Artificial Magnetic Conductor Unit Cells Research Articles

A miniaturized dual wide‐band polarization reconfigurable antenna integrated with artificial magnetic conductor for next‐generation wireless applications

SummaryIn today's intricate wireless communication environment, ensuring system quality demands the use of a reliable and versatile antenna system. This research article introduces a polarization reconfigurable antenna integrated with a 4 × 4 Artificial Magnetic Conductor (AMC) surface. The AMC unit cell exhibits a triple‐band reflection phase response at 1.8GHz, 4.5GHz, and 5.5GHz, demonstrating double negative metamaterial behavior. The antenna features two distinct C‐shaped metal strips connected to two PIN diodes, enabling dynamic current distribution adjustment. Consequently, the proposed antenna offers three reconfigurable states, facilitating seamless switching between dual circular polarization (left and right‐hand circular polarization) and linear polarization. With a frequency coverage ranging from 1.29 to 2.52GHz and 3.59 to 6.15GHz, the antenna boasts a maximum axial ratio (AR) bandwidth of 31.96%. Additionally, it achieves a maximum peak gain of 5.5 dB and maintains front‐to‐back ratio (FBR) values exceeding 25 dB, while recording a minimum specific absorption rate (SAR) value of 0.1059 W/kg. The integration of the AMC surface ensures enhanced performance of the antenna. Experimental results from constructed prototypes closely align with simulation outcomes, validating the effectiveness of the proposed antenna. Consequently, this antenna holds significant promise for next‐generation wireless applications.

Terahertz RCS reduction employing reconfigurable graphene-based AMC structures

Recently, modern technology has towards stealth technology, especially in military applications so, this paper presents a terahertz radar cross-section (RCS) reduction utilizing reconfigurable graphene-based artificial magnetic conductor (AMC) arrays. The AMC unit cell has a Vivaldi shape with circular slots etched in the radiator to reduce the RCS from metallic surfaces at THz bands. The AMC cells affect the surface impedance of the metallic objects which reduces the reflected EM waves from them. The RCS reduction bandwidth is achieved and controlled by varying the voltage applied to graphene cells which varies its chemical potential (µc). The effect of changing the graphene conductivity on the RCS reduction is investigated. Different arrangements to obtain maximum RCS reduction are presented. A 12 × 12 hybrid arrangement of the graphene-based AMC structures achieved maximum RCS reduction from 1.5 to 4 THz with 22 dB greater than the unloaded metallic surface. The CST simulator is employed in the simulation.

Angularly stable Artificial magnetic conductor (AMC) loaded circularly polarized antenna array and filter Co-Design for K-band satellite applications

This paper investigates an angularly stable artificial magnetic conductor (AMC) loaded circularly polarized (CP) antenna array and filter co-design for the K-band satellite application. The AMC array is constructed from a periodic array of square metal patch unit cells with rectangular and annular slots. The AMC unit cell has good angular stability under various incidence angles and operates in a frequency range of 18 GHz to 21 GHz. The AMC-surrounded and bandpass filter (BPF) loaded antenna array is simulated and fabricated on the single side of a 0.508 mm thick Roger/5880 substrate. The impedance matching, gain, directivity, and efficiency (%) are enhanced due to the constructive interference between AMC and antenna mutual coupling. In contrast, the axial ratio (AR) is preserved. The manufacturing of the proposed structure is comparatively less complex. Finally, based on the simulation and measured results, the suggested AMC-loaded compact, wideband, and filter-inserted array with enhanced gain and efficiency can be a good choice for the 3U satellite application working in K-band.

Design and performance investigation of metamaterial-inspired dual band antenna for WBAN applications.

This paper presents the design and analysis of a metamaterial-based compact dual-band antenna for WBAN applications. The antenna is designed and fabricated on a 0.254 mm thick semi-flexible substrate, RT/Duroid® 5880, with a relative permittivity of 2.2 and a loss tangent of 0.0009. The total dimensions of the antenna are 0.26λo×0.19λo×0.002λo, where λo corresponds to the free space wavelength at 2.45 GHz. To enhance overall performance and isolate the antenna from adverse effects of the human body, it is backed by a 2×2 artificial magnetic conductor (AMC) plane. The total volume of the AMC integrated design is 0.55λo×0.55λo×0.002λo. The paper investigates the antenna's performance both with and without AMC integration, considering on- and off-body states, as well as various bending conditions in both E and H-planes. Results indicate that the AMC-integrated antenna gives improved measured gains of 6.61 dBi and 8.02 dBi, with bandwidths of 10.12% and 7.43% at 2.45 GHz and 5.80 GHz, respectively. Furthermore, the AMC integrated antenna reduces the specific absorption rate (SAR) to (>96%) and (>93%) at 2.45 GHz and 5.80 GHz, meeting FCC requirements for low SAR at both frequencies when placed in proximity to the human body. CST Microwave Studio (MWS) and Ansys High-Frequency Structure Simulation (HFSS), both full-wave simulation tools, are utilized to evaluate the antenna's performance and to characterize the AMC unit cell. The simulated and tested results are in mutual agreement. Due to its low profile, high gain, adequate bandwidth, low SAR values, and compact size, the AMC integrated antenna is considered suitable for WBAN applications.

A broadband AMC metasurface for radar cross section reduction and application in microstrip antenna

ABSTRACTA broadband checkerboard artificial magnetic conductor (AMC) metasurface with a 61% bandwidth is proposed. Two different AMC unit cells with 180° (±37°) effective reflection phase difference over a wide frequency range from 7.3–14 GHz are designed. A checkerboard metasurface is structured with two AMC unit cells and is applied in a microstip antenna for radar cross section (RCS) reduction. The simulated results show that the antenna can achieve more than 10 dB RCS reduction from 7.2–13.1 GHz. The maximum RCS reduction is 36 dB. Meanwhile, the radiation performance of the antenna has been well kept. Finally, the low RCS antenna is manufactured and measured. The measured results are in agreement with the simulations.

Enhancement of off-body communications with a low-SAR, high-gain multiband patch antenna designed with a quad-band artificial magnetic conductor

Abstract The increasing demand for wireless communication has emphasized the need for multiband antennas. This study presents a novel design for a multiband antenna with reduced specific absorption rate (SAR), high gain, and improved front-to-back ratio (FBR) achieved through the integration with a 4 × 4 artificial magnetic conductor (AMC) surface. The proposed antenna covers a wide range of wireless frequency bands, including Industrial, Scientific, and Medical, Wireless Local Area Network, Worldwide Interoperability for Microwave Access, Wi-Fi 6E, and 7, with resonating frequencies at 2.4, 3.2, 5.5, 7.5, and 10 GHz. The AMC unit cell creates four zero-degree reflection phases with double negative properties at 2.5, 3.8, 5.5, and 7.5 GHz. The compact design measures 0.23λ0 × 0.296λ0 × 0.0128λ0 and placed 0.104λ0 above an AMC surface of size 0.512λ0 × 0.512λ0 × 0.1296λ0. This structure enhances the gain by up to 8.55dBi at 6.01 GHz. The proposed antenna has −10 dB impedance bandwidth for these corresponding frequencies viz 2.34–2.43 GHz (3.77%), 2.81–3.83 GHz (30.72%), 4.82–6.21 GHz (25.20%), 7–7.65 GHz (8.87%), and 8.06–10.31 GHz (24.5%). An overall average percentage reduction value of SAR taken at these frequencies has been found to be 96.11% with AMC structure. The antenna sample was successfully fabricated, and the experimental results have been found to match well with the simulation results. This integrated design offers a promising solution for wearable off-body communication devices.

High-Gain Fabry–Perot Cavity Antenna With an Artificial Magnetic Conductor Side Wall

We propose a novel design method for a Fabry–Perot (FP) cavity antenna with an artificial magnetic conductor (AMC) side wall intended to provide a high gain in the tilted target direction. However, multiple reflections in the FPC caused by the AMC side wall make it extremely difficult to design the antenna. To solve this problem, we suggest a new design method based on a more generalized image theory, which transforms our antenna into a regular FPC problem that is more straightforward to analyze. The AMC unit cells of the AMC side wall and the ground plane are deliberately designed to have the antenna satisfy the FP resonance condition, which is required to produce a high gain. As a result, the antenna provides a relatively high gain of 12.6 dBi in the target direction of 30° and has reasonable aperture efficiency of 29%, which were validated experiments.

Design of a quint-band antenna with a hybrid-AMC reflector for internet of vehicle applications

In this paper, a low-profile, high gain enhancement quint-band antenna system backed with a hybrid artificial magnetic conductor (AMC) reflector is proposed. Firstly, a quint-band microstrip antenna was designed. Its radiation patch looks like a Chinese knot composing of many slots and branches, and the ground plane is etched 8-shaped and cross-shaped grooves to form the defected ground structure (DGS). Then, a hybrid-AMC reflector was developed and placed underneath the antenna for improving its radiation performance. This hybrid-AMC reflector consists of a cross-shaped AMC array with twenty one-unit cells and four PEC patches. The AMC unit cell includes five nested rings producing five in-phase reflection bands which are perfectly coincident with the antenna’s five operation bands. On the basis of simulations, the antenna and the hybrid-AMC array were fabricated and tested. The measured results agree well with the simulated data, and show that the hybrid-AMC backed antenna system achieves five working frequency bands resonating at 2.45, 3.36, 4.6, 5.9 and 7.4 GHz with strong directional patterns. Thanks to the hybrid-AMC reflector, the maximum gain enhancement of the antenna reaches 7.3 dBi at 4.6 GHz. The proposed antenna system covers WLAN, WiMAX, 5G and satellite bands, and is suitable for multi-channel communications in Internet of vehicle applications.

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%).

A compact triband antenna using artificial magnetic conductor for wireless body area network communicationsFront

The proliferation of the Internet of Things devices and advancements in wireless communication have fostered the growth of Wireless Body Area Networks (WBAN). This research provides a triband antenna supported by a 4 × 4 Artificial Magnetic Conductor (AMC) array surface that has a low Specific Absorption Rate (SAR), a high Front to Back Ratio (FBR), and increased gain for use in wearable devices. For WBAN communications, the proposed antenna operates in the Industrial, Scientific, and Medical (2.4 GHz) band, the C (3.7–4.2 GHz), and the Wi-Fi 6E (5.925–7.125 GHz) bands. The dual-band AMC unit cell exhibits Double-Negative and angular stability behaviour at 2.45 GHz and 6.5 GHz. AMC-backed antenna achieved multiband functionality by incorporating slots into the unit cell and a defective ground structure into the antenna. The antenna was positioned 0.139λ0 above the AMC surface, which measured 0.556λ0 × 0.556λ0 × 0.013λ0 (at 2.45 GHz). The antenna exhibited good gain and return loss variations when mounted on curved surfaces. The proposed integrated design yielded substantial enhancements, as evidenced by the increase of 8.2 dBi in maximum gain, 25.2 dB in FBR, and over 93% in total efficiency. The AMC-backed antenna’s − 10 dB impedance bandwidth is 18.4%, 21.2%, and 22.3%, with corresponding frequency ranges of 2.25–2.66 GHz, 3.66–4.53 GHz, and 5.9–7.35 GHz. Additionally, the AMC surface showed an average reduction in SAR of 93.22%. Vector Network Analyzer and Anechoic chamber measurements proved simulation accuracy. As a result, it is strongly recommended that the integrated antenna design be acknowledged in WBAN communications.

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.

AMC-Loaded Low-Profile Broadband Printed 2×2 Array With Gain and Isolation Enhancement Using Equivalent Circuit Model for Wireless Systems

A 2×2 array of printed antenna loaded by planar Giuseppe Peano artificial magnetic conductor (AMC) is presented for vehicular wireless systems. The four-element of the proposed array by utilizing diverse polarized directions of the printed dipoles with a 5×5 AMC reflector achieves a wideband antenna with enhanced properties. It shows the measured S-parameters of the wide bandwidths from 3.30 to 6.02 GHz with increased stable gains and efficiencies (more than 90%) for all elements. Moreover, the appropriate isolation of greater than 30 dB between the elements is achieved. The proposed design of the printed dipoles includes T-shaped microstrip dipoles and a feedline system as a T-shape to broaden the bandwidth in 4.7-6.02 GHz (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> ≤ -10 dB). By utilizing the 3×3 Giuseppe Peano AMC reflector into the one element of the printed dipole, enhanced radiation efficiency and -10 dB measured bandwidth from 3.26 to 6.02 GHz (60%) is achieved for vehicular wireless systems. The proposed design with AMC with respect to the antenna without AMC indicates a reduced size of 70%, increased gain up to 8.4 dBi, and uni-directional radiation patterns. The new AMC unit cell is configured by the Giuseppe Peano design to resonate at 5.36 GHz in 4.27-6.34 GHz (39%). Finally, the suggested equivalent transmission line model of the 2×2 array with AMC surface is introduced with a suitable agreement between the results of reflection coefficients.

AMC-Based Low-Profile Dual-Band Slotted Patch Antenna for IoT Devices in the Healthcare System

An artificial magnetic conductor (AMC)-based patch antenna with a low profile is developed for wireless devices in IoT-based healthcare systems. The proposed antenna comprises two pairs of circular-shaped patches with circular-shaped slots and a dual-band 4 × 4 array of AMC reflectors with two zero-degree reflection responses to enhance the antenna's radiation performance. For the 2.45 GHz ISM and 5.4 GHz WLAN bands, the patch antenna has dimensions of 0.44λ0 × 0.52λ0 × 0.013λ0, with partial ground structures to improve radiation characteristics. Following that, a unique dual-band symmetrical AMC unit cell with dimensions of 22 × 22 × 1.6 mm3 is developed. There is a gap of 15 mm between the antenna and the AMC surface. The antenna is supported by a 4 × 4 AMC array that has a total dimension of 0.72λ0 × 0.72λ0 × 0.15λ0. The reflection coefficient values of less than − 10 dB in the 1.7–2.5 and 5.1–5.6 GHz bands, with a bandwidth percentage of 38 and 9.3%, respectively. The antenna's gains were 7.2 and 4 dBi inside the bands. Furthermore, the Specific Absorption Rate (SAR) value did not match the WHO's safety and health guidelines. The issue was solved by including an AMC surface in the proposed antenna. At 2.45 and 5.4 GHz, SAR values of 0.58 and 1.04 W/Kg were measured. Vector network analyser and anechoic chamber were used to test the performance of antenna and AMC surface prototypes. There is a substantial agreement among measured and simulated parameters of an antenna. Consequently, the developed antenna combination with the AMC structure is suited for wireless devices in ISM and WLAN bands, often used in IoT-based healthcare systems.

Design and development of a double spiral antenna with an artificial magnetic conductor structure for hyperthermia treatment

A double spiral antenna with an artificial magnetic conductor (AMC) is designed, fabricated, and experimentally tested for hyperthermia treatment as a microwave power radiator. The proposed double spiral antenna has a compact structure, designed on an FR4 substrate with a thickness of 1.6 mm, and the dimensions of the proposed antenna is 32 × 32 × 3.27 mm3. The width and space between the spiral arms is 1.54 and inner and outer radius of the spiral is arm 1 and 12.82 mm. The antenna is fed by aperture feeding having dimensions of 16 × 14 mm2 that enhances the antenna's bandwidth. Further, an AMC unit cell (as a reflector) is designed to enhance the proposed antenna's performance, which is designed on an FR4 substrate with a size of 16 × 16 × 1.6 mm3. The size of an AMC structure is optimized to 64 × 64 mm2, consisting of 4 × 4 unit cells and placed at a 5 mm distance at the backside of a double spiral antenna, which enhances the directivity, and gain of the proposed antenna and also converges backfield in the forward direction. At a 5 mm distance, the AMC structure behaves as a reflector and converges all back field radiation in the required direction to make a directional radiation pattern which enhances the antenna's bandwidth and gain. The proposed applicator (antenna + AMC structure) is simulated with a heterogeneous phantom (112 × 112 × 86 mm3), and the performance of the applicator is evaluated by using a specific absorption rate (SAR) in terms of penetration depth (PD) and effective field size (EFS) inside the phantom. The PD and EFS are improved when an AMC structure is placed at the backside of the antenna. Further, the proposed applicator is analyzed for the regular shape of the tumor inserted in the phantom, with the tumor size as 20 × 20 × 10 mm3, located at 10 mm distance from the skin surface. The study of temperature distribution inside the phantom is also done when 2.5 W of power is applied to the applicator in a simulation environment, a temperature rise of the tumor that between the range of 41–45°C is observed, allowing the proposed antenna with an AMC structure to be a good choice for the hyperthermia treatment.

Single-Layer Planar Monopole Antenna-Based Artificial Magnetic Conductor (AMC)

In this paper, a coplanar waveguide (CPW)-fed patch antenna is fabricated on a layer of metasurface to increase gain. The antenna is fabrication on Roger substrate with a thickness of 0.25 mm, with the overall dimension of the proposed design being 45 × 30 × 0.25 mm3. The size of the patch antenna is 24 × 14 × 0.25 mm3, and the AMC unit cell is 22 × 22 × 0.25 mm3. This metasurface is designed based on the split-ring resonator unit cells forming an array of the artificial magnetic conductor (AMC). Meanwhile, the antenna operation on 3.5 GHz is enabled by etching a split-ring resonator slot on the ground plane with a small gap to enhance antenna gain and improve impedance bandwidth when integrated with a metasurface. This simulation planer monopole antenna is applied for 5G application. The experimenter test is applied for the antenna performance in terms of return loss, gain, and radiation patterns. The operating frequency range with and without MTM is from 3.41 to 3.68 GHz (270 MHz) and 3.37 to 3.55 GHz (180 MHz), respectively, with gain improvements of about 2.7 dB (without MTM) to 6.0 dB (with MTM) at 3.5 GHz. The maximum improvement of the gain is about 42% when integrated with the AMC. The AMC has solved several issues to overcome the typical limitation in conventional antenna design. A circuit model is also proposed to simplify the estimation of the performance of this antenna at the desired frequency band. The proposed design is simulated by CST microwave studio. Finally, the antenna is fabricated and measured. Result comparison between simulations and measurements indicates a good agreement between them.

Analysis of 2 × 2 MIMO array loaded by artificial magnetic conductor with improved gain, isolation, and bandwidth using equivalent transmission line model for indoor wireless base station

A low profile printed dipole antenna (PDA) backed by broadband Giuseppe Peano fractal artificial magnetic conductor (AMC) is introduced for wireless communications. First, a suggested PDA with a pair of microstrip dipoles excited by an E-shaped microstrip feedline is used to expand the bandwidth in the range of 5.96–7.04 GHz (S11 ≤ −10 dB). Then, the suggested Giuseppe Peano fractal AMC surface as a reflector of the antenna is inserted into the PDA to gain improved radiation efficiency. The PDA with the 6 × 6 Giuseppe Peano AMC array exhibits −10 dB measured impedance bandwidth of 4.95–7.05 GHz (35%) for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The suggested PDA with AMC compared to the PDA without AMC exhibits a size reduction of 38%, enhanced gain up to 8.2 dBi, and excellent impedance matching (at least −20 dB) with directional radiation patterns. The novel AMC unit cell is realized based on the Giuseppe Peano fractal patch to operate at 6.10 GHz with an AMC bandwidth of 5.15–7.10 GHz (32%). Besides, by loading 12 × 12 AMC reflector into the four-element array of PDA, low profile wideband structure with enhanced radiation properties are achieved. The measured results show the broad bandwidths of 5–7 GHz for all elements with enhanced gains and good isolations between the elements (more than 24 dB) for multiple-input multiple-output (MIMO) systems.

Artificial magnetic conductor‐backed dual‐band shared‐aperture antenna array for base station applications

A low-profile dual-band dual-polarized base station antenna array is proposed. The dual-band array is backed by an artificial magnetic conductor (AMC) surface. The AMC achieves profile reduction to 0.159 λL0 in the low band (LB), but it acts as a bandpass metasurface in the high band (HB). The nested design of AMC unit cell creates two out-of-phase induced currents with lower intensities, enabling suppression and cancelation of HB scattered fields. The back cavities establish clear and independent radiating environments for the LB and HB antennas. They aid in further radiation pattern restoration and antenna profile reduction. The proposed antenna array was fabricated and experimentally measured. The simulated and measured results are presented. The operating principles of the proposed AMC and back cavities are also investigated.

High‐isolated broadband eight‐element linear multi‐input multi‐output array over artificial magnetic surface for wireless and sub‐6 GHz 5G communications

SummaryA low‐profile eight‐element printed dipole antenna (PDA) array backed by broadband rhomboid artificial magnetic conductor (AMC) is introduced for wireless communication systems. By loading a 4 × 27 AMC reflector into the eight‐element array of PDA, a low‐profile wideband structure with enhanced radiation properties is achieved. The measured S parameters show the broad bandwidth from 4.75 to 7.05 GHz in C‐band with enhanced gains of eight elements (more than 8 dBi) and the suitable isolation between the array elements of more than 23 dB for multi‐input multi‐output (MIMO) systems. The suggested PDA with a pair of the microstrip meandered folded poles excited by an E‐shaped microstrip feedline expands the bandwidth in the range of 5.85–6.95 GHz (S11 ≤ −10 dB). The novel AMC unit cell is realized based on the recognized method as rhomboid coupled parasitic patches. The rhomboid AMC design operates at 6.26 GHz with an AMC bandwidth of 5.20–7.24 GHz (32.8%). Then, the suggested rhomboid AMC surface as a reflector of the antenna is inserted into the PDA to exhibit −10 dB measured impedance bandwidth from 4.94 to 6.93 GHz (more than 33%) for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The suggested PDA with AMC compared to the PDA without AMC exhibits a size reduction of 34%, enhanced gain up to 8 dBi, and excellent impedance matching (at least −20 dB) with directional radiation patterns.

Radiation Properties Improvement of 1 × 4 Array of Wideband Printed Antenna Supported by AMC Surface for Vehicular MIMO Systems

AbstractA 1 × 4 array of printed dipole antenna (PDA) with a broadband rhomboid artificial magnetic conductor (AMC) is introduced. A suggested PDA using a pair of microstrip dipoles with unequal arms excited by a T‐shaped microstrip feedline expands the bandwidth in the measured range of 5.27–6.74 GHz. Then, the suggested 3 × 3 AMC reflector is inserted into the PDA to exhibit −10 dB measured impedance bandwidth from 4.20 to 7.11 GHz for WLAN and WiMAX applications. The suggested PDA with AMC compared to the PDA without AMC exhibits a size reduction of 46.72%, enhanced gain up to 8.4 dBi, and excellent impedance matching with unidirectional radiation patterns. The novel AMC unit cell operates at 6.20 GHz with an AMC bandwidth of 5.09–7.21 GHz. Also, by loading a 3 × 8 AMC periodic array on a FR4 substrate with 3 mm thickness underneath the four‐element array of PDA with a gap distance of 3 mm, a low‐profile wideband structure with enhanced radiation properties is achieved. The measured S‐parameters show the broad bandwidth from 4.26 to 7.28 GHz with enhanced gains and efficiencies of all elements. Besides, the suitable isolation between the array elements of more than 30 dB for multiple‐input multiple‐output (MIMO) systems is achieved by applying various polarized directions of PDAs and loading the 3 × 8 periodic AMC reflector. Finally, the proposed MIMO design introduces remarkable advantages of good size reduction and bandwidth enhancement, low‐profile antenna with high stable gain, high efficiency and large isolation, and unidirectional radiation patterns with reduced backside direction.

Towards durable and efficient antenna with SAR reduction analysis for on-body applications

Abstract This paper is focused on providing a viable solution to wearable antenna performance disconcertment caused by the underlying human body. Direct placement of the antenna on the body yields undesired results owing to the frequency detuning effect. The simplest possible way out is to make use of a metallic reflector. Hence, a reflector backed antenna is presented for 5.8 GHz ISM band with total lateral dimensions of 28 × 28 × 13.58 mm3. The reflector makes use of a conformal high dielectric laminate coated with a thin copper layer owing to which the assembled design achieves low SAR (Specific Absorption Rate). The prototype provides excellent results at the cost of some extra volume occupation in an off-body direction. Another AMC (Artificial Magnetic Conductor) backed technique is followed and implemented separately to have the structural compactness lacking in the former case. The antenna at hand is backed by a 2 × 2 array of AMC unit cells. The overall design dimensions are reduced. The reflector backed design achieves 8.2 dB gain, above 90% efficiency, and 99% bandwidth overlap with the primary antenna. The AMC backed design provides good spectrum coverage from 5.73 to 5.94 GHz with high gain. Free space response, on-body performance, and investigation of SAR analysis of the proposed designs substantiate effective wireless data transfer in body-centric communication.