Dual-band Performance Research Articles

Experimental investigations of dual functional substrate integrated waveguide antenna with enhanced directivity for 5G mobile communications

Antennas with higher gain and efficiency deliver superior performance across a wide frequency range. Achieving these characteristics at high frequencies while keeping a compact size necessitates sophisticated design approaches. This research presents a substrate-integrated waveguide (SIW) cavity-backed slotted patch antenna (SPA) tailored for the 28 GHz and 34 GHz frequency bands. Additionally, a linear tapered slot antenna is designed with a compact profile of 27.5 mm × 7.5 mm × 0.254 mm. The SIWs are implemented using vias on the outer profile of the antenna, and circular and rectangular slots are etched on the radiating surface. The goal of optimizing the antenna geometry is to enhance return loss within the desired frequency bandwidth, which means the Genetic Algorithm (GA) will determine the optimal antenna shape to achieve lower return loss than the original design within this bandwidth. The antenna exhibits dual resonance at 28 GHz and 38 GHz in the millimeter-wave range, providing an impedance bandwidth of 211 MHz (27.72 GHz–27.94 GHz) at 28 GHz and 127 MHz (37.88 GHz–37.98 GHz) centered at 38 GHz. The proposed antenna demonstrates gains of 8.04 dBi and 9.72 dBi at these operating bands. A prototype of the antenna is fabricated on RT/duroid 5880 and its characteristics are measured. The overall VSWR of the antenna ranges from 1 to 2, with a radiation efficiency of 94 %. The proposed antenna achieves dual-band performance with increased directivity and stable gain, exhibiting enhanced electric field distribution, radiation patterns, and reflection coefficient (S11), all of which contribute to a comprehensive understanding of the antenna's performance. This study compares the designed antenna's performance to that of the fabricated prototype. The proposed antenna is ideal for 5G applications due to its small size, broad spectral coverage, and excellent gain.

Sol–gel derived ceramic nanoparticles as an alternative material for microstrip patch antenna in WLAN applications

In the fast-evolving realm of communication technology, microstrip patch antennas (MPAs) are in high demand owing to their compact size, lightweight, inexpensive, ease of integration, and compatibility with modern electronic devices. This research focuses on the synthesis of ZnAl2O4Ca (ZAC) ceramic nanoparticles using an economical sol–gel method suitable for microstrip patch antenna applications. The structural analysis study of ZAC nanoparticles confirmed the polycrystalline nature with 8.1 nm of crystallite size whereas an investigation of functional groups showed the corresponding vibration modes. Morphological investigation revealed the spherical grains having their mean diameter of 12.32 nm. The dielectric property’s examination, revealed the dielectric permittivity of 13, loss tangent of 0.02, and conductivity of 67 μΩ−1 cm−1. Furthermore, a prototype patch antenna fabricated using ZAC ceramics demonstrated a dual-band performance at frequencies 2.8 GHz and 4.8 GHz, with return losses of − 25.78 dB and − 28.5 dB, respectively. This work suggests the suitability of ZAC ceramic nanoparticles for use in WLAN applications.

EARTHEN LAMP-SHAPED DGS DUAL BAND MICROSTRIP PATCH ANTENNA FOR HIGH RETURN LOSS IN BIOMEDICAL APPLICATION

This study illustrates a dual-band circular and pentagon antenna with dual-band configuration for the high return loss. When an antenna has a greater return loss, less power is reflected toward the transmitter, implying that the antenna and transmission line are better suited. Due to its accessibility, the FR4 substrate is used to replicate the design. With a bandwidth of 150 MHz and 200 MHz, respectively, the antenna's dual-band performance is between 2.32 GHz to 2.47 GHz and 2.9 GHz to 3.1 GHz. The body phantom design in CST Studio is used to test the design's biocompatibility. It is demonstrated by the improved antenna in the industrial, scientific, and medical (ISM) band region that it can be utilized for telemetry or medical services.

Dual-Band Dual-Output Four-Way Doherty Power Amplifier for Unsynchronized Time-Division Duplexing

This article proposes a dual-input dual-output dual-band four-way Doherty power amplifier (DPA) architecture, capable of linearized operation at one frequency band without being disturbed by arbitrary load switching at the other frequency band. The proposed technique is demonstrated through the design, implementation, and measurement of a prototype circuit operating at 1.85-and 2.65-GHz bands with 70-MHz bandwidth for each band. The prototype dual-band DPA (DB-DPA) achieves a peak output power of 49.1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm$</tex-math> </inline-formula> 0.2 dBm for the 1.85-GHz band and 49.3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm$</tex-math> </inline-formula> 0.5 dBm for the 2.65-GHz band. Furthermore, the measured drain efficiency at 9-dB power back-off (PBO) is 59%–64% and 60%–65% for the 1.85-and 2.65-GHz bands, respectively. Concurrent dual-band performance, dynamic power sharing capability, and utility of the proposed DB-DPA in unsynchronized time-division duplexing (TDD) applications are demonstrated by using 20-MHz new radio (NR) signals with 9-dB peak-to-average power ratio (PAPR). For an average output power of 39 dBm per band, the concurrent dual-band measurement yields 49% average drain efficiency and better than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 48-dBc adjacent channel leakage ratio (ACLR).

Dual-band Via-less Band-pass Filter Based on Cascaded Closed Ring Resonator

A band-pass filter (BPF) is an essential part of a wireless communication system as it functions to reduce interference and noise. Many structures have been proposed to achieve a high-quality BPF. Typically, these structures utilize vias. However, vias has several drawbacks, including impedance discontinuities, increased resistance values, and complex structures. In this study, we propose a dual-band BPF based on a cascaded closed ring resonator (CCRR) without using vias. Specifically, the proposed structure consists of multiple CCRRs connected at the corner pattern and incorporates capacitive coupling to the input impedance. Additionally, the CCRR configuration has dual sizing to achieve dual-band performance. Subsequently, the proposed BPF is simulated and fabricated using Duroid Rogers RT 5880 with dielectric constant εr = 2.2, dissipation factor tan δ = 0.0009, and thickness h = 1.575 mm. The measurement results demonstrated that the dual-band BPF operated at a resonant frequency of 2.50 GHz with a transmission coefficient (S21) value of -2.18 dB in the first band. In the second band, a resonant frequency of 3.70 GHz was obtained with an S21 value of -1.43 dB. The bandwidth in the first band was 160 MHz, and in the second band, it was 110 MHz. Moreover, based on the measurement results, the reflection coefficient (S11) in the first band was -11.05 dB, while in the second band, it was -23.3 dB. The excellent agreement between the simulation and measurement validates the proposed method.

An Effective Design Scheme of Single- and Dual-Band Power Dividers for Frequency-Dependent Port Terminations

Flexible design schemes for single- and dual-band power dividers terminated in arbitrary port impedances are proposed in this paper. The proposed architecture provides the inherent impedance transformation to real, complex, and frequency-dependent complex impedances at the input and output port terminations. Furthermore, the proposed design is supported by flexible design procedures with independent design variables to enhance rapid prototyping in microstrip technology. It is demonstrated that the presence of independent design variables enhances the design flexibility for varied ranges of frequency and impedance transformation ratios. Two different prototypes, one each demonstrating single- and dual-band performances, are developed to validate the performance of the reported designs with real and frequency-dependent complex port impedances. The prototypes exhibit excellent agreements between the simulated and measured results. The single-band impedance transforming power divider (ITPD) possesses a low-amplitude imbalance of 0.5 dB, a phase imbalance of less than ±0.5∘, and an isolation of −26 dB at the design frequency of 5.8 GHz. The dual-band prototype also exhibits a low-amplitude imbalance of 0.5 dB and a phase imbalance of less than ±0.5∘ at both the design frequencies of 1 GHz and 2.6 GHz. The isolation is also better than −30 dB at both design frequencies. It is thus shown that the overall performance advances the state of the art in the design schemes of ITPDs.

A compact channel patch antenna with reconfigurable circularly polarized pattern for mobile satellite communications

A compact dual-band circularly polarized antenna with a characteristic of pattern reconfiguration is proposed for S-band satellite handsets. The antenna works as a patch antenna in a channel shape with no ground beneath reaching an overall size of 0.55λ × 0.14λ × 0.1λ. The dual-band performance is realized through multi-branch slots of the patch. The antenna mainly consists of a channel metal patch, a channel dielectric, and a simple feeding network. The overall shape of slot can be changed by the PIN diode on the patch to adjust the surface current direction, which in turn achieves 180° switching of the left-hand circularly polarized radiation beam direction. In addition, by combining the quadrifilar helical antenna, which is switchable in the end-fire beam direction, the designed antenna can realize the switching of four main beam directions to achieve 360° 3D spatial coverage. The proposed antenna is fabricated and measured to verify the proposed design. The test results show that the designed antenna obtains circularly polarized radiating characteristics in S-band with the center frequency of 1.98 GHz and 2.2 GHz, and the test results and simulation results are basically consistent, which indicates the superior performance of the designed antenna.

Hybrid Absorber With Dual-Band Performance and High Absorption Rate

Low-profile absorbers are of interest for compact shielded enclosures for making antenna measurements. Furthermore, the cost should be minimized for practical systems since massive production is required. In this work, a novel dual-band hybrid absorber based on structured resonators and lossy dielectric material is proposed to meet these requirements. The lossy material enables improvement in the absorption rate and operating bandwidth. The proposed absorber operates at 2.4- and 5.0-GHz Wi-Fi spectra and covers the low-frequency bands with a reflection coefficient lower than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula> 25 dB and a large part of the high-frequency ones with reflection lower than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula> 20 dB. Moreover, some of the Wi-Fi bands are covered with a reflection coefficient better than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula> 30 dB. In order to validate the proposed concept, the dual-band absorber is manufactured and tested, and the agreement between the simulation and measurement results is good. The presented structure is cost-effective since it only uses conventional printed circuit board (PCB) technology for manufacturing and commercial lossy dielectric material.

Dual-band and dynamic regulated terahertz linear polarization converter based on graphene metasurface

In this paper, a highly efficient dual-band and dynamic regulated terahertz linear polarization converter is proposed. Based on the principle of electromagnetic (EM) wave polarization control, a periodic array metasurface composed of graphene split square ring and elliptical patches is designed to realize dual-band and high efficiency linear polarization conversion in terahertz band. The simulation results show that the polarization conversion ratio (PCR) is higher than 90% in the frequency range of 0.656–0.730 THz and 0.809–1.449 THz, and corresponding relative bandwidths are 10.7% and 56.7%, respectively. The dual-band performance is maintained within the incident angle of 50°. In addition, the dynamic regulation of dual-band terahertz linear polarization converter is obtained by modifying the Fermi level and relaxation time of graphene. The designed dual-band terahertz linear polarization converter has a broad application prospect in terahertz communication, sensing and spectrum.

Dual‐band shared‐aperture antenna with high aperture reuse ratio and high isolation

This work presents a dual-band (3.5/26 GHz) shared-aperture antenna with high aperture reuse ratio and high isolation. The proposed 26-GHz 4 × 4 substrate integrated waveguide (SIW) cavity-backed slot array antenna consists of four hybrid TE130–TE310-mode SIW cavities, which can simplify the design of feeding network. The radiating slots are unequally offset and inductance windows are added for good impedance matching. The entire structure of the 4 × 4 slot array antenna also functions as an equivalent TM10-mode patch antenna at 3.5 GHz. The resonant frequency of the patch is fine-tuned by inserting an air gap instead of enlarging the patch length, thus ensuring high aperture reuse ratio. To enhance channel isolation, the patch is designed with a bandpass filtering response centered at 3.5 GHz by introducing a stub-loaded resonator feeding structure. For demonstration, a prototype of the proposed dual-band antenna was fabricated and measured. The measured results show that the proposed antenna achieves excellent dual-band performance, and its aperture reuse ratio and channel isolation are as high as 87.5% and 62 dB, respectively.

Design of multimode broadband circularly polarized antenna using characteristics mode analysis

In this article, as low-profile fish-shaped monopole antenna is proposed for circular polarization radiation. The modal characteristics of the proposed antenna were analyzed and manipulated using characteristic mode analysis technique. Four characteristic modes with different resonant frequencies and current distributions were chosen as operating modes. In addition, a suitable position excited the desired modes, which achieve broadband circular polarization performance and dual-band performance. Based on the above analysis, a prototype of the proposed antenna was fabricated with dimensions of 60 mm × 60 mm × 1.5 mm to validate simulated results. Measured results show that the 3-dB axial ratio bandwidth (ARBW) of the proposed antenna is 40.7% (4.9–7.4 GHz) and the antenna broadside peak gain is 4.2 dBic within usable bandwidth. In addition, the measured impedance bandwidths of the proposed antenna are 12.2% (2.3–2.6 GHz) and 53.7% (4.5–7.8 GHz). Compared to other designs, the proposed circularly polarized antenna is a promising design operating in WiMAX band and industrial, scientific, and medical bands.

Novel method for reshaping TM 00 mode radiation patterns of rectangular patch antenna by using characteristic mode analysis

Based on characteristic mode analysis (CMA), a novel method for reshaping the TM00 mode of the rectangular patch antenna (RPA) is presented. Initially, the RPA loaded by periodic shorting vias, as the basic structure for generating the TM00 mode, is investigated by CMA. The nonbroadside pattern of TM00 mode is revealed to be caused by the vertical currents on the shorting vias. And it can be transformed into a broadside direction by replacing the vertical vias with a new shorting structure possessing strong horizontal currents. Moreover, to further verify the feasibility of the proposed method, a compact CPW-fed aperture-coupled RPA for the WLAN application is designed. By simultaneously exciting a reshaped TM00 mode, a fundamental TM10 mode, and a slot mode, the proposed RPA can achieve dual-band performance with broadside radiation features. Finally, the proposed antenna is fabricated and tested. The results illustrate that the fabricated antenna can achieve good impedance matching and broadside radiation characteristics in 2.4–2.46 GHz and 5.1–5.6 GHz bands.

Novel series fed dual band circular polarization antenna for navigational satellite system

A novel series fed dual band stacked microstrip patch antenna (SMPA) offering circular polarization (CP) over wide beam is proposed for Indian regional navigation satellite system (IRNSS). The antenna is designed to function at far apart dual frequencies 1.176 GHz (L5 band) and 2.492 GHz (S band) intended for the receiver terminals of IRNSS system. The dual band performance with large frequency ratio (about 1:2.1) has been obtained by two stacked patches with an air layer between them. The square notches at the corners along the diagonal of lower square patch, one sided corner truncation along the diagonal of upper square patch and feeding along central axis is used to obtain CP (with axial ratio &lt; 2) at both the operating bands. The square patches are excited with novel series feed technique. The proposed novel antenna has been designed, simulated and developed to meet the stringent design requirements for IRNSS navigation system. The antenna has achieved an impedance bandwidth of 2.6% and 2.2% at L5 and S band frequency respectively. It possesses positive gain beamwidth of 120and 3 dB axial ratio beamwidth of 120 ◦ and 60 ◦ at L5 and S band frequencies respectively.

A Dual-Band Antenna Design for 2.4 and 5 GHz Wi-Fi Applications

In these days, with the improvement of wireless and mobile communication, Wi-Fi technology is everywhere in life. When wireless communication standards are examined, it is observed that 2.4 GHz (2.4-2.4835 GHz) and 5 GHz (5.15-5.825 GHz) frequency bands are used as the Wi-Fi frequency band. Therefore, in this paper, a microstrip Wi-Fi antenna design with dual band performance at 2.4 GHz and 5 GHz frequencies has been achieved. Thanks to the choice of microstrip antenna. It will be ensured that the proposed antenna has the advantageous features of microstrip antennas compared to other antennas. The feed of the antenna will realize with a microstrip line. FR-4 substrate is used as dielectric material with a thickness of 0.8 mm. Thanks to the preferred materials and cheap production cost, fabrication of the antenna is considered. The CST Studio Suite is preferred by the world's largest technology and engineering companies, as it provides a market advantage over the products by providing a shorter development period and lower cost. The design stages of the antenna have been carried out using CST Studio Suite. Also, important parameters of the antenna have been examined and optimized bandwidth, input impedance, resonance frequency, reflection coefficient, return loss, etc. As a result, dual-band Wi-Fi antenna design has been determined with wide bandwidth and high gain.

Circular Complementary Split Ring Resonator Rotation for Linear Array Millimeter Wave Microstrip Patch Antenna

This paper proposes multiple linear array millimeter wave MPAs that could operate at various frequencies depending on the angular rotation of the CSRR structure. The main contribution of this work is the range of frequencies of the linear array MPA found when the position of the CSRR structure is changed angularly. This is achieved by positioning the CSRR structure on the ground plane of the MPA and rotate it to an incremental of 22.5°. Computer Simulation Technology software is used to simulate the antenna designs. The performance of the antenna is evaluated against the single element millimeter wave MPA with similar angular rotation to the CSRR structure. The reflection coefficient graph shows at 0° rotation, the antenna has dual band performance at 26 GHz and 28 GHz. At 22.5° and 45° CSRR structure rotation, the antenna shows triple band performance with different operational frequencies and different polarization depending on the frequencies. Finally, at 67.5° CSRR structure rotation, the antenna now is operational only at 20 GHz frequency with horizontal polarization performance. Plus, the results between the single element MPA with circular CSSRR and the linear array MPA with circular CSRR shows similar behavior in which the rotation of the CSRR did not affect the antenna differently even with an increase of the number of elements. The millimeter wave MPA with CSRR angular rotation can be utilized in various applications as it covers multiple frequencies depending on the angle of rotation of the CSRR structure.

Dual-Band Antenna Integrated With Solar Cells for WLAN Applications

A single-port dual-band antenna integrated with solar cells is reported for the 2.4/5-GHz wireless local area network (WLAN) applications. Thirty solar cells are adopted and integrated into the antenna structure for both energy harvesting and wireless communication. The solar cells can act as a director for the lower band, and the main radiation structure for the higher band. The slot and microstrip antennas are incorporated into the compact structure and multiple resonant modes are utilized for dual-band performance. The measurement results show that the lower band is from 2.27 to 2.5 GHz with an omnidirectional radiation pattern and the upper band is from 4.8 to 6.9 GHz with a directional radiation pattern. The proposed solar cell antenna can provide a dual-band performance with the ability of DC power generation, which can be a potential candidate for future green low-carbon communication.

Compact and Simple High-Efficient Dual-Band RF-DC Rectifier for Wireless Electromagnetic Energy Harvesting

(1) Background: This work presents a high-efficiency, high sensitivity, compact rectifier based on a dual-band impedance matching network that employs a simple and straightforward T-matching circuit, for sub-1 GHz license-free applications. The development of a low-cost RF energy harvester dedicated to the ISM bands is introduced. The proposed rectifier design is optimized to operate at the sub-GHz frequency bands (0.9 to 2.4 GHz), specifically those at the ISM 900 and 2400 MHz. The motivation for this band is due to the low attenuation, well-known fundamental electromagnetic theories and background, and several wireless communications are emitting at those bands, such as RFID (2). Methods: The rectifier design is based on a simple, balanced single-series diode connected with a T-matching circuit. The dual-band performance is achieved by deploying reactive elements in each branch. The full mathematical analysis and simulation results are discussed in the manuscript. (3) Results: The rectifier can achieve a 80 MHz bandwidth around 920 MHz frequency and 200 MHz around the higher band 2.4 GHz. The resultant conversion efficiency level is maintained above 45% at both bands with a peak efficiency reaches up to 70% at the higher band. The optimum terminal load attached to the circuit at which the peak efficiency is achieved, is given as 4.7 kΩ. (4) Conclusion: Due to the compactness and small footprint, simple design, and simple integration with microwave circuits, the proposed rectifier architecture might find several potential applications in wireless RF energy harvesting.

Design of Dualband Bandpass High-Temperature Superconducting Filter With Group Delay Equalization

A novel dualband high-temperature superconducting (HTS) bandpass filter is proposed with group delay equalization for 5G emergency communication receivers with N41 and N79 bands in this paper. The dual-folded stub-loaded stepped impedance resonator (DSLSIR) is applied to realize dualband performance. The proposed DSLSIR has miniaturized circuit size and more design freedom to independently adjust the two designed center frequencies, comparing with other reported DSLSIRs. Two cross-coupling transmission lines are added at the top and bottom parts of the cascaded sixth-order filter with DSLSIRs to flatten the group delay of the passband at both bands. A dualband bandpass HTS filter etched on the YBCO superconducting material is fabricated to verify the proposed design method. The measurement is actualized at the temperature of 77 K to make YBCO microstrip lines perform superconducting features. The results show that the first center frequency is 2.595 GHz with 6.2% bandwidth for N41 band and 0.3 dB insertion loss while the second center frequency is 4.85 GHz with 2% bandwidth for N79 band and 0.4 dB insertion loss. Meanwhile, the group delays at the N41 and N79 bands keep 2 ns fluctuations in the 60% passband. The agreement between the measured and simulated results indicates that the proposed dualband bandpass HTS filter with low insertion loss, sharp roll-off skirt and flat group delay is a promising candidate for emergency communication receiver.

Dual-Band Microstrip Resonant Sensor for Dielectric Measurement of Liquid Materials

A novel compact microstrip resonant dielectric permittivity sensor with dual-band operation is presented in this paper. The circuit makes use of a single stepped-impedance-resonator as the sensing element, working at the 2.45-GHz and 5.8-GHz ISM bands, under differential and common modes, respectively. Sensitivity of the circuit and resonator coupling at each band can be configured independently. Moreover, testing of the sample is done by using a single sensing region without the need of duplicating the sample location. Experimental measurements are carried out using a very small amount of liquids and the results are presented validating the theory. This work delivers a compact, reusable, label-free and non-destructive microwave device and paves a way for sensing dielectric properties of chemicals with accuracy due to the dual-band performance.

Dual-Band Folded-End Dipole Antenna for Plastic CubeSats

In this article, a dual-band folded-end dipole antenna is proposed for plastic CubeSat platforms. The proposed antenna has a compact structure which is integrated in a miniaturized satellite, i.e., CubeSat, without any deployment mechanism. This is achieved by folding the dipole antenna around the CubeSat circumference. In addition, by folding the dipole, the antenna provides a dual-band performance centered at 2.5 and 4.7 GHz, respectively. The folded-end dipole forms a square loop with a gap of tunable width which can be adjusted to tune its impedance. Finally, the measured gain of the proposed design is 7 and 4.3 dBi with a −10 dB bandwidth of 500 and 250 MHz at S- and C-band, respectively.