The U-Band Pattern Steerable Active Patch Antenna

Combing the active antenna concept with the reconfigurable antenna technique, a pattern steerable active patch antenna is presented and designed in this paper. A Gunn diode is used to generate the millimeter wave signal and loaded at the centre of the patch antenna. This antenna system has a stable oscillation frequency f : 44.0GHz and operates as a quasi-Yagi patch antenna. The radiation patterns of the antenna can scan in the whole horizontal plane with 3-db beam width by using four reconfigurable states and the radiation main beam of each state directs to the elevation angle 59° in the elevation-plane. The antenna can be applicable to the millimeter wave half-duplex communication and identification systems.     

Design of Reconfigurable Millimeter-Wave Patch Antenna

Reconfigurable antenna is a novel concept of antenna. A novel reconfigurable millimeter-wave patch antenna is proposed and simulated by the finite-difference time-domain (FDTD) method. The simulation results demonstrate that the antenna can operate in two states and shift the operation frequency band between 22.830.8GHz and 28.737.3GHz as the state is changed. This antenna is useful for millimeter-wave wireless communication and radar systems.     

Dual-Band Bi-Directional Pattern Reconfigurable Fractal Patch Antenna for Millimeter Wave Application

A novel dual-band bi-directional reconfigurable antenna based on Koch patch is presented in this paper. By controlling the switches in the slots etched on the Koch patch, different far field bi-directional patterns at the dual-band around 60 GHz/80 GHz could be achieved. And full azimuthal coverage at this dual-band is possible by electronically controlling the switches in the slots of the patch. This work was supported by the National Natural Science Foundation of China (No. 60371008, No. 90505001) and the CRT Program of UESTC.     

Full-Wave Analyses for a Multi-Layered Microstrip Patch Antenna

This paper describes numerical modelling of a dual band multi-layered microstrip patch antenna operating at 35GHz on an in-house semi-insulating GaAs substrate. The simulated and measured resonant frequencies at both lower and upper resonant frequencies will be compared to check the accuracy of the different numerical modelling techniques.     

复合基底圆极化微带贴片天线建模与仿真

设计了一种用于无源射频识标签,中心谐振频率为2.45GHz的圆极化微带贴片天线。设计中引入了Rogers RO4232 (tm),Rogers RO4003 (tm)以及玻璃短纤维增强聚四氟乙稀三种材质的复合基底,利用Ansoft HFSS 10.0进行建模,并对设计模块进行仿真和优化处理,仿真结果表明天线的方向性良好,有效增益为5.534dB, 带宽>50MHz(S11<-15dB),阻抗匹配良好。驻波比、辐射效率均与理论期望吻合,各项指标达到了航空配件管理及维修记录的实际需求且易于实现,价格低廉,可靠性好。     

ADAPTIVE NEURO-FUZZY INFERENCE SYSTEM FOR COMPUTING THE PHYSICAL DIMENSIONS OF ELECTRICALLY THIN AND THICK RECTANGULAR MICROSTRIP ANTENNAS

A new method for calculating the patch length and width of rectangular microstrip antennas (MSAs) with thin and thick substrates, based on adaptive neuro-fuzzy inference system (ANFIS), is presented. The ANFIS is a class of adaptive networks which are functionally equivalent to fuzzy inference systems (FISs). It combines the powerful features of FISs with those of artificial neural networks (ANNs) to achieve a desired performance. The results of ANFIS are in excellent agreement with the experimental results available in the literature.     

Accurate Analysis of Planar Microstrip Antenna Array

For the microstrip patch resonator, as a planar antenna of a microstrip, a set of equations that represents the electromagnetic fields in the x and z direction as function of the electric field in the y direction are obtained applying the TTL method. This method is very suitable at microwave and antenna applications, and gives accurate complex resonant frequency, which contributes definitively to obtain higher precision antenna parameters. For each type of array is calculated the array factor, considering the excitation, phase and the relative displacement between the elements as well as the dimensions and number of elements.     

A Circularly Polarized Stacked Patch Aperture Coupled Microstrip Antenna for 2.6 GHz Band

A circularly polarized stacked patch microstrip antenna and a 2 × 2 subarray for circular polarization are proposed in this paper. The proposed design has the input impedance bandwidth and axial ratio bandwidth of about 10% and 4.7% respectively. Circular polarization is obtained with the help of slits cut in the patch. A size reduction of around 37% is also achieved with the help of the slits. A subarray based on sequentially rotated feeding technique for circular polarization is also presented in this paper. Array element was deigned using a high dielectric constant laminate for feed network. In addition to low boresight axial-ratio, the subarray has impedance and 3-dB axial-ratio bandwidths of 12% and 8% respectively.     

Novel Broadband Reflectarray Antenna with Windmill-Shaped Elements for Millimeter-Wave Application

A novel broadband millimeter-wave reflectarray antenna composed of windmill-shaped elements of variable lengths is proposed. Compared to the conventional single-layer reflectarray elements, the windmill-shaped elements can realize much larger phase variation range (over 600°), leading to broader bandwidth. Using this technique, a 15°-beam-steering reflectarray operating at 30 GHz is designed. The computed results demonstrate the agreement of the main beam steering with the design requirement, and a 1-dB gain bandwidth close to 20% is obtained. The validity of the obtained results is verified by comparing the ones generated by Ansoft High Frequency Structure Simulator (HFSS) with those produced by Ansoft Designer. The antenna is useful for millimeter-wave applications. This work was supported by the National Natural Science Foundation of China (No. 90505001), the High-Tech Research and Development Program of China (No. 2006AA01Z275), and the Creative Research Group Program of UESTC.     

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.     

基于北斗的警犬天线设计及优化

为了有效完成铁路沿线的安全监测,基于北斗警犬状态远程监测系统应运而生,目前存在着监测系统中天线受环境影响大、接收性能差等问题,针对上述问题设计了一种平面微带天线。本文以单支节调配器为主线,以应用角度出发,分别对其平面及馈线弯折等情况进行了仿真分析,克服铁路特殊环境北斗天线安装困难、频带窄易受干扰等缺点。采用ANSOFT HFSS软件进行天线性能仿真,仿真结果表明,设计的北斗天线有效中心频率为1571MHz,电压驻波比小于1.5,符合警犬状态远程监测的实际应用要求。     

A Novel Feeding Scheme for Bandwidth Enhancement of Suspended Planar Antenna

A suspended planar antenna with a novel feeding structure is proposed for bandwidth enhancement. This feeding structure can provide extra degrees of freedom to tune the antenna for compensating for the large inductance induced by the long feeding probe. An impedance bandwidth of 56% for VSWR<2 is obtained. Simulated and measured results are compared and good agreements are observed.     

一种精确计算毫米波矩形微带天线贴片元物理尺寸的新方法

为了使矩形微带天线的实际谐振频率和设计频率相一致,矩形贴片元物理尺寸的精确计算是非常重要的。文中在腔模理论的基础上,计入辐射损耗,提出了一种精确计算毫米波矩形微带天线贴片元物理尺寸的新方法,并利用该方法计算设计了四元毫米波矩形微带贴片天线,仿真和实测结果证实了该方法的有效性。     

A Broadband CPW-to-Microstrip Modes Coupling Technique

A broadband vertical transition from coplanar waveguide (CPW)-to-microstrip modes is presented. The transition has a double resonance and can be tuned for very wide-band operation. The CPW-to-microstrip modes coupling technique is useful for the vertical integration of multi-layer millimeter-wave circuits, packaging and antenna feeding networks. A vertical transition has been fabricated on 100 m silicon substrate for operation at W-band frequencies and shows less than 0.3 dB of insertion loss and better than 12 dB of return loss from 75 to 110 GHz. A 94 GHz CPW-fed microstrip antenna showing a 10-dB bandwidth of about 30 % has been built using the same transition technique.     

A Novel Reconfiguration CPW Leaky-Wave Antenna for Millimeter-Wave Application

A novel reconfigurable millimeter-wave leaky-wave antenna is proposed according to the radiation characteristics of periodically loaded coplanar waveguide and simulated by the finite-difference time-domain method. The simulated results demonstrate that the single main beam of this antenna operating at 35.0GHz can scan with small steps in the E-plane from –90° to 90° except the angle around 0°. The main beam scanning is obtained by the antenna structure reconfiguration with nine discrete states controlled by embedded switches and two feed ports. The antenna is useful for millimeter-wave applications.     

A Novel UWB Antenna with Small Side-Leakage

A successful design for a UWB (ultra-wideband antennas) antenna based on NRD-guide (nonradiative dielectric waveguide) with small side-leakage is presented. The rule of the theoretical selection of its parameters, if NRD-guide is used as the UWB antennas, is studied firstly, then the temporal propagation characteristics of the NRD-guide and the radiation characteristics for an tapered open-ended NRD-guide are calculated by FDTD (finite-difference time-domain) method.     

A High-gain Wideband Antenna with Double Fabry-perot Cavities

A high-gain wideband antenna, using the electromagnetic resonances of double Fabry-Perot (F-P) cavities, is proposed. The two cavities are excited by a patch antenna placed in the cavities on top of the ground plane. One of the double F-P cavities is formed by a ground plane and a single metallic strips array, and the other consists of the patch and the metallic strips array. The two F-P cavities have different resonance points which yield the frequency bandwidth of 7% between 13.0 and 14 GHz with S₁₁ ≤ 10 dB, meanwhile, in this frequency region high gain is also obtained. Moreover, the center frequency and bandwidth could be adjusted by changing the cavity length. The high-gain wideband antenna was manufactured and measured. The measured VSWR is less than 2 from 13.3 GHz to 15.2 GHz, the measured gain is 13.5 dB at 13.5 GHz. In addition to that, a considerable improvement of 7 dB in terms of gain is obtained when compared to the same antenna without metallic strips.     

A High-Power Reflector Impulse Antenna with Dual-Tem Source

There are different demands on radiation efficiency and direction pattern according to various ultra-wideband (UWB) antennas and high power applications. To obtain more radiating gain on bore-sight of paraboloidal reflector and centralized radiating direction, a novel feeding structure called dual-TEM source has been designed and applied in half-paraboloidal reflector impulse radiating antenna (IRA) applications. Simulation results proved that this proposed half-paraboloidal reflector IRA with dual-TEM source provided greater radiation performance on bore-sight as a result of the synthesized power in the aperture space of paraboloid. Moreover, lots of simulation work and comparison have been done in different feeding models to summarize a relative optimal feeding structure.     

A Plane-Wave Beam-Steering Lens Design Using Microstrip Switched-Line Phase Shifters

A compact beam-steering lens design appropriate for millimeter-wave and submillimeter-wave applications is experimentally verified with an X-band test model. The lens achieves coupling to plane-wave beams through arrays of patch antennas placed on its two outer surfaces. The isolation between input and output antennas is accomplished by inserting a metal ground plane in the middle of the lens. The two closest patch antennas on the front and the backside are connected together with microstrip circuits that include switched-line phased shifters and interconnecting vias through the lens substrate. Three different X-band 100-element plane-wave microstrip lenses that use passive delay lines instead of actual phase-shifters were fabricated to successfully demonstrate the beam-steering angles of 20 and 40 degrees. From a separate waveguide measurement on the unit-cell element only, the insertion loss of the lens was estimated to be approximately 3.5 dB with bandwidth of 2% at 10 GHz.     

A conical microstrip antenna with uniform substrate

A novel conical microstrip antenna with uniform substrate is investigated. The far field radiation patterns of wraparound microstrip antennas mounted on such a structure are studied theoretically. Results for a wraparound antenna of half-wavelength in width excited by TM₀₁ are given, which are verified accurate and efficient by the ones of wraparound cylindrical antennas when the cone angle is very small.