Planar Artificial Magnetic Conductor Research Articles

Miniaturized High Gain Broadband 16‐Element MIMO Array Using Planar Artificial Magnetic Conductor With Enhanced Isolation for WLAN/WiMAX Applications

AbstractA low‐profile 16‐element printed dipole antenna (PDA) array backed by a planar artificial magnetic conductor (AMC) is introduced for multiple‐input multiple‐output (MIMO) wireless communications. The proposed 16‐element MIMO array loaded by a 13 × 13 AMC reflector with various polarized directions exhibits a low‐profile wideband structure, which includes the broad measured bandwidths from 4.25 to 7.25 GHz with increased gains (>8 dBi) and high efficiency. The high isolation between the 16 elements with diverse polarizations is larger than 27 dB and reaches 67 dB over the operating band for MIMO systems. The suggested PDA with a microstrip V‐shaped dipole excited by a V‐shaped microstrip feedline is used to expand the broad simulated band spanning 5.34–6.70 GHz (S11 ≤ −10 dB). Moreover, the suggested 13 × 13 planar fractal AMC reflector is loaded into the PDA array to exhibit a reflection coefficient, S11, of less than −10 dB across the band of 4.26–6.90 GHz for wireless local area network and worldwide interoperability for microwave access applications. The proposed design with AMC compared to the design without AMC exhibits a size reduction of 50.3%, increased gain up to 8.2 dBi, and excellent impedance matching with unidirectional radiation patterns. The novel AMC unit cell is realized based on the planar patch with inserted slots to operate at 6.10 GHz with an AMC band spanning 5.15–7.10 GHz (32%).

Broadband Printed Tapered Slot Antenna Fed by CPW Fulfilled with Planar Artificial Magnetic Conductor for X-Band Operation

A low-profile printed slot antenna (PSA) backed by broadband planar artificial magnetic conductor (AMC) is introduced in this study. Firstly, a suggested PSA with the radiating tapered slots excited by coplanar-waveguide (CPW) is used to expand the bandwidth in the measured range of 9-11 GHz (S11≤ -10 dB). Then, the suggested planar AMC surface as the ground plane of the antenna is inserted into the PSA to gain improved radiation efficiency. The realized result from the PSA with the 9×9 planar AMC array exhibits -10 dB measured impedance bandwidth from 6.63 to 13.73 GHz (70%). The suggested PSA with AMC compared to the PSA without AMC exhibits a size reduction of 60%, enhanced bandwidth of 50%, and excellent impedance matching with a minimum value of almost -40 dB. The novel AMC unit cell is realized to operate at 10.14 GHz with an AMC bandwidth of 8-12.35 GHz (43.1%) for X-band operation. Besides, by loading a periodic AMC unit cells into PSA, a high gain of more than 11 dBi with uni-directional radiation patterns is achieved.

Solar Cell Integrated Wearable Patch Antenna on Artificial Magnetic Conductor for On-Body and In-Body Communications

This paper presents a patch antenna on a jeans textile with an artificial magnetic conductor (AMC) structure stacked on a solar cell for wearable applications in the Industrial, Scientific, and Medical (ISM) band. Meanwhile, the loading of the AMC reflector increases the radiation efficiency and antenna gain and also results in a reduction in specific absorption rate levels. As examination cases, two textile antenna designs loaded on 7 × 8 patches of AMC plane with the ground plane of both fully copper conductor and partially copper aided with solar cells were fabricated and tested, presenting a strong agreement between simulation and measurement. Its measured impedance bandwidth is 13.79% (2.16 GHz–2.48 GHz) with good return loss and voltage standing wave ratio features in the operating band where it is being used. Besides being a source of electricity, the silicon solar cells are also used as a radio frequency ground plane for the AMC plane. They can produce363.08 mW.

Printed Slot Antenna Fed by CPW Supported by Broadband Planar Artificial Magnetic Conductor with Enhanced Features

Printed Slot Antenna Fed by CPW Supported by Broadband Planar Artificial Magnetic Conductor with Enhanced Features

Analysis of the Electromagnetic Absorption in a New Design of PIFA Antenna Using Metamaterials

This paper presents the design, simulation and fabrication of a miniaturized wearable dual-band antenna put on a rigid substrate and operable at 2.45/5.8 GHz for wireless local area network applications. The electrical and radiation characteristics of the developed antenna were obtained by means of the technical insertion of a slot to tune the operating frequencies. To study the impact of the electromagnetic radiation of the structure of the human body, it is necessary to minimize the back radiation towards the user. Therefore, in this work, a multi-band artificial magnetic conductor (AMC) was placed directly above a dual-band planar inverted F antenna to achieve a miniaturization with excellent radiation performance. The simulations were carried out using the computer simulation technology CST Microwave Studio (CST MWS). A good agreement was achieved between the simulation and experimental results. The comparison of the measurement findings indicates that, when the antenna was backed by the AMC plane, the gain improved from 1.84 to 3.8 dB, in the lower band, and from 2.4 to 4.1 dB in the upper band. The front-to-back ratio of the AMC backed PIFA antenna was also enhanced. Then, to ensure that the proposed AMC structure is harmless to the human body, this prototype was placed on three-layer human tissue cubic model. It was observed that, due to the inclusion of an AMC plane, the peak specific absorption rate (SAR) decreased to 1.45 and 1.1 W/kg at 2.45 and 5.8 GHz, respectively (a reduction of around 3.7 W/kg, compared with an antenna without (AMC).

Near-perfect transmission of a low-profile resonant structure with artificial magnetic conductor metamaterials

In this paper, we present a low-profile selective-transmittance resonant structure developed with artificial magnetic conductor (AMC) metamaterials. A planar AMC is used for the two reflectors of the structure. The two reflectors cause no phase shift on reflection at the resonance frequency. The cavity can have zero thickness due to this in-phase reflection. The overall thickness of the structure is only 1.626 mm, which is less than 1/18 of the resonance wavelength. The electromagnetic characteristics of the resonant structure were simulated using simulation software. The simulated maximum transmittance was 0.999 at 9.72 GHz, with the electric field being localized at the interface of the two AMC layers. The measured maximum transmittance was 0.941 at 9.64 GHz. The experimental results are therefore in good agreement with the simulation results. The developed system can excite the interface mode at the resonance frequency and achieve near-perfect transmission of electromagnetic waves.

Gain Optimization of Low-Profile Textile Antennas Using CMA and Active Mode Subtraction Method

This paper presents an active mode subtraction method based on the characteristic mode analysis to estimate the forward directivity based on the difference in modal significance curves. This made the optimization of the antenna gain in the design process to be more efficient. To the best of the authors' knowledge, such method is innovative and proposed in literature for the first time. This method is derived on the basis that the total radiated field of the antenna, and consequently, the directivity is mainly contributed by the excited dominant modes. To demonstrate its effectiveness, three compact, planar, and wearable antennas with increasing complexity will be designed and optimized using this method. The first is a conventional circular patch antenna operating at 5.3 GHz, whereas the second one is a planar loop antenna operating at 3.08 GHz. The third design is a crown-shaped planar antenna (CPA) with a 3 × 3 artificial magnetic conductor (AMC) plane integrated underneath to reduce potential coupling effects from the body. All three antennas are made fully using textiles with the same thicknesses: felt fabric as its substrate and ShieldIt Super as its conductive textile. For all designs, the use of the proposed method, which is validated using the method of moments, has predicted the maximum direction of radiation and its respective gain at the desired frequencies with good accuracy. Besides that, the design of the AMC plane for the CPA is also optimized using CMA prior to the integration with the antenna and a leather wrist strap. Measurements of the final crown-shaped antenna design indicated a good agreement with simulations, with an operating bandwidth of more than 240 MHz, FBR of 15.73 dB and a directional radiation pattern outward from the body.

Gain enhancement of a CPW-fed dipole antenna using a novel multiband planar artificial magnetic conductor surface for UWB applications

Gain enhancement of a CPW-fed dipole antenna using a novel multiband planar artificial magnetic conductor surface for UWB applications

Gain enhancement of a CPW-fed dipole antenna using a novel multiband planar artificial magnetic conductor surface for UWB applications

Gain enhancement of a CPW-fed dipole antenna using a novel multiband planar artificial magnetic conductor surface for UWB applications

Design of wideband AMC integrated monopole antenna with enhanced radiation performances for off‐body systems

AbstractA low‐profile, wideband, high gain artificial magnetic conductor (AMC) integrated monopole antenna is proposed in the letter. The bowl‐shaped stair styled monopole with defected round type partial ground is integrated with the AMC containing 2 × 2 unit‐cells to broaden the impedance bandwidth by 92.7%/66.2%/53.9% at the three resonating notches at 6/8.4/10.3 GHz respectively. The AMC has covered ±90° reflection phase bandwidth from 6.20 to 7.44 GHz (18.56%). The planar AMC proffers mu‐negative (MNG) properties and polarization independent behavior. Introduction of AMC beneath the monopole achieves wideband from 5.39 to 10.95 GHz. The AMC integrated monopole provides peak gain up to 10.6 dB which is 66.8% better than that of the only monopole. The integrated antenna offers low‐profile features with unidirectional radiation behavior, up to 18.6 dB front to back ratio (FBR) and >90% efficiency. The proposed design reduces 1‐g averaged Specific Absorption Rate (SAR) at 1 mm distance up to 96.6% at the respective bands.

A Low Profile, Dual-band, Dual Polarized Antenna for Indoor/Outdoor Wearable Application

A planar, low-profile, dual-band and dual-polarized antenna on a semi-flex substrate is proposed in this paper. The antenna is fabricated on Rogers substrate with a thickness of 3.04 mm and sized at $70.4 \times 76.14 \times 3.11$ mm3 ( $0.37\lambda _{0} \times 0.40\lambda _{0}\times 0.016 \lambda _{0}$ ) only. The circular polarization property is enabled in the global navigation satellite system (GNSS) L1/E1 (lower) band by introducing a complementary split ring resonator on the antenna patch. Meanwhile, the antenna operates in the second (upper) 2.45 GHz WLAN band is enabled by etching a U-shaped slot on its ground plane. This simultaneous, dual-band and dual-polarized operation enables the proposed antenna to be applied in the indoor/outdoor wearable application. To isolate the antenna against the influence of the human body, a multiband artificial magnetic conductor (AMC) plane is added on the reverse side of the dual-band radiator. Comparison of the antenna without AMC in free space and when evaluated on the chest of a human body backed by AMC showed improved gain; from 3–5.1 dBi in the lower band, and from 1.53–5.03 dBi in the upper band. Besides that, the front-to-back ratio of the AMC backed monopole antenna also improved from 11–21.88 dB and from 2.5–24.5 dB in the GNSS and WLAN bands, respectively. Next, the specific absorption rate (SAR) of the monopole antenna with and without the AMC plane is assessed. Evaluation results indicate that the maximum SAR value decreased by up to 89.45% in comparison with the antenna without AMC in the lower band. This indicates the effectiveness of the AMC array in increasing gain and FBR, besides reducing EM absorption in the human body.

Gain enhanced circularly polarized antenna integrated with artificial magnetic conductor for S-band pico-satellites

A circularly polarized (CP) antenna integrated with an artificial magnetic conductor (AMC) plane is presented. The AMC plane is aimed at enhancing the gain of the CP antenna, besides reduced back-radiation, and avoiding radiation toward other high-frequency components on the CubeSat. It consists of a 3 × 3 array of diamond-shaped unit cells placed behind the complementary dipole-based antenna. To enable deployability and compact deployment size, the AMC structure is designed on a thin flexible Kapton film as substrate, whereas its metallic components are formed using Nickel conductive paint. Meanwhile, the CP antenna is designed on a thin Rogers RO4003C substrate and located on top of the AMC plane at a 20 mm distance. The combined structure operates at 2.4 GHz with satisfactory reflection and radiation performance. It is sized at 99 mm × 99 mm × 21.485 mm3, with 450 MHz (18%) of 10 dB impedance bandwidth and 250 MHz (10%) of 3 dB axial ratio bandwidth. The AMC plane also improved its gain from 3.05 dBi up to 5.35 dBi.

High‐gain broadside dipole planar AMC antenna for 60 GHz applications

A novel 60 GHz high-gain planar artificial magnetic conductor (AMC) antenna is proposed. The prototype of the antenna is a dipole structure with a broadband input impedance match. Parasitic patches and a novel AMC plane are successively used to enhance its broadside gain. The antenna has a compact size of 7.5 mm × 8 mm, including the modified AMC plane. Simulated and measured results both show the antenna has good properties of return losses better than 10 dB, stable peak gains up to 10.9 dBi and favourable radiation patterns from 57 to 64 GHz, which all denote that it is fit for 60 GHz wireless portable communication systems.

Design of the artificial magnetic conductors with meander line elements: reduction in the first and second resonant frequencies

A novel design for a planar artificial magnetic conductor (AMC) with meander line element is used to achieve miniaturization, reduction in the second/first resonant frequency ratio, and multi-band operation. It is known that various parameters—such as geometry, dielectric substrate thickness, the gap between patches, the length and width of a patch, the size of unit cell, permittivity, and permeability—strongly affect the resonant frequency. To obtain a miniaturized AMC, in this paper, we investigate the role of the metallic patch effective length on resonant frequency. Meander-shape is used to change the effective length in the direction of the incident wave polarization. A discussion of the design parameters and the electric field distribution is presented. Six different configurations are proposed. Miniaturization and reduction in the first/second resonant frequency ratio is achieved. In addition, the meander-shape allows the appearance of different operating bands that depend on the number of meanders. For instance, four bands are observed for one meander (U-shape). Therefore, a simple way to obtain AMC miniaturization and multi-band devices is proposed. The results are obtained by the finite element method. To validate our design some results have been compared against experimental testing presented in literature.

Dual-band wearable fluidic antenna with metasurface embedded in a PDMS substrate

A flexible fluidic antenna with an artificial magnetic conductor (AMC) plane is presented in this work. The overall structure is embedded in polydimethylsiloxane (PDMS), while the radiator is fabricated using eutectic gallium indium alloy (EGaIn) conductor. This radiator operating over an AMC plane is designed based on a rectangular patch which is integrated with slot and slits to enable dual-band WLAN ISM (2.4 and 5.8 GHz) operation, while maintaining a compact form. The integration of the AMC plane behind the proposed antenna reduced backward radiation towards the human users and improved gains. The evaluation of the antenna integrated with the AMC plane indicated satisfactory performance in terms of reflection coefficient, bandwidth and radiation patterns.

Bandwidth enhancement of an array antenna using slotted artificial magnetic conductors

An artificial magnetic conductor (AMC)-integrated array antenna operating at 9.41 GHz is proposed in this work. The AMC plane consists of an array of 9 × 12 rectangular elements slotted using four circular slots. The rectangular circular-slotted AMC unit cell acts as a metamaterial with high permeability of 10.05 and non-unity permittivity of 1.52, respectively. The integration of the AMC plane into a reference array antenna operating at 9.41 GHz increases the impedance bandwidth by 76%, from 1.12 to 1.98 GHz. Besides that, the efficiency is also enhanced from 95.91 to 96.31%. Both reference and proposed antenna show a satisfactory agreement in terms of simulated and measured reflection coefficients and radiation patterns.

A wideband textile antenna with a ring-slotted AMC plane

A wideband microstrip-based textile planar antenna with artificial magnetic conductor (AMC) plane is presented. The antenna is initially designed using the combination of two rectangular microstrip antennas operating at 1.5 and 2.5 GHz before being further optimized for wideband operation using various broadbanding techniques. This optimized radiator is then placed over an array of unit elements forming an AMC plane. Each unit element is formed using a square patch slotted using a circular ring and is designed to resonate at 2 GHz. To validate the contribution of the AMC plane in reducing backward radiation toward the human user, the performance of the proposed antenna is compared to a similar antenna without the AMC plane. This investigation indicated that the proposed antenna is capable of reducing backlobe while simultaneously increasing gain to 3.38 dB and improving bandwidth up to 52%.

Conformal dual-band textile antenna with metasurface for WBAN application

This paper presents the design of a dual-band wearable planar slotted dipole integrated with a metasurface. It operates in the 2.45 GHz (lower) and 5.8 GHz (upper) bands and made fully using textiles to suit wireless body area network applications. The metasurface in the form of an artificial magnetic conductor (AMC) plane is formed using a rectangular patch incorporated with a diamond-shaped slot to generate dual-phase response. This plane is then integrated with the planar slotted dipole antenna prior to its assessment in free space and bent configurations. Simulations and measurements indicated a good agreement, and the antenna featured an impedance bandwidth of 164 and 592 MHz in the lower and upper band, respectively. The presence of the AMC plane also minimized the backward radiation toward the human body and enhanced realized gains by up to 3.01 and 7.04 dB in the lower and upper band.

Textile antenna integrated with compact AMC and parasitic elements for WLAN/WBAN applications

A wearable antenna fully designed and fabricated using textile is presented. Both antenna and artificial magnetic conductor plane are designed for operation in the wireless local area network (WLAN)/wireless body area network (WBAN) band from 2.4 to 2.5 GHz. The AMC unit element is designed based on the rectangular patch structure, which is then integrated using slots and slits for bandwidth broadening. Meanwhile, the combination of the slits and L-shaped parasitic elements applied at four edges of the rectangular antenna structure enabled unidirectional radiation outwards from the body. The structure is coaxially fed using a rectangular ring slot centered on the radiating element. Simulated and measured reflection and radiation performance indicate a satisfactory agreement, fulfilling the requirements for WLAN/WBAN applications both in free space and on body. The shielding effectiveness provided by the AMC plane is also evaluated numerically in terms of specific absorption rate, indicating levels below the European regulatory limit of 2 W/kg.

3D package-integrated artificial magnetic conductor antenna arrays for 60 GHz transceivers

We present a low-profile design of dipole antenna arrays integrated on a planar artificial magnetic conductor (AMC) based on spiral unit cells. The whole system is designed and manufactured on a multi-layer organic laminate packaging technology and can be integrated with a single-chip 60-GHz radio transceiver die. We analyze two fabricated arrays of different total area both of which contain 16 elements fed through a combiner network exciting the array elements either in phase or for 45° scan angle. The integrated antenna-AMC array element presented has twice the impedance bandwidth necessary to cover all international 60-GHz radio bands, small form factor suitable for on-package integration, and 5 dBi gain including all losses. The larger 16-element array, occupying 11 × 11 mm2 package area, has a measured gain of 17 dBi at broadside and 15 dBi at 45° scan angle, while the smaller array, occupying a 6.6 × 11 mm2 package area, has a gain of 15 dBi at broadside and 14 dBi at a 45° scan angle. These arrays are an ideal 3D-integrated package solution for 60 GHz radio transceivers.