Dual-band Design Research Articles

Design, Development and Analysis of High-Frequency Dual-Band 4 × 1 Monopole Array Antenna

Design, Development and Analysis of High-Frequency Dual-Band 4 × 1 Monopole Array Antenna

Design of Cross-Coupled Bandpass Filters with Flexible Coupling via Half-Mode Substrate-Integrated Waveguide

In this article, a simple approach for achievement of flexible coupling is presented based on the half-mode substrate-integrated waveguide (HMSIW). Since both electric and magnetic fields vary along the magnetic wall of the HMSIW, there exists mixed coupling between two adjacent HMSIWs. In this context, only by adjusting the width of the coupling slot at specific regions, both coupling property and strength can be conveniently controlled. Besides, as the coupling slot possesses the merits of simple structure and high flexibility, it is also expected to achieve desired couplings between multimode resonators. For demonstration, three cross-coupled bandpass filters (BPFs) with different kinds of frequency responses are constructed based on the typical cascaded trisection coupling topology by mixing one SIW and two HMSIWs, including two single-band and one dual-band designs. All measured results are highly consistent with the simulated ones, validating that the HMSIW not only has the inherent advantage of smaller size than the conventional SIW counterparts but also possesses unique feature in providing flexible coupling without extra circuit.

Reconfigurable and Modular Wireless Charger Based on Dual-Band Design

Reconfigurable and Modular Wireless Charger Based on Dual-Band Design

An optically transparent dual-band frequency selective surface for polarization independent RF shielding

This article reports on a compact dual band, Frequency Selective Surface (FSS) based spatial filter for Wi-Fi and WLAN shielding applications on a transparent glass surface with optical transparency of 70%. The unit cell comprises an outer square loop resonator with a disconnected and concentric annular ring resonator. To introduce frequency tuning and compactness T shape stubs are strategically loaded on these resonators and it is ensured that the mutual coupling remains minimal. The outer square resonator suppresses the 2.4 GHz band, and the inner circular ring resonator stops the 5.4 GHz band. The unit element is four-fold symmetric thus it offers complete polarization independence. A detailed parametric and electromagnetic field analysis has been conducted to elucidate the significance of different sections of the unit element. An equivalent lumped circuit model is also derived for the proposed unit element to better explain the underlying working mechanism. A finite prototype of 15 × 11 elements is fabricated on a soda lime float glass by using ordinary adhesive copper foils with a standard chemical etching process. Polarization independence and angular stability up to 45° are measured and compared with the simulated responses. The FSS shield offers frequency suppression up to 45 dB and 43 dB for 2.4 GHz and 5.4 GHz bands respectively. With high optical transparency, the design allows maximum light through it and causes no extra burden on energy consumption for indoor applications. The compact dual band design and the possibility of direct application on host surfaces like glass windows and doors make this design an excellent candidate for data security and privacy applications in secure installations with an esthetically pleasing outlook.

Scattering suppression with dual-band single-layer mantle cloak for cylindrical metasurface

This paper investigates scattering suppression with a dual-band and single-layer mantle cloak by using the proper structure for cylindrical objects. The mantle cloak’s surface impedance is calculated according to the Mie Theory to obtain considerable scattering reduction at all angles of the cylinder. The analytical formulation assists in determining the proper unit cell dimensions to obtain design parameters. Firstly, the patch array geometry is applied on the mantle cloak for a single operating frequency with different unit cell numbers. Then a new design of a dual-band single-layer mantle cloak is made with the findings obtained. Simulations are conducted for both mantle cloaks, and bi-static Radar Cross-Section (RCS) analyses are carried out, generating simulated outcomes for cylinders that are both cloaked and uncloaked. The comparison of the scattering suppression between them reveals that the cloaked cylinders demonstrate a significant reduction in scattering. These achievements apply to both single-band and dual-band designs. A novel dual-band single-layer mantle cloak is presented with a new design method and scattering suppression is observed in more than one operating frequency. As evidence of the subject, a dual-band cloaked cylinder is designed with a total radius of 0.13λ0, a total length of 2.59λ0, and a thin dielectric layer’s thickness of 0.0127λ0(λ0i s the wavelength at design frequency f0=3 GHz). This dual-band cloaked cylinder has 7.6 dB absolute RCS reduction at f=2.05 GHz and 5.6 dB absolute RCS reduction at f=3.75 GHz. An efficient scattering suppression is achieved for these two different frequencies in all directions. The considerable degree of invisibility observed in this study opens up possibilities for future investigations in various fields, including radar applications, sensing applications, and antenna isolation for the purpose of blockage reduction.

Design and Optimization of Metamaterial-Based Dual-Band 28/38 GHz 5G MIMO Antenna With Modified Ground for Isolation and Bandwidth Improvement

This letter presents a high-isolation dual-band multiple-input multiple-output (MIMO) antenna based on the ground plane modification and optimized metamaterials (MMs) for 5G millimeter-wave applications. The antenna is a monopole providing a dual-band response at 5G 28/38 bands with a small physical size (4.8 × 2.9 × 0.762 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , excluding the feeding line). The MIMO consists of two symmetric radiating elements arranged adjacently with the mutual coupling of −19 dB and −17 dB at 28 and 38 GHz, respectively. Reducing the ground length enhances the isolation to 34.6 dB at 28 GHz, whereas embedding the MMs diminishes the coupling to −47 dB at 38 GHz. The trust-region gradient-based search algorithm is employed to optimize the MM structure dimensions and to enhance the isolation at 38 GHz. The MMs also contribute to the enhancement of bandwidth from 1.6 GHz to 1.7 GHz at 28 GHz (27.1–28.8 GHz) and from 2.75 GHz to 3.7 GHz at 38 GHz (35.2–38.9 GHz). The proposed system is capable of covering both 28/38 bands with low profile structure, high isolation, low envelope correlation coefficient (ECC) ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lt 0.2 \cdot 10^{-4}$</tex-math></inline-formula> ), and high diversity gain (DG) (>9.99 dB). These properties demonstrate the system applicability for 5G millimeter-wave cellular communications.

Input-Reflectionless Quasi-Elliptic-Type Single- and Dual-Band Bandpass Filters Based on Passive Channelized Principles

An approach to design quasi-elliptic-type planar filters with single- and dual-band bandpass transfer functions and input-absorptive capabilities is presented. Two-branch channelized passive circuit configurations are exploited for this purpose, in which the low-order reflective-type filtering profile of their branches is converted into the desired sharp-rejection input-reflectionless filtering action in the overall circuit. This is achieved by means of fully-destructive and frequency-selective transversal signal-interference effects at the total input and output accesses of the channelized filter, respectively. The theoretical operational principles of the proposed concept of single/dual-passband input-reflectionless two-branch channelized filter are detailed, along with design considerations for their RF transmission-line-based implementation. Besides, its generalization to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {N}$ </tex-math></inline-formula> -channel architectures is also analyzed. Furthermore, as the fundamental elements of the devised channelized filtering philosophy to increase selectivity, alternative solutions to realize their output phase-delay sections for a more-flexible control of the transmission zeros in the overall transfer function are discussed. For experimental-demonstration purposes, two microstrip proof-of-concept prototypes are developed and measured. They consist of 3-GHz single-band and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.58/3.43$ </tex-math></inline-formula> -GHz dual-band designs with input-quasi-reflectionless spectral ratio above 2.5:1 and 3:1, respectively.

Solar X-ray and EUV imager on board the FY-3E satellite

The solar X-ray and Extreme Ultraviolet Imager (X-EUVI), developed by the Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences (CIOMP), is the first space-based solar X-ray and Extreme ultraviolet (EUV) imager of China loaded on the Fengyun-3E (FY-3E) satellite supported by the China Meteorological Administration (CMA) for solar observation. Since started work on July 11, 2021, X-EUVI has obtained many solar images. The instrument employs an innovative dual-band design to monitor a much larger temperature range on the Sun, which covers 0.6–8.0 nm in the X-ray region with six channels and 19.5 nm in the EUV region. X-EUVI has a field of view of 42′, an angular resolution of 2.5″ per pixel in the EUV band and an angular resolution of 4.1″ per pixel in the X-ray band. The instrument also includes an X-ray and EUV irradiance sensor (X-EUVS) with the same bands as its imaging optics, which measures the solar irradiance and regularly calibrates the solar images. The radiometric calibration of X-EUVS on the ground has been completed, with a calibration accuracy of 12%. X-EUVI is loaded on the FY-3E satellite and rotates relative to the Sun at a uniform rate. Flat-field calibration is conducted by utilizing successive rotation solar images. The agreement between preliminarily processed X-EUVI images and SDO/AIA and Hinode/XRT images indicates that X-EUVI and the data processing algorithm operate properly and that the data from X-EUVI can be applied to the space weather forecast system of CMA and scientific investigations on solar activity.

Design of Dual-Band, 4-Ports MIMO Antenna-Diplexer Based on Quarter-Mode Substrate Integrated Waveguide

Here, a compact, dual band, 4-elements multi-input and multi-output (MIMO) antenna diplexer is designed to use in wireless local area network (WLAN) applications. The antenna is accomplished in a planar profile by employing Substrate Integrated Waveguide (SIW) technology. To reduce the size of a single element by 75%, a quarter-mode substrate integrated waveguide (QMSIW) technology is introduced. The QMSIW is realized by bisecting the full-mode SIW along the two magnetic walls and considering the quarter-mode for the operation. Initially, two-QMSIW cavities of distinct dimensions are designed to operate in two frequency bands, 5.2 GHz and 5.8 GHz, respectively. Later, two more radiating elements operating at the same frequencies are integrated with a 2-elements antenna. For better polarization decoupling, the identical elements are placed perpendicular to each other, and a parasitic metallic strip loaded with shorting vias is placed between two identical frequency antenna elements; hence, the port isolation is improved up to −25 dB. The antenna covers a bandwidth of 1.8% in the lower frequency band while 2.2% in the upper frequency band. The antenna prototype is fabricated, and its results are verified with experimental data. It is observed that the measured results are closely following the simulated results.

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.

Compact dual-band design and analysis of half-circular U-shape MIMO radiator for wireless applications

Compact dual-band design and analysis of half-circular U-shape MIMO radiator for wireless applications

Performance Analysis of Wearable Dual-Band Patch Antenna Based on EBG and SRR Surfaces.

This paper presents the performance comparison of a dual-band conventional antenna with a split-ring resonator (SRR)- and electromagnetic bandgap (EBG)-based dual-band design operating at 2.4 GHz and 5.4 GHz. The compactness and dual-frequency operation in the legacy Wi-Fi range of this design make it highly favorable for wearable sensor network-based Internet of Things (IoT) applications. Considering the current need for wearable antennas, wash cotton (with a relative permittivity of 1.51) is used as a substrate material for both conventional and metamaterial-based antennas. The radiation characteristics of the conventional antenna are compared with the EBG and SRR ground planes-based antennas in terms of return loss, gain, and efficiency. It is found that the SRR-based antenna is more efficient in terms of gain and surface wave suppression as well as more compact in comparison with its two counterparts. The compared results are found to be based on two distinct frequency ranges, namely, 2.4 GHz and 5.4 GHz. The suggested SRR-based antenna exhibits improved performance at 5.4 GHz, with gains of 7.39 dbi, bandwidths of 374 MHz, total efficiencies of 64.7%, and HPBWs of 43.2 degrees. The measurements made in bent condition are 6.22 db, 313 MHz, 52.45%, and 22.3 degrees, respectively. The three considered antennas (conventional, EBG-based, and SRR-based) are designed with a compact size to be well-suited for biomedical sensors, and specific absorption rate (SAR) analysis is performed to ensure user safety. In addition, the performance of the proposed antenna under bending conditions is also considered to present a realistic approach for a practical antenna design.

Dual-Band Design Techniques for Microwave Passive Circuits: A Review and Applications

The introduction of new technology in the wireless communication industry increases the number of frequency bands in the communication environment. Therefore, a communication system capable of functioning over several frequency bands, known as a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">multiband communication system</i> , is required. In addition, multiband communication systems support technology upgrades by smoothly bridging the migration from the existing technology to a newer technology. A multiband communication system can be developed with the help of two approaches. The first approach is a multiband communication system that contains multiple microwave circuits, with each circuit optimized for a single band; for example, a dual-band communication system has two low-pass filters and two power amplifiers. But this approach increases not only the size but also the cost of the system. In the second approach, rather than using a separate power amplifier and filter for each frequency band, a single power amplifier, filter, and other components are used that can support more than one frequency band. These circuits are known as <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">multiband microwave circuits</i> . Multiband circuits not only minimize size but also reduce the cost of designing the multiband communication system.

The Design of Dual Band Stacked Metasurfaces Using Integral Equations

An integral equation-based approach for the design of dual band stacked metasurfaces which are invariant in one-dimension is presented. The stacked metasurface will generate collimated beams at desired angles in each band upon reflection. The conductor-backed stacked metasurface consists of two metasurfaces (a patterned metallic cladding supported by a dielectric spacer) stacked one upon the other. The stacked metasurface is designed in three phases. First the patterned metallic cladding of each metasurface is homogenized and modeled as an inhomogeneous impedance sheet. An Electric Field Integral Equation (EFIE) is written to model the mutual coupling between the homogenized elements within each metasurface, and from metasurface to metasurface. The EFIE is transformed into matrix equations by the method of moments. The nonlinear matrix equations are solved at both bands iteratively resulting in dual band complex-valued impedance sheets. In the second phase, optimization is applied to transform these complex-valued impedance sheets into purely reactive sheets suitable for printed circuit board fabrication by introducing surface waves. In the third phase, the metallic claddings of each metasurface are patterned for full-wave simulation of the dual band stacked metasurface. Using this approach, two dual band stacked metasurfaces are designed

Transparent dual-band ultraviolet photodetector based on graphene/p-GaN/AlGaN heterojunction.

Versatile applications have driven a desire for dual-band detection that enables seeing objects in multiple wavebands through a single photodetector. In this paper, a concept of using graphene/p-GaN Schottky heterojunction on top of a regular AlGaN-based p-i-n mesa photodiode is reported for achieving solar-/visible-blind dual-band (275 nm and 365 nm) ultraviolet photodetector with high performance. The highly transparent graphene in the front side and the polished sapphire substrate at the back side allows both top illumination and back illumination for the dual band detection. A system limit dark current of 1×10-9 A/cm2 at a negative bias voltage up to -10 V has been achieved, while the maximum detectivity obtained from the detection wavebands of interests at 275 nm and 365 nm are ∼ 9.0 ×1012 cm·Hz1/2/W at -7.5 V and ∼8.0 × 1011 cm·Hz1/2/W at +10 V, respectively. Interestingly, this new type of photodetector is dual-functional, capable of working as either photodiode or photoconductor, when switched by simply adjusting the regimes of bias voltage applied on the devices. By selecting proper bias, the device operation mode would switch between a high-speed photodiode and a high-gain photoconductor. The device exhibits a minimum rise time of ∼210 µs when working as a photodiode and a maximum responsivity of 300 A/W at 6 μW/cm2 when working as a photoconductor. This dual band and multi-functional design would greatly extend the utility of detectors based on nitrides.

Design of Dual-Band Notched UWB Antenna Loaded with Split Ring Resonators for Wide Band Rejection

ABSTRACT Nowadays, the design of a miniaturised ultra-wideband (UWB) antenna with wide dual band-notched characteristics gained widespread demand in wireless communications to reduce interference. The design of a planar CPW-fed circular UWB antenna loaded with split ring resonators and stubs is presented to eliminate two frequency bands. Two symmetrical circular split ring resonators are etched below the CPW feed at the backside of a circular UWB monopole antenna to suppress 3.61 GHz–5.57 GHz (sub-6 GHz band) wideband interference, whereas the 7.06 GHz–8.79 GHz (X-band uplinks and downlinks) band is suppressed by loading two L-shaped stubs. Slots are also made on the patch and ground to enhance impedance matching at a lower resonance frequency. The proposed notch band antenna has a compact size of 38 × 32 × 1.6 mm3 and has the highest gain of 5.75 dB at a frequency of 9 GHz. The parametric analysis has been performed to obtain optimised dimensions for better performance. The designed antenna is simulated, prototyped and tested to validate the antenna design.

A Compact Dual-Band Four-Port Ambient RF Energy Harvester With High-Sensitivity, High-Efficiency, and Wide Power Range

The design of an ambient radio frequency (RF) energy harvesting system is introduced to replace the battery of the mass Internet-of-Things devices. This system can achieve high sensitivity with high efficiency over a wide input power range by optimizing the differential-drive cross-coupled (DDCC) rectifier and the load. The impedance of the dual-band four-port loop antenna array is directly conjugated to match with the rectifier, which reduces insertion loss of the matching network to improve efficiency. At 915 and 945 MHz for ISM and GSM bands, the rectenna can achieve high sensitivity of −30 dBm with 22% and 24% efficiency, high efficiency of 65% and 48% with −20-dBm input power, and a wide input power range from −30 to −18 dBm with 22–65% and 24–48% efficiency. The dual-band design explores the frequency diversity to harvest more RF energy from the environment, while the cross-shaped antenna array utilizes the space diversity to harvest RF energy from different directions with a compact size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.15\lambda \times 0.15\lambda $ </tex-math></inline-formula> per antenna element (where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> is the free space wavelength at 915 MHz). This new harvesting system can provide output dc power of 21.4 and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.95~\mu \text{W}$ </tex-math></inline-formula> in real-world outdoor and indoor ambient environments, respectively.

Design of a New Dual-Band Balanced-to-Balanced Filtering Power Divider Based on the Circular Microstrip Patch Resonator

A novel compact dual-band balanced-to-balanced (BTB) filtering power divider (FPD) based on the circular microstrip patch resonator is presented, for the first time in this brief. Firstly, in order to elucidate its principle of operation, the resonant property of the circular microstrip patch resonator is researched. After that, a prototype of the dual-band BTB FPD is developed. It is mainly constructed by two coupled circular patch resonators, two impedance matching ports, and three pairs of balanced ports. Its operating mechanism can be strictly illustrated by the field distributions of the concerned resonant modes. Hereinto, desired dual-band balanced filtering response is attained by elaborately exploiting TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">31</sub> modes while suppressing other modes from the patches. Ultimately, for validation, a dual-band BTB FPD centered at 4.2 GHz and 9.4 GHz is designed, fabricated, and tested. Good agreement between simulated and measured results validates that expected differential mode (DM) response, prominent DM isolation, nice common-mode (CM) suppression, high selectivity, and satisfactory harmonic suppression.

Design of a passive optical athermalization of dual-band IR seeker for precision-guided systems

The optical design of a seeker, operating in two bands of infrared (MWIR-LWIR), is performed. The dual-band design has been developed on Zemax OpticStudio. Considering the optical parameters of commercially available dual-band IR detectors, the design of the IR imaging seeker is completed for the operation within the wavelength range of 3–10 µm. The temperature dependence of the optical design is also examined for four different lens barrel materials, for the large temperature interval ranging from −40°C to 80°C. The defocusing effect caused by using different lens barrel is fixed by the passive-optical-athermalization technique. The field of view of the optical system is found to be 16°. The modulation transfer function (MTF) value of each field is higher than 0.50 when the spatial frequency takes a value of 20.8 lp/mm. The results are analyzed and discussed in terms of spot diagram, MTF.

Microstrip Grid and Patch-Based Dual-Band Shared-Aperture Differentially Fed Array Antenna

The design of a shared-aperture dual-band differentially fed array antenna with microstrip grid and patches is presented in this letter. The patches as high-frequency elements operating at 38 GHz are inserted into microstrip grid array antenna (MGAA) operating at the low-frequency band of 28 GHz. The impedance bandwidth of MGAA can be enhanced from 3% to 16% at 28 GHz due to the introduced resonance from its coupling with the patches. The measurement shows that the proposed antenna can achieve the impedance bandwidths of 15.65% and 16.7%, isolation of more than 20 dB, and peak gains of 14.7 and 14.5 dBi at dual bands of 28 and 38 GHz, respectively. Therefore, the design scheme will be useful for the dual-band millimeter-wave 5G applications.