加载电磁带隙结构的阶梯型微带天线设计及分析

为了减弱大气摩擦引起的高温损伤,航空飞行器雷达天线一般都会加装天线罩或介质窗,将电磁带隙(EBG)结构的禁带特性和阶梯型微带天线的带宽及良好的匹配特性相结合,设计了一种含介质窗的EBG结构阶梯型微带天线,并计算分析了天线的辐射特性及介质窗对辐射特性的影响。结果表明:EBG结构产生的带隙能够制约天线表面波的传播,改善天线的带宽和增益性能,且当介质窗存在时,该结构亦可降低天线与介质窗间的互耦效应。这为含介质窗的EBG结构阶梯型微带天线的设计和应用提供了一定理论参考。     

Performance enhancement of a compact patch antenna using an optimized EBG structure

In this paper, an Electromagnetic Band Gap (EBG) based structure is proposed and simulated with other conventional structures on a thick substrate, to tackle the narrow bandwidth problem in microstrip patch antenna, and to take advantage of using a high permittivity substrate in terms of compactness. However, using this later degrades the antenna’s radiation pattern and gain even further. An optimized mushroom like EBG structure using Genetic Algorithm (GA) is used to cover the frequency band of interest, two different bandgap characterization methods were used to determine it. The results show significant improvements in terms of the bandwidth, gain and radiation pattern compared to the use of thick substrate.     

级联电磁带隙结构对双频微带天线互耦的影响

一种均匀面片尺寸的图钉型电磁带隙结构只能实现一个表面波带隙,而将不同参数的图钉型电磁带隙结构级联可以实现多个或宽带的表面波带隙。利用不同金属面片尺寸的图钉型电磁带隙结构级联的方法实现双带的表面波带隙。设计两种均匀的电磁带隙结构,使其带隙范围分别覆盖天线的两个工作频带,然后将这两种结构级联起来,加载于两个缝隙天线单元之间。仿真分析和实验结果表明,级联型的电磁带隙结构可以有效抑制表面波,在两个频率带内同时减小互耦。     

Investigated new embedded shapes of electromagnetic bandgap structures and via effect for improved microstrip patch antenna performance

Three novel shapes of mushroom-like electromagnetic bandgap (EBG) structures are presented in this paper. The three shapes are based on a rectangular metal strip with different combinations. The performances of the three-shape structures are studied by using both an incident plane wave method and transmission coefficient approach. The effect of height and via location is also studied to achieve multi or wide bandgap. These shapes are embedded in microstrip patch antenna substrates. The performance of the MPA is improved as increasing the antenna gain by 5 dBi, decreasing the surface current so improving the antenna radiation pattern as well as reducing the antenna size by more than 70% compared to the original size. The new shapes of EBG structures are integrated with MPA as a ground plane, where the conducting ground plane is replaced by a high impedance surface EBG layer. Parametric studies are conducted to maximize their impedance bandwidth and gain. It is found that the antenna bandwidth increased by approximately four times than the original band and its gain is similarly increased. Sample of these antennas are fabricated and tested to verify the designs.     

电磁带隙微带天线馈源阵设计

 针对阵列天线在大反射面馈电中的应用,设计一种基于电磁带隙（EBG）结构的馈源阵列。在深入研究EBG结构带隙特性的基础上,制作一个基于EBG结构的六边形7元微带天线阵,并对其性能进行了实测和分析。结果表明：EBG结构可以有效抑制天线阵元之间的互耦,改善天线匹配及圆极化特性;基于EBG结构的六边形馈源阵列较无EBG结构性能有较大提高,适用作反射面天线的焦平面馈电阵。     

Metamaterial Superstrate and Electromagnetic Band-Gap Substrate for High Directive Antenna

A high directive planar antenna made from a metamaterial superstrate and an electromagnetic band-gap (EBG) substrate has been investigated. A patch antenna surrounded with EBG structures is used as the radiation source. The CST Microwave Studio is used for the simulation. The results show that the gain of the antenna with metamaterial is 21.6 dB at the operating frequency of 14.6 GHz. Compared with the patch feed with the same aperture size but without the metamaterial superstrate, the performance of the antenna is improved obviously and the gain increases about 12.4 dB.     

35GHZ Patch Antenna Array Based on the Electromagnetic Band‐Gap Structure

The electromagnetic bandgap (EBG) structure, also called photonic bandgap structure, consisted by triangular arrays of air columns on the dielectric structure is designed and studied by using the FDTD method. According to the simulated and measured results, the EBG structure effectively suppressing surface wave for TE and TM modes is designed. The optimized EBG structure is presented.The proposed EBG structure is applied to the fourelement microstrip patch array antenna. As results of simulation and measurements, the impedance bandwidth and the gain of proposed EBG patch array antenna are improved.     

Three-dimensional electromagnetic band-gap structure containing TiO2 fabricated by rapid-prototyping

Three-dimensional (3D) diamond structure electromagnetic band-gap (EBG) structures containing TiO₂ fabricated by rapid-prototyping (RP) technique were investigated. The simulations based on finite element method (FEM) were employed to model the band structures. The influence of aspect ratio on the band gap width was studied. The optimal band gap width EBGs were fabricated and investigated experimentally. Gel-casting together with RP technique were used in the fabrication. TiO₂ gel was cast into the diamond structure molds fabricated by RP method to obtain the green EBG structures. The transmission characteristics of the EBG structures were measured by transmission/reflection (T/R) methods using a vector network analyzer. Complete band-gap was observed in the transmission characteristics in the frequency from 11 GHz to 12 GHz, which agreed well with the simulation results.     

复合缺陷型电磁帯隙谐振腔

提出了一种复合缺陷型电磁带隙(EBG)谐振腔,通过对该EBG结构的带隙分析,指出该谐振腔可在大尺寸下实现单模工作,提供更大的容差空间,且具有高Q值.数值模拟结果表明,基于复合缺陷EBG结构构成的谐振腔,单模工作条件可以放宽到外圈金属柱直径与周期之比为0.6,内圈金属柱直径与周期比为0.9;而传统中心缺陷型EBG结构的小于0.3. 关键词： 电磁带隙 复合缺陷 谐振腔 单模     

Rectangular patch antennas over electromagnetic band gap structures

In this paper, I propose a new design of a defected structure (DS) for use as an electromagnetic band gap (EBG) configuration to enhance the performance of low profile microstrip antennas. The proposed defected structure embodies a honeycomb lattice of cylindrical air holes. The proposed DS is applied to three different configurations using a dielectric substrate (dielectric constant 6 and thickness 1.5 mm); namely: a dielectric substrate backed by a defected ground plane, a defected dielectric substrate backed by a normal substrate and a defected dielectric substrate backed by a defected ground plane. The simulated values of the transmission coefficient S ₂₁ for the last one show two well-defined stop bands around 8.5 and 9.5 GHz, respectively. The first band has been used to reduce mutual coupling in a microstrip array. On the other hand, the stop band defined around 9.5 GHz has been applied to enhance the characteristics of a rectangular patch antenna and improve the operational 10-dB bandwidth.     

电磁带隙结构在天线雷达散射截面减缩中的应用

 提出了一种使用电磁带隙结构来减小微带印刷对称阵子天线雷达散射截面的方法。该方法利用电磁带隙结构的带阻特性,使其能作为天线的地板,在带外(非谐振)时,电磁带隙结构对入射电磁波起滤波作用。仿真和实验的结果表明,电磁带隙结构能保证天线在带内辐射不受影响的同时,还大幅度地降低了天线带外的雷达散射截面。     

Reconfigurable wideband to narrowband antenna using tunable EBG structure

In this paper, frequency reconfigurable electromagnetic band gap (EBG) structure that integrates with a wideband antenna is proposed. The EBG structure consists of a circular patch shorted to the ground plane and a secondary circular patch connected to the circular patch. Switches are positioned between the via and the ground plane and by controlling the state of the switch, the band-stop operation of the EBG can be activated or deactivated. In order to control the single and dual band-stop operation, another switch is place between the circular patch and the secondary circular patch. The EBG structure is then placed underneath the feed line of a wideband antenna. The antenna is capable of reconfiguring to three different frequency bands. The proposed antenna has the potential to provide useful features for the wireless communication applications.     

基于超材料吸波体的低雷达散射截面微带天线设计

设计了一种高吸波率、宽入射角、无表面损耗层的超材料吸波体, 并将其用于微带天线的带内雷达散射截面(radar cross section, RCS)减缩.实验结果表明: 设计的吸波体的厚度为0.3 mm, 吸波率达99.9%, 相比普通微带天线, 加载该吸波体后的天线在工作频带内法向RCS减缩都在3 dB以上, 最大减缩16.7 dB, 单站RCS在-30°–+30° 角域、双站RCS在-90°–+90°角域减缩超过3 dB, 且天线辐射性能保持不变. 证实了该吸波体具有良好的吸波效果, 可以应用于微带天线的带内隐身. 关键词： 超材料吸波体 微带天线 雷达散射截面     

Transient analysis of dielectric step discontinuity of microstrip lines containing a nonlinear layer

Tansient signal propagation characteristics through step discontinuities on microstrip lines with nonlinear substrate are presented. In the proposed model structure, the transient electromagnetic wave propagates from microstrip line with linear substrate to one with nonlinear substrate or vice versa, where two structures are connected to create abrupt discontinuities. The distortions of transient signal through this two abrupt discontinuity structures are numerically simulated by three dimensional FD-TD method. Results show that the distortions of transient signal are evidently influenced by the density of electric field propagating along the microstrip line with nonlinear substrate.     

Active Microstrip Antenna with a Gunn Diode

Continuous electromagnetic emission from a Gunn diode built in a microstrip log-periodic antenna in the frequency range from 25 to 60 GHz is studied experimentally. The microstrip antenna was located on an insulating substrate with a thickness of about a quarter of the wavelength and with a metallized back side. It is shown that the output radiation power of such an antenna reaches 5 mW, which is over 50% of the power received from similar diodes in the waveguide cavity. The oscillation regime was varied from single-mode to noise-like, depending on the dielectric thickness and could be synchronized by external emission. Such a quasi-optical structure based on a Gunn diode is convenient for summing up powers from individual oscillators in an open resonator and is of great interest for the terahertz frequency band.     

Millimeter wave propagation in transmission lines with magnetized semiconductor element

The peculiarities of electromagnetic wave propagation in transmission lines with a gyromagnetic semiconductor element are analysed. Electromagnetic radiation control is shown to be possible when semiconductor element contacts with the waveguide from the outside and constitutes a part of the transmission line itself. The afore-named possibility is demonstrated using rectangular metal and dielectric waveguides as well as a microstrip line.     

Analytical formulation of the radiation field of printed antennas in the presence of artificial magnetic superstrates

In this paper, the cavity model of a microstrip patch antenna in conjunction with the reciprocity theorem is used to develop a fast analytical solution for the radiation field of a microstrip patch antenna loaded with a novel artificial magnetic superstrate and to investigate the effect of the engineered superstrate layer on the directivity and radiation pattern of the printed patch antenna.     

一种电磁带隙结构的快速分析方法

 使用直接传输方法分析有限周期Mushroom-like 电磁带隙结构的表面波带隙,与无限周期的电磁带隙结构表面波色散能带图相比,该方法能大大缩短分析时间。将电磁带隙结构放置于波导底面,通过计算波导的传输系数,分析了不同波导高度和电磁带隙结构周期数对带隙范围的影响。加工了Mushroom-like电磁带隙结构样品,并使用一对探针耦合的方法测量了电磁带隙结构的TE和TM表面波带隙,实验结果表明使用直接传输方法确定的表面波带隙与测量数据吻合良好,证明了此方法的有效性。     

Investigation of frequency-selective devices based on a microstrip 2D photonic crystal

The frequency-selective properties of structures based on a 2D microstrip photonic crystal have been investigated theoretically and experimentally. It is shown that various microwave devices, including diplexers, bandpass filters, and double bandpass filters, can be designed based on these structures.