Artificial Ground Plane Research Articles

Low‐profile wideband Fabry‐Perot resonator antenna using artificial magnetic conductor surface

AbstractA low‐profile, high gain Fabry‐Perot Resonator antenna with a wide operation bandwidth (BW) is presented in this paper. The proposed design consists of an ellipse‐shaped dipole as a wideband radiating source, which is reflected by an artificial magnetic conductor ground plane to achieve low‐profile structure. The antenna gain can be significantly enhanced by the use of a half‐wavelength‐thick dielectric slab as a partial reflecting surface. Additionally, this dielectric slab also contributes to improving the radiation pattern characteristics of the proposed design, especially in the high frequency region. A final prototype with an overall size of 1.2λ L × 1.2λ L × 0.4λ L (λ L is free‐space wavelength at the lowest frequency of 3‐dB gain BW) has been fabricated to validate the concept. The measured results show that the proposed antenna yielded a wide 3‐dB gain BW of approximately 50.3% with a peak gain of 14 dBi and impedance matching BW of 48.9%.

Reconfigurable, Wideband, Low-Profile, Circularly Polarized Antenna and Array Enabled by an Artificial Magnetic Conductor Ground

A reconfigurable, wideband, and low-profile circular polarization (CP) antenna is presented. Its wideband CP reconfigurability is realized by incorporating RF switches into a cross-bowtie radiator. A compact, wide bandwidth, and polarization-independent artificial magnetic conductor ground plane is developed to minimize the overall profile of the antenna while maintaining its wide bandwidth. The simplicity of this single-element design facilitates the realization of a reconfigurable, wide bandwidth CP array that achieves higher directivity without changing its overall profile. Prototypes of the single element and of a $1 \times 4$ array of these elements were fabricated and tested. The measured results for both prototypes are in good agreement with their simulated values, validating their design principles. They are low profile with a height $\sim 0.05\lambda _{\mathrm {\mathbf {0}}}$ . The array exhibits a wide fractional operational bandwidth: 1.65 GHz (21.7%), and a high realized gain: 13 dBic. Since they would enhance their channel capacity and avoid polarization mismatch issues, these reconfigurable CP antenna systems are very suitable for modern wireless systems.

A Compact Dual-Band Antenna Enabled by a Complementary Split-Ring Resonator-Loaded Metasurface

In this paper, the design of a compact dual-band antenna with operational bands centered at 1.9 and 2.5 GHz is introduced and validated numerically as well as experimentally. The proposed antenna is comprised by placing a monopole feeding antenna above an engineered multilayer metasurface (MS) which functions as an artificial ground plane. Moreover, complementary split-ring resonator structures are incorporated into the multilayer MS design to realize the dual-band operation of the proposed monopole-MS integrated antenna system. Dispersive analysis of the MS unit cell reveals the underlying radiation mechanism of the antenna. It is observed that the designed MS resonates in both frequency bands with a resonance mode pattern resembling that of the $TM_{10}$ mode of a rectangular patch antenna, thereby yielding a broadside radiation pattern in both bands. The overall footprint of the antenna is only $\mathrm {0.062}{\lambda }_{0}^{2}$ , where ${\lambda }_{0}$ is the free space wavelength at 1.9 GHz. Importantly, by using the proposed artificial ground plane, even with a highly miniaturized form factor, the antenna still maintains a peak gain of above 5 dBi and a front-to-back ratio higher than 6 dB within the two operational bands.

Compact, Highly Efficient, and Fully Flexible Circularly Polarized Antenna Enabled by Silver Nanowires for Wireless Body-Area Networks.

A compact and flexible circularly polarized (CP) wearable antenna is introduced for wireless body-area network systems at the 2.4GHz industrial, scientific, and medical (ISM) band, which is implemented by employing a low-loss composite of polydimethylsiloxane (PDMS) and silver nanowires (AgNWs). The circularly polarized radiation is enabled by placing a planar linearly polarized loop monopole above a finite anisotropic artificial ground plane. By truncating the anisotropic artificial ground plane to contain only 2 by 2 unit cells, an integrated antenna with a compact form factor of 0.41λ0 × 0.41λ0 × 0.045λ0 is obtained, all while possessing an improved angular coverage of CP radiation. A flexible prototype was fabricated and characterized, experimentally achieving S 11 <- 15dB, an axial ratio of less than 3dB, a gain of around 5.2dBi, and a wide CP angular coverage in the targeted ISM band. Furthermore, this antenna is compared to a conventional CP patch antenna of the same physical size, which is also comprised of the same PDMS and AgNW composite. The results of this comparison reveal that the proposed antenna has much more stable performance under bending and human body loading, as well as a lower specific absorption rate. In all, the demonstrated wearable antenna offers a compact, flexible, and robust solution which makes it a strong candidate for future integration into body-area networks that require efficient off-body communications.

Design and SAR Analysis of Wearable Antenna on Various Parts of Human Body, Using Conventional and Artificial Ground Planes

This paper presents design and specific absorption rate analysis of a 2.4 GHz wearable patch antenna on a conventional and electromagnetic bandgap (EBG) ground planes, under normal and bent conditions. Wearable materials are used in the design of the antenna and EBG surfaces. A woven fabric (Zelt) is used as a conductive material and a 3 mm thicker Wash Cotton is used as a substrate. The dielectric constant and tangent loss of the substrate are 1.51 and 0.02 respectively. The volume of the proposed antenna is 113×96.4×3 mm3. The metamaterial surface is used as a high impedance surface which shields the body from the hazards of electromagnetic radiations to reduce the Specific Absorption Rate (SAR). For on-body analysis a three layer model (containing skin, fats and muscles) of human arm is used. Antenna employing the EBG ground plane gives safe value of SAR (i.e. 1.77W/kg 2W/kg). The efficiency of the EBG based antenna is improved from 52 to 74%, relative to the conventional counterpart. The proposed antenna can be used in wearable electronics and smart clothing.

DESIGN AND ANALYSIS OF META-MATERIAL BASED WLAN ANTENNA

In this paper, a 2.42 GHz micro-strip patch antenna is designed and analyzed using a conventional and a metamaterial (artificial) based Electromagnetic Bandgap (EBG) ground planes. The directivity, return loss and VSWR of the conventional 2.42 GHz patch antenna were found to be 5.23dB, -13.2dB, and 1.5 respectively. The proposed antenna then being mounted on a Mushroom-type EBG structures (artificial ground plane) produced better far-field performance as compared to conventional counterpart i.e. the return loss, directivity and VSWR were improved by 80.3%, 58.5% and 24.6%. The WLAN antenna was designed and tested on a miniaturized slotted EBG structure. The slotted EBG was 11.4 % compact as compared to the mushroom structure. The directivity, return loss and VSWR of the antenna using the slotted EBG are improved by be 51%, 31.8%, 15.4% respectively as compared to the patch conventional WLAN patch antenna. The antenna can be used for WLAN applications.

Artificial Ground Plane Based on Electromagnetic Bandgap for Stripline Transmission Line

This paper presents a study of the interaction between mushroom-type electromagnetic bandgap (EBG) surfaces replaced the conventional electric conductor ground plane of a stripline. The proposed EBG surface has both artificial magnetic conductor (AMC) and stopband performances. Compared to the conventional stripline, the EBG as artificial ground plane exhibits bandstop behavior which unlike all-pass behavior of the conventional stripline with electric conductor ground plane. The rejected frequency range is resulted from 6.76 to 10.08GHz (3.32GHz), which has fractional bandwidth of 40%. Promising results give future possibilities for practical suppression noises and interferences of systems.

A Novel Low-Profile High-Gain UHF Antenna Using High-Impedance Surfaces

A novel wideband low-profile planar antenna design based on the use of a high-impedance surface (HIS) is presented for digital television (DTV) reception in the UHF band. The proposed design is based on a wideband monopole antenna in close proximity to an artificial ground plane, composed of an array of square metal loops at the top, an air gap and a ground plane at the bottom, without grounded vias. Low-cost substrates are employed in the design: rigid PVC for the antenna and foamed PVC for the artificial ground plane. The advantages of the proposed design for DTV applications are high gain, low profile, light weight, low cost and large bandwidth. Details of the proposed antenna design are described, and measurements together with a comparison to a conventional antenna with PEC ground plane are presented.

High-gain antenna using an intelligent artificial magnetic conductor ground plane

We propose a high-gain antenna using an intelligent ground plane composed of artificial magnetic conductors (AMCs). The main role of the ground plane is removing difference in phase delays caused by different path lengths from a signal-feeding dipole onto each AMC cell. Hence, the ground plane consists of AMC cells with different lengths corresponding to the phase delays to be compensated. As a consequence, we can obtain a planar wave front of a reflected wave, which is perpendicular to a boresight direction. By maximizing constructive interference between the reflected waves and direct waves from the dipole, we can significantly increase our antenna gain without deteriorating impedance matching bandwidth behavior. Experimental data has shown good agreement with the prediction, which validates the accuracy and effectiveness of our proposal.

Compact multiband printed-IFA on electromagnetic band-gap structures ground plane

Fourth mobile generation requiring of multistandard operating handsets of small physical size as well as increasing demand for higher data rates.Compact multiband printed inverted-F antennas (IFA) for available wireless communications are proposed in this article. New design of printed IFA based on uniplanar compact electromagnetic band gap (EBG) concept is proposed. A printed-IFA with L-loaded shaped over artificial ground plane is designed as the main antenna to cover the GSM, LTE, UMTS, Bluetooth, and WLAN. The multiband is created by means of an EBG structure that is used as a ground plane. Different shapes of uniplanar EBG as ring, split ring resonator, and spiral rather than mushroom-like structure are investigated. The proposed antenna is built on the uniplanar EBG ground plane with size of 35 × 45 mm2, which is suitable for most of the mobile devices. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1670–1676, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27633

Compact multiband printed-IFA on electromagnetic band-gap structures for wireless applications

Fourth generation mobiles require multi-standard operating handsets with small physical size as well as increasing demand for higher data rates. Compact multi-band printed inverted-F antennas (IFA) for available wireless communications are proposed in this paper. New design of printed IFA based on uniplanar compact electromagnetic band-gap (EBG) structure concept is proposed. A printed-IFA with L-load shaped over an artificial ground plane is designed as the main antenna to cover most wireless applications such as GSM, LTE, UMTS, Bluetooth, Wimax, and WLAN. The multi-band is created by means of an EBG structure that is used as a ground plane. Different shapes of uniplanar EBG such as ring, split ring resonator, and spiral rather than mushroom-like structure are investigated. The proposed antenna is built on the uniplanar EBG ground plane with size of 35 × 45 mm2, which is suitable for most of the mobile devices.

Compact Multiband Printed IFA on Electromagnetic Band-Gap Structures Ground Plane for Wireless Applications

The fourth mobile generation requires of multistandard operating handsets of small physical size as well as has an increasing demand for higher data rates. Compact multiband printed inverted-F antennas (IFAs) for available wireless communications are proposed in this paper. A new design of a printed IFA based on a uniplanar compact EBG concept is proposed. An L-loaded printed IFA shaped over an artificial ground plane is designed as the main antenna to cover the GSM, LTE, UMTS, bluetooth, and WLAN. The multi-band is created by means of an electromagnetic band-gap (EBG) structure that is used as a ground plane. Different shapes of uniplanar EBG as ring, split ring resonator, and a spiral rather than mushroom-like structure are investigated. The proposed antenna is built on the uniplanar EBG ground plane with a size of 35×45 mm2, which is suitable for most of the mobile devices.

Artificial Ground Planes for Performance Enhancement of Microstrip Antennas

In this work we investigate three different artificial ground planes for microstrip antenna design, which are useful for different applications. The three different ground plane configurations studied include: (i) conventional dielectric substrate backed by a perfect conductor; (ii) a loop type of artificial magnetic conductor (AMC); and a spiral-type of AMC. Both the loop and spiral types of AMCs tend to lower the resonant frequency of the microstrip patch antenna (MPA), as compared to that of the dielectric substrate, for the linearly polarized case. However, the spiral AMC can be used to realize circular polarization as well, at a different frequency band, hence, is useful for designing dual-band dual-polarization microstrip antennas.

Wideband Miniaturized Polarization-Dependent HIS Incorporating Metamaterials

The use of metamaterial as a substrate for a high-impedance surface (HIS), which can miniaturize the size and significantly enhance the axial ratio bandwidth of a polarization dependent HIS, is introduced. The electromagnetically small Ω-type inclusions have been used to achieve the effective permeability and permittivity greater than that of the host dielectric. It is demonstrated that the proposed high-impedance surface can provide performance superior to the polarization-dependent electromagnetic band-gap (PDEBG) surfaces. This complex artificial ground plane is designed utilizing two reversed Ω patterns back to back on each side of a substrate board to avoid chiral effects.

Effect of surface resistor loading on high‐impedance surface radar absorber return loss and bandwidth

AbstractA simple method for the selection of the appropriate choice of surface‐mounted loading resistor required for a thin radar absorber based on a high‐impedance surface (HIS) principle is demonstrated. The absorber consists of a HIS, (artificial magnetic ground plane), thickness 0.03λ0 surface‐loaded resistive‐elements interconnecting a textured surface of square patches. The properties of absorber are characterized under normal incident using a parallel plate waveguide measurement technique over the operating frequency range of 2.6–3.95 GHz. We show that for this arrangement return loss and bandwidth are insensitive to ±2% tolerance variations in surface resistor values about the value predicted using the method elaborated in this letter, and that better than −28 dB at 3.125 GHz reflection loss can be obtained with an effective working bandwidth of up to 11% at −10 dB reflection loss. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1773–1775, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24454

Salisbury screen with reduced angular sensitivity

A new Salisbury screen absorber design is presented, which yields a significantly reduced sensitivity to angle of incidence. This is achieved by using an artificial magnetic ground plane, which is designed to scatter the reflected signals in a conjugate phase relationship with respect to the change in the electrical spacing between the ground plane and the resistive screen. Numerical and experimental results in the range 8-12 GHz are used to demonstrate that scan compensation can be obtained over the angular range 0-40deg thus removing the shift in the resonant frequency that occurs in conventional Salisbury screen absorbers when operated off normal incidence.

Effects of Artificial Magnetic Conductors in the Design of Low-Profile High-Gain Planar Antennas With High-Permittivity Dielectric Superstrate

Cavity resonance antennas with dielectric superstrate are considered with different ground plane types namely, perfect electric conductor (PEC), perfect magnetic conductor (PMC), and artificial magnetic conductor (AMC). Radiation properties of these antennas are computed using transverse equivalent network (TEN) model. It is shown that the effects of angular and polarization dependency of artificial ground planes can be beneficial or detrimental to the antenna performance in directivity.

Application of polarization and angular dependent artificial ground planes in compact planar high‐gain antenna design

An artificial surface demonstrating angular and polarization dependency to the polarization of the applied field is introduced. This artificial surface consists of a periodic strip grating on a grounded dielectric slab. A method based on Floquet's modal expansion is presented to solve the scattering problem of such surfaces. A code based on method of moments (MoM) is also developed to analyze and design these artificial surfaces. The obtained results using these methods are compared against each other. The extracted reflection parameters are then employed to characterize the surface impedance of the artificial surface for different incident angles and both TE and TM polarizations. This artificial surface is used as the ground plane of cavity resonance antennas. Next, a highly reflective frequency selective surface (FSS) is designed to show high reflectivity at two different frequencies. This FSS is to be used as the superstrate layer of the cavity resonance antenna. The impedance surface of the artificial ground plane and the equivalent admittance of the designed FSS are employed in the transverse equivalent network (TEN) model to obtain radiation properties of such antennas. Finally, compact high‐gain dual‐band dual‐orthogonally polarized antennas are designed based on the aforementioned analyses.

Analysis and Design of Sub-Wavelength Resonant Cavity Type 2-D Leaky-Wave Antennas

A rigorous analysis is presented together with novel designs of high-gain sub-wavelength resonant cavity antennas. The antennas under investigation are formed by partially reflective surfaces placed in close proximity over artificial periodic metamaterial ground planes with specific reflection phase responses. A full-wave periodic leaky-wave analysis is applied to this class of antennas for the first time and the results are reported and discussed. Finite-size antenna designs are studied at wireless LAN frequencies (3.7 GHz) using 3-D full-wave software and the results are compared to the predictions of the leaky-wave analysis. Furthermore, the field distribution and the effect of losses are investigated. Finally, practical designs of sub-wavelength 2-D leaky-wave antennas with high-gain performance are presented.

APPLICATION OF ARTIFICIAL GROUND PLANES IN DUAL-BAND ORTHOGONALLY-POLARIZED LOW-PROFILE HIGH-GAIN PLANAR ANTENNA DESIGN

Application of artificial ground planes in design of compact cavity-resonance dual-band high-gain antennas is presented. The artificial ground plane consists of periodic strip grating on grounded dielectric slab. A code based on method of moment (MoM) is developed to analyze and design such artificial ground planes. The reflection parameters obtained using the MoM code are employed to characterize the surface impedance of the artificial ground plane for different incident angles and both TE and TM polarizations. Then, this impedance surface is used in transverse equivalent network (TEN) model of the cavity-resonance antenna with high-permittivity dielectric superstrate. Using TEN model radiation properties of such antennas are analyzed. Finally, the antenna with the compact size is designed to demonstrate the maximum directivity. An interesting characteristic of this antennas is that when the antenna ground plane acts as an artificial magnetic conductor the height of the antenna is almost reduced by a factor of two, while its directivity is increased by about 1 dB compared to the conventional antennas of this class having PEC ground plane.