AMC Surface Research Articles

Multiband Antenna Design with Integrated AMC Surface and FSS Superstrate for Wireless Body Area Network Communications

Multiband Antenna Design with Integrated AMC Surface and FSS Superstrate for Wireless Body Area Network Communications

Bandwidth and Gain Improvement of Low-profile MIMO Printed Arrays by Utilizing AMC Surface for Wireless Communications

Bandwidth and Gain Improvement of Low-profile MIMO Printed Arrays by Utilizing AMC Surface for Wireless Communications

Low-Cost Quasi-Planar Dielectric Patch Resonator Filters Shielded by AMC Surface

Low-Cost Quasi-Planar Dielectric Patch Resonator Filters Shielded by AMC Surface

Analysis of High Gain Wideband 2 × 2 Printed Slot Array With AMC Surface by Presenting Equivalent Transmission Line Model for C and X-Band Applications

Analysis of High Gain Wideband 2 × 2 Printed Slot Array With AMC Surface by Presenting Equivalent Transmission Line Model for C and X-Band Applications

A Robust, Compact and Efficient AMC-Enabled Dual-Band Antenna for Wearable Healthcare

This paper details an antenna design with a minuscule lateral footprint of [Formula: see text][Formula: see text]mm3. The antenna operates for the two bands of WiMAX 3.5[Formula: see text]GHz (for wireless communication standard) and industrial, scientific and medical radio (ISM) 5.8[Formula: see text]GHz (for healthcare applications). Optimization and computer-aided performance analysis of the proposed design are carried out using Computer Simulation Technology (CST) Microwave Studio. Required electromagnetic performance in close proximity to the human body is achieved by backing the primary CPW-fed antenna with a fabric-based dual-band AMC surface. Several prototypes of the formulated design are characterized experimentally to validate the computationally obtained performance parameters. The proposed AMC-integrated dual-band design readily meets directional radiation characteristics desired for off-body communication with 7.53-dB and 8.58-dB gains in the lower and upper resonance frequencies, respectively. Moreover, the antenna’s top layer consists of a semi-flexible laminate, while textile constitutes the bottom layer to maximize user comfort. Further analysis reveals a significant reduction in SAR by 16.7[Formula: see text]W/kg at the lower band and by 13.5[Formula: see text]W/kg at the upper band. The precedence of the reported structure demonstrated in the results endorses its application in robust wearable devices.

A Low-RCS and Wideband Circularly Polarized Array Antenna Co-Designed With a High-Performance AMC-FSS Radome

In this letter, we investigate a low radar cross-section (RCS) wideband circularly polarized microstrip array antenna co-designed with a high-performance artificial magnetic conductor and frequency selective surface (AMC-FSS) radome. Compared with the absorbent frequency selective radome-based antenna, the proposed co-designed antenna can achieve a relatively low gain loss in an extremely wide frequency range with wideband in-band and out-of-band RCS reduction, due to the introduction of a novel AMC-FSS radome which can achieve low insertion loss and wideband transmission by combining a double-layer miniaturized bandpass FSS and a single-layer chessboard AMC surface. We demonstrate the effectiveness of the proposed AMC-FSS radome and co-designed antenna through simulations and measurements. The results show that the gain deterioration of the co-designed antenna is only 0.42 dB at the central frequency of 4.8 GHz and less than 1 dB in the wide frequency band, ranging from 4.23 to 5.38 GHz with a relative bandwidth of 23.9%. At the same time, the monostatic RCS for a normal incidence is greatly reduced from 4 to 18 GHz.

Design and analysis of varactor‐loaded bi‐state switchable active artificial magnetic conductor reflector for wearable antenna integration

A low profile, bi-state switchable, and flexible active AMC (AAMC) reflector metasurface is presented for wearable antenna integration to improve radiation performance with low specific absorption rate (SAR). The unit cell structure contains concentric rectangular rings with 2-varactor diodes. The unit cell is designed on a flexible PDMS substrate with dimensions 20 × 20 × 1 mm3. Controlled DC bias is applied to both varactor diodes. In state-1, that is, on state, the AMC surface resonates at 3.5, 5.8, and 8.1 GHz frequency, and in state-2, that is, off state, it resonates at 3.5, 5.8, and 7.5 GHz frequencies with zero degrees reflection phase. The proposed AAMC reflector performance is analyzed by integrating a 3 × 3 AAMC surface with the quad-band wearable textile antenna designed to resonate at 3.5, 5.8, 7.5, and 8.1 GHz frequencies. By controlling operating voltages of the integrated AAMC, the antenna radiation performance is improved in bi-state by adapting to reflection pattern switching. In On-state, the peak gain (dBi), FBR (dB) of integrated antenna improved to 7.36, 9.05, 8.9, 7.53 and 9.25, 11.9, 19.7, 16.70; In Off-state, the values are improved to 7.8, 8.98, 8.33, 7.92 and 12.24, 11.37, 14.6, 16.85, respectively. The proposed AAMC with antenna integration is fabricated, and its measured results are well satisfying. The low SAR values are obtained under a 2 mm gap (<0.924 W/kg) and direct contact (<1.5 W/kg) as well. The enhanced radiation performance characteristics with the bi-state switchable feature make it preferable for wearable antenna integration to meet current WBAN demands.

Performance Enhancement of Low-Profile Wideband Multi-Element MIMO Arrays Backed by AMC Surface for Vehicular Wireless Communications

Performance Enhancement of Low-Profile Wideband Multi-Element MIMO Arrays Backed by AMC Surface for Vehicular Wireless Communications

High-gain dual-band antenna with AMC surface for satellite communications

ABSTRACT A dual-band planar dipole antenna, incorporated with a zigzag-shaped dual-band artificial magnetic conductor with gain enhancement, is proposed here. By using 5×9 AMC surface as substrate to the dipole antenna, the bidirectional radiation pattern of the dipole antenna is transformed to unidirectional radiation pattern. The separation distance between the dipole antenna and the AMC surface is λ/6 at 5.5 GHz. The proposed antenna has been fabricated and measured to verify the simulation results. The experimental results ensure good impedance matching (S11 < −10 dB) over two frequency bands (i.e. 5.1–6.2 GHz and 6.75–7.24 GHz). The composite antenna also provides a maximum gain of 8.94 dB at 5.5 GHz with a gain variation of only 0.5 dB over the two operating frequency bands. In addition, the cross-polarization level is less than −15 dB for both E and H planes.

A low‐profile four‐element MIMO antenna array with new decoupling structures

AbstractA low‐profile four‐element multiple‐input multiple‐output (MIMO) antenna array with new decoupling structures is proposed in this letter. The presented MIMO antenna array contains four parts: dual‐polarized antennas, power dividers, the AMC surface, and the new decoupling structures. The height of the dual polarized antenna is 10 mm (0.08λ0, λ0 is the wavelength propagating in free space at 2.5GHz). Meanwhile, the proposed MIMO antenna array can offer an impedance band from 2.5 GHz to 2.7 GHz. The new decoupling structures can greatly improve the isolation of each port in the four‐element MIMO antenna array. Comparing with the tested results and the simulated results, they are relatively consistent.

Chessboard AMC Surface Based on Quasi-Fractal Structure for Wideband RCS Reduction

A chessboard artificial magnetic conductor surface based on the quasi-fractal structure is proposed for wideband radar cross-section (RCS) reduction. The chessboard configuration is formed by two different cells with 180° ± 37° phase difference over more than 90% frequency bandwidth. The quasi-fractal structure is utilized to achieve the wideband and compact characteristics. Monostatic and bistatic RCS of the proposed chessboard surface are analyzed, and the results are compared with those of equal-sized perfect electric conductor ground plane. Because the scattered fields of the chessboard surface are redirected toward four quadrants, a remarkable RCS reduction of 10 dB can be realized from 5.4 to 14.2 GHz. Measured results of the fabricated prototype satisfactorily agree with the simulated ones.

A metasurface-based slit-loaded wideband circularly polarized crossed dipole antenna

A metasurface-based low-profile crossed dipole antenna with wide circularly polarized bandwidth for 2.45 GHz ISM band wireless communications is proposed and fabricated in this article. Consisting of four slit-loaded rectangular patches, the double-sided printing crossed dipoles are fed by a pair of vacant-quarter printed rings which circularly polarized (CP) radiation could be generated. With slits loaded, by properly combining the fundamental mode of the two inverted L-shaped dipole, the slot mode and extra resonance generated by the AMC surface, a wideband circularly polarized operation can be obtained. After optimization, the final design with an overall size of 0.44λ0 × 0.44λ0 × 0.1448λ0 at 2.4 GHz had measured a 31.6% (2–2.75 GHz) impedance bandwidth and 3 dB axial ratio bandwidths of measured were 23.2% (2.1–2.65 GHz), respectively. In addition, the antenna performed a small gain variation (7.0–7.5 dBic) and a front-to-back ratio (FBR) of over 25 dB across the whole CP region.

Miniaturised dual-band artificial magnetic conductor with reduced mutual coupling

Presented is a novel design of an artificial magnetic conductor surface implementing a dual-band performance with a miniaturised unit cell of λ/23 and dual-band separation of up to 118 MHz, at 430 MHz. Miniaturisation is achieved by loading the AMC with lumped components. A wideband monopole antenna was fabricated and tested over the proposed AMC surface to validate the approach and demonstrate the potential for multiband antenna systems. The measured reflection coefficient of the integrated antenna/AMC system was satisfactory and good matching was achieved.