Layers Of Dielectric Substrate Research Articles

Asymmetric transmission for dual-circularly and linearly polarized waves based on a chiral metasurface.

We propose a chiral metasurface (CMS) that exhibits asymmetric transmission (AT) of double circularly and linearly polarized waves at the same frequency band. In order to realize the manipulation of electromagnetic (EM) waves in the whole space, the unit cell of CMS consists of three layers of dielectric substrate and four layers of metal patches. The Z-shaped chiral micro-structure and a grating-like micro-structure are proposed and designed to achieve AT. The simulated results show that the x-polarized wave that is incident along one direction can be transmitted into the right-hand circularly polarized (RHCP) wave and the left-hand circularly polarized (LHCP) wave that is incident along the opposite direction can be reflected as the LHCP wave in the frequency band of 4.69GHz-5.84 GHz. The maximum chirality response can be reflected by AT and circular dichroism (CD) and they can reach up to 0.38 and 0.75, respectively. In addition, we also produced the sample of CMS, and the experimental results are in good agreement with the simulated results.

Wideband air‐filled ridge substrate‐integrated waveguide

A wideband air-filled ridge substrate integrated waveguide (AFRSIW) and its transition to microstrip are proposed first in this paper. The AFRSIW combines the broadband advantage of the ridge substrate integrated waveguide (RSIW) and the low loss of the air-filled SIW (AFSIW). Therefore, the AFRSIW allows for lower cut-off frequency and broader mono-modal bandwidth compared with AFSIW with same width and height, because of the involvement of the ridge made of an additional layer of dielectric substrate. Moreover, the AFRSIW has lower loss compared with RSIW due to the removal of the dielectric. The transition from AFRSIW to microstrip consists of a tapered microstrip line and two suppressing stubs. The tapered microstrip line is used to ensure impedance matching, and two suppressing stubs preventing the undesired radiation are introduced to improve the impedance match broadening the operating bandwidth of the transition. The AFRSIW together with the transition is simulated and optimized with HFSS. For demonstration, a back-to-back transition prototype is fabricated and measured. A mono-modal bandwidth of 77.6% with 15 dB return loss is obtained from 8.6 to 19.5 GHz.

Generating Bessel Beams Efficiently in Microwave With High Transmission Metasurfaces

In this article, two transmissive metasurfaces with different phase control mechanisms and working polarization condition are proposed to efficiently generate zero order Bessel beams (BBs), respectively. For the linear polarization condition, a dual-mode meta-atom constructed by three layers of dielectric substrate and four layers of metal patch is designed. By changing the size of metal patches of meta-atom along x-axis and y-axis, respectively, the phase shift for x- and y-polarized incident wave can be tuned relative independently of 0-2 π while the transmission coefficient keeps high value at 10 GHz. For the circular polarization condition, a sandwich type meta-atom applying geometric phase to realize full phase control while keep high efficiency near 10 GHz is designed. According to the designed phase profile of BBs, select meta-atoms with certain phase and efficiency, then arrange them to construct metasurfaces. Full wave simulation results indicate that the dual-mode metasurface working in linear polarization condition generates BBs with the maximum transmission efficiency 0.79 and 0.85 for x and y polarization wave, respectively, and the geometric phase metasurface working in circular polarization condition generates BBs with the maximum transmission efficiency 0.92. Besides, the propagation characteristics of the excited BBs are studied.

Design of U-Shaped Slot Quad Band Patch Antenna

A four-band microstrip antenna with a U-shaped slot and two straight slots is proposed in this study. As the width of the dielectric substrate layer is extended, the frequency bands and antenna gain are observed to rise. In this current study, the suggested antenna is intended for using in wireless devices operating at frequencies between 5 GHz to 9 GHz.

A Compact SIW Monopulse Antenna Array Based on Microstrip Feed

In this letter, a compact substrate integrated waveguide (SIW) monopulse antenna array based on microstrip feed is proposed. The antenna cell is composed of two layers of dielectric substrates, the model of the dielectric substrate is Rogers 5880. The TE20 mode is excited in the bottom SIW cavity, and the mirrored TE20 mode is used to realize the function of a monopulse comparator, which makes the structure of the antenna simple and superior in performance. Furthermore, an array is formed on the basis of the cell. The performance of the array was verified in simulated software and the prototype was fabricated for testing. The measured results are consistent with simulated results. The antenna works in the X-band, and the measured and beam gain reaches 16.4 dBi, and the null depth is 33.8 dB. The antenna aperture efficiency reaches 43%, which has great advantages compared with similar antennas.

A Wideband High-Gain Endfire Antenna Based on Spoof Surface Plasmon Polaritons

A novel endfire antenna based on spoof surface plasmon polaritons (SSPPs) is proposed in this letter. The main radiator of the antenna is excited by the SSPP waveguide, due to the high transmission performance of the SSPP waveguide, which is realized by etching a series of periodic corrugated grooves on the metal strip. The gradient corrugated grooves are used as the transition to transform the quasi-TEM mode in the microstrip line to the SSPP mode and get maximum impedance matching. In the bottom layer of the proposed antenna, to improve the front-to-back ratio of the endfire antenna, an extended U-shaped metal plane is positioned to act as the reflector of the antenna. Three printed metal strips are designed as the directors of the endfire antenna and improve the directivity. A prototype of the endfire antenna was fabricated and measured in this letter. The simulation and measurement results demonstrate that the gain of the antenna is about 9.1 dBi at the designed frequency 7 GHz, the fractional bandwidth of the antenna is up to 31%. The endfire antenna, which is implemented on a single layer dielectric substrate has the advantages of high efficiency, good directivity, high gain, wide band, easy fabrication, and compact size.

Statistical Analysis of Fabrication Discrepancy Effects on Periodic Circuit Analog Electromagnetic Absorbers

Periodic circuit analog absorbers (PCAAs) are widely used to reduce electromagnetic (EM) scattering fields in various applications. Their performances are sensitive to various geometric parameters. Thus, the stability and sensitivity of the EM absorbing characteristics of PCAAs during a fabrication discrepancy due to the manufacturing uncertainty were investigated. These discrepancies are large in terms of the wavelengths at high frequencies. This article considered randomly produced nonuniform thicknesses of a conductive ink to fabricate the array structure of a PCAA and its two sandwiching dielectric substrate layers on both sides. To examine the discrepancies in fabrication, the thicknesses of the conductive ink were generated from random numbers with a desired mean value and a reasonable standard deviation of the normal distribution. To indicate the EM-field absorbing capability, we studied characteristics, such as S-parameters (reflection and transmission coefficients) and the resulting power efficiency, using numerical high frequency structure simulator (HFSS) full-wave simulations at a frequency band of 10 GHz. They were further validated by conducting experiments on prototype samples. We observed that the resonant frequencies were considerably affected by the thickness of the conductive ink in the PCAA structures. A fabrication accuracy of less than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> - 4</sup> λ was required to attain a stable performance.

Temperature Compensation of an Air-Filled Stacked Ring Resonator

A temperature-compensated resonator based on stacked rings is proposed in this letter. The resonator is made of several layers of machined dielectric substrates where the copper rings stand. These rings define an air-filled TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">011</sub> cavity with an unloaded quality factor better than 1800. Due to a low sensitivity of the air gap between the layers and metallic contact of the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">011</sub> mode, a cavity with low building constraints (no vias and no connection between layers) is realized. Furthermore, a multilayer design allows the introduction of a controlled amount of dielectric material in the cavity with a negative thermal coefficient of permittivity to realize temperature compensation of the device and to counteract its natural thermal expansion. Thus, this compensation layer allows proper management of a frequency drift from of -18 to +18 MHz for a temperature range of 20 °C-80 °C. However, there is a tradeoff, and the quality factor decreases as the compensated layer is inserted. A guideline demonstrating the performance of the design and the compensation technique is thus presented in this letter.

A Novel MIMO Patch Antenna for 5G Applications

In this paper, a new MIMO patch antenna is proposed, the proposed antenna consist of patch with certain dimensions in the top layer of FR-4 dielectric substrate, and ground plane in the bottom of it, this antenna is feeding by microstrip feed line with 50-ohm characteristic impedance. The dimensions of the proposed antenna are (50 × 50 × 1.6) mm3, the FR-4 epoxy substrate has relative dielectric constant εγ=4.3, loss tangent tan (δ) =0.025. This antenna is realized a bandwidth of 4.337 GHz (24.22 – 28.557) GHZ and gain (3.68) dBi which is compatible with 5G applications. Some modifications were done in the ground plane and some of slots are etched on the patch to achieve the desired gain and bandwidth, all dimensions of these slots were chosen by using sweep parameter method to achieve the optimum value of them. The simulation results are obtained using CST software. And the proposed antenna is manufactured in the Electronic Manufacturing Center at the Ministry of Science and Technology, also the vital parameters are measured, a good agreement between simulation and measured results are achieved.

An ultra-wideband, polarization insensitive metamaterial absorber based on multiple resistive film layers with wide-incident-angle stability

AbstractIn this work, we propose a broadband, polarization-insensitive and wide incident angle stable metamaterial absorber (MA) based on the resistive film. The absorber consists of a three-layer structure with each layer of dielectric substrate printed with different shapes of resistive film. The multilayer structure not only extends the absorption bandwidth but also maintains high absorption under large wave incident angles. Numerical simulation shows that the absorptivity of a normal incident wave is above 90% in the frequency range 2.34–18.95 GHz, corresponding to a relative absorption bandwidth of 156%. Moreover, the whole MA structure has a total thickness of 11.3 mm, corresponding to 0.09 λ0 at its lowest absorption frequency. Due to the high symmetry of the structure, the absorber has good polarization insensitivity. In addition, for both transverse electric and transverse magnetic incidence, the proposed absorber achieves an absorptivity of more than 80% at incident angles of up to 45° and thus has good stability for wide incident angles. The absorption principle of the absorber is analyzed by the surface current and power loss density distribution. Parameter analysis is also performed for bandwidth optimization. Due to its advantages of wideband absorption with high efficiency, the proposed absorber has the potential to be applied to the energy-harvesting and electromagnetic stealth fields.

A Novel Linear Sparse Array with Reconfigurable Pixel Antenna Elements

In this paper, on the basis of multifunctional reconfigurable pixel antenna (RPA) elements, a novel linear sparse array with an attractive compound reconfigurability is presented. It has the potential advantages of its beam scanning with low gain fluctuation, low sidelobe in two orthogonal planes, and polarization reconfigurable performance. Specifically, an RPA with simultaneous polarization and pattern reconstruction capabilities, consisting of the driven patch and the parasitic pixels on the same layer of dielectric substrate, is firstly designed, which can work in several operation modes corresponding to steerable beam directions θ=0°;θxoz=25°, 45°;θyoz=15° with two circular polarizations in X-band. Cross-slot coupling feed is used to improve polarization reconstruction capability and reduce the complexity of hybrid reconstruction topology optimization. Then, those RPAs are integrated into the 1×8 linear sparse array to realize the reconfiguration of two circular polarizations and beam steering in xoz- and yoz-plane. Simulation results show that the gain fluctuation and sidelobe level of the array during beam scanning have significant advantages over the previous phased array, and the generation of antenna grating lobes is avoided. Moreover, both RPA element and RPA array prototypes have been fabricated and measured to testify the efficiency. The measured results agree well with the simulated ones, which indicates the application potential in the field of modern wireless communication system of the proposed linear sparse array.

Research of microscale silver particle paste on Al2O3, pre-dried dielectric layer and pre-fired dielectric layer substrate by a co-firing process

In this paper, the silver paste was prepared by highly dispersed spherical silver powders with an average particle size of 0.85 um. The silver conductive thick films were printed on Al2O3 and dielectric layer by screen-printing, the dielectric layer had been heat-treated differently, one was dried, the other fired. The corresponding sintering behaviors, electrical and mechanical properties of silver films were investigated systematically. Besides, we made a chip resistor to test performance. The results show that the silver conducting film on fired dielectric is compact, uniform and defect-free, the resistivity and adhesion are 2.54 uΩ·cm and 20.3 N mm−2 respectively. With the increase of sintering times, the conductivity of silver films on the fired dielectric layer increases first and then decreases, while the adhesion increases continuously. We proposed that the diffusion quantity of glasses from the dielectric layer to the surface was the key step in the period of the properties of silver films. The silver film on the fired dielectric layer has better applications in the high current chip resistors.

Antena Susun Berpolarisasi Sirkular dengan Menggunakan Distribusi Daya Dolph Tschebycheff (Circularly Polarized Array Antenna Using Dolph Tschebycheff Power Distribution)

This paper discusses the design and realization of circularly polarized array antenna using Dolph Tschebycheff power distribution. The advantages of implementing circular polarization yield the array antenna suitable for outdoor communication system and can minimize the Faraday effect. The Dolph Tschebycheff power distribution is used to suppress the side lobe of array antenna. The proposed array antenna, which is intended to operate at the frequency of 5.3 GHz, consists of five square patch elements with seven diagonal slots upon each element to enhance the bandwidth and to produce the circular polarization. The array antenna is designed and realized using two layers of FR-4 epoxy dielectric substrate with the dimension of 119 mm × 44.1 mm and the thickness of 0.8 mm for each dielectric substrate. Each patch element is fed using a proximity coupling technique excited through a 50 Ω SMA connector. The measurement results show the bandwidth of 720 MHz, the side lobe level of 12.39 dB, the gain of more than 6 dBi around the frequency of 5.3 GHz, and the 3 dB axial ratio bandwidth of 200 MHz. It seems that the realized array antenna could produce wide bandwidth, low side lobe level, and circular polarization, so that it is suitable for WLAN application.

Millimeter-Wave Butler Matrix Beamforming Circuit Using Finline in Double-Layer Dielectric Substrate

This article presents a new kind of finline in double-layer dielectric substrate and its beamforming circuit of Butler matrix in the millimeter-wave band. The finline is constructed by inserting a slotline between two dielectric substrate layers. In this configuration, it is bounded within a closed structure composed of a double-layer dielectric substrate and two rows of via-hole arrangement, contributing to low dispersion and low radiation loss of the finline characteristics. The proposed finline design aims to provide a low-complexity and low-loss transmission line which is applied to the Butler matrix design. A $4\times 4$ Butler matrix for 4 switchable beams is realized by using the finline in the double-layer dielectric substrate. In addition, a waveguide-to-finline transition is developed as a feeding circuit for the Butler matrix. Characteristics of the proposed transition and the Butler matrix were analyzed by electromagnetic analysis of the finite element method and demonstrated by experiments at 79 GHz. The proposed Butler matrix obtains a wideband characteristic and an acceptable insertion loss of 2.42 dB. The array factor which is calculated from the measured amplitude and phase outputs 4 switchable beams with the beam directions of +14°, −46.5°, +46.5° and −14°, respectively. The proposed beamforming circuit using finline in double-layer dielectric substrate would be attractive for millimeter-wave applications due to its performance and low cost.

Analysis and design of new chiral metamaterials with asymmetric transmission characteristics

Asymmetric transmission (AT) metamaterials are extensively studied and applied in the fields of polarization converters and photodiodes. In order to further improve the properties of polarization conversion and unidirectional conduction in the high frequency band and to implement their tunability, the novel chiral electromagnetic metamaterials are studied. By the topology optimization technique, a new type of double-layer L-shaped variant metamaterial structure with excellent asymmetric transmission characteristics is designed. The objective function is to maximize the asymmetric transmission coefficient for the linear polarization wave. The rotationally symmetrical design domain is determined by considering polarization conversion and computation efficiency simultaneously. The design domain of upper layer is divided into two parts which are both the 180° rotationally symmetrical. The design domain of the upper layer and lower layer are the 90° rotationally symmetrical around the &lt;i&gt;x&lt;/i&gt; and &lt;i&gt;z&lt;/i&gt; axis respectively. Therefore, the number of design variables is only 18. Asymmetric transmission of linear polarization wave in the K band and Ka band are implemented. Numerical simulation results and experimental results show that the optimized chiral metamaterial has excellent asymmetric transmission characteristics, and its asymmetric transmission coefficient reaches 0.8562 at a frequency of 21.65 GHz and 0.8175 at a frequency of 28.575 GHz. Its asymmetric transmission mechanism is expounded by analyzing the electric field and surface current distribution at the resonance frequency. Based on the optimized chiral metamatertials, the reasonable geometric parameters are selected and the rotation angle of the metal layer is changed in order to further achieve the tunable AT characteristics. First, the influences of the dielectric substrate layer, the thickness of the metal layer and the side length of the grid on resonance frequency and asymmetric transmission coefficient are analyzed respectively, which provides the basis for the reasonable adjustment of the structural parameters to obtain better asymmetric transmission characteristics. After the reasonable geometric parameters are determined, the rotational angle of the upper metal layer and lower metal layer are changed. The linearly and circularly polarized wave are simultaneously achieved in the K band. In this article, the topology optimization technique is used to design the asymmetric transmission chiral metamaterial structure. The design process has a clear direction. The optimized asymmetric transmission chiral metamaterial has the simple structure type and the easy tunability of its asymmetric transmission characteristics. It can be used widely and easily in the fields of polarization converters and photodiodes. This design method has a broad application prospect in the chiral metamaterial field.

Specific absorption rate reduction of multi split square ring metamaterial for L- and S-band application

In this paper, a framework for investigation on mobile phone and human head interaction are presented for L- and S-band applications. The proposed compact metamaterial design helps to reduce the Specific Absorption Rate (SAR) value that exposed to the human head. A recent achievement in metamaterial field allows this unusual material widely used in mobile phone applications to enhance the accomplishment and consequently received substantial attention among researchers. Hence, a multi-split square ring metamaterial design developed on a 1.6 mm thick dielectric substrate layer known as Epoxy Resin Fiber (FR-4). Electromagnetic properties of the proposed metamaterial structure were calculated through numerical simulation tool using the Finite Integration Technique (FIT) in Computer Simulation Technology Microwave Studio (CST). A few designs were used to conduct parametric studies with altering the substrate material, design structure, array arrangement and phone distance from the human head. 0.3–4 GHz frequency range was utilized in this simulation, where the proposed design established resonance frequencies precisely at 1.81 (L-band) and 3.79 GHz (S-band). The measured results show the resonance frequencies occurred at 1.82 and 3.72 GHz. Therefore, with a little bit discrepancy between the numerical and measurement results, it made the comparison was largely in agreement. The SAR value shows that a reduction by 36.87% and 45.54% at L- and S-band respectively for averaged over 1 g of tissue volume. While for averaged over 10 g of tissue volume, integrated metamaterial design in mobile phone reduced by 35.29% and 48.36% at L- and S-band respectively.

Composite circular split ring resonator (CSRR)-based left-handed metamaterial for C- and Ku-band application

The aim of this study is to introduce a compact metamaterial structure for dual-band (C- and Ku-band) applications. Due to their unique electromagnetic properties, metamaterials find wide use in satellite applications to improve performance, and have therefore received great attention from researchers all over the world. In this article, a left-handed circular split ring resonator metamaterial structure is designed for satellite application. The inner circular split rings are split with thickness of 0.20 mm and a 0.25 mm thickness rectangular bar tilted at angles of 0°, 90°, 180° and 270° to connect all the main resonator rings. The metamaterial design proposed here is developed on a square Epoxy Resin Fiber (FR-4), which serves as the dielectric substrate layer. The metamaterial structure was successfully designed and simulated using numerical analytical methods such as Finite Integration Technique (FIT)-based electromagnetic simulator, and Computer Simulation Technology Microwave Studio (CST). Several designs were used to perform parametric studies while varying the subtract strip line thicknesses and subtraction angles. A frequency range of 0–18 GHz was used in simulation, where the design manifested resonance frequencies at 6.46 GHz and 16.92 GHz. In addition, the fabricated metamaterial showed resonance frequencies at 6.54 GHz and 17.06 GHz, making this design applicable for both C- and Ku-bands. Comparison between experimental and numerical results showed that transmission coefficient graphs obtained from the two methods were largely in agreement with each other and showed only small differences. The resonance frequency at Ku-band exhibited left-handed metamaterial behavior that makes the designed metamaterial suitable for satellite communication system.

Design and Analysis of Miniaturized Low Profile and Second-Order Multi-Band Polarization Selective Surface for Multipath Communication Application

In this paper, a novel frequency selective surface (FSS) is designed; it has the characteristics of the low profile, second-order, multi-band, and the remarkable polarization selection properties. In the following, such an FSS having polarization selection characteristics will be referred to simply as a polarization selection surface (PSS). In a specific frequency band, the proposed PSS has a second-order selective transmission characteristic for TE and TM waves. Based on the coupling resonance filtering mechanism, the proposed PSS is composed of three metallic layers separated by two layers of dielectric substrates, which serves as the spatial form of the second-order microwave filter. The proposed PSS uses a sub-wavelength periodic structure array consisting of a non-resonant unit, and the unit size and the period within the range of 0.08λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> -0.15λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> , where the λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> = 40.76 mm is the first passband wavelength of free space, so the PSS miniaturization characteristic is remarkable. The theoretical analysis and measure results show that the proposed bandpass PSS has good second-order polarization selection characteristics, out-of-band suppression level, and the flat transmission band, compared with the first-order bandpass PSS. In the range of incident angle of 0°-60°, it has a stable frequency response. It provides a reference for the design of a polarization wave generator and a polarization separation structure in a multipath communication system.

Design of Ultra-Wide Band Metal-Mountable Antenna for UHF Partial Discharge Detection

This paper presents an ultra-wideband metal-mountable antenna used in the ultra-highfrequency (UHF) partial discharge (PD) detection. The designed antenna combines a coplanar waveguide antenna and multilayer substrates to effectively broaden its bandwidth when mounted on a conductive surface. These substrates consist of two layers of FR-4 dielectric substrates and two layers of the absorbing gasket, which is adapted to absorb the reflected electromagnetic signals. The parametric study is conducted to optimize antenna performance. A prototype is fabricated to confirm the design, and the measurement results show good agreement with the simulation. When mounted on the metal plate, the proposed antenna covers the UHF bandwidth of 400 MHz-3 GHz for S 11 <; -10 dB with a compact size (282 mm × 242 mm × 8.75 mm). As the thickness of the antenna is only 8.75 mm, the safety distance of electric insulation in electrical equipment will not be affected. A PD experiment has been carried out, and a reference antenna is used in the experiment for comparison. Compared with the conventional antenna, the proposed antenna has a better performance when mounted on the metal plate. It is shown that the designed antenna is a very good candidate for UHF PD detection inside of high-voltage equipment.

Bandwidth enhancement for thin substrate UHF RFID patch antenna

Abstract This paper presents an unconventional bandwidth enhancement technique for thin substrate UHF RFID linearly polarized patch antennas. The patch antenna is made from polyethylene dielectric substrate and aluminum adhesive strip conductive layers. A microstrip fed rectangular patch antenna is designed to operate between 902 and 928 MHz UHF RFID frequencies. Impedance bandwidth is enhanced by intentional impedance mismatch at the edge of the patch. An 88.98 MHz impedance bandwidth was achieved through a –32% intentional impedance mismatch. Antenna’s gain and other parameters were not majorly affected by this technique. This technique is also suitable for other applications operating in 433 MHz or 2.4 GHz. Transceivers that can handle reflected power is recommended to use with this type of bandwidth enhancement.