Multiband Function Research Articles

Design and development of a compact, wide-angle metamaterial electromagnetic energy harvester with multiband functionality and polarization-insensitive features

This article presents a compact, wide-angle, polarization-insensitive metamaterial harvester that can efficiently harvest electromagnetic (EM) energy in the S, C, X, and Ku bands. The harvester's unit cell consists of a split ring resonator, two strip lines, and two split strip lines, giving it a total size of (10 × 10) mm2. Each split gap is filled with a 50 Ω resistive load. The input impedance of the harvester is precisely designed to match that of free space, allowing for efficient absorption of EM power and appropriate redirection towards the resistive loads. The harvester's performance is also evaluated for various polarization and incident angles, considering the Transverse Electric and Transverse Magnetic modes. The simulation results reveal that the proposed harvester exhibits a notably greater conversion efficiency of around > 95%. The simulation outcomes were carefully validated through experimental tests conducted in an anechoic chamber using a 3 × 3 cell array of the proposed design. This ensured the accuracy and reliability of the results. The strong correlation between the experimental data and the full-wave simulations strongly supports the effectiveness of the proposed harvester. Therefore, the demonstrated efficiency and compact size make it a perfect fit for energy harvesting systems in wireless sensor networks.

Thin film resonant metasurface absorbers using patch-based arrays on liquid crystal polymer substrates for centimeter-wave applications

This paper reports the design and development of thin-film resonant absorbers for narrowband and multiband operation in the frequency regions centered at 10 GHz. The structure of the resonant metasurface absorber (RMA) is based on a liquid crystal polymer (LCP) thin-film spacer with a copper patch array on the front surface and un-patterned copper film on the back surface of the LCP film. The design and simulation works were carried out using full-wave analysis of the RMA characteristics. The copper-based periodic patch array acts as a metasurface. The perfect RMA for a given LCP film thickness can be obtained through impedance optimization by adjustment of the dimensions of the lattice periods. The electric and magnetic field distributions were studied. The resonant film absorber based on a 100 μm thick LCP film has an electrical thickness of λ/300 at 10 GHz. The experimental work was conducted using a narrowband RMA prototype consisting of 11×11 cells. The measured result of the resonant absorption is at 10.1 GHz, which is in close agreement with the design frequency of 10 GHz. For multiband functionality, double- and quad-band film resonant absorbers have been designed based on a coplanar supercell utilizing the superposition of the resonance effect. The LCP film-based absorbers have the potential to be used in EM shielding and sensing applications in centimeter-wave applications.

Innovative flexible and compact patch antenna for multiband terahertz applications

Terahertz antennas have garnered significant attention for use in the fields of telecommunications and medical applications. One of the major issues with THz antennas is the integration of flexibility with multiband characteristics. This article focuses on designing and constructing a new, compact, and flexible dual-band THz antenna using different slots for terahertz applications. The essence of the antenna design is rooted in a careful strategy for positioning slots, both on the ground plane and within the patch. The rising need for flexible electronics is the primary motivation behind the investigation of this flexible, multiband antenna. The examined antenna is supported by a flexible polyimide substrate with small dimensions of 1.5 × 1 × 0.15 mm3. Several adjustments are made to the radiating patch to enable multiband functionality, resulting in operation at 123 GHz and 180.4 GHz. The corresponding return losses are -35.03 dB and -38.71 dB, while the bandwidths for the two frequency bands are 3.3 % and 8.86 %, respectively. For all working bands, the VSWR of the given antenna is lower than 2, with a gain of 4.12 dB and 5.05 dB at the resonating frequency, as well as a radiation efficiency of 81.6 % and 89.3 % inside the resonating bands. Moreover, a parametric investigation was additionally carried out to ascertain the ideal dimensions of the suggested antenna. As the antenna is constructed using a flexible substrate, this article also delves into the analysis of antenna bending in both the x- and y-axes. The suggested antenna can be applied in modern handheld fifth-generation (5 G) and terahertz medical imaging applications, such as breast cancer detection.

High-Order Wideband Band-Pass Miniaturized Frequency-Selective Surface with Enhanced Equivalent Inductance

To extend the wideband performance of high-order band-pass filtering applications, optimized designs with knitted structures based on traditional miniaturized frequency-selective surfaces (FSSs) are proposed in this paper. The presented miniaturized FSSs consist of multiple metallic capacitive layers, knitted inductive layers, and substrates. In contrast to the conventional high-order miniaturized FSSs composed of metallic frames, patches, and substrates, the optimized miniaturized FSSs replace the original metallic wire frames with knitted structures. Both proposed modified miniaturized FSSs achieve a flat pass-band from 5.5 GHz to 10.3 GHz with a 3 dB bandwidth of 71.6% under vertical incidence. The unit cells have dimensions of 0.16 λ0 × 0.16 λ0 × 0.284 λ0 and 0.16 λ0 × 0.16 λ0 × 0.279 λ0, respectively, where λ0 is the free space wavelength at 7.9 GHz, which is the center frequency of the operating band. Numerical simulations and measurements demonstrate that the proposed modified miniaturized FSSs exhibit excellent wideband performance with clean transition bands around the pass-band during oblique incidence and are suitable for applications such as radomes, where wideband filtering is essential for covering multi-band functions of radar or communication instruments.

A Spiral Flower Shape Wearable Antenna for Smart Internet of Things Applications

In this paper a small patch antenna is proposed for smart wearable internet of things applications. The antenna is proposed to be the main piece of a In this paper a small patch antenna is proposed for smart wearable internet of things (IoT) applications. The antenna is proposed to be the main piece of a necklace. It works for the 2.4 - 2.5 GHz industrial, scientific and medical (ISM) band. It also works for other bands such as 5.564 - 5.65 GHz, 6.79 - 6.973 GHz, 7.7614 - 7.883 GHz and 8.5 - 8.65 GHz with a small size of 40 × 50 mm2 and robust performance. The proposed design showed to have many appealing features such as small size, conformity and multi-band functionality and, thus, it could be a good candidate for IoT wearables.

Symmetrical L-slots Reconfigurable Triple band Antenna for Mutiband Applications

This paper introduces a novel compact reconfigurable antenna that utilizes monopole technology and tunable frequencies through switch control. The antenna is fed by a coplanar waveguide (CPW) and features a unique patch design with two L-shaped slots and integrated switches. This inventive design enables remarkable reconfigurability, allowing the antenna to operate within the frequency ranges of [3.8-3.93 GHz], [5.05-5.3 GHz], and [7-7.5 GHz]. These frequency ranges are strategically chosen to align with specific application requirements. The antenna also boasts an almost omnidirectional radiation pattern. The experimental outcomes highlight the efficacy of the proposed antenna, which occupies a compact footprint of 34x35.4 mm², making it particularly well-suited for applications requiring multiband functionality.
 Keywords: CPW-fed, multiband antenna, reconfigurable.

Miniaturized frequency-reconfigurable single-feed multi-band antenna with bandwidth enhancement for wireless applications

We propose a miniaturized frequency-reconfigurable multiband antenna with bandwidth enhancement. The main radiating patch is shorted from one edge to reduce the antenna footprint. An inverted U-shape microstrip line is integrated onto the antenna structure to excite more resonant frequencies. Indeed, by shorting the U-shape's arms, seven frequency bands can be created and controlled. The activation of the two p-i-n diodes is ensured by employing a simple symmetrical DC bias network. Furthermore, by adjusting the arms’ lengths, two resonances are combined to enhance the working bandwidth. Measurements reveal that the antenna resonates around the operating frequencies of 2.91 GHz, 3.55 GHz, 3.69 GHz, 3.83 GHz, 4.14 GHz, 4.18, and 4.24 GHz. The antenna exhibits stable patterns, with a measured peak gain and efficiency of 5.5 dBi and 86%, respectively. The antenna is compact; thus, it is recommended in wireless systems requiring multiband function with stable patterns and a reduced area.

Design of a multi-band Raman tweezers objective for in situ studies of deep-sea microorganisms.

The investigation of deep-sea microorganisms holds immense significance and value in advancing the fields of life sciences, biotechnology, and environmental conservation. However, the current lack of specialized underwater objectives specifically designed for in situ studies of deep-sea microorganisms hampers progress in this area. To address this limitation, we present the design of a multi-band Raman tweezer objective tailored for deep-sea environments. The objective is integrated into a high-pressure chamber capable of withstanding depths up to 1.5 km, enabling in situ microscopic imaging, optical tweezer capture, and Raman detection of deep-sea microorganisms. Through meticulous structural optimization, meticulous material selection, and thorough mechanical analysis of the underwater optical window, the objective exhibits remarkable attributes such as multi-band functionality, extended working distance, and high numerical aperture. Our design yields image quality near the diffraction limit, successfully achieving flat-field and apochromatic performance in each respective wavelength bands. Moreover, the tolerance analysis demonstrates that the full-field root mean square (RMS) wave aberration approaches λ/14, effectively meeting the demands of manufacturing and practical applications. This objective lens constitutes a vital tool for the in situ exploration of deep-sea microorganisms.

A Conformal Tri-Band Antenna for Flexible Devices and Body-Centric Wireless Communications.

A conformal tri-band antenna tailored for flexible devices and body-centric wireless communications operating at the key frequency bands is proposed. The antenna is printed on a thin Rogers RT 5880 substrate, merely 0.254 mm thick, with an overall geometrical dimension of 15 × 20 × 0.254 mm3. This inventive design features a truncated corner monopole accompanied by branched stubs fed by a coplanar waveguide. The stubs, varying in length, serve as quarter-wavelength monopoles, facilitating multi-band functionality at 2.45, 3.5, and 5.8 GHz. Given the antenna's intended applications in flexible devices and body-centric networks, the conformability of the proposed design is investigated. Furthermore, an in-depth analysis of the Specific Absorption Rate (SAR) is conducted using a four-layered human tissue model. Notably, the SAR values for the proposed geometry at 2.45, 3.5, and 5.8 GHz stand at 1.48, 1.26, and 1.1 W/kg for 1 g of tissue, and 1.52, 1.41, and 0.62 W/kg for 10 g of tissue, respectively. Remarkably, these values comfortably adhere to both FCC and European Union standards, as they remain substantially beneath the threshold values of 1.6 W/kg and 2 W/kg for 1 g and 10 g tissues, respectively. The radiation characteristics and performance of the antenna in flat and different bending configurations validate the suitability of the antenna for flexible devices and body-centric wireless communications.

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.

Triple band single layer microwave absorber based on closed loop resonator structures with high stability under oblique incidence

A novel triple-band microwave absorber design which is independent of polarization with extremely high stability under oblique incidence is described in this paper. The proposed absorber structure's unit cell architecture contains three closed loop microstrip resonator components with rotational symmetry. The suggested design engenders three reflection nulls at 2.4 GHz (WiMAX), 5.5 GHz (WLAN) and 7.51 GHz (downlink satellite communication frequencies in the X-band). These gives rise to triple absorption peaks with near-unity (almost 100 %) absorptivity at the mentioned frequencies. The absorber design is fully immune to polarization for both TE and TM modes of propagation. Furthermore, the structure offers very high stability under oblique incidence for both TE and TM modes where beyond 90 % absorptivity is obtained up to 520 incident angles and beyond 80 % absorptivity is achieved up to 750 incident angles. The unit cell size is 0.12λ0 × 0.12λ0, where λ0 is the wavelength corresponding to the lowest absorption frequency. The advantage of the proposed structure over other reported absorbers is assessed by its superiority in terms of multiband functionality, full polarization insensitivity, stability under oblique incidence and compactness. A prototype of the proposed absorber was fabricated and the measured results agree closely with the simulation results.

MIMO ANTENNA ARRAY WITH DIRECTIONAL DIAGRAM SPREAD FOR 5G SMARTPHONES

Multiple-input/multiple-output technology can exponentially increase the data transfer rate and spectrum efficiency without any need of increasing the transmission power and bandwidth. It is the most promising technology to be used in the upcoming 5G communications. To be more accurate, the fourth generation smartphones are set to use the long-term evolution MIMO technology and operate in multi-bands. Therefore, MIMO antennas are to use in future portable devices such as mobile handsets and tablets. A new multiple-input/multiple-output (MIMO) antenna design is introduced for future smartphones. The proposed design contains four pairs of double-fed circular-ring resonators located at different edges of the smartphone printed circuit board (PCB) with an FR-4 substrate and a dimension of 75 × 150 mm2. The antenna elements are fed by 50-Ohm microstriplines and provide polarisation and radiation pattern diversity function due to the orthogonal placement of their feed lines. By inserting a rectangular slot under each microstrip feed-line, the mutual coupling characteristic of the antenna ports is reduced. A good frequency bandwidth (S11 ≤ − 10 dB) of 3.3–3.9 GHz has been obtained for the smartphone antenna array. Nevertheless, for S11 ≤ −6 dB, this value is 3.1–4.3 GHz. More than 3 dB realised gain and 80% total efficiency are achieved for the single element radiator. The design provides not only sufficient radiation coverage supporting different sides of the mainboard but also the polarisation diversity. In addition, sufficient properties are obtained in the vicinity of human-hand/human-head. The proposed MIMO antenna design is also capable to generate dual- or multi-band function. Moreover, a new and compact phased array millimeter-wave (mm-wave) antenna design with end-fire radiation beams is introduced which can be easily integrated into smartphones.

A quad-band miniaturised compact Π-shaped CSRR-based metamaterial-inspired DG resonator antenna

ABSTRACT Proposed in this paper is a new configuration for a quad-band antenna based on using a metamaterial-inspired defected ground structure. The presented structure is introduced as a new modified metamaterial Complementary Split Ring Resonator (CSRR) with a compact electrical size. The new modified CSRR has been employed in Composite Right/Left-Handed (CRLH) transmission line configuration for ultra-size reduction. Validation for the particle small size is introduced and the detailed analysis for the NRI characteristics has been discussed by extracting the cell constitutive parameters. Hence, a multi-band antenna is designed based on using only one cell of the proposed NRI-TL. Subsequently, a small multi-band antenna is presented for different multi-band functionalities and different radiation properties. The antenna displays quad-resonances at 1.78 GHz, with the typical omnidirectional radiation pattern, 3.28 GHz, 4 GHz, and 4.3 GHz, with the directive broadside radiation properties. The proposed antenna footprint is 10 × 10 cm2, which exhibits a size reduction of up to 80% in comparison with a rectangular patch antenna operating at the lowest frequency band.

Two‐port ring shaped MIMO antenna with quad‐band

This article presents a quad-band multiple-input multiple-output antenna with two-element. Its radiator, composed of four rings, realizes multi-band function, and isolation between the two antenna elements is improved by using the cross-shaped defective ground structure and the goblet shaped stub at the center of the back ground plane. The total size of the design is only 25 mm × 32 mm, but it can obtain good performance in the four frequency bands (4.6-5.0 GHz, 6.82-7.83 GHz, 10.3-10.8 GHz, and 14.1-16.96 GHz), which can be concluded from the simulation and measurement results on the desired bands: (a) the input reflection coefficient (S11) less than −17 dB, (b) the isolation (S21) better than −15 dB, (c) the envelope correlation coefficient below 0.04 and the peak gain greater than 1.23 dBi. The proposed antenna is suitable for wireless communication of small unmanned aerial vehicle operating in the beyond-line-of-sight range. The first of the four bands (4.6-5.0 GHz) is used for 5G cellular network communication and the other three bands can be applied for downlink of X-band (7.25-7.75 GHz) satellite communication, X-band (8-12 GHz) and Ku-band (12-18 GHz) satellite communication, respectively.

Fractal microstrip patch antennas for dual-band and triple-band wireless applications

Abstract In this paper, the design and development of dual-band and triple-band fractal microstrip patch antennas with enhanced gain are presented. The structure is based on the Sierpinski carpet fractal, where the multiband functionality is achieved by applying the fractal iteration technique. The fractal antenna characteristics along with analysis of the reflection coefficient and the radiation patterns for each iteration are presented. The dual-band fractal microstrip patch antenna (DBFMPA) is operating at 4.9 and 5.3 GHz and the triple-band fractal microstrip patch antenna (TBFMPA) is operating at 2.4, 5.3, and 5.9 GHz. The defected ground structure (DGS) and a reflector plane is utilized for enhancing the gain of the antenna. Design and optimization of the DBFMPA and TBFMPA are done using the Computer Simulation Technology (CST) Microwave Studio Suite. The presented DBFMPA and TBFMPA are suitable for industrial, scientific, and medical (ISM) wireless applications.

Frequency Reconfigurable Compact Antenna for Multiband Wireless Communication Application

This pioneering work suggests a reconfigurable multiband frequency antenna for applications in wireless networking The miniaturization and multi-band function of the mounted antenna is done by inserting a rectangular hole, and the reconfiguration of the frequency is achieved by utilizing two PIN diode switches. The ON and OFF state of the PIN diode determines the surface current distribution of the radiating patch resulting in the multiband resonance and reconfiguration of the proposed device. Application and analysis dependent on parameter of the antenna such as lack of return loss, VSWR, gain, and radiation pattern. The developed antenna is used for the intended application of wireless communication. Simulation is performed using Ansys HFSS.

Social Spider Optimized Design Configuration of Multiband Reconfigurable Antenna for 5G Applications

Reconfigurable antennas receive more attention for many application due to their special characteristics like polarization diversity, multi band function and steerable diversity. However, reconfigurable antennas are capable of providing single and multiple reconfigurability. Nowadays, there is an increasing demand for multi-service radios for various spectrum standards. Many exiting works have been discussed about the enhancement of multi-band operation in reconfigurable antenna design. Most of them exhibit huge design complexity with high-cost consumption during the design optimization process. Thus, the proposed work uses Social Spider Algorithm for optimizing the design configuration of the reconfigurable antenna. Similarly, the band pass filter used at the feed line of the proposed antenna structure to easily achieve multi-band operation. The proposed design developed in ANSYS HFSS implementation platform and result analysis is performed in terms of bandwidth, VSWR, return loss, radiation pattern, gain, and directivity. The proposed reconfigurable antenna structure achieves 26.75 GHz bandwidth with 9.9 dB total gain and 8.8 dB directivity when comparing with existing works. Thus, the proposed antenna design suitable for 5G application applications by providing multi-band operation like WLAN, UWB, and Wi-Fi.

A CIRCULAR SHAPED MULTIBAND SEMI-COMPOUND RECONFIGURABLE ANTENNA WITH FREQUENCY AND PATTERN DIVERSITY FOR WIRELESS APPLICATIONS

Context. The problem of achieving multi band functionality and two or more reconfiguration capabilities by using a single antenna for diversified Wireless communication applications. The objective of the work is to model a prototype that combines the above functionalities.Objective. The major goal of the work is to produce a very efficient and compact antenna satisfying all the requirements for wireless applications combining semi compound reconfigurability and multi-band functionality for Wireless communication applications.Method. This paper reports design and investigations on a planar multi-band frequency– and pattern-circular shaped reconfigurable antenna by the use of PIN diodes. It consists of symmetrically placed, seven PIN diodes on each half of the circle cutting the longitudinal axis. By changing the controlled activation of the slots placed on a circular disk which is fed by Coplanar Waveguide feed, the required reconfiguration mechanism is achieved. The antenna can be operated in 8 different modes by the use of 15 PIN diodes. A beam shape pattern reconfigurability is achieved by operating the antenna in all the modes. The basic antenna is a circular disk without slots and is designed to operate at 2.4GHz. Frequency reconfigurability is achieved by changing the overall electrical length of the slot by activating the switches in appropriate positions in different operating modes. Pattern reconfigurability is achieved by maintaining the same overall electrical length in each operating mode but changing the switch positions orient in a particular direction in each half of the circle. Results. The model has been developed and investigative simulations were carried out using Ansys HFSS.Conclusions. The proposed antenna resonates at three frequencies 2.2GHz, 4.98GHz and 5.72GHz when operated in pattern reconfigurability mode. A simultaneous frequency reconfigurability along with pattern is achieved with more (at 6.2GHz, 8.2GHz and 9GHz) or less number of new frequency bands (at 7.1GHz) than pattern reconfiguration mode. The area of the antenna occupied is 40 X 60 mm2. An acceptable gain is obtained in all of the operating modes. The prototype of the designed antenna has been developed and the simulation results have been verified experimentally.

Size Miniaturized Coaxial Probe Fed Antenna for Multiband Applications

A novel coaxial cable-fed antenna with a combination of L-shaped elements is proposed for multiband applications. The obtained resonances at different frequency bands are realized by adding L-shaped strips with different lengths to the antenna geometry. The antenna is printed on a low-priced FR-4 substrate with overall size of 14×14×1.6 mm3. Experimental results indicate the coverage of 1.32, 1.80, 2.34, 3.30, 3.66, 4.26, 5.28, 7.68, 8.1, 9.72 and 10.38 GHz, compatible with L-band, WLAN, WiMAX, C-band, ITU 8 GHz, and X-band. Suitable radiation properties, multiband functionality, desirable gain values and agreement of simulated and measured results confirm the suitability of the proposed structure for multiband communication applications.

Radio Frequency Energy Harvesting System Making Use of 180° Hybrid Couplers and Multiple Antennas to Improve the DC Output Voltage

This paper introduces the implementation and experimental results obtained with a radio frequency energy harvester system. A radio frequency combining power circuit based on the characteristic of the 180o hybrid coupler to combine energy is proposed here to be used in radio frequency energy harvesting schemes. Through experimental validations, this proposal demonstrates to offer important advantages compared with other radio frequency energy harvesters found in the literature, including a harvesting voltage enhanced, ease implementation, since is not require any modification in the hybrid coupler,and multi-band function using wideband antennas. The system is designed to harvest energy in the GSM, UMTS, and Wi-Fi frequency bands. The validation of the proposed system using four receiving antennas showed a direct current harvested voltage of 301 mV at 2.5 GHz for an input power of -7 dBm. In addition,the terms of accumulated voltage gain and cumulative efficiency are introduced to evaluate the performance of the proposed combining circuit in radio frequency harvesting schemes.