A Novel Miniature Broadband/Multiband Antenna Based on an End-Loaded Planar Open-Sleeve Dipole

Open-sleeve dipoles are versatile antennas primarily because they have several design parameters that can be varied to achieve a wide range of VSWR performance and operating bandwidth. By properly adjusting their parameters, it is possible to create versions of these antennas that have either a broadband or a dual-band response. In this paper, a new variation of the conventional open-sleeve dipole antenna is introduced, which we call an end-loaded planar open-sleeve dipole (ELPOSD). This configuration provides a degree of miniaturization while retaining a comparable bandwidth in terms of the VSWR response to that of conventional open-sleeve dipoles. Several designs are presented for the conventional and end-loaded configurations that demonstrate the VSWR and miniaturization capabilities of this class of antennas. Measured results have been compared with simulations and found to be in good agreement for an end-loaded planar open-sleeve monopole     

Design of electrically small wire antennas using a pareto genetic algorithm

We report on the use of a genetic algorithm (GA) in the design optimization of electrically small wire antennas, taking into account of bandwidth, efficiency and antenna size. For the antenna configuration, we employ a multisegment wire structure. The Numerical Electromagnetics Code (NEC) is used to predict the performance of each wire structure. To efficiently map out this multiobjective problem, we implement a Pareto GA with the concept of divided range optimization. In our GA implementation, each wire shape is encoded into a binary chromosome. A two-point crossover scheme involving three chromosomes and a geometrical filter are implemented to achieve efficient optimization. An optimal set of designs, trading off bandwidth, efficiency, and antenna size, is generated. Several GA designs are built, measured and compared to the simulation. Physical interpretations of the GA-optimized structures are provided and the results are compared against the well-known fundamental limit for small antennas. Further improvements using other geometrical design freedoms are discussed.     

Wideband double-fed planar monopole antennas

Planar monopole antennas with multiple feed points are proposed to improve pattern and impedance bandwidth. A square planar monopole antenna including two feed points and a bevelled variant are designed. These antennas exhibit an excellent performance compared to existing planar monopoles     

Broadband planar antenna with parasitic radiator

A novel kind of planar monopole broadband antenna with a parasitic radiator is presented. Measurements show that the bandwidth of the monopole antenna has been considerably improved with a parasitic element earthed with a matching inductor. The achieved impedance bandwidth reaches over 85% for VSWR/spl les/2, and the measured radiation patterns have little distortion when the frequency changes. The impedance bandwidth parameters are compared for different dimensions of ground planes     

宽带平面直角双频单极天线

对于超宽带系统,需要具备可工作频率为3.1~10.6GHz的宽带天线。本文介绍了四种宽带平面单极天线,分别为圆形平面单极天线、平面直角单极天线、平面双频单极天线和平面直角双频单极天线。其中平面直角单极天线兼具宽频和全向特性,平面双频单极天线和平面直角双频单极天线在两个谐振点都具有宽带特性,平面直角双频单极天线在整个频带内水平面的辐射方向图几乎都可以达到全向。     

A study of pulse radiation from several broad-band loaded monopoles

Five previously proposed designs for broad-band monopole antennas are evaluated for pulse radiation. These designs use continuous resistive loading and/or discrete capacitive loading to increase the bandwidth over that of a simple, metallic monopole. The parameters for each of the designs are scaled so that the designs can be compared on a common basis (frequency range). Each of the antennas is analyzed numerically, and quantities characteristic of their pulsed performance are computed. These quantities include the reflected voltage in the feeding transmission line, radiated electric field, radiating efficiency, time-domain gain, fidelity, and symmetry when the monopoles are excited by a differentiated Gaussian pulse. In addition, the input reflection coefficient and gain at broadside for monochromatic excitation are shown. Explanations are provided for the differences in performance for these designs     

Built-in folded monopole antenna for handsets

A built-in folded monopole antenna for handsets (BFMA) is introduced and investigated. The characteristics of the BFMA are compared with those of a planar inverted-F antenna (PIFA), which is one of the conventional handset antennas. As a result, it has been confirmed that the BFMA has smaller size and wider bandwidth compared with the PIFA.     

Measurement and analysis of miniature multilayer patch antenna

Although the microstrip patch antenna has a number of advantages such as low-cost and light weight, its physical size is quite large at low microwave frequencies. The designs of multilayer miniature patch antennas with coaxial feed are presented. The first design is a rectangular two-layer patch antenna. Measured results and the results of a preliminary analysis are presented. The projection area of the two-layer patch antenna is kept the same as the single-layer rectangular patch antenna. The resonant frequency of the two-layer antenna is reduced by 50% and has bandwidth of 5%, which is wider than the single-layer rectangular patch antenna. In the second design, the upper patch is cut into a bow-tie shape. This results in a 60% reduction in resonant frequency and a 12% bandwidth. Both the two-layer rectangular and the two-layer bow-tie antennas have good radiation patterns, with cross-polarization level lower than the copolarization level by more than 20 dB     

Genetic algorithm based inversion of neural networks applied to optimised design of UWB planar antennas

An inversion of artificial neural networks using a genetic algorithm is presented for a novel concept of optimisation applied to UWB planar antennas of bow-tie type with respect to specified values of antenna performance in the frequency range 3.1-10.6 GHz. This efficient concept is shown to achieve significant reduction in computing time for optimisation. The multidimensional inversion is characterised by a simple composite fitness or target function that includes antenna parameters as a function of signal frequency or/and angle dependence. Good impedance matching and gain performance is achieved over the whole frequency range by adequately modifying the radiating contour profile of the conventional triangular bow-tie antenna.     

Impedance characteristics of planar bow-tie-like monopole antennas

The impedance characteristics of planar bow-tie-like monopole antennas have been studied experimentally. The planar bow-tie-like monopole antenna achieves a broad bandwidth, typically of >75%. A modified formula is suggested to accurately evaluate the frequency corresponding to the lower edge of the impedance bandwidth     

A Wideband Cross Monopole Antenna

Configurations of planar cross monopole antennas have been investigated. The cross-shaped patch comprises vertical microstrip and two rectangular patches (area A). Effect of rectangular patches (A) of planar cross monopole antennas on the bandwidth has been studied. Another dielectric substrate (075BCT) is used in order to optimize the size. Those antennas provide wideband characteristic and nearly omni-directional radiation pattern. Simulations and experiments demonstrate that this structure exhibits a wide impedance bandwidth, which is over 70% for ${rm S}_{11}leq 10 {rm dB}$ ranging from 2.18–4.78 GHz, which is enough to cover DECT/IMT-2000/3G/UMTS/2.45-GHz ISM band (WLAN, IEEE 802.11b and g)/Bluetooth/ZigBee 2.4 GHz/2.5-GHz WiMAX/3.5-GHz WiMAX bands.      

超宽带平面天线技术

对近年来发展的超宽带平面天线技术进行了综述,依次介绍了超宽带平板单极天线、超宽带印刷单极天线和超宽带印刷缝隙天线的进展,并作了比较.最后也介绍了具有带阻功能的超宽带印刷天线..     

Planar Miniature RFID Antennas Suitable for Integration With Batteries

A class of planar, electrically-small UHF antennas suitable for direct integration with electronic components such as batteries is introduced. The new design approach combines a meander line section and a capacitive strip section. The geometries of the two sections can together be scaled in size over a wide range of planar form factors while still maintaining self-resonance and practically realizable line widths and spacings. No external matching network is required. Moreover, batteries can be mounted above or below the capacitive strip section, significantly reducing the total size of a wireless device. Three designs are demonstrated on printed circuit board at 433 MHz. Measurements show that the antennas provide good gain and excellent bandwidth, omnidirectional radiation patterns, and electrically small size. The results of this work have numerous uses in radiofrequency identification (RFID)     

Design of electrically small planar antennas using inductively coupled feed

A class of electrically small planar antennas with an inductively coupled feed structure is proposed. The antennas are optimised using the Pareto genetic algorithm. These antennas are self-resonant and capable of good efficiency and bandwidth performance without any additional matching networks. Several prototypes are fabricated and measured and the results agree well with simulation. A lumped element circuit model is presented to explain the operating principle of these antennas.     

一种新型UWB平面单极子微带天线阵的设计

提出了一种新型平面单极子微带天线阵,以平面矩形单极子天线为原型,通过改变辐射贴片的形状实现对原有天线性能的优化。设计了中心频率为2.4 GHz,相对带宽是42%,增益达13 dBi的宽频带四单元平面单极天线阵。通过仿真与实验表明,该天线在1.93 GHz~2.93 GHz频带内反射系数均小于-10 dB。     

应用于WLAN的宽频带天线设计

为了设计出可以覆盖无线局域网WLAN的2.4GHz,5.2GHz,5.8GHz三个频带的天线,采用一种结构简单的宽带双频共面波导馈电的单极子天线。该天线由一个平面倒L形和一个倒U形贴片连接构成,实际加工制作了一个天线并且实测了S11参数,结果表明该天线具有两个独立的谐振模式,并且在应用范围内具有良好的阻抗匹配特性。     

Design of Shared Aperture Wideband Antennas Considering Band-Notch and Radiation Pattern Control

Two wideband antennas sharing a common aperture are presented. One antenna consists of an electrically loaded rectangle monopole, an electrically loaded inverse L-shape monopole, and a lowpass matching network between the two monopoles. It covers 30–600 MHz (VSWR ${≪}3$) with band-rejection characteristic in 86–110 MHz. The other one is a planar open-sleeve monopole, which covers 820–1200 MHz with VSWR${≪}2$. These two antennas are integrated in an aperture with size of only 420$,times,$ 200 mm $^{2}$. Both antennas are planar, which are promising candidates for either vehicular or airborne applications.      

Electrically small complementary pair (ESCP) with interelement coupling

Electrically small (reduced size) antennas are inherently narrow-band or inefficient, or both. A summary is presented of prior work on complementary pair antennas and the use of the coupling between the two elements to optimize the impedance match and efficiency of such structures. The design of electrically small complementary pairs is described, and preliminary measurement results are shown for monopoles. These measurements indicate a substantial improvement in gain-bandwidth product as compared to conventional matching techniques for electrically small antennas. The power delivered to the external region is analyzed for both an individual monopole, and a pair of monopoles, by establishing the scattering matrices for both cases. The potential gain is calculated for the pair over the individual monopole, and it is shown that the pair can deliver up to twice the power to the exterior region if the mutual impedance term is optimized. In addition, the complementarization circuit in conjunction with the hybrid feed can reduce the effects of mutual impedances in steerable-beam arrays. Various special cases are discussed, varying from full complementarity to zero complementarity, and general conclusions are presented on the optimization of gain-bandwidth product. Applications include small individual antennas and scatterers as well as linear, planar, or circular arrays in a variety of fixed-station or vehicular uses.     

An Evolutionary Method for Synthesizing Low-Sensitivity Lossless Matching Networks

Whereas the present practice of designing matching networks for antennas is limited to conventional topologies, requiring a significant amount of domain knowledge, evolutionary algorithms can be used for automatically identifying unconventional designs that are more effective than would otherwise be developed. In this work, an automatic method to design lossless matching networks driven by an evolutionary algorithm (EA) that considers the sensitivities of the network parameters during the synthesis process is presented. To this end, a closed-form expression for the transducer power gain (TPG) sensitivity with respect to the component values is employed in such a way that the effects of the components tolerance on the matching network performance can easily be quantified. A 3D data structure based on the adjacency matrix is conveniently used to represent any type of network topologies. The proposed EA employs a novel set of topology variation operators, tailored for changing the circuit topology, and an association step, with the aim of reducing the number of nodes of the matching circuit. The efficiency of the proposed EA is tested in the synthesis of an impedance matching network for a VHF monopole whip antenna. This study’s results indicate a matching bandwidth improvement, a more uniformly distributed TPG along the operation frequency band and a more stable TPG regarding the components tolerance compared to the results obtained by previous approaches.     

Wideband monopole antennas for multi-band wireless systems

The planar monopole antenna is shown to provide extremely wideband impedance characteristics. Recently, many techniques to tailor and optimize the impedance bandwidth of these antennas have been investigated. These include the use of bevels, slots and shorting posts. These antennas are becoming popular, and have been proposed for modern and future wideband wireless applications. The radiation performance is also shown to be acceptable over a wide frequency range.