Multiband Performance Research Articles

Antenna Booster Element for Multiband Operation.

The escalating demand for versatile wireless devices has fostered the need to reduce the antenna footprint to support the integration of multiple new functionalities. This poses a significant challenge for the Internet of things (IoT) antenna designers tasked with creating antennas capable of supporting multiband operation within physical constraints. This work aims to address this challenge by focusing on the optimization of an antenna booster element to achieve multiband performance, accomplished through the design of a band-reject filter. This proposal entails a printed circuit board (PCB) measuring 142 mm × 60 mm, with a clearance area of 12 mm × 40 mm, incorporating an antenna booster element of 30 mm × 3 mm × 1 mm (0.07 λ). This configuration covers frequencies in the LFR (low-frequency range) from 698 MHz to 960 MHz and the HFR (high-frequency range) from 1710 MHz to 2690 MHz. A theoretical analysis is conducted to optimize bandwidth in both frequency regions. Finally, a prototype validates the analytic results.

Compact Liquid Crystal Polymer Based Tri-Band Flexible Antenna for WLAN/WiMAX/5G Applications

In this paper, a new compact coplanar waveguide (CPW)-fed liquid crystal polymer (LCP) based tri-band antenna is presented and fabricated for Wireless Local Area Network (WLAN), Worldwide Interoperability for Microwave Access (WiMAX) and 5th-Generation (5G) systems. The antenna combines two strips with the main radiation rectangular patch and coplanar waveguide ground. The proposed antenna is printed on a LCP substrate with a thickness of 0.1 mm and has a small overall dimensions of 20mm×32mm×0.1mm. To analyze the characteristics, the antenna is designed and fabricated, and then the performance of the antenna is measured and tested. The measurement results show that the proposed antenna has three operating bandwidths, including 2.38-2.79 GHz, 3.27-4.05 GHz, and 4.80-8.44 GHz. To test the flexibility of the antenna, the antenna is simulated and measured in bent configurations for radii of 10 mm and 50 mm. In addition, the antenna is attached to different parts of the human body to test the integration effect in wearable equipment. The experimental results show that the performance of the antenna remains reliable under bending conditions and that the specific absorption ratio (SAR) value meets the European Union (EU) standard. The proposed antenna shows reasonable gains and good radiation characteristics in the operating bands. The flexible, compact, simple design and multiband performance indicates that the antenna is suitable for integration in flexible electronic devices.

Highly Efficient and Multiband Metamaterial Microstrip-Based Radiating Structure Design Showing High Gain Performance for Wireless Communication Devices

High-speed wireless communication devices need antennas to operate at multiple frequencies with high gain. The need for such antennas is increasing day by day. The proposed metamaterial superstrate antenna gives a high gain and multiband performance, which is required in high-speed wireless communication devices. The designed antenna is also applicable for C- and X-band communication devices. The structure consists of a simple patch and multiple split-ring resonator metamaterials on the superstrate region. The performance optimization is achieved by adjusting the feed position, varying the height of the superstrate layer and changing the thickness of metamaterial rings. The proposed design is analyzed for 4 GHz to 12 GHz. The performance analysis regarding the reflection coefficient, directivity, gain and electric field is observed. FR4 is used as a dielectric material that makes the design low-cost. The proposed design represents a minimum reflection coefficient response of −49 dB, a bandwidth of 490 MHz, a maximum electric field of 1.29 × 104 v/m, good directivity and a broader radiation pattern. The comparison between the simulated and the measured results is incorporated in the manuscript. A comparison of the presented design with other articles is included to check the novelty of the design. The proposed method helps to target applications such as WiFi, Earth observation and microwave links.

Multiband Elastic Waveguide Cloak in Thin Plates

Vibration in thin plates is a common issue in structural engineering that can significantly impact the performance of structures. One crucial objective is to control vibration intensity. Metamaterials offer a promising solution to this challenge. Herein, a multiband elastic waveguide cloak that uses metamaterials and does not require active components or complex designs is introduced. By converting flexural waves to waveguide‐trapped waves, a cloaking region with negligible vibration can be created. Herein, independent mode conversion channels for elastic waves, which could lead to new approaches to modulating elastic waves, are discovered. The experiment results are in excellent agreement with the numerical simulation results and demonstrate a waveguide cloaking effect. This design has a compact structure and exhibits multiband performance, making it highly suitable for vibration control in various scenarios, including the aerospace industry, bridge engineering, and shock‐absorbing platforms.

Investigation of resonant mode and simultaneous excitation of multiple modes in slot‐coupled rectangular dielectric resonator antenna for multiband applications

AbstractA low‐profile rectangular dielectric resonator antenna (RDRA) through the slot‐based feed method is studied for the multiband operation. Based on the perfect magnetic wall (PMW) model and dielectric waveguide model (DWM), field distributions and resonant frequencies of the RDRA intrinsic modes are calculated for multimodal analysis. The microstrip backed slot coupling scheme is employed for the simultaneous excitation of multiple modes. A prototype is fabricated and validated. By generating 10 modes simultaneously including TEy111 to TEy711, and TEx221 to TEx421 modes. The RDRA is able to provide good multiband performance.

Design of Novel Multiband Radar Absorbers Using Cylindrical Frequency Selective Surfaces

Abstract In this paper, a novel ultra-thin and multi-band radar absorber structure using cylindrical frequency selective surfaces (FSS) is proposed. The unit cell of the structure consists of a curved square ring printed on a cylindrical dielectric spacer to realize strong resonance to achieve efficient absorption of the incident microwave energy. The use of novel cylindrical FSS coating results in a considerable decrease of the radar cross section of a perfect electric cylinder. Furthermore, our studies prove that the proposed absorbing structure can be easily scaled to desired frequencies, and extension to dual- and multiband performances is possible. Meanwhile, the operational principle of the proposed absorbers is briefly introduced.

Design and Implementation of Multi-Band Fractal Slot Antennas for Energy Harvesting Applications

This paper introduces a design and optimization procedure of multiband fractal slot antennas for RF energy harvesting applications. The antennas were simulated using CST Studio Suite. A parametric study is conducted to determine the critical structural parameters that influence the antenna performance. The parametric study included varying the size ratio of the structure, the shape of the ground plane and the length of the feeding inset. Simulation results showed that the proposed antennas in this work exhibit multiband performance and they offer the possibility of controlling the resonant frequency at any specific frequency band. The optimized antenna has seven resonant frequencies at 1.8 GHz, 2.4 GHz, 3.45 GHz, 3.6 GHz, 4 GHz, 4.6 GHz and 5.3 GHz covering several ambient communication networks (GSM, UMTS and 5G), Bluetooth and WLAN systems. Simulation results shows that Antenna 1 has achieved a gain of more than 4.5 dBi at all the resonant frequencies with a radiation efficiency ranged between 87%–95%; whereas Antenna 2 has achieved more than 3 dBi gain at lower frequencies while reaching around 7 dBi at higher frequencies with a radiation efficiency ranged between 80%–97%. Finally, two fractal slot antennas were fabricated and tested in the lab to validate the simulation results and to proof the concept of the feasibility of this type of antennas for this application. Experimental results showed a good agreement with simulations.

Miniaturized tri-band bandpass filter design using quarter-wavelength shunted-line stepped-impedance resonators (SLSIRs) with multi-transmission zeros

In this paper, a miniaturized tri-band bandpass filter (BPF) is proposed with a pair of quarter-wavelength shunted-line stepped-impedance resonators (SLSIRs). The resonant characteristics, high design freedom and tuning relationship of multi-dimension parameters of SLSIR are studied and applied to the tri-band design. To obtain the great enhancement of skirt slope, multi-transmission zeros (multi-TZs) are introduced below and above the passbands and the selectivity is improved significantly. The miniaturization of subwavelength and electric/magnetic coupling are introduced and the propagation of electromagnetic wave is manipulated. Moreover, different kinds of generation mechanisms of the produced five TZs are investigated, illustrated and classified. Based on the multi-path transmission of signal, self-coupling effect and self-resonance of feed lines, the multi-TZs are excited and produced. The electric/magnetic coupling and current density distributions are plotted and analyzed. For validation, the designed second-order tri-band BPF centered at 2.35/4.89/7.42 GHz is fabricated and measured. Good agreement between the measured multi-band performances and the simulated frequency responses are observed and can be used to verify the feasibility of design concept.

Ultrathin, polarization-insensitive multi-band absorbers based on graphene metasurface with THz sensing application

This article presents multi-band plasmonic absorbers based on a graphene array at terahertz frequencies. The absorbers are made of a very simple structure including a graphene disk array printed on the top surface of a dielectric spacer backed by a metallic ground plane. Multi-band performance is achieved with more than 90% absorption in the 1–8 THz frequency range by exciting surface plasmon polaritons of graphene. It is shown that the resonance frequencies of the proposed absorber can be tuned by varying the chemical potential between 0.8–1 eV for a triple-band absorber and 0.7–0.9 eV for a quad-band one, while keeping more than 80% absorption. The results obtained by means of full-wave simulation are verified with the results obtained by the analytical circuit model. The proposed absorbers are polarization-insensitive and provide stable absorption performance for both of the TE and TM polarizations. As an application, we designed a refractive index sensor based on the triple-band absorber. The results verify that the absorption bands are sensitive to the variations of the refractive index of the coating layer.

Fractal Antenna Based on Split Ring Resonators with Defected Ground Structure

In this paper presents the design of a circular microstrip fractal antenna (CMFA) loaded with parasitic edge-coupled (EC) split ring resonators (SRR) and defected ground structure (DGS). The basic resonant structure is a circular patch antenna designed at 3.2 GHz on FR4 substrate with relative permittivity 4.4, and 1.6 mm thickness. One iteration of circular patch and slots is employed to form it fractal and so as to attain multiband performance, the antenna is inset fed by a 50? microstrip line. Further the work is extended to demonstrate the effect of placing split ring resonator to particular position of substrate, improves the impedance matching leading to improved bandwidth. In addition L shaped defected ground structures are used to improve the antenna performance. . A comparison between fractal antenna with and without SRRs and DGS is made and the results verifies that a better gain improvement and return loss. The dimensions of the antenna are 45 mm x 45 mm and it can be used for ultra wide band (UWB) applications.

Additive manufactured graphene composite Sierpinski gasket tetrahedral antenna for wideband multi-frequency applications

Here we report a pre-fractal antenna design based on the Sierpinski tetrahedron that has been developed with additive manufacturing. The Sierpinski tetrahedron-based antenna was simulated with finite element method (FEM) modeling and experimentally tested to highlight its potential for wideband communications. The Sierpinski tetrahedron-based antennas were fabricated by two methods, the first involves printing the antenna out of acrylonitrile butadiene styrene (ABS), followed by spin casting a coating of an ABS solution containing graphene flakes produced through electrochemical exfoliation, the second method involves 3D printing the antenna from graphene-impregnated polylactic acid (PLA) filament directly without any coating. Both fabrication methods yield a conductive medium to enable receiving EM signals in the low GHz frequency range with measured input return losses higher than 35 dB at resonance. These antennas incorporate the advantages of 3D printing which allows for rapid prototyping and the development of devices with complex geometries. Due to these manufacturing advantages, self-similar antennas like the Sierpinski tetrahedron can be realized which provide increased gain and multi-band performance.

A Highly Independent Multiband Bandpass Filter Using a Multi-Coupled Line Stub-SIR With Folding Structure

The main problem in designing a multiband bandpass filter (BPF) is making each passband response highly independent, where each bandwidth of multiband BPF can be controlled and adjusted separately. To overcome this problem, this paper proposes a highly independent multiband BPF based on a multicoupled line stub-SIR with a folding structure. The proposed multiband BPF is constructed as a multicoupled line to generate a highly independent inter-passband. Moreover, the multiband performance is produced separately and independently by using three sets of resonators: resonator A1/A2 (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A1</sub> and R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">A2</sub> ), resonator B1/B2 (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B1</sub> and R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B2</sub> ), and resonator C1/C2 (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C1</sub> and R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C2</sub> ). The three passband frequencies can be independently arranged and designed. To miniaturize the multiband BPF, a folding structure is also proposed. As a result, the multiband BPF has a compact size that is reduced by over 61.29 % compared to previous structures. The even-odd excitation model and the equivalent circuit model are used to analyze the multiband BPF structure. This BPF is designed for GPS applications at 1.57 GHz, WCDMA (3G) at 1.8 GHz, WLAN (WiFi) at 2.4 GHz, LTE (4G) at 2.6 GHz, and 5G communication at 3.5 GHz. To evaluate and validate the proposed structure of the multiband BPF, the circuits are fabricated and tested. The simulated and measured results of the multiband BPF show good agreement. In conclusion, the proposed multiband BPF structure has a highly independent inter passband response and a compact size.

Compact and miniaturized metamaterial-based microstrip fractal antenna with reconfigurable qualification

Design procedure of a small dual-band antenna based on composite right/left-handed (CRLH) transmission line is proposed in this article. The conventional microstrip patch is assumed as a primary antenna and then, Minkowski-like fractal geometry is applied. The antenna has a compact size of 20 × 20 mm2, and operates efficiently at 4.4 GHz and 6.1 GHz. The antenna provides high gain of 3.8 dB and 6.2 dB in the two operating bands, respectively. It also has an omnidirectional radiation pattern with low cross-polarization level. The effect of the fractal structure along with CRLH transmission line concepton the miniaturization and multiband performance of the antenna have been studied. The related results show the accuracy of the theoretical studies and good agreement between simulated and measured results, which verify that the antenna is a suitable candidate for wireless communication applications.

Multiband low‐cost fractal antenna based on parasitic split ring resonators

This study presents the design of a low-cost fractal antenna loaded with parasitic edge-coupled (EC) split ring resonators (SRR). Parasitic EC SRR elements result in improved impedance matching leading to improved bandwidth. The basic resonant structure is a circular patch antenna designed at 3.2 GHz on low-cost FR4 substrate with relative permittivity 4.4, and 1.6 mm thickness. A single iteration of circular patch and slots is used to make it fractal and in order to achieve multiband performance, the antenna is inset fed by a 50 Ω microstrip line. A prototype of the proposed antenna is fabricated and tested for results, a comparison between fractal antenna with and without SRRs is made and the results confirm that a better impedance matching is achieved in the later case, also a 3% increase in bandwidth is achieved at 8.5 GHz. A good agreement between simulated and measured results is obtained, an estimated gain of 13.3 dB is provided by the proposed antenna. The overall dimensions of the antenna are 45 mm × 45 mm and it may be used for wireless applications at 3, 5, 6.8, 7.5 and 8.5 GHz with an average bandwidth of 200 MHz.

生物材料紫外红外复合消光性能测试

Aiming at current conditions and shortages of laboratory dynamic experiment of extinction materials, test device and method, which was used to test composite extinction performance of biological materials in ultraviolet and infrared band, was presented based on single optical path. The device mentioned above was designed and made, transmittance of ultraviolet and infrared band, and mass concentration of self-made biological materials smoke in the smoke box were respectively 29.597%, 14.514%, and 0.389 g/m3. Average mass extinction coefficient of biological material in ultraviolet and infrared band were respectively 0.794 75 m2/g, 1.241 59 m2/g based on data processing system. Experimental result shows that the designed device is used to test composite extinction performance of biological materials in ultraviolet and infrared band based on single optical path successfully, and enriches test methods of multiband extinction performance of biological materials further.

Multi-band terahertz metasurface absorber

A terahertz metasurface perfect absorber with multi-band performance is demonstrated. The absorber is composed of a ground plane and four split-ring resonators (SRRs) with different dimensions, separated by a dielectric spacer. The numerical simulation results illustrate that the proposed absorber has four distinct absorption peaks at resonance frequencies of 4.24, 5.66, 7.22, and 8.97 THz, with absorption rates of 96.8%, 99.3%, 97.3%, and 99.9%, respectively. Moreover, the corresponding full width at half-maximum (FWHM) values are about 0.27, 0.35, 0.32, and 0.42 THz, respectively, which are much broader than those of previously reported absorbers. Besides, the calculated magnetic field distributions allow us to understand the absorption mechanism in detail. The effects of incident angle and azimuthal angle on the absorber are also investigated. The results show that the proposed absorber is partially sensitive to the incident angle, which makes this design promising for practical applications in terahertz imagers and detectors.

An FSS Structure Based on Parallel &lt;italic&gt;LC&lt;/italic&gt; Resonators for Multiband Applications

An frequency selective surface (FSS) structure based on parallel LC resonators is proposed to achieve multiband bandpass filtering responses. The parallel LC resonator, implemented by a via-connected metallic line and a parallel-plate capacitor (PPC), serves as the basic element for intentionally constructing FSS unit cell, which exhibits a single-band bandpass filtering response. As a result, the proposed FSS structure can provide a multiband performance by introducing multiple VCMLs and PPCs with different resonance frequencies. Because of the compact resonator resulting from a PPC, the proposed FSSs feature miniaturized unit cell size inherently, for example, the single-band FSS element is as compact as 4.8% of the operating wavelength. Moreover, this kind of FSS structure is also beneficial for independent control of the frequency performance under different polarizations, efficient optimal design of desired resonance frequencies, and easy realization of multiband response with wideband ratio range (e.g., 1.13 to 3.32 for the dual-band FSS). Equivalent circuits of these FSSs are established for explaining the resonating mechanisms and precisely modeling the frequency performances. Finally, prototypes of the dual- and tri-band FSSs are fabricated and measured. The measured results exhibit stable filtering performance under different polarizations and incidence angles (up to 60°).

Miniaturized Single-Feed Multiband Patch Antennas

This communication introduces an approach for designing miniaturized single-feed multiband patch antennas. The size reduction is obtained by loading shorting metalized vias on one edge of the radiating patch, while multiband is obtained by etching inverted multiple U-shapes. A dual-band antenna with a large measured frequency ratio of 2.74 is first discussed. Then triple-band, and further quad-band antennas are, respectively, designed. The antennas have sufficient electrical small size when considering the radius of the minimum enclosing sphere to the radiating patch. A radius value of 0.09λ 0 is obtained for the quad-band antenna with respect to the lowest operating frequency centered at 3.04 GHz. Simulated and measured results of the antennas' reflection coefficient and radiation patterns are provided. Good agreement between the simulation results and measurement results is achieved. The antennas' measured peak gains and efficiencies vary from 1.43 to 3.06 dBi and 42% to 74%, respectively. Compared with other designs, the proposed antennas exhibit multiband performance by using a simple single-feed structure, realize different combinations of highly isolated frequency bands with wide tunability of frequency ratios, and have directional stable radiation patterns that are compact and of electrically small size. Indeed, they have the potential to meet the practical requirements for wireless applications.

Multiband Operation and Performance Enhancement of the PIFA Antenna by Using Particle Swarm Optimization and Overlapping Method

Recently, the demand for wireless devices that support multiband frequency has increased. The integration of such technology in mobile communication system has led to a great demand in developing small size antenna with multiband operation, which is able to operate in the required system. In this paper, a novel type planar inverted F antenna (PIFA) with gridded ground plane structure and overlapping cells is presented. By controlling the overlapping size, we improve the characteristics of the proposed antenna. This antenna is developed to achieve multiband operation with small size and good performance. The particle swarm optimization (PSO) is employed to a PIFA antenna to get rid of the limitations of single band operation by searching the optimal localization and length of linear slots on the ground plane to give triband operation. This PIFA antenna can be integrated to operate for several mobile applications as Bluetooth/WLAN, WIMAX, and 4G (UMTS2100, LTE). The optimized antenna is simulated by both Ansoft HFSS and computer simulation technology microwave studio (CSTMWS) in terms of S-parameters. A good agreement between simulated performances by both software types is achieved. A parametric study is made to analyze the effect of different PIFA parameters on the operating frequency and the reflection coefficient in order to enhance the antenna performances. In these frequency bands, the antenna has nearly omnidirectional radiation pattern.

Compact dual-band antenna for smart wristband application

A compact dual-band antenna for smart wristbands was proposed. The proposed antenna consisted of a shorted hook-shaped radiating element and a rectangular ground plane. The antenna satisfied the −10 dB reflection coefficient bandwidth requirement in WLAN (2.45/5.8 GHz) bands both in free space and on the arm phantom. The gain of the proposed antenna was greater than 2 dBi at the center frequency of each operating band. To apply the proposed antenna to a practical smart wristband, a battery was considered in this letter. This antenna attained a multiband performance and size miniaturization compared with an existing antenna used for a commercially available smart wristband. In addition, the specific absorption rate (SAR) of the proposed antenna was analyzed. The experimental and simulated results of the proposed antenna were in good agreement. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1462–1466, 2016