共查询到20条相似文献,搜索用时 15 毫秒
1.
A 90° microstrip bend with an arbitrary miter is characterized using the finite difference time-domain (FDTD) method. In this method, to simplify computations, the microstrip structure is enclosed by four electric walls; thus radiation effects are neglected. Time histories generated by FDTD techniques are Fourier-transformed to yield broadband scattering parameters of the microstrip bend. A miter is introduced to improve the transmission characteristics of the bend, and an optimal miter length is found such that the reflection from the microstrip bend over a broad frequency range is minimized 相似文献
2.
A convenient method for evaluating radiation loss from microstrip discontinuities is presented. A planar multiport network model of the discontinuity configuration and the segmentation method are used to evaluate the voltage distribution around the edges of the discontinuity. This voltage distribution is expressed as an equivalent magnetic current line source distribution which is used to calculate the far-zone field (for radiation loss). As an example, the results show that for a 90° bend in a 50-Ω line on a 10-mil-thick substrate with ϵr =2.2, the radiation loss is 0.1 dB at 30 GHz. Typical power levels radiated by several other discontinuities are reported. The analysis model was verified experimentally by fabricating microstrip resonators with discontinuities incorporated therein and measuring the Q factors of these resonators 相似文献
3.
Compact shorted variations of circular microstrip antennas 总被引:1,自引:0,他引:1
A circular microstrip antenna has been modified by shorting along the zero field to yield shorted semi-circular and 90° sectoral microstrip antennas. Experimental results on these antennas are presented. The shorted 90° sectoral antenna results in a size reduction of four times without any significant change in performance. The area is further reduced by partially shorting one of the edges of the 90° sectoral antenna 相似文献
4.
A generalization of the finite-difference time-domain (FDTD) algorithm adapted to nonorthogonal computational grids is presented and applied to the investigation of three-dimensional discontinuity problems. The nonorthogonal FDTD uses a body-fitted grid for meshing up the computation domain and, consequently, is able to model the problem geometry with better accuracy than is possible with the staircasing approach conventionally employed in the FDTD algorithm. The stability conditions for the nonorthogonal FDTD algorithm are derived in two an three dimensions. Numerical results, including an H-plane waveguide junction, a circular waveguide with a circular iris, a circular waveguide with a rectangular iris, and a microstrip bend discontinuity, are presented to validate the approach 相似文献
5.
A direct three-dimensional finite-difference time-domain (FDTD) method is applied to the full-wave analysis of various microstrip structures. The method is shown to be an efficient tool for modeling complicated microstrip circuit components and microstrip antennas. From the time-domain results the input impedance of a line-fed rectangular patch antenna and the frequency-dependent scattering parameters of a low-pass filter and a branch-line coupler are calculated. These circuits were fabricated and the measurements made on them are compared with the FDTD results and shown to be in good agreement 相似文献
6.
Compact shorted variations of triangular microstrip antennas 总被引:1,自引:0,他引:1
Equilateral and triangular 30°-60°-90° microstrip antennas have been modified by shorting along the zero field to yield shorted 60 and 30°-sectoral microstrip antennas, respectively. Experimental results on these antennas are presented. The shorted 60 and 30°-sectoral antennas result in area reduction by factors of 2.5 and 5.0, respectively, compared to the equilateral triangular antenna with the same resonant frequency. The frequency is further reduced by partially shorting the curved edges of the sectoral antennas 相似文献
7.
基于时域有限差分方法和传输线方程,结合高效网格建模技术,文中提出了一种高效的时域建模算
法,它能有效解决微带线的电磁耦合建模问题,实现空间电磁场与微带线瞬态响应的同步计算。首先,结合经验公
式,计算得到微带线的单位长度分布参数,构建适用于微带线电磁耦合分析的传输线方程。然后,采用时域有限差
分(Finite-Difference Time-Domain, FDTD)方法,结合非均匀网格技术和自动网格生成技术,仿真得到微带线激励场,
并在每个时间步进上引入传输线方程获得等效分布源项。最后,对传输线方程使用FDTD 的中心差分格式进行离
散,实现微带线及其端接电路上瞬态响应的迭代求解。为了验证时域建模算法的正确性和高效性,通过自由空间和
屏蔽腔内PCB 上微带线电磁耦合的数值模拟,从计算精度和耗时两方面与传统FDTD 方法的计算结果进行了对比。 相似文献
8.
Mount-Learn Wu Ping-Lin Fan Jui-Ming Hsu Ching-Ting Lee 《Lightwave Technology, Journal of》1996,14(11):2604-2614
We propose an ideal structure for lossless bends in optical waveguides for the first time. The ideal structure is obtained by applying a series of conformal mappings to transform a single-mode straight waveguide into the equivalent bend configuration. The expressions used to determine the waveguide path and the refractive index are derived for the lossless bends with arbitrary bend angles, even up to 90°. Also, variations in the waveguide path and the refractive index are illustrated by adopting lossless bends with six different bend angles (4, 10, 30, 45, 60, and 90°). The simulated results show that the refractive-index distribution can be controlled within the range of interest for the practical bend structure. Moreover, the characteristics of the phase front for the modal field in a lossless bend are thoroughly discussed to verify that no transmitted power would be lost by conversion to radiation modes 相似文献
9.
Jong-Sik Lim Chul-Soo Kim Jun-Seok Park Dal Ahn Sangwook Nam 《Electronics letters》2000,36(21):1784-1785
The authors present a 10 dB 90° branch line coupler operating at 1.8 GHz and having a defected ground structure (DGS), a type of periodic structure realised by etching on the ground plane under the microstrip line. Owing to the additional effective inductance of the DGS, the characteristic impedance of the microstrip line is increased for the same width of conductor. A microstrip line of 150 Ω of characteristic impedance with 1 mm conductor width is realised by adding the DGS, while 1 mm corresponds to 82 Ω of conventional microstrip line on the RT/Duroid 5880 substrate with 2.2 dielectric constant and 31 mils of thickness. It is shown that a 90° branch-line 10 dB coupler can be fabricated using the 150 Ω line with DGS. Its measured performances are in good agreement with the predicted results 相似文献
10.
This study presents the original inclusion of right singular vertex conditions in integral equations solved by the method of moments for accurate evaluation of the frequency-dependent microstrip discontinuity models required in microwave integrated circuits (MIC) and monolithic microwave integrated circuits (MMIC) design. The 90° wedges singularity function for the current density, weighted with a novel sampling function for “corner cells,” and the harmonic Green's function for shielded structures, is accurately and efficiently integrated in the conical geometry of the 90° sector. The frequency-dependent effective length and excess equivalent capacitance of a shielded open-ended microstrip line are calculated to a higher accuracy with respect to previous two-dimensional and three-dimensional “full wave analyses” 相似文献
11.
The finite-difference time-domain (FDTD) technique is used to analyze boxed microstrip with both rectangular and trapezoidal cross sections. It is confirmed that the exact shape of the conductor has a marked effect on the effective permittivity of the microstrip. Results using this method are compared to the findings of K.A. Michalski et al. (1989) using the analytically more complicated boundary element method; very good agreement is observed. The effect of adding a thin passivation layer is also calculated and it is found that such an addition noticeably reduces the effective permittivity of the microstrip. It is shown that the FDTD technique is capable of treating microstrip with a general cross section and producing accurate results 相似文献
12.
In this paper, the application of the finite-difference time-domain (FDTD) algorithm combined with the short-open calibration SOC technique to three-dimensional microstrip discontinuity is presented. This SOC technique is directly accommodated in the FDTD algorithm. It is used to remove the unwanted parasitic errors brought by the approximation of the impressed voltage sources and the feed lines. The FDTD is formulated in such a way that the port voltages and currents are explicitly represented through relevant network matrices. This new method is also used to analyze finite periodic structures. The scattering parameters of the whole periodic structure can be approximately obtained through analyzing only one cell of it. The results for microstrip discontinuities and finite periodic structures are compared with the conventional FDTD method. 相似文献
13.
14.
A sector-shaped configuration for designing planar power divider-combiner circuits that are compatible with microstrip circuits is discussed. This configuration is analyzed using the two-dimensional planar circuit approach. Expressions for impedance matrix parameters of multiport sectorial planar circuits are given. Theoretical and experimental results reported for 90° and 180° power dividers are in good agreement 相似文献
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16.
A concentric microstrip triangular-ring antenna structure using the log-periodic principle for increasing the impedance bandwidth of the microstrip patch antenna is described. The finite-difference time-domain (FDTD) method is applied to analyze the proposed structure. A special technique to model the slanted metallic boundaries of the triangular ring has been used in the general FDTD algorithm to avoid the staircase approximation. The method improves the accuracy of the original FDTD algorithm without increasing the complexity. The radiation patterns at different frequencies over a wide bandwidth are obtained experimentally 相似文献
17.
Z. B. Ye Wanchun Tang S. S. Li 《Journal of Infrared, Millimeter and Terahertz Waves》2006,27(8):1109-1117
In this paper, the modified matrix pencil (MMP) method is used in the finite difference time domain (FDTD) method to eliminate the late time instability of time domain responses when analyzing the novel microstrip circulator with a magnetized ferrite sphere. The frequency dependent scattering parameters: reflection, isolation and insertion parameters of the microstrip circulator calculated over a wide band of frequencies with this hybrid method are compared with that obtained by direct FDTD method which agree well with the experimental results. 相似文献
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19.
Analysis of shielded membrane microstrip line using the finite-difference time-domain method 总被引:1,自引:0,他引:1
A simple and efficient analysis method of the shielded membrane microstrip (SMM) line using the finite-difference time-domain (FDTD) method is presented. New FDTD equations are derived using the contour path FDTD concept for the Yee cell which contains three thin dielectric sheets of membrane. The characteristic impedance and the effective dielectric constant of the SMM line are calculated using our proposed method. The method is validated by comparison with the results shown by Robertson et al. [1996]. 相似文献