Some studies on two-layer electromagnetically coupled microstrip antenna with dielectric cover

Experimental investigations are carried out for two configurations, namely a driven hexagonal patch and an electromagnetically coupled microstrip antenna (EMCA), with different dielectric superstrates. Superstrate loading of the antenna is found to cause a considerable shift in the resonance frequency. The driven patch with superstrate behaves as an RL network. The maximum bandwidth of 6.21% is observed for the EMCA with a bakelite superstrate when the dielectric constant of the superstrate and the substrate of the antenna are equal.     

Efficiency enhancement of microstrip antenna by elevating radiating edges of patch

A new structure for a microstrip patch antenna fabricated on a highly lossy and thin FR4 substrate is presented. Elevated radiating edges of the metallic patch with notches as inductive loading form the patch antenna. This structure effectively reduces the dielectric loss and enhances the radiation efficiency. The proposed antenna has been designed and tested at 3.1 GHz as an example. It showed increased radiation power levels of more than 3 dB in both E- and H-plane radiation patterns when compared with those of a conventional planar patch antenna, indicating enhanced radiation efficiency.     

Design of Dielectric Grating Antennas for Millimeter-Wave Applications

At theoretical procedure well suited for generating design data on dielectric grating antennas for the millimeter-wave region is presented. The procedure utilizes the effective dielectric constant (EDC) method to determine the phase constant of the leaky modes supported by the antenna structure of finite lateral width. The radiation or leakage constant of these modes is obtained from the relatively simple boundary value problem of dielectric grating antennas of infinite width. For single-beam radiation, the practicably interesting case, the phase and leakage constants completely determine the field distribution in the antenna aperture, from which the directivity gain and radiation pattern are then calculated. The dependence of the antenna characteristics on the dimensions of the radiating structure is presented and discussed for epsilon = 12, the dielectric constant of typical millimeter-wave materials, such as silicon and GaAs.     

Microstrip dipoles on electrically thick substrates

Certain basic radiation properties of microstrip dipoles on electrically thick substrates are investigated, and a comparison is made with the case of dipoles printed on a dielectric half-space. It is concluded that the microstrip dipole radiation properties become sensitive to substrate loss as the substrate thickness increases, with the half-space properties obtained for an adequate amount of loss. Asymptotic formulas for radiated power and efficiency are given for both the thick substrate and half-space problems, showing the behavior with increasing dielectric constant. The method of moments is used to extend the analysis to center-fed strip dipoles, and a method of improving both the efficiency and gain of a printed antenna by using a superstrate layer is discussed.     

Coupling Reduction Between Dipole Antenna Elements by Using a Planar Meta-Surface

The mutual coupling between dipole antenna array elements using a planar meta-surface as superstrate is experimentally investigated. The meta-surface is based on grids of short metal strips and continuous wires. A comparison between the mutual coupling when the dipoles are radiating in free space and in presence of the superstrate is presented. On average, between 3 to 14 dB reduction of the mutual coupling is achieved when the superstrate is used. The effect of the mutual coupling on the radiation performance of the array is studied by spherical near-field measurements of the radiation pattern when one driven dipole is fed and the others are matched with 50 $Omega$ loads. The back-projected field on the aperture and on the E-plane is shown.      

Radiation of a rectangular microstrip patch antenna covered with a dielectric layer

The effect of a protecting dielectric superstrate on the radiation pattern of a rectangular microstrip patch antenna is investigated theoretically. The analysis approach is based on the spectral-domain method of moments in conjunction with the stationary phase method. A new concise expression is derived for computing the radiation electric field. The validity of the solution is tested by comparing the computed results with the experimental data. At higher superstrate thicknesses, numerical results indicate that the radiation pattern drastically changes into three lobes. The resonant frequency, on the other hand, increases with the increase of the thickness of the dielectric cover.     

Investigation Into the Effects of the Patch-Type FSS Superstrate on the High-Gain Cavity Resonance Antenna Design

Results of modeling, design, simulation and fabrication are presented for a high-gain cavity resonance antenna (CRA), employing highly-reflective patch-type superstrates. In order to determine the resonant conditions, the antenna is first analyzed using the transverse equivalent network (TEN) model, as well as the well known simple ray-tracing method. Prior to that, a highly-reflective patch-type frequency selective surface (FSS) is designed in order to be employed as the superstrate layer of the CRA. Next, a 2.5-D full-wave analysis software package, based on the method of moments (ANSOFT Designer v4.0), is utilized to analyze the antenna structure. Using this full-wave analyzer, the input impedance properties of an actual antenna are investigated as well. Then, a 3-D full-wave analyzer, based on the finite element method (ANSOFT HFSS), is used to extract the directivity and radiation patterns of the CRA, taking into account the finiteness of the substrate, superstrate and ground plane. Some previously unaddressed issues, such as the effects of the FSS superstrate on the input impedance characteristics of the probe-fed microstrip patch antenna, acting as the excitation source of the CRA are also studied. The effects of the highly-reflective FSS superstrate size on the CRA directivity, and explicitly its aperture efficiency, are investigated as well. A comparative study is also performed between CRAs with patch-type FSS and high permittivity dielectric superstrates. Measurement results are provided to support the modelings and simulations.      

Resonance and radiation of a superstrate-loaded spherical-circularmicrostrip patch antenna

The effects of the dielectric superstrate cover on the resonance and radiation problems of a spherical-circular microstrip patch antenna are studied, using the Green's function formulation in the spectral domain and the Galerkin moment method calculation. Numerical results for the resonant frequency, half-power bandwidth, and radiation pattern of the superstrate-loaded antenna are presented. The effects of curvature on these characteristics are also shown     

低雷达截面的超宽带扇形天线

 本文研制了一种新型可用于低可见平台的超宽带扇形天线.该扇形天线利用由一个矩形条带和对称分布在该矩形条带上的8个圆弧条组成的扇形结构设计天线的辐射单元;利用两边倒有90度圆弧角的矩形设计辐射地板;并将辐射单元和辐射地板分别印制在FR-4介质材料板(介电常数为4.4)的两侧.研究天线的辐射和散射特性,并与参考天线作对比,发现在满足超宽带天线的相关指标要求下,本文提出的天线具有良好的雷达截面减缩效果.本扇形天线适用于对超宽带天线有低雷达截面要求的场合.     

A dual-band multiple-input multiple-output microstrip antenna with metamaterial structure for LTE and WLAN applications

A method to enhance the gain of microstrip dual-band multiple-input multiple-output (MIMO) antenna using partially reflective surface (PRS) layer is introduced and investigated in this paper. The proposed antenna consists of two FR4 substrates. The lower substrate has two radiating patches with parasitic elements that are supplied independently and create the MIMO property of the antenna. The upper substrate which is known as superstrate is arrays of PRS unit cells. The PRS layer printed on either side of a dielectric substrate and causes the antenna gain to increase in both frequency bands. The proposed antenna is appropriate for LTE (2.4–3.1 GHz) and WLAN (5.1–5.8 GHz) applications. The measured values of S₁₁ and S₂₂ parameters of the antenna are less than −10 dB and its FBR and gain are 12.5 dB and 5dBi, respectively. The average half power beam-width (HPBW) is roughly 108^○.     

On the optimal radiation bandwidth of printed slot antennas surrounded by EBGs

This paper describes a design strategy to achieve the maximum bandwidth and efficiency for a printed slot antenna surrounded by EBGs. First the dielectric constant and the thickness of the dielectric slab that guarantees an acceptable front to back radiation ratio is identified. Then electromagnetic bandgap (EBG) structures are designed to achieve the optimal bandwidth (BW) while obtaining high surface wave efficiency in the radiating half space. To achieve this goal the wave interaction between the slot and the EBG structures is investigated in depth and clearly described. For the case of Planar circularly symmetric (PCS) EBGs the maximum of radiation BW is shown to occur when the distance between the central antenna and the EBG is approximately half wavelength of the first surface wave, /spl lambda//sub sw//2.     

Enhanced‐Gain Planar Substrate‐Integrated Waveguide Cavity‐Backed Slot Antenna with Rectangular Slot Window on Superstrate

A novel substrate‐integrated waveguide (SIW) cavity‐backed slot antenna is proposed in this study to achieve enhanced‐gain performance. The peak gain is remarkably improved with the use of an SIW cavity and metallic superstrate. The superstrate comprises a single rectangular slot window and two half‐wavelength patches. The gain can be enhanced by combining the in‐phase radiating fields. Further, the 10 dB bandwidth of the proposed antenna ranges from 2.32 GHz to 2.49 GHz, which covers the wireless local area network band. The measured peak gain is 9.44 dBi at 2.42 GHz.     

Design of an efficient miniaturized UHF planar antenna

The design aspects and the measured results of a novel miniaturized planar antenna are described. Such architectural antenna design is of great importance in mobile military communications where low visibility and high mobility are required. Slot radiating elements, having a planar geometry and capable of transmitting vertical polarization when placed nearly horizontal, are appropriate for the applications at hand. Slot antennas also have another useful property, so far as impedance matching is concerned. Basically, slot dipoles can easily be excited by a microstrip line and can be matched to arbitrary line impedances simply by moving the feed point along the slot. Antenna miniaturization can be achieved by using a high permittivity or permeability substrate and superstrate materials and/or using an appropriate antenna topology. We demonstrate miniaturization by designing an appropriate geometry for a resonant narrow slot antenna. A very efficient radiating element that occupies an area as small as 0.12/spl lambda//sub 0//spl times/0.12/spl lambda//sub 0/ is designed and tested. Simulation results, as well as the measured input impedance and radiation patterns of this antenna, are presented. This structure shows a measured gain of 0.5 dBi on FR4 substrate, which has a loss-tangent of the order of 0.01. Also, the effect of finite ground plane size on gain and resonant frequency is investigated experimentally.     

Perturbation Analysis of Dielectric Grating Antenna with LHM Substrate

A dielectric grating leaky wave antenna with a substrate consisted of left handed material (LHM) is presented in this paper, the case where the n?=??1 space harmonic of TM mode radiating into the space is carefully investigated through the improved perturbation analysis, which tremendously simplifies the analysis procedure with good calculation accuracy and brings considerable physical insight into the overall behavior of the dielectric grating antenna. It has been found that the new leaky wave antenna is of larger leakage constant than that of the traditional antenna with substrate of the right handed material (RHM). As a result the dimension of the antenna could be largely reduced, which is of practical significance for some applications. Extensive numerical results of the radiation characteristics are given to establish useful guidelines for the design of the new grating antenna.     

Circular polarization microstrip antenna on a conical surface

A theoretical model to analyze the performance of a circular polarization microstrip antenna printed on a conical surface is presented. The radiation pattern of the antenna is simulated by the radiation from its four radiating edges (two axial and two circumferential). The electromagnetic field is expanded in terms of spherical wave modes and it is shown that the circular polarization is obtained by exciting in the antenna two spherical TE_r orthogonal modes with 90° phase difference. The impedance analysis is based on the cavity model. Experimental data fits well the theoretical predictions of the model     

基于零阶谐振的高增益共形全向微带天线

为了实现与飞行器的共形,通过对等效磁流模型及负介电常数零阶谐振器的研究,设计了一种零阶谐振的共面磁流环阵列天线。该天线的工作频率为5 GHz,工作于TM01模式,具有全向辐射特性,水平面增益为3.4 dB,不圆度为2 dB,半功率波瓣宽度为50°。该天线具有水平面增益高,方向图不圆度小,剖面低的特点,且易于共形。     

Triple Band Circular Patch Microstrip Antenna with Superstrate

A novel compact triple band slit cut circular patch antenna with superstrate is proposed; slits on the patch provide additional resonances. The superstrate (cover) of dielectric layer provides protection to printed circuit antenna from environmental hazards due to abnormal weather conditions. The slits add two resonances in the resonance of a circular patch to achieve triple band antenna for multi services. The dielectric superstrate or cover above the microstrip patch causes the change in fringing fields between the patch and ground plane. The change in fringing field is accounted to calculate the effective relative permittivity. The effective permittivity is considered to evaluate the changes in resonance frequency due to superstrate. The various parameters of the antenna have been investigated and the antenna is simulated on Ansoft’s HFSS software simulator. A prototype of antenna is fabricated to confirm the return loss by measurement using the Agilent Technologies’ N5230A PNA-L Network Analyzer. The proposed structure with superstrate possess triple band characteristics and provides protection from environmental hazards. The resonating frequencies of the bands are 7.3, 8.7 and 10.3 GHz. The analytical results are found in good agreement with the simulated results obtained by Ansoft’s HFSS and further confirmed by measurement. Antenna is worth for X band operations such as remote sensing, WPAN and military satellite communication and vehicular applications.     

Broadband Planar Superstrate Antenna for Integrated Millimeterwave Transceivers

In this paper, a new planar superstrate antenna concept suitable for integration with millimeter wave (mmWave) transceiver integrated circuits (ICs) is presented. The antenna is printed on the bottom of a dielectric superstrate with a ground plane below. The new design provides high bandwidth and high efficiency. Two different examples of the new concept have been designed and manufactured for the 60 GHz industrial scientific medical (ISM) band using folded dipoles. Simulated and measured input impedance matching and far field radiation patterns for both antennas will be shown and discussed. Both designs achieve over 10% bandwidth while maintaining better than 80% efficiency.     

A High‐Gain Microstrip Patch Array Antenna Using a Superstrate Layer

A dielectric superstrate layer above a microstrip patch antenna has remarkable effects on its gain and resonant characteristics. This paper experimentally investigates the effect of a superstrate layer for high gain on microstrip patch antennas. We measured the gain of antennas with and without a superstrate and found that the gain of a single patch with a superstrate was enhanced by about 4 dBi over the one without a superstrate at 12 GHz. The impedance bandwidths of a single patch with and without a superstrate for VSWR < 2 were above 11%. The designed 2×8 array antenna using a superstrate had a high gain of over 22.5 dB and a wide impedance bandwidth of over 17%.     

Design of RFID tag antenna for metallic surfaces using lossy substrate

A novel low-cost antenna design suitable for radio frequency identification (RFID) tags mountable on metallic surfaces is presented. The antenna consists of two shorted patches printed on a lossy FR4 substrate and their radiating edges are facing each other. A tag chip feed is placed between two patches and a stacked shunt capacitor is formed to adjust the antenna impedance. The proposed design reduces the substrate loss and improves the radiation efficiency by more than double compared with a conventional planar inverted-F antenna, which is verified by simulation and measurement.