基于介质片加载实现MIMO介质谐振器天线解耦

提出了一种通过在介质谐振器(DR)上表面侧边加载介质片(DS)来实现1×2 MIMO介质谐振器天线(DRA)解耦的新方法。1×2 MIMO DRA采用双层介质基板结构以优化阻抗匹配特性和辐射特性,两DR的边到边间距为0,天线工作在毫米波频段。所加载的DS使得DR内的场重新分布并向DS加载区域以及DS内集中,从而减弱耦合到另一DR单元的场强以实现解耦效果。基于ANSYS HFSS的仿真结果表明天线的-10 dB阻抗匹配带宽为25.6%(22.75～29.43 GHz),带内最大实现了30 dB的隔离度的增强。     

Bandwidth enhancement of dielectric resonator antenna by loading alow-profile dielectric disk of very high permittivity

The aperture-coupled cylindrical dielectric resonator (DR) antenna loaded by a low-profile DR disk of very high permittivity is studied experimentally. By using the low-profile parasitic DR disk the antenna bandwidth can be increased from 8% bandwidth to 25%. The characteristics of the new configuration are measured and discussed     

A new inverted F antenna with a ring dielectric resonator

A new antenna combining the use of a ring dielectric resonator (DR) and an inverted F antenna (IFA) is proposed and investigated experimentally. In this application, the DR not only fills the role of a dielectric coating, but also serves the function of a radiator. The measurements of input impedance, return loss, and radiation pattern for both the IFA with the DR (IFA-DR) and the wire IFA (WIFA) are conducted at the S band. The measured data demonstrate that the IFA-DR operates in multiple resonance modes unlike a WIFA. Compared with the WIFA, the one proposed here incorporating a ring DR and an IFA is more attractive in having a smaller size and a larger impedance bandwidth     

Rigorous Analysis of Rectangular Dielectric Resonator Antenna With a Finite Ground Plane

A probe-fed rectangular dielectric resonator antenna (RDRA) placed on a finite ground plane is numerically investigated using method of moments (MoM). The whole structure of the antenna is exactly modeled in our simulation. The feed probe, coaxial cable and ground plane are modeled as surface electric currents, while the dielectric resonator (DR) and the internal dielectric of coaxial cable is modeled as volume polarization currents. Each of the objects is treated as a set of combined field integral equations. The associated couplings are then formulated with sets of integral equations. The coupled integral equations are solved using MoM in spatial domain. The effects of ground plane size, air gap between dielectric resonator and ground plane, probe length, and position on the radiation performance of the antenna including resonant frequency, input impedance, radiation patterns, and bandwidth are investigated. The results obtained for the antenna parameters based on the MoM investigation shows that there is a close agreement with those obtained by measurement. Moreover it is shown that the MoM results are more accurate than other simulation results using software package such as High Frequency Structure Simulator (HFSS).      

Gain-enhanced miniaturised rectangular dielectric resonator antenna

A double-layered high permittivity dielectric resonator (DR) was investigated experimentally at the 1.8 GHz band. The measured results show that the double-layered DR antenna has a 1.2 dB gain enhancement and 25% height reduction over a single-layered antenna. The bandwidth is 2.7% and antenna gain is 6.2 dBi     

Performance Analysis of a Low Profile Hybrid Antenna for Broadband Applications

In this paper, a low profile dielectric resonator antenna (DRA) is proposed and investigated. To achieve the broad impedance bandwidth the proposed antenna geometry combines the dielectric resonator antenna and an underlying microstrip-fed slot with a narrow rectangular notch, which effectively broadens the impedance bandwidth by merging the resonances of slot and DRA. The physical insight gained by the detailed parametric study has led to find out a set of guidelines for designing the antennas for any particular frequency band. The design guidelines have been verified by simulating a set of antennas designed for different frequency bands. For validation, a prototype antenna is fabricated and tested experimentally. The measured results show that the proposed DRA offers an impedance bandwidth of about \(125.34\%\) from 1.17 to 5.1 GHz with reasonable gain between 3.5 and 5.7 dBi. The volume of the proposed DRA is \(0.16\lambda _{dr}^{3}\), where \(\lambda _{dr}\) is the wavelength at center operating frequency of the DR. A comprehensive study on bandwidth shows that the proposed DRA provides maximum bandwidth in terms of the DR volume (\(\hbox {BW}/V_{dr}\)) and the DR height (\(\hbox {BW}/h_{dr}\)) than the other similar reported work on hybrid wideband DRA designs.     

Broadband Dielectric Resonator Antenna With Metal Coating

A broadband dielectric resonator (DR) antenna is proposed, which consists of a rectangular DR coated with metal on three sides and placed on a ground plane. The structure is analyzed by modelling the dielectric-air interface as perfect magnetic conductor (PMC). A coplanar waveguide (CPW) with terminating slots is used to feed the antenna. Measurement results exhibit a wide bandwidth of about 47% over which the E_thetas pattern on the horizontal plane is nearly omnidirectional. The 10-dB bandwidth of this broadband DR monopole covers 4.2-6.8 GHz. Hence, it can be used for WLAN 802.11a applications     

Rectangular dielectric resonator antenna for ultrawideband applications

A new dielectric resonator antenna (DRA) is introduced for ultrawideband applications. A rectangular dielectric resonator, a bevel feeding patch and an airgap between the DR and ground plane are used to obtain an ultrawideband impedance bandwidth. The effective dielectric constant and the Q-factor can be reduced by using the airgap and the bevel-shaped feeding mechanism, which can provide a smooth transition from one resonant mode to another. Measured results demonstrate that the proposed DRA has a wide bandwidth from 2.6 to 11 GHz with VSWR less than two, covering the frequency range of more than 120%. Experimental and numerical results are carried out and discussed, showing good agreement.     

Offset Cross-Slot-Coupled Dielectric Resonator Antenna for Circular Polarization

A cross-slot-coupled cylindrical dielectric resonator antenna (DRA) is studied theoretically and experimentally. In previous papers, a cross-slot of unequal slot lengths was centered under the dielectric resonator (DR), resulting in circular polarized operation of the antenna. In the present study, the design is enhanced by setting the centers of the two slots at different positions and taking into consideration the partial independence of the slot modes from the DRA mode. Thus, circular polarization (CP) bandwidth of up to 4.7% is attained experimentally in the broadside direction. It is also shown that a largely asymmetrical structure results in a very high bandwidth, but with the tradeoff of distorted CP operation off-broadside.     

FDTD analysis of probe-fed cylindrical dielectric resonator antenna

The finite-difference time-domain (FDTD) method is employed to analyze a probe-fed cylindrical dielectric resonator antenna. Numerical results for the input impedance and radiation patterns of the dielectric resonator (DR) antenna operating in HEM_11δ mode are presented and compare favorably with measurements. The effects of various parameters on the characteristics of the DR antenna are studied. Fabrication imperfection effects and the cross-polarization characteristics of this type of DR antenna are also investigated for the first time     

一种宽频带介质谐振器天线的设计与实现

摘 要：带宽拓展,一直以来是介质谐振器天线研究重要内容之一。基于此,本文设计了一款宽频带介质谐振器天线。采用共面波导馈电的单极天线与介质谐振器天线的混合结构,通过调节谐振器尺寸和共面波导的结构,使各个工作模式的频带互相重叠,展宽所设计天线的带宽;同时地板上引入开槽技术,对馈线进行阻抗匹配。利用仿真软件对天线参数进行优化仿真,实现天线频带宽度为2.98-7.18GHz（S11<-10dB）,相对带宽达到84.3%,带内最大增益达到4.9dBi。对该天线进行加工测试,仿真与测试基本吻合,结果表明,该天线不仅可实现宽频带,且结构简单,尺寸小,易集成,可广泛应用于WLAN/WIMAX等通信领域。     

蒙皮天线的浅介质腔体散射特性分析

随着隐身技术的不断发展,天线雷达散射截面( RCS)的缩减成为实现低散射平台电磁隐身特性的关键。蒙皮天线是天线RCS缩减的重要技术方向,而腔体散射又是蒙皮天线难以避开的问题,因此,介质浅腔的RCS缩减是实现低RCS天线的重要保障。通过仿真软件FEKO对浅腔、介质及介质浅腔的散射特性进行研究,得到了介质浅腔散射随介质浅腔深度呈现单调变化的条件,给出了一种具有低RCS值的菱形介质浅腔设计方法。该方法利用天线电性能及介质浅腔隐身性能对介质板厚度呈现单调变化的特性,在满足天线驻波比要求的基础上,通过尽量减薄介质基板的厚度实现介质浅腔RCS的缩减。实测结果表明,通过上述方法设计的介质浅腔的RCS得到了接近10 dB的缩减效果。     

一种高介GPS微带天线的设计与研究

针对传统GPS天线体积较大的问题,提出了一种改进的圆极化微带贴片天线,该天线用高介电常数的陶瓷作为天线基板,采用单端口背馈方式馈电,缩小了天线尺寸,结构简单。通过仿真优化,获得了比较好的阻抗带宽和轴比带宽,并以此为基础研究了介质基板厚度及损耗对天线性能的影响,为GPS微带天线设计提供一种思路。     

Cross-slot-coupled microstrip antenna and dielectric resonatorantenna for circular polarization

Circular polarization (CP) design of microstrip antennas and dielectric resonator (DR) antennas through a cross slot of unequal slot lengths in the ground plane of a microstrip line is demonstrated. The proposed CP design is achieved by choosing a suitable size of the coupling cross slot, which results in the excitation of two near-degenerate orthogonal modes of near-equal amplitudes and 90° phase difference. This CP design can be applied to both configurations of microstrip antennas and DR antennas and has the advantages of easy fine-tuning and less sensitivity to the manufacturing tolerances, as compared to their respective conventional single-feed CP designs. For the proposed design applied to a low-profile circular disk DR antenna of very high permittivity studied here, a large CP bandwidth, determined from 3-dB axial ratio, as high as 3.91% is also obtained. Details of the proposed antenna designs are described, and experimental results of the CP performance are presented and discussed     

Small eletric monopole mode dielectric resonator antenna

A novel dielectric resonator (DR) antenna is reported. The lowest order mode of the proposed antenna radiates like an electric monopole. The dimensions of the antenna are much smaller than a previously reported structure radiating in a similar mode, e.g. for an antenna fabricated out of ε_r=20 material, the diameter and height of the DR are ~0.08 λ₀ each     

Compact slot and dielectric resonator antenna with dual-resonance, broadband characteristics

The goal of this study is to improve the bandwidth of a miniaturized antenna. The proposed technique combines a slot antenna and a dielectric resonator antenna (DRA) to effectively double the available bandwidth without compromising miniaturization or efficiency. With proper design it is observed that the resonance of the slot and that of the dielectric structure itself may be merged to achieve extremely wide bandwidth over which the antenna polarization and radiation pattern are preserved. In addition, using the DRA, a volumetric source, improves the radiation power factor of the radiating slot. A miniaturized antenna figure of merit (MAFM) is defined to simultaneously quantify aspects of miniaturized antenna performance including the degree of miniaturization, efficiency, and bandwidth. Figures for various common types of antennas are given and compared with that of the proposed structures. In order to determine the effects of varying design parameters on bandwidth and matching, sensitivity analysis is carried out using the finite-difference time-domain method. Numerous designs for miniaturized slot-fed dielectric resonator antennas are simulated and bandwidths exceeding 25% are achieved. Two 2.4 GHz antennas are built, characterized, and the results compared with theory.     

Impedance, bandwidth, and Q of antennas

To address the need for fundamental universally valid definitions of exact bandwidth and quality factor (Q) of tuned antennas, as well as the need for efficient accurate approximate formulas for computing this bandwidth and Q, exact and approximate expressions are found for the bandwidth and Q of a general single-feed (one-port) lossy or lossless linear antenna tuned to resonance or antiresonance. The approximate expression derived for the exact bandwidth of a tuned antenna differs from previous approximate expressions in that it is inversely proportional to the magnitude |Z'/sub 0/(/spl omega//sub 0/)| of the frequency derivative of the input impedance and, for not too large a bandwidth, it is nearly equal to the exact bandwidth of the tuned antenna at every frequency /spl omega//sub 0/, that is, throughout antiresonant as well as resonant frequency bands. It is also shown that an appropriately defined exact Q of a tuned lossy or lossless antenna is approximately proportional to |Z'/sub 0/(/spl omega//sub 0/)| and thus this Q is approximately inversely proportional to the bandwidth (for not too large a bandwidth) of a simply tuned antenna at all frequencies. The exact Q of a tuned antenna is defined in terms of average internal energies that emerge naturally from Maxwell's equations applied to the tuned antenna. These internal energies, which are similar but not identical to previously defined quality-factor energies, and the associated Q are proven to increase without bound as the size of an antenna is decreased. Numerical solutions to thin straight-wire and wire-loop lossy and lossless antennas, as well as to a Yagi antenna and a straight-wire antenna embedded in a lossy dispersive dielectric, confirm the accuracy of the approximate expressions and the inverse relationship between the defined bandwidth and the defined Q over frequency ranges that cover several resonant and antiresonant frequency bands.     

Novel Utilization of the Dielectric Resonator Antenna as an Oscillator Load

For the first time, the idea of using the dielectric resonator antenna (DRA) as an oscillator load, named as DRAO, is presented in this paper. Unlike the conventional dielectric resonator oscillator (DRO), where the DR was merely used as a resonator, the DR here serves as both the radiating and oscillating loads. In addition, a compact tri-function hollow DR that incorporates the packaging function to the above dual function is demonstrated. The design procedures of the dual- and tri-function DRAOs are discussed. For demonstration, the DRAOs are designed at 1.85 GHz, which is used in the popular personal communications system (PCS). The return losses, input impedances, antenna gains, signal spectrums, phase noise, and radiation patterns of the two DRAOs are presented. It is shown that the loaded Q_L factor of the DRA can be increased by internally embedding a compact metallic cavity to the DR. It is found that with a higher loaded Q_L factor, the phase noise of the antenna oscillator using the hollow DRA (tri-function DRAO) is better than that using a solid DRA (dual-function DRAO).     

A New Class of Miniature Embedded Inverted-F Antennas (IFAs) for 2.4 GHz WLAN Application

A new class of miniature printed embedded inverted-F antennas are proposed for operation in the 2.4–2.485 GHz wireless local-area network band. One of the proposed antennas on FR4 substrate (dielectric constant = 4.4) measures 9.2 mm by 4.1 mm and has a bandwidth of 3.5%. The peak gain of this antenna is 1.4 dBi. An overall size reduction of 70% is achieved compared to a conventional inverted-F antenna. Effects of dielectric loss tangent and material conductivity on the bandwidth and efficiency of these antennas are also investigated. Finally, two embedded antenna elements are analyzed to demonstrate the feasibility for a decoupled antenna pair consisting of switched and combining diversity schemes.     

FDTD analysis of probe-fed cylindrical dielectric resonator antennaoperating in fundamental broadside mode

An analysis of a cylindrical dielectric resonator antenna operating at the fundamental broadside mode using the finite-difference time-domain (FDTD) method is presented. Good agreement between theoretical and experimental results on the input impedance of the DR antenna is obtained. The effects of the probe length, feed position and the dielectric constant on the input impedance are presented