Geometry Aspects and Experimental Results of a Printed Dipole Antenna

Detail experimental measurements of a 2.4 GHz printed dipole antenna for wireless communication systems is presented and discussed. A group of printed dipoles with integrated balun have been designed and constructed on a dielectric substrate. This paper is based on modifications of the known printed dipole architecture. The corresponding printed dipole antennas have differences on their forms that are provided by two essential geometry parameters. The first parameter l is related to the bend on microstrip line that feeds the dipole and the second w corresponds to the form of the dipole’s gap. The impact of these parameters on reflection coefficient and radiation pattern of antenna has been investigated. The corresponding measured results indicate that the return loss and radiation pattern of a printed dipole antenna are independent of the w parameter. Instead, variations in the value of the l parameter in the dipole’s structure affect the form of the corresponding return loss. These observations are very important and provide interesting considerations on affecting design and construction of antenna elements at frequency range of 2.4 GHz.

Measurements of Balun and Gap Effects in a Dipole Antenna

In the present paper, design and analysis of a 2.4 GHz printed dipole antenna for wireless communication applications are presented. Measurements on return loss and radiation pattern of this antenna configuration are included in this investigation. The printed dipole is combined with the feeding structure of a microstrip via-hole balun and is fabricated on an FR-4 printed-circuit-board substrate. Two inevitable discontinuities are introduced by this antenna architecture in the form of right-angle bends in the microstrip feed line and in the dipole’s gap, respectively. The impact of mitering these bends in the reflection coefficient, resonance bandwidth and radiation pattern of antenna has been investigated by means of simulation and experiment.

Envelope Correlation Parameter Measurements in a MIMO Antenna Array Configuration

In a 2 × 2 MIMO antenna array system envelope correlation coefficient “ρ” shows the influence of different propagation paths of the RF signals that reach the antenna elements. The approximated value of this coefficient is based on a simple closed-form equation and also varies from 0 to 1. Quite perfect performance for MIMO applications is achieved when this parameter approximates to zero. In this paper, we evaluate an antenna diversity MIMO system by measuring the envelope correlation coefficient. The corresponding results in our antenna array configurations show that the measured “ρ” has very small values and approximates to zero. This observation indicates quite perfect behavior and performance of our MIMO antenna array system.

一种方向图可重构印刷振子天线的设计

为了在同一副天线上实现定向和全向方向图,提出了一种方向图可重构印刷振子天线。通过控制开关的状态,天线实现单极子和带反射器的偶极子两种工作方式,分别实现全向和定向方向图。用Ansoft HFSS软件对天线尺寸进行了分析和优化。根据仿真结果对于所提出的天线进行了制作和测试,并给出了测试结果。测试结果表明:开关断开时,天线带宽为2.09～2.44GHz;开关闭合时,天线带宽为2.64～2.94GHz。

一种基于缝隙电磁耦合馈电的印刷振子阵列天线研究

本文研究了一种采用缝隙电磁耦合馈电的印刷振子阵列天线。该阵列天线使用对称印刷振子阵列作为辐射器,通过引入印刷平面巴伦对平衡振子辐射器进行馈电;基于缝隙电磁耦合的方式对印刷巴伦进行激励,馈电的功分网络布置在金属地板下方以减少电磁耦合干扰。设计了电磁耦合结构和尺寸参数,对4单元印刷振子直线阵列天线进行了仿真和优化,实现了预期阻抗匹配要求。仿真结果表明:在18.7~19.2 GHz频率范围内,该印刷振子阵列天线的电压驻波比小于2,在中心频率点上的增益约为8.9 dBi,E面和H面上的波束宽度分别约为21°和43°。对设计的天线进行加工测试,测试结果验证了该印刷振子阵列天线方案的有效性。本文提出的天线具有结构简单、效率高和电磁兼容性好的特点,适用于飞行器载体平台应用。

FDTD算法在等离子体振子天线辐射特性分析中的应用

采用了FDTD算法,结合MATLAB软件对不同等离子体参数(密度、碰撞频率)及不同工作信号频段下的等离子体柱天线S参数和归一化电场辐射方向图进行了仿真计算;并分析了等离子体参数变化时所对应的天线电参数变化规律。研究结果表明:等离子体天线的各种电参数会随着等离子体参数及信号频率的变化而改变,进而达到控制等离子体天线辐射特性的目的。

同频方向图可重构印刷振子天线设计

为了在同一副天线、同一频段实现方向图可重构,提出了一种方向图可重构印刷振子天线。通过改变开关的状态,天线实现单极子和带反射器的偶极子两种工作方式。单极子辐射全向方向图,带反射器的偶极子辐射方向图为定向。利用Ansoft HFSS10.0仿真软件对天线尺寸进行了分析和优化。仿真结果表明:开关断开、闭合时,天线实现了在2.34～2.64GHz工作频带上的定向和全向方向图;在2.45GHz处,最高点增益分别为6.7dB和3.1dB。