Dual Band Research Articles

A Dual‐Band Dual‐Polarized Rectenna for Efficient RF Energy Harvesting in Battery‐Less IoT Devices With Broad Power Range

ABSTRACTThe demand for maintenance‐free, battery‐less IoT devices, driven by sustainable Industry 4.0 practices, necessitates efficient RF energy harvesting solutions. Addressing the limitations of single‐frequency harvesting, a novel dual‐band, dual‐polarized rectenna operating at 3.6 GHz and 5.8 GHz is proposed. The antenna resonates at 3.6 GHz with linearly polarized (LP) characteristics and 5.8 GHz with circularly polarized (CP) characteristics with impedance bandwidth (IBW) of 2.2% and 5.63%, respectively, achieving a gain of 4.85 dBi and 6.75 dBic, respectively. A rectenna consists of an antenna at the front end and an RF‐DC rectifier at the backend. This approach maximizes power conversion efficiency by minimizing impedance mismatches and reflection losses and mitigates interference between the dual bands within the rectifier circuitry. The rectifier achieves peak efficiencies of 65.5% at 3.6 GHz with a 3 dBm input and 44% at 5.8 GHz with a −1 dBm input, both with 2KΩ load. Efficiency exceeds 30% at 3.6 GHz for an input range from −10 to 6.5 dBm and exceeds 20% at 5.8 GHz for an input range from −13 to 3 dBm. These design considerations enable reliable harvesting of ambient RF energy across a range of −20 to 20 dBm, enabling continuous IoT device operation. Our measurements confirm the design's effectiveness in converting low‐power RF signals into usable energy, supporting sustainable and autonomous IoT deployments at 3.6 and 5.8 GHz.

Dual Band Modified Complementary Split Ring Resonator Loaded Substrate Integrated Waveguide Based Bandpass Filter

This study presents a dual-band bandpass filter design that implements microstrip to substrate integrated waveguide (SIW) transition to decrease radiation losses. The proposed filter is designed with using four complementary split ring resonators (CSRR) to minimize its size and to gain double negative property. A bowtie shaped slot is etched inside CSRR to have a second resonance at the spectrum. After the simulation results are performed the designed filter is fabricated on a Rogers RT5880 dielectric substrate and the experimental results are compared with the simulation results. The proposed filter has center frequencies at 6.57 and 12.55 GHz with fractional bandwidth (FBW) of 22.05% and 26.29%, respectively. Moreover, the presented filter offers the best bandwidth-to-size result with the size of 0.327λg×0.352λg (where λg is the wavelength at the first passband’s center frequency).

A New Dual‐Band Filtering Power Divider Based on a Single Multimode Modified Triangle Patch Resonator

ABSTRACTThis letter proposes a new design of a dual‐band (DB) filtering power divider (FPD) on a single multimode‐modified triangle patch resonator. The proposed design leverages the resonant characteristics of an equilateral triangle patch resonator to exploit the TM10, TM11, TM21, and TM30 resonant modes within a single multimode‐modified triangle patch resonator, enabling the realization of an FPD with DB operation. To achieve two assumed second‐order filtering passbands, a metal via and multiple perturbed slots are introduced, providing flexible control over the resonant mode frequencies. The first passband is formed by the TM10 and TM11 modes, while the second passband is formed by the TM21 and TM30 modes. To ensure in‐band isolation for both passbands, two sets of isolation networks are developed. A prototype is designed, fabricated, and measured to validate the proposed method. The measured results demonstrate excellent agreement with the simulated ones.

Transparent dual‐band wide‐angle polarization‐insensitive single‐layer frequency selective surface for mm‐wave 5G communication systems

AbstractA highly transparent single‐layer frequency selective surface (FSS) with an optical transmittance of 92.7% at 550 nm, designed for 5G communication systems operating in dual frequency bands of 26 and 38 GHz is proposed. The dual‐band FSS not only achieves high optical transparency but also maintains good electrical performance. The transmission performance of the FSS is stable to the polarization and angles of incidence for electromagnetic waves. As a proof of concept, the FSS with periodic square loops patterned on a 188‐µm‐thick substrate is fabricated. Each loop is constructed with metallic mesh electrodes having a pitch of 10 µm. Measurements are conducted using two different systems: a free‐space measurement system and a vector network analyser‐based material characterization kit. After calibrating the measurement systems, the scattering parameters of the fabricated surface are measured. The results obtained from both measurement systems show good agreement and also agree with the simulated results. The designed surface has an insertion loss of less than 3 dB in the dual passband region. The proposed dual‐band FSS has the merits of polarization independence, angular insensitivity, and high transparency.

A Compact Dual Band Wearable Slot Antenna with Partial Ground for WLAN and X Band Applications

A Compact Dual Band Wearable Slot Antenna with Partial Ground for WLAN and X Band Applications

Magnetic properties and dual band microwave absorption in conjunction with red shifted resonance of γ-Fe2O3 linked with 2-BOP dispersed on graphene oxide

Magnetic properties and dual band microwave absorption in conjunction with red shifted resonance of γ-Fe2O3 linked with 2-BOP dispersed on graphene oxide

Bias Selectable Dual Band Detectors Based on Vertically Aligned In2S3‐coated ZnO Nanorod Arrays Grown on p‐GaN

Herein, we report vertically aligned In2S3 coated ZnO nanotube arrays deposited on p‐GaN substrate by wet chemical method. The fabricated device based on In2S3/ZnO/p‐GaN heterostucture structure displays an enhanced photoresponse with self‐driven operation. The device based on ZnO/p‐GaN structure coupling with In2S3 nanoparticles exhibits bias selectable photodetection by detecting UV and UV/visible light through bias voltage modulation. This strategy can benefit to fabricate broadband photodetector based on ZnO/GaN structure.

Reflective linear polarization converter with multimode, dual band and high efficiency

Abstract A thin, dual-band, highly efficient linear polarization converter based on a multi-mode metasurface was proposed. The high-efficiency manipulation of polarization states of electromagnetic waves in dual-band frequencies was achieved by utilizing a diagonally etched metasurface as a square joined by a ring. The metasurface transforms incident linearly polarized (LP) waves into cross-polarized LP waves at various frequencies. Numerical simulations reveal that the metasurface operates efficiently in the bands from 7.724 GHz to 8.192 GHz and 13.142 GHz to 15.95 GHz, with a polarization conversion rate (PCR) of 95% in both bands. To validate the theoretical analysis and simulation results, a model is fabricated and measured. The experimental results confirm that the proposed metasurface successfully achieves dual band-and dual-mode polarization conversion, showing reasonable consistency of theoretical and simulated findings. This converter can optimize the signal performance by clarifying polarized radio waves.

120 GHz MIMO FMCW radar chipset in a SiGe bipolar technology

Abstract This paper presents a flexible SiGe monolithic microwave integrated circuit (MMIC) chipset for 120 GHz ultra-wideband frequency-modulated continuous wave radar systems. The highly integrated chipset is implemented with multiple-input and multiple-output radar in mind which leads to transmit and receive MMICs with four integrated channels in each chip. The transmitter achieves an output power of 12.9 dBm with a total power consumption of only 403 mW. The receiver chip incorporates a sub-harmonic approach for suppression of leakage radiation at 120 GHz through a receive channel. Both chips integrate active multiplier chains that are driven by a third reference dual band voltage-controlled oscillator (VCO) MMIC that can deliver an output at center frequencies of 15 or 30 GHz. The reference VCO MMIC demonstrates relative tuning ranges of 32%.

Dual-Band High-Throughput and High-Contrast All-Optical Topology Logic Gates.

Optical computing offers advantages such as high bandwidth and low loss, playing a crucial role in signal processing, communication, and sensing applications. Traditional optical logic gates, based on nonlinear fibers and optical amplifiers, suffer from poor robustness and large footprints, hindering their on-chip integration. All-optical logic gates based on topological photonic crystals have emerged as a promising approach for developing robust and monolithic optical computing systems. Expanding topological photonic crystal logic gates from a single operating band to dual bands can achieve high throughput, significantly enhancing parallel computing capabilities. This study integrates the topological protection offered by valley photonic crystals with linear interference effects to design and implement seven optical computing logic gates on a silicon substrate. These gates, based on dual-band valley photonic crystal topological protection, include OR, XOR, NOT, NAND, NOR, and AND. The robustness of the implemented OR logic gates was verified in the presence of boundary defects. The results demonstrate that multi-band parallel computing all-optical logic gates can be achieved using topological photonic crystals, and these gates exhibit high robustness. The all-optical logic gates designed in this study hold significant potential for future applications in optical signal processing, optical communication, optical sensing, and other related areas.

A metasurface integrated self-decoupled multiport tunable antenna for THz applications

Abstract A four port multiple-input multiple-output (MIMO) antenna is initially designed on silicon dioxide (quartz) substrate by arranging the antenna elements in an orthogonal configuration by using self-decoupling mechanism. Mean effective gain lower than 0.5 and radiation efficiency greater than 95% are obtained. Characteristic mode analysis of the proposed MIMO antenna has been performed using finite integration technique to validate the resonant modes. Further, a dual band self-multiplexing MIMO antenna has been constructed by loading each antenna element with a graphene constituted stub. Graphene loading in the antenna elements is done to introduce tunability in the MIMO operation in two frequency bands. The dual resonance frequencies range from 4.3–4.6 THz and 5.2–5.6 THz while the chemical potential is varied from 0.1 eV to 0.9 eV. The diversity performance of the MIMO antenna with and without graphene loading have been analyzed through numerical simulations. Envelope correlation coefficient lower than 0.0002 and diversity gain of 10 dB have been obtained. By biasing each of the antenna elements with different voltages, quadruplexing mechanism can be performed since each antenna resonates at a different frequency. Finally, a metasurface is designed on silicon dioxide (quartz) substrate to function as a reflective surface from 3.75–6.42 THz covering the resonance band of the tunable MIMO antenna for enhancing its gain to 14 dBi.

Compact multiband cuff button antenna for WBAN application

Abstract A compact dual layer conformal wearable quad band antenna is proposed for wireless body area network applications. The proposed button like patch antenna resonates at 2.5 GHz (industrial, scientific, and medical bands)/3.6 GHz sub six 5G band/5.75 GHz (wireless local area network/ISM band)/ and 9.8 GHz (X band) frequencies. The circular textile antenna is constructed with jean and polydimethylsiloxane substrate having a slotted ground of radius 10 mm and thickness 1.5 mm. The simulated gains obtained at the operating bands are 1.85/2.03/1.49/3.27 dBi, respectively. The designed antenna’s directed radiation pattern assures reduced backward radiation to body tissue. The specific absorption rate (SAR) analysis for the antenna at multiple resonant frequencies has also been reported, which are well below the SAR threshold of 1.6 W/kg for 1 gm of tissue, indicating that the model works adequately for wearable applications. The experimental characterization on- and off-body of the fabricated antenna validates the simulated results.

High isolation dual band circularly polarized CPW based MIMO antenna with improved diversity performance for WLAN and C band wireless applications

ABSTRACT This paper presents a 2-port MIMO antenna with a CPW feed, designed for dual-band operation with high isolation. We resolved bandwidth and polarization issues in the antenna’s initial CPW-fed design by modifying the radiating patch and incorporating an asymmetrical ground plane. These adjustments enabled dual-band and dual-polarization functionality. The first band, with linear polarization, operates between 2.75 GHz and 2.86 GHz for sub-6 GHz wireless applications, while another band exhibits circular polarization with wide-band resonating at two frequencies, in the (4.7–5.6) GHz and (7.1–8.5) GHz ranges, respectively, covering the entire C-band and suitable for wide-band applications. The antenna, built on a Rogers-5880 substrate (1.57 mm thickness, εr = 2.2, tan δ = 0.0009), offers low loss and excellent thermal stability. The antenna, measuring 45.5 × 27 × 1.57 mm3, attains port isolations of 27 dB and 22.4 dB, with peak realized gains of 2.8 dB and 5.4 dB in the two bands. Furthermore, we analyze the key performance of the MIMO antenna, including the envelope correlation coefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), and channel capacity loss (CCL), and confirm that they fall within an acceptable range, making it an excellent choice for many portable wireless applications.

Compact metasurface antenna for Sub-6 GHz applications with isolated n77/n78 bands using CSRR

Abstract A compact (0.35 λ 0 × 0.35 λ 0 where λ 0 is free space wavelength at the lower resonance frequency 3.50 GHz) bio-inspired tulip flower-shaped antenna (TFSA) is proposed. A double negative (DNG) metamaterial complementary split ring resonator (CSRR) is introduced near the feed in the hybrid triangular-circular patch which inserts a notch-band (4.20–4.38 GHz) in the wide bandwidth (3.15–7.05 GHz) and makes the antenna response dual-band. Consequently, this results in in-band interference reduction in 5G-Sub-6 GHz applications. A slotted FSS is placed at a distance of 28.507 mm beneath the monopole-reduced ground of the antenna to enhance the reduced gain from 4.39 dBi to 7.22 dBi. A further gain is improved to 12.84 dBi by placing a full copper surface (0.35 λ 0 × 0.35 λ 0 ) as the reflector layer is placed below FSS at 1.6 mm. Finally, prototyped TFSA with FSS and reflector model achieve a dual bands reflection coefficient response (3.15–4.20 GHz): n77/n78, and (4.38–7.03 GHz): n46/n47/n96/n102/n79. The antenna reflection coefficient is tested using Keysight 14 GHz FieldFox Microwave Analyzer N9916A, and radiation patterns in the E-plane and H-plane are measured using an 18 GHz anechoic chamber. The comparison of simulated results with measured results is found an excellent match in bandwidth and with shapes of gain radiation patterns. The reflector and FSS jointly make the radiation pattern strong in the E-plane above the TFSA radiator. The antenna is well suited for n77/n78 (3.30–4.20 GHz), n79(4.40–4.99 GHz), n46 (5150–5925 MHz), n47 (5855–5925 MHz), n96/n102 (5925–6425 MHz), 5.8 GHz HiperLAN, WiMAX 3.5 GHz applications. An electrical equivalent circuit model of the proposed TFSA antenna is presented and validated using ADS software.

A butterfly metasurface with efficient multi-functional polarization conversion operating in the Ku-Ka band

A highly efficient and multi-functional butterfly polarization conversion metasurface is proposed for the Ku-Ka frequency range, designed to reduce the radar cross-section. The suggested converter enables dual frequency bands linear-to-cross (LX) and linear-to-circular (LC) polarization transformations. The efficiency of cross-polarization conversion exceeds 90% over the frequency ranges of 14.57–16.30 GHz and 25.70–37.03 GHz, with relative bandwidths of 11% and 36%, respectively. Reflections of left-hand (LHCP) and right-hand circularly polarized (RHCP) waves are realized within the frequency ranges of 17.78–25.31 GHz and 37.38–37.73 GHz, with relative bandwidths of 35% and 0.9%. The oblique incidence significantly affects the metasurface conversion performance, and the proposed model manifests angular robustness up to 60°. Additionally, the butterfly metasurfaces are deployed in a triangular chessboard configuration to achieve radar cross section (RCS) reduction spanning the frequency bands of 14–15.17 GHz, 24.60–35.20 GHz, and 36.30–38 GHz. Drawing from simulation results and test-based validation data, the proposed converter holds promising applications in wireless communication, antenna engineering, and radar stealth.

A High Gain Dual Band Hexagonal Metamaterial Inspired Antenna for 5G Applications

Microstrip patch antennas play an important role in wireless communications to improve speed. Some of their benefits are low cost, low profile, and easy to fabricate. Existing research on microstrip patch antennas examines difficulties such as limited diversity performance, low radiation characteristics, and low efficiency. To address these issues, metamaterials are used to enhance diversity. This study focuses on designing a dual-band microstrip patch antenna for 5G applications to meet user demands with high data rates and enhance communication speed. To improve isolation and gain, a hexagonal-shaped Split Ring Resonator (SRR) was added to the substrate of the antenna. The proposed antenna model operates at frequencies greater than 28 GHz. The antenna dimensions are 25×25×0.15 mm, designed on a polyamide substrate with a loss tangent tan δ of 0.004, dielectric constant εr of 4.3, and relative permeability of 1. The suggested model was evaluated using several performance parameters, such as reflection coefficient, axial ratio, Voltage Standing Wave Ratio (VSWR), gain, and radiation patterns. The proposed model has S-parameter values of -17.6192 dB and -20.3264 dB, and gain values of 7.1 dB and 7.3 dB at 28.900 and 33.7400 GHz, respectively.

Circularly Polarized Reconfigurable Antenna Based on Liquid Metal Switching for Dual WiMAX Bands

Circularly Polarized Reconfigurable Antenna Based on Liquid Metal Switching for Dual WiMAX Bands

Design of Dual Band Bowtie Slot Antenna with Rectangular-Shaped Defected Ground Structure

Abstract The need for 5G antenna has been increasing rapidly due to the development of 5G communication which recently has become popular and advanced. In this research, a bowtie slot antenna with rectangular-shaped defected ground structure (DGS) that can operate at 2.4 GHz and 3.5 GHz, which is used in 5G communication, was designed, simulated and optimized. Parametric study was conducted to study the effect of DGS on the antenna’s performance. The dual band bowtie slot antenna with two rectangular-shaped DGS have been proposed in this paper. The proposed antenna displayed excellent performance in the reflection coefficient of the operating frequency with simulated S 11 around -69 dB and -68 dB at 2.4 GHz and 3.5 GHz respectively. It was observed that multiple rectangular-shaped DGS were able to improve the antenna’s impedance matching, reflection coefficient and bandwidth performance.

Dual-band ESSPP-SSPP transmission line with independently controllable cutoff frequencies.

In this work, an effective spoof surface plasmon polariton (ESSPP)-SSPP transmission line (TL) is proposed, which can operate in dual bands. Unlike SSPP TL, our ESSPP-SSPP TL allows for relatively accurate parameter estimation, independent control over each cutoff frequency, and low insertion loss. We provided the dispersion relation and closed-form formulas for calculating each cutoff frequency and explained the mechanism behind the independent controllability of each cutoff frequency. This allows us to quickly estimate the structural parameters with an analytical design approach. By leveraging the dispersion of the ESSPP-SSPP mode, we designed a dual-band filter operating in the millimeter-wave range, and its performance was validated through experimental measurements. This work paves the way for the development of novel SPP-like microwave/millimeter-wave devices.

Low-profile pattern reconfigurable patch antenna with dual bands characteristic for 5G NR communication

Abstract In this paper, a low-profile antenna with characteristic of reconfigurable of dual bands’ pattern for 5G New Radio (NR) communication is proposed to mitigate the problems of signal fading and multipath propagation. The design incorporates a turnstile-shaped patch, a circular patch with etched rectangular slots and a discontinuous ring patch. The circular patch with etched rectangular slots and discontinuous ring patch are placed in the same plane to obtain dual band characteristic. The discontinuous ring patch works as a near-field resonant parasitic unit to improve the front-to-back ratio values at the resonance points and adjust the beam direction. Eight diodes are loaded to control the connection states of the rectangle slots on the circular patch. By combining an electric dipole formed by diode-controlled slot with a magnetic dipole formed by the turnstile-shaped patch, then a dual-band antenna with diverse patterns is designed. The measured results show that the designed antenna has dual-band characteristics and operates in the bands of 3.39–3.62 GHz and 4.77–5.01 GHz with peak gains of 3.6 dBi and 4.2 dBi, respectively. Furthermore, the measured radiation pattern results show that it is feasible to reconfigure the pattern in both bands simultaneously at 45° intervals.