一种具有宽带双极化低散射特征的微带阵列天线

针对阵列天线宽带散射缩减设计进行研究,设计了一种基于无源对消技术的低散射阵列天线,该新型微带阵列天线在宽频带内具有双极化低雷达散射截面（RCS, Radar Cross Section）性能;对基于两种散射性能不同的单元组成阵列的RCS性能进行了理论研究,进行了单元的散射幅度和相位对阵列RCS的影响分析;提出了一种加载T型缝隙的新型微带天线结构,该单元结构的辐射性能与散射性能能够进行独立调控和综合优化,该单元与传统微带贴片单元具有相似的辐射特性,并可在宽频带（带内和带外）内与传统微带单元产生有效相位差;将传统微带单元和加载T型缝隙的新型微带单元组成4×4阵列天线,仿真结果表明,提出的阵列天线在3GHz～7GHz（相对带宽80%）频带内实现了同极化RCS缩减,在3.3GHz～7GHz（相对带宽71.8%）频带内实现了交叉极化RCS缩减,缩减峰值分别为16.3dB和36.3dB,带内RCS缩减均值分别为14.1dB 和17.6dB;与传统微带阵列天线相比,提出的阵列天线增益下降小于0.1dB;提出的微带阵列天线具有高效率辐射和宽频带双极化低散射性能,为低散射阵列天线设计提供了新的思路。     

Modified circular common element four‐port multiple‐input‐multiple‐output antenna using diagonal parasitic element

A four‐port multiple input multiple‐output (MIMO) antenna with common radiating element is proposed for 2.4 GHz Wi‐Fi applications. It comprises a modified circular radiator fed by four identical modified feedlines, partial ground planes, and a diagonal parasitic element (DPE). The parasitic element is used to enhance the interport isolation. The antenna has a 2:1 Voltage standing wave ratio (VSWR) impedance band 2.34‐2.56 GHz and nearly omnidirectional radiation patterns. The radiation efficiency is more than 79% and gain is 2 dBi at resonant 2.43 GHz. The isolation in the given frequency band is 10 dB. At the 2.43 GHz, the isolation between adjacent ports (1, 2 and 1, 4) is 14 dB and between opposite ports (1, 3) is 12 dB. The mean effective gain (MEG) ≤ ?2.7 dB and envelope correlation coefficient is <0.01. The ?10 dB total active reflection coefficient bandwidth is 202 MHz. The antenna is designed for a Wi‐Fi device and the effectiveness of antenna has been checked for distance of ½ feet from the human head. The specific absorption rate (SAR) is found to be ≤0.17 W/Kg by CST simulation tool.     

A dual‐polarized cross‐dipole antenna with wide beam and high isolation for base station

In this paper, a dual‐polarized cross‐dipole antenna with wide beam and high isolation is designed and analyzed for base station. The proposed antenna consists of two planar cross dipoles with four square patches, two L‐shaped microstrip lines, two ground plates, four parasitic patches, and a reflector. The square patches are placed between the center of cross dipoles to couple with L‐shaped microstrip lines. By introducing the parasitic patches, the wide beam can be realized. The measured results show that the proposed antenna achieves an impedance bandwidth (|S₁₁| < ?10 dB) of about 18.7% (1.9‐2.35 GHz) and an isolation better than 30 dB. A measured gain of 5.7 dBi and a half‐power beamwidth over 120° at the center frequency are obtained. Furthermore, the size of the proposed antenna is only 0.5λ₀ × 0.5λ₀ × 0.22λ₀ (λ₀ is wavelength at the center frequency).     

A compact double‐layer wideband circularly polarized microstrip antenna with parasitic elements

In this article, a new broadband circularly polarized (CP) microstrip patch antenna (MPA) with a sequential phase (SP) square‐loop feeding structure is proposed. The presented antenna is composed of a square‐loop feeding structure, four L‐shaped parasitic patches with L‐shaped slots, four parasitic square patches, and a corner‐truncated square patch. At first, a SP square‐loop is designed as a feeding structure. Then, four L‐shaped parasitic patches with L‐shaped slots are utilized to generate one CP mode by a capacitive coupled way. At last, four parasitic square patches and a corner‐truncated square patch are together placed above the SP feeding structure to broaden the circularly polarized bandwidth (CPBW). The presented antenna has a wide 3‐dB axial ratio bandwidth (ARBW) of 16.7% (5.4 GHz, 4.95‐5.85 GHz), and a wide 10‐dB return loss bandwidth of 25.5% (5.5 GHz, 4.8‐6.2 GHz). The proposed antenna features compact structure and broad 3‐AR bandwidth which could completely cover the WLAN (5.725‐5.85GHz) band. Therefore, the proposed antenna is suitable for circular polarization applications in C band.     

A high‐gain compact circularly polarized microstrip array antenna with simplified feed network

A broadband high‐gain circularly polarized (CP) microstrip antenna operating in X band is proposed. The circular polarization property is achieved by rotating four narrow band linearly polarized (LP) microstrip patch elements in sequence. Since the conventional series‐parallel feed network is not conducive to the miniaturization of the array, a corresponding simplified feed network is designed to realize the four‐way equal power division and sequential 90° phase shift. With this feed network, the impedance bandwidth (IBW) of the CP array is greatly improved compared with that of the LP element, while maintaining a miniaturized size. Then, parasitic patches are introduced to enhance the axial ratio bandwidth (ARBW). A prototype of this antenna is fabricated and tested. The size of proposed antenna is 0.93λ₀ × 0.93λ₀ × 0.017λ₀ (λ₀ denotes the space wavelength corresponding to the center frequency 10.4 GHz). The measured 10‐dB IBW and 3‐dB ARBW are 13.6% (9.8‐11.23 GHz), 11.2% (9.9‐11.07 GHz) respectively, and peak gain in the overlapping band is 9.8 dBi.     

An off‐center‐fed compact wideband antenna with truncated corners and parasitic patches for circular polarization

A novel single‐fed circularly polarized wideband, compact and lightweight microstrip patch antenna (MPA) is proposed. The antenna is designed in a simple two‐phase procedure to achieve wideband and circular polarization. In the first phase, an off‐centered L‐shaped feeding arrangement is employed to obtain wideband (|S₁₁| < ?10 dB) over 10.6 GHz to 14.7 GHz with an improved peak gain of 5.25 dBi. In the second phase, the radiating patch is symmetrically truncated and two modified‐parasitic patches are added to ensure <3 dB axial ratio over 11.4 GHz to 12.8 GHz. A prototype has been fabricated and the measured results show close agreement with the simulation. The proposed antenna is suitable for fixed satellite and broadcast satellite communication in Ku‐band range.     

Dual polarized triple band hybrid MIMO cylindrical dielectric resonator antenna for LTE2500/WLAN/WiMAX applications

In this communication, triple band hybrid multi‐input–multi‐output (MIMO) cylindrical dielectric resonator antenna (CDRA) with high isolation is examined. The proposed MIMO antenna includes two symmetric folded microstrip line feeding structures along with CDRA at two different ends of substrate. Two inverted L‐shaped strips on the ground plane are used to enhance the isolation (S₁₂ < ?15 dB) as well as to generates 2.7 GHz frequency band. Metallic strip on the ground plane act as an electromagnetic reflector and also enhance the isolation between two antennas (S₁₂ < ?20 dB). Archetype of proposed MIMO antenna design has been fabricated and tested to validate the simulated results. The proposed antenna operates at three different frequency bands 2.24–2.38 GHz, 2.5–3.26 GHz, and 4.88–7.0 GHz (S₁₁ < ?6 dB) with the fractional bandwidth 6.06%, 26.4%, and 35.7%, respectively. Folded microstrip lines generate path delay between the electric field lines and originate circular polarization characteristics in the frequency range 5.55–5.75 GHz with the fractional bandwidth of 3.55%. In order to satisfy the different performance requirement of MIMO antenna such as envelop correlation coefficient, mean effective gain, effective diversity gain, peak gain are also examined. The proposed antenna is found suitable for LTE2500, WLAN, and WiMAX applications. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2016.     

A wideband compact antenna with quad‐circular polarized bands in its operating regions

This article presents the design of an offset CPW‐fed slot antenna which exhibits a narrow impedance bandwidth (IBW; |S₁₁| ≤ ?10 dB) extending from 1.20 GHz to 1.45 GHz and another wide impedance bandwidth from 1.86 GHz to 8.4 GHz thus covering almost all the conventional operating frequencies. The antenna is loaded with semicircular and rectangular stubs and meandered microstrip lines to realize circular polarization at 1.35 GHz, 3.3 GHz, 4.9 GHz, and 7.5 GHz with axial ratio bandwidth (axial ratio ≤ 3 dB) of 19.25% (1.2‐1.46 GHz), 4.24% (3.24‐3.38 GHz), 4.1%(4.8‐5 GHz), and 5.2% (7.3‐7.69 GHz) respectively thus covering the GPS, WiMAX, WLAN, and X‐band downlink satellite communication application bands. The mechanism of generation of CP is discussed using vector analysis of surface current density distribution. The gain is fairly constant in the wide IBW region with maximum fluctuation of 1.2 dB. The structure is compact with an overall layout area of 0.27λ × 0.27λ, where λ is the free‐space wavelength corresponding to the lowest circular polarized (CP) frequency. A comparison of the proposed antenna with previously reported structures is performed with respect to impedance bandwidth, compactness, number of CP bands, LHCP to RHCP isolation and gain to comprehend the novelty of the proposed design. A prototype of the proposed antenna is fabricated and the measured results are in accord with the simulated results.     

A hybrid printed monopole antenna loaded with dielectric resonator for wideband and circular polarization applications

This article presents a novel compact circularly polarized antenna with wideband operation. The proposed antenna consists of a microstrip‐line‐fed printed monopole, a finite truncated ground, and a dielectric resonator (DR). Compared to the printed monopole antenna, the proposed DR‐loaded antenna has an increased impedance bandwidth, a large axial ratio bandwidth, and a good realized gain across the desired frequency range. An antenna prototype is fabricated and experimentally tested. The measured antenna impedance match is better than ?10 dB over 90% from 4.5 to 11.8 GHz frequency band and the 3‐dB axial‐ratio bandwidth is better than 35% covering the 5.4–7.65 GHz frequency band. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2012.     

Compact microstrip antennas with very wide ARBW and triple circularly polarized bands

This article presents two compact circularly polarized microstrip antennas with a very wide 3 dB axial ratio bandwidth and triple circularly polarized bands. A hexagonal stub (circular polarization element) along with tuning element in the ground plane is used for achieving wide 3 dB ARBW in antenna‐1, while a novel approach of using a parasitic strip around the circular polarization element is used in antenna‐2 for introducing band elimination notches in the circularly polarized band of antenna‐1. The antenna‐1 has a ?10 dB impedance bandwidth of 12.34% (3.8‐4.3 GHz), 84.02% (4.9‐12 GHz), and 3 dB ARBW of 79.94% (4.9‐10.9 GHz). The antenna‐2 displays circularly polarized band elimination notch characteristics with ?10 dB impedance bandwidth of 24.80% (3.85‐4.94 GHz), 31.72% (6.1‐8.4 GHz), 25.35% (9.3‐12 GHz), and 3 dB ARBW of 4.84% (4.63‐4.86 GHz), 19.08% (6.02‐7.29 GHz), and 5.7% (9.54‐10.1 GHz). Both the antennas are designed and fabricated on FR4 substrate of dimension (0.52 × 0.52 × 0.04)λ₀ at a frequency of 7.9 GHz.     

A compact wideband circularly polarized antenna with two pairs of driven patch arrays

In this article, a new wideband circularly polarized (CP) antenna is presented. The antenna is composed of a circular‐loop feeding structure which provides sequential phase (SP), four primary‐parasitic crown patches and four secondary‐parasitic crown patches. The circular‐loop SP structure is used to feed the two pairs of crown patches by a capacitively coupled way. The presented antenna features a wide 10‐dB impedance bandwidth (IBW) of 23% (6 GHz, 5.31‐6.69 GHz), and a wide 3‐dB axial ratio bandwidth (ARBW) of 11.1% (5.875 GHz, 5.55‐6.2 GHz). The proposed antenna features compact structure and broad 3 dB‐ARBW, which could include the WLAN (5.725‐5.85 GHz), ITS (5.8 GHz), and WIFI (5.85‐5.925 GHz) band.     

A compact wide band textile MIMO antenna with very low mutual coupling for wearable applications

This communication presents a compact wide band wearable MIMO antenna with very low mutual coupling (VLMC). The proposed antenna is composed of Jeans material. Two “I” shaped stubs are connected in series and are employed on the ground plane between the two patches separated by 0.048 λ to increase isolation characteristics of the antenna‐port. The antenna covers frequency spectrum from 1.83 GHz to 8 GHz (about 125.5%) where the minimum port isolation of about 22 dB at 2.4 GHz and maximum of about 53 dB at 5.92 GHz are obtained. The envelope correlation coefficient (ECC) of the MIMO antenna is obtained to be less than 0.01 with a higher diversity gain (DG > 9.6) throughout the whole operating band. The proposed MIMO antenna is cost effective and works over a wide frequency band of WLAN (2.4‐2.484 GHz/5.15‐5.35 GHz/5.72‐5.825 GHz), WiMAX (3.2‐3.85 GHz) and C‐band downlink‐uplink (3.7‐4.2 GHz/5.925‐6.425 GHz) applications. Simulation results are in well agreement with the measurement results.     

High gain transmitarray antenna based on ultra‐thin metasurface

This article presents a bandwidth enhanced transmitarray (TA) antenna based on ultra‐thin metasurface (MS) for high gain operating at X‐band. The antenna consists of a three layers continuous flat structure and an aperture coupled microstrip antenna as the feed source. The relative phase shift of 360° is achieved by the unit cell design based on ultra‐thin MS, and the quasi‐spherical wave could be focused as plane wave when the wave goes through TA. The aperture coupled microstrip feed is designed with a bandwidth of 20.6%, and the bandwidth enhanced property of feed source will reduce the negative effect of elements mutual coupling on TA and increase the bandwidth of the TA antenna. The TA antenna gain increases from 8.25 to 18.98 dB and with a side lobe level of ?14.3 dB. Owing to the low‐profile and easy configuration, this kind of TA antenna has great potential, wireless communication.     

星载合成孔径雷达双极化天线阵研究

介绍了一种宽带双极化星载SAR有源相控阵天线阵,该天线以TR组件和双极化线阵组成的有源线阵为基础,并根据相控阵天线对雷达信号瞬时带宽的限制条件,选择合适的实时延迟子阵,结合结构安装的要求,构成电气独立的模块。在此基础上,根据雷达对天线孔径大小的需要,通过馈电网络激励拓展成大型有源相控阵天线,该天线可以通过波控灵活的控制和网络的合成,实现多极化、波束扫描、波束赋形和多通道等功能。其中对于双极化辐射天线,分别针对微带贴片天线阵和波导缝隙天线进行了分析和研究,并给出了实验验证结果。微带天线阵采用宽带的双层贴片辐射单元和并馈网络实现大带宽要求,两种正交极化模式分别由共面微带线和缝隙耦合来激励,其馈电网络居于开有耦合缝隙接地板的两侧,实现复杂网络空间安排和降低馈线耦合的功能。对于贴片单元的激励,采用对称、反相馈电和分组优化等方法,有效地提高了极化隔离度和极化纯度;而双极化波导缝隙阵中,以脊波导宽边纵缝谐振阵实现垂直极化,波导窄边非倾斜缝隙阵实现水平极化,在每种线阵中都通过分组馈电、过载技术和辐射/馈电波导一体化设计,实现了宽带和压缩横截面的目的。两种形式的天线阵比较,阵面剖面高度相当,微带阵具有宽带、轻质、易于加工和成本低等优势,而波导缝隙阵则具有高效、高隔离度和低交叉极化等性能,但是其缺点是结构复杂、加工难度大和重量大等。     

Investigation on decoupling of wide band wearable multiple‐input multiple‐output antenna elements using microstrip neutralization line

An investigation to enhance the decoupling between the elements of a compact wide band multiple‐input multiple‐output (MIMO) antenna is presented in this communication. A microstrip neutralization line (NL) is designed on the top of antenna surface to enhance the port isolation. The geometry is embedded on a jeans material to be apposite for the on‐body wearable applications. The antenna covers the frequency spectra from 3.14 to 9.73 GHz (around 102.4%) and fulfills the bandwidth requirements of WiMAX (3.2‐3.8 GHz), WLAN (5.15‐5.35/5.72‐5.85 GHz), C band downlink‐uplink (3.7‐4.2/5.9‐6.425 GHz), downlink defense (7.2‐7.7 GHz), and ITU (8‐8.5 GHz) bands. The port isolation is found to be more than 32 dB over the whole application bands. The antenna is appraised in a rich scattering environment with very minimal envelope correlation coefficient (ECC < 0.12) and great amount of diversity gain (DG > 9.8). The proposed MIMO antenna system is able to achieve the channel capacity loss (CCL) of less than 0.2 BPS/Hz throughout the whole operating band. The proposed structure is etched on an area of 30 × 50 mm². The simulated and measured performances of the proposed antenna are in well‐matched state.     

Meander line MIMO antenna for 5.8 GHz WLAN application

A four port compact low profile planar MIMO antenna with meander line radiators and with polarization diversity effect has been proposed to cover 5.8 GHz wireless local area network application. The proposed MIMO antenna has ?10 dB impedance bandwidth of 1.4 GHz (5.3–6.7 GHz) along with the compact size of 38 × 38 mm² and an envelope correlation coefficient (ECC) of less than 4 × 10^?4 in the whole band. The proposed antenna resonates at 5.8 GHz frequency, having return loss of ?43.2 dB. The isolation between diagonal and opposite ports is more than 10 and 12 dB, respectively, in the presented frequency band. The total active reflection coefficient frequency response shows more than 1.0 GHz of bandwidth in the whole band. The antenna gain is more than 4.0 dBi in the operating frequency band. The radiating elements are very close to each other to make the design very compact.     

An ultrawideband unidirectional modified foursquare antenna

This study introduces an ultrawideband unidirectional modified foursquare antenna. The antenna consists of two radiating loops and two truncated parasitic patches. A microstrip‐to‐stripline transition is used as a balun to feed the two radiating loops. A square cavity works as a reflector to realise a unidirectional radiation. This antenna has a total size of 0.56λ_L × 0.56λ_L × 0.15λ_L (λ_L: free space wavelength at lowest operating frequency). The measured results show that a broad operating bandwidth of 103.8% (2.67–8.44 GHz) for return loss being higher than 10 dB is achieved. Meanwhile, measured stable unidirectional radiation patterns with a gain (6.9–11.3 dBi) in +z direction, a front‐to‐back ratio better than 14.5 dB and low cross‐polarization level (相似文献   

A wideband aperture coupled magneto‐electric dipole with high gain stability

In this article, a wideband aperture coupled magneto‐electric (ME) dipole is proposed. The proposed dipole antenna is based on the traditional ME dipole which consists a pair of horizontal patches and a pair of vertical shorted patches. To achieve a wide impedance bandwidth, a stepped microstrip to slot transition is introduced in the antenna. Then, the vertical part of the dipole is tilted and two metal triangular prisms are employed to enhance the stability of the gain. A prototype antenna is fabricated and tested. Good agreements are found between the simulated and measured results. The measured impedance bandwidth for VSWR ≤2 is more than 125% (2.24‐10.0 GHz). The 1 dB gain bandwidth is about 108% (2.4‐8.0 GHz). Moreover, a stable unidirectional radiation patterns can be found across the 1 dB gain bandwidth.     

Design of a dual‐band MIMO dielectric resonator antenna with high port isolation for WiMAX and WLAN applications

A novel dual‐band MIMO dielectric resonator antenna with high port isolation for WiMAX and WLAN applications is designed and investigated. The proposed antenna operates at 3.5 and 5.25 GHz bands. High port isolation is achieved using hybrid feeding mechanism that excites two orthogonal modes at each frequency bands. The measured impedance bandwidth of the proposed antenna covers the entire WiMAX (3.4–3.7) GHz and WLAN (5.15–5.35) GHz bands. The scalable behavior along with the frequency ratio of the antenna has also been investigated in this work. The measured isolation between antenna ports is ?52 dB at the lower band and ?46 dB at the upper band, respectively. Envelope correlation coefficient, diversity gain and mean effective gain have also been investigated. Moreover, measured results are in good agreement with the simulated ones.     

A compact UWB MIMO antenna with neutralization line for WLAN/ISM/mobile applications

A novel design of 2 × 2 multiple‐input‐multiple‐output (MIMO) antenna is reported for ultra‐wideband applications. The neutralization line is implemented to minimize the mutual coupling between the radiating patches. The overall dimension of the designed antenna is 21 × 34 × 1.6 mm³. This antenna covers the measured bandwidth of 95.0% (3.52‐9.89 GHz) with better isolation (≤?22 dB) over the entire operating frequency band. The measured gain varies from 3.08 to 5.12 dBi over the entire band. The various antenna parameters such as S‐parameters, gain, efficiency, envelope correlation coefficient, mean effective gain, channel capacity loss, total active reflection coefficient, and radiation patterns are calculated and corresponding results are validated with the measured results.