field within each cell :thickness of substrate , The antenna is designed to {k, l, m} h , 1.5mm operate in the transmitting and receiving frequency bands of tx ,,, x ,,, , E E 3 0 100 100 GSM, where the receiving frequency band is 935-960 MHz and , the transmitting frequency band is 890-915 MHz. In order to ,,, ,,, y ,,, y ,,, z z ,， H HH H , ,,,, 1 1 1 101 102 x 110 1201 (5) , , , create two resonances at the transmitting and receiving bands ,, 1 100 y z ,, ,,Efor GSM, with non-resonance between these bands, point A by where denotes, respectively, trial and error is adjusted to be 1 mm from the bottom edge, ,0,1,2,3, {u, u ， 1/ 2, u 1/ 2, u ， 1} .for each In formula (5), there are three and its length adjusted to be 22.5mm. u , {k , l, m, n} different E value within one time step, this brings about By adopting stacked structure and adding microstrip x inconvenience for program design. In order to avoid the transmission line at a proper situation, the bandwidth of the shortcoming, we can adopt approximation as follows: antenna was efficiently broadened, while by setting a short wall at one end of the patch, the antenna was greatly miniaturized. 1 x ,,, x ,,, x ,,, (6) E , ，E ， E ， 1 3 1 100 100 100 Because silicon-based micromaching process is 2 compatible with standard IC technology, and avails integration Similar expressions are obtained for the other field with other components, silicon wafer ( ) was selected components. , , 11.7 r as a layer of microstrip substrate. Between the ground plate and 2.2 Absorbing boundary condition the wafer there is a layer of TEFLON ( ), which could, , 2.3 r The field computation domain must be limited in size suppress surface wave induced in the wafer substrate, as a because the computer can not store an unlimited amount of result, the efficiency and the bandwidth of the antenna were data. The computation domain must be large enough to enclose increased, and the radiation pattern improved. the structure of interest. In this paper, we adopted uniaxial 2 3-D H-MRTD algorithm perfectly matched layer (UPML) absorbing boundary conditions, Consider one dimension wave equation 2.1 Numerical formulations of the 3-D H-MRTD propagated along +z direction: method ,, 1 ， ,(7) E E , 0, , x x Maxwell’s curl equations in an isotropic medium: z v t v , , Vol. 16 No. 10 ?2268 ? 系 统 仿真学报Oct. 2004 0 , where , , , / , , v is the phase velocity in the me asured concerned volume. Because the conductivity , is projected in FD T D H- M RT D computation domain, it will result in numeric dispersion if we -5 use directly discrete approximation for formula (7), Let ) ~ , ,(dB , then E ( z, t ) , E ( z, t )e x x t 11-10 S ~ 1 ， ,(8) , ,E , 0 x z v t , , -15 its finite difference form is 0.94 1 0.980.84 0.86 0.88 0.9 0.92 0.96 2v t k ，1 k 1 k (9) E (n) , E (n) ， b(i)E (n ， i)Frequency( G H z) x x x z i Fig.2 Return loss for antenna operating in GSM band The difference form of formula (7) is two monopole antennas. It can be seen that the new dual-band 2v t ,,k k ，1 2, t k , (10) E (n) , e E (n) ， e b(i)E (n ， i)x x x t 1 antenna’s reception between the 935-960 MHz and 890-915 z i MHz bands is comparable to that of a monople antenna. , ( x) b(i) , , ( x ， i 1 / 2)dx where are the MRTD coefficients.， However, an advantage of the new design over a monopole is x that it filters out frequencies outside of GSM’s transmitting and The UPML material parameters are chosen to be receiving bands. The experimental results show that two , , 0 for the inner computation region, The , (, , x, y , z ) resonances can be created in the GSM transmitting and maximum value of , at the end of the UPML region is receiving frequencies, and that these resonances show desirable chosen to be , where is the cell, , 1 /(30 , ) max r Sand transmission characteristics. The same antenna design 11 dimension perpendicular to the UPML interface to the regular may be used for antennas that operate at frequencies region. The UPML region is backed by a perfect electric corresponding to other digital or analog systems. conductor wall implemented using the mirror principle. 3 Numerical results In microwave circuit analysis, Gauss impulse is generally mea sured theoretci selected as an excitation for smoothness in time domain and H- M RT D easy spectrum width setting. The width of gauss pulse is O ,Assume that the time delay ,The T , 12 ps t, 3T , 36 ps 0 response value of the frequency domain can be calculated by Fourier-transforming the time domain value. The circle wave loss of antenna measured and computed are shown in Fig.2. The computed curves based computation domain Fig.3 Smith chart of antenna operating in GSM band From ,. and z , 0.015mm 100 120 60 ,, x , y , 0.15mm Fig.2, we can find the measured results are in good agreement S12 log MAG 0.0 dB with computed results by using FDTD method and H-MRTD REF 5.0 dB 4 method. The measurements carried out on an Agilent 8720C -0.4054 dB vector network analyzer. The drifts between the measured hp value and the computed value by using FDTD and H-MRTD c SCALE are about 3%and 5%, respectively. The length of the novel dB/div 5.0 patch antenna is less than 1/16 wavelength, By using stacked 4 structure and adding transmission line in a proper situation, the 1 relative bandwidth of the antenna is approximately 8%, while that of a conventional microstrip antenna is only 0.6~3%. The efficiency this novel antenna arrive at 78%. The characteristic parameters such as effective dielectric START 0.300000000 GHz constant, the characteristic impedance in spectrum domain STOP 1.020500000 GHz could be worked out by Fourier transition. Through dealing Fig.4 S12 of new antenna compared to monopole antenna with the computed data using MATLAB, The antenna radiation These simulations were performed by XFDTD, the patterns are shown in Fig. 3. There has a good agreement information about dual-frequency antenna simulations is shown between the measured and theoretic or H-MRTD method. The in Table1. We can find when use different space cell sizes, there drift is less than 2%. has different simulation results. For FDTD method, Although Traditionally, in most cellular phones, the antenna used for transmitting and receiving is a monopole antenna. time-step t selected satisfied the Courant- Friedrich-Levy [13]Therefore, the new antenna proposed in this paper is compared (CFL) condition, the accuracy of the simulation results to the monopole antenna. A plot of Sis shown in Figure.4, 12 appears diversity when we adopt respectively fine-grid and where the new dual band antenna is the receiving antenna and coarse-grid , it makes clear the numeric errors arrive at 10% in a monopole is the transmitting antenna. Sis calibrated using 12 coarse-grid case. If the space-steps change more and more larger, its numeric precision can not be assured. In case of the Reference H-MRTD method, its numeric errors are in accord with each [1] Zhang-Fa Liu, Pang-Shyan Kooi, et.al. A Method for Designing other in fine-grid and coarse-grid case, but there has larger Broad-Band Microstrip Antenna in Multilayered Planar Structures numeric errors compared with FDTD method in fine-grid case. [J]. IEEE Trans. Antennas and Propagat., 1999, 47(9): 1416-1420. Although the time-step of FDTD method is approach 3 times ZAID L, KOSSIAVAS G, et al. Dual-frequency and broad-band [2] that of H-MRTD method. The CPU time is quite approach. antennas with stacked quarter wavelength elements [J]. IEEE Trans., 1999, AP-47(4): 654-660. TABLE1 Information on the dual-frequency antenna Wu Zhengzhong, Zhong Xianxin, Li Xiaoyi, Yu Wenge. [3] NO. of Yee’s cel l Conditions FDTD H-MRTD Broadband micromachined antenna for Bluetooth device [A]. 0.0315ns 0.0315ns t ISIST’2002. 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