Planar microstrip UWB bandpass filter using U-shaped slot coupling structure

A compact planar microstrip UWB bandpass filter is proposed. It is realised by cascading a lowpass filter and a highpass filter. A transmission line with U-shaped slots coupled with two DGS units on the back of the circuit board has the characteristic of highpass, while a periodic uniform DGS array has the characteristic of lowpass. Combining these two structures, a new UWB bandpass filter (BPF) is fabricated and measured. Measured results show that the proposed BPF has wide bandwidth from 3.0 to 10.9 GHz, all the measured return loss less than 13 dB in the passband. The BPF achieves a wide stopband with 18 dB attenuation up to 18.0 GHz     

Full-wave analysis of microstrip floating-line discontinuities

A full-wave analysis of the resonance generated by a floating line is presented. Beginning with the dyadic Green's function for a dielectric slab, an integral equation is formulated. This integral equation is then solved by the method of moments in obtaining the transmission and reflection coefficients, as well as current distributions along the transmission line and on the floating line, both longitudinal and transverse. Employing these results, the near- and far-zone fields, as well as radiation patterns are computed. It was found that under resonance conditions the radiation power can exceed 13% of the feeding power, which may cause a potential problem in electromagnetic compatibility. Singularities involved in the Sommerfeld integrals are carried out by a novel pole extraction technique in conjunction with conventional folding methods. The new technique reduced the relative error of the singular integrals due to inaccurate pole position about one order in magnitude in comparison to the traditional approaches. To verify the new approach, a number of cases of open-ended transmission lines and gap discontinuities are examined. The results obtained from this method showed good agreement with those of previous publications     

Full-wave analysis of aperture-coupled microstrip lines

Two methods are presented for the analysis of aperture-coupled microstrip lines. Assuming a quasi-transverse electromagnetic traveling wave incident on the feeding line, an expression for the wave on the coupled line is derived. First, the moment method is used and the current on the coupled line is represented by a traveling wave propagating away from the slot. In the second method, the reciprocity theorem is applied to the coupled line. Both the moment method and the reciprocity method make use of the exact Green functions and produce results that are in very close agreement. An equivalent circuit is derived and the S-parameters are computed. Theoretical results are verified with measurements     

角馈微带天线的全波分析

利用积分方程法对角馈型微带天线进行了分析,对其中的奇异振荡函数积分,给出了有效的数值积分方法。数值实验证明了该方法的有效性。同时,给出了角馈微带天线的输入阻抗特性,方向图特性和带宽特性。     

Full-wave spectral analysis and design of annular patch antenna with electromagnetically coupled microstrip feed line

This paper presents a full-wave analysis, and the ensuing design considerations, of the annular patch antenna fed by an electromagnetically coupled microstrip line. The numerical analysis employs the spectral domain version of the integral equation, with the method of moments formulation; the basis functions on the ring patch are the eigenmodes of the corresponding magnetic wall cavity, and subsectional (rooftop) functions are employed on the access line. Both TM and TE modes are used, along with more-efficient "collective" solenoidal modes; mode sorting criteria are given to ensure uniform convergence. Efficient schemes are presented for the calculation of the spectral-domain reaction integrals, along with criteria to avoid calculation of negligible mode-to-mode couplings, based on the spectral analysis of the matrix condition number. Very good agreement is shown with measured data, and design considerations are given for matching the radiator.     

管道内微带天线的FDTD全波分析与设计

针对金属管道中探测作业无缆机器人微波供能系统,对其能量接收部分的接收天线进行了设计, 采用时域有限差分法(FDTD)结合PML边界条件全波分析了管道内圆极化微带天线,数值结果与测试结果比较吻合,验证了此数值算法的有效性.     

蝶形微带天线的全波分析与宽带设计

介绍了蝶形微带贴片天线的一种全波分析方法－矩量法,与多端网络法相比,其适应范围更广。然后介绍了展宽天线频带的一种设计方法。通过不对称馈电方式,激励起两个相近频率的模式,从而使微带天线驻波比带宽获得明显展宽。测试结果与计算结果相当吻合,证实了数值分析与设计方法的有效性。     

一种宽频带圆柱共形微带天线全波分析和设计

采用双层介质双贴片结构展宽天线的阻抗带宽,并利用小的贴片电容补偿由厚介质衬底引起的探针电感效应,进一步扩展了频带宽度.基于共形FDTD法结合圆柱分层媒质中并矢格林函数的新方法,对此类天线的近场和远场特性进行了严格的全波分析.提出了系统的设计流程,使得天线的设计过程变得简单易行.设计和仿真结果表明,在不增加剖面厚度的情况下,工作于L和C波段的天线带宽(VSWR≤2.0)可达近30%甚至更宽.     

Full-wave analysis of radiation effect of microstrip transmission lines

A full-wave analysis of radiation effects produced by discontinuities in microstrip and buried microstrip transmission lines is presented. Beginning with the dyadic Green's function for a dielectric slab, with an embedded source, an integral equation is formulated. This equation is then solved by the method of moments to obtain the current distributions along the transmission line, in particular, near the discontinuities. Employing these results, the near- and far-zone fields, as well as radiation patterns are computed. The results from our method showed good agreement with those of previous publications in complex reflection and transmission coefficients, and equivalent capacitance values. It is found that under resonance conditions the radiation efficiency of a simple structure can exceed 41%, which may cause a potential problem in electromagnetic compatibility. Our analytic result also shows that the maximum radiation occurs when the source is located at the height of from the bottom ground plane, which should be prevented.     

Full-wave space-domain analysis of open microstrip discontinuitiesincluding the singular current-edge behavior

A full-wave space-domain analysis is presented for the high-frequency characterization of microstrip discontinuities. This approach solves the electric field integral equation (EFIE) for the surface current density on the microstrip using the method of moments. The current expansion functions incorporate the singular edge behavior of the surface current, yielding a very accurate current modeling. Special attention is devoted to the analytical treatment of the singular terms in the electric field Green's dyadic. The numerical results focus on the S-parameters of some simple microstrip discontinuities and the comparison with results obtained with other techniques and from measurements     

Analysis of a slot microstrip antenna

The slot microstrip antenna is used as a folded slot dipole symmetrically fed across a gap by means of a strip line. A theoretical model equivalent to several lossy transmission lines had been described previously to explain the bandwidth and the radiation admittance. The theory is improved when coupling between the two equivalent radiating lines of every slot is taken into account, and explains a fourth resonance near the third one, which had been measured on several models. Theoretical results and experiments are in good agreement. They are radiation admittance in a wide frequency band, current distribution along each slot and radiation patterns.     

Full-wave analysis and wide-band design of probe-fed multilayered cylindrical-rectangular microstrip antennas

The input impedance and radiation pattern of the probe-fed multilayered cylindrical-rectangular microstrip antennas (PMCMSA) are analyzed by using a novel approach which combines the conformal finite-difference time-domain (FDTD) and Gedney's unsplit version of the perfectly matched layer absorbing boundary condition method and the Green's functions in cylindrically stratified media. The near fields of such antennas and the current distributions on the patches are obtained by the conformal FDTD method numerically and then the modified spectral-domain Green's functions in arbitrary cylindrically stratified media are used to determine the radiation pattern. The effect of the small radius of the probe on the performance of antennas is investigated through the thin-wire algorithm in cylindrical coordinates. A simple design scheme of the probe-fed cylindrically stacked antennas is also proposed for increasing the impedance bandwidth.     

Compact microstrip bandpass filter with two transmission zeros using a stub-tapped half-wavelength line resonator

A compact microstrip bandpass filter is developed using a half-wavelength (/spl lambda//2) transmission line resonator with a pair of tap-connected open-ended stubs. Such paired stubs with total length of about /spl lambda//2 constructs an equivalent line resonator. Together with two separated /spl lambda//4 line resonators, the three transmission poles can be achieved inside the passband. Meanwhile, two stub lengths are adjusted slightly longer and shorter than /spl lambda//4 to realize the two transmission zeros at both low and high rejection bands. Further, the long tapped-stub is kept wider than its short counterpart to improve the low rejection behavior. A filter sample is designed and fabricated to provide an experimental verification on the proposed filter.     

Static analysis of microstrip discontinuities using the excesscharge density in the spectral domain

Galerkin's method in the spectral domain is applied to solve for the excess charge density existing on the strips of open-end and symmetric gap discontinuities in multilayered anisotropic substrates. The excess charge density is used to determine the capacitance components of the equivalent circuits, of these discontinuities. Numerical results are provided and a comparison with previous results is carried out     

Transmission line analysis of nonlinear slot coupled microstrip antenna

The transmission line method is used for the analysis of microstrip antennas fed by several nonlinear slots with 'H' shapes or new geometries. This analysis allows the input impedance of nonlinear slot coupled microstrip antennas to be calculated for the four different structures.<>     

Meander microstrip photonic bandgap filter using a Kaiser taperingwindow

Compact photonic bandgap structures in microstrip technology with reasonable physical sizes have recently been proposed as efficient frequency-band reflectors. Here, it is shown how the application of a Kaiser tapering window to the periodic pattern etched in the ground plane of the structure provides appreciable performance improvement, reducing both passband ripple and stopband attenuation and increasing bandwidth     

Design and analysis of a structure-based microstrip bandpass filter

A structure-based microstrip passband filter with the center frequency of 2.6 GHz was put forward by using double-mode resonator based on defected ground structure （DGS） technology. A double-mode coupling resonator combined with DGS structure was used to achieve the resonance frequency and the filter size. CST microwave studio was used to optimize the attenuation performance to get the filter parameters. A structure-based passband filter was fabricated. Simulation is consistent with the measurement. Performance shows that the proposed filter could be suitable for the time division-long term devolution （TD-LTE） microwave systems at 2.6 GHz.     

Miniaturisation of microstrip patch antenna using perturbation of radiating slot

A highly miniaturised rectangular microstrip patch antenna using deformation of the patch structure has been designed and fabricated at a frequency of 1.575 GHz (GPS). The fabricated antenna has a patch with an overall rectangular shape and depressed at its four corners (corner depressed microstrip patch antenna, CDMPA). In the linear polarisation, at a fixed rate of 1.2 of width/length (W/L), the CDMPA (53/spl times/63.6 mm) is reduced to 43.9% of the general plane type microstrip patch antenna (MPA, 80/spl times/96 mm) in patch size. The gain is 4.3 dBd which is lower than that of the general MPA (8 dBd) by 3.7 dB. In the circular polarisation, the patch size of the CDMPA (54.2/spl times/61.5 mm) is reduced to 52.8% of that of the MPA (76/spl times/83 mm). The axial ratio (AR) and axial ratio band width (ARBW) within 2 dB are 1.5 dB and 20 MHz (1.27%), respectively. The gain is 2.5 dBd, which is lower than that (4.2 dBd) of the general MPA by 1.7 dB.     

Full-wave computation of constitutive parameters for losslesscomposite chiral materials

Composite chiral materials are realized by embedding large numbers of handed inclusions within a host material. A computational methodology is presented whereby the effective constitutive parameters of artificial chiral materials are computed while accounting for all self and mutual interactions among the inclusions. This technique combines a full-wave, Monte-Carlo scattering solution for randomly oriented inclusions together with an analytical solution for the scattering by a canonically-shaped body having a properly chosen constitutive model. It is believed that the effective constitutive parameters shown in this paper are the first full-wave computation of these quantities to appear in the literature     

A reciprocity method of analysis for printed slot and slot-coupled microstrip antennas

A method is presented for the analysis of slot-type discontinuities in microstripline. The approach is based on the reciprocity theorem and uses the exact Green's functions for the grounded dielectric slab in a moment method solution for the unknown antenna currents. The method is applied to two specific geometries: a radiating slot in the ground plane of a microstripline, and an aperture coupled microstrip patch antenna. Results for antenna impedance are compared with measurements, and far-zone patterns are calculated. The method is shown to be quite versatile, and should find application to related problems.