Impedance Bandwidth Research Articles

High‐Gain Triple‐Band T‐Shaped Dielectric Resonator Based Hybrid Two‐Element MIMO Antenna for 5G New Radio, Wi‐Fi 6, V2X, and C‐Band Applications With a Machine Learning Approach

ABSTRACTIn this article, a rectangular dielectric resonator (DR) based multiple input multiple output (MIMO) hybrid antenna with a machine learning (ML) optimization approach for 5G New Radio (NR), WiMAX, WLAN, Wi‐Fi 6, Vehicle to Everything (V2X), and C‐band uplink applications are presented. The proposed antenna provides a triple band. It covers n1, n2, and n39 5G NR at a lower frequency (1.59–2.26 GHz), n48 5G NR at the middle frequency (3.1–3.87 GHz), and n46, n47, n96, WiMAX, WLAN, and C‐band uplink at higher frequency (5.25–6.91 GHz). It achieved more than 20% impedance bandwidth and 20 dB isolation in all frequency bands. The maximum gain of the proposed antenna is 15 dBi. The calculated MIMO parameters are within the accepted range. It is optimized through various ML algorithms, including random forest (RF), K‐nearest neighbor (KNN), artificial neural network (ANN), extreme gradient boosting (XGB) and decision tree (DT). The RF ML algorithm gives 98.09% accuracy compared to other ML algorithms for S parameter prediction.

Machine Learning Enabled Compact Frequency‐Tunable Triple‐Band Hexagonal‐Shaped Graphene Antenna for THz Communication

ABSTRACTIn this article, a compact triple‐band frequency‐tunable (FT) hexagonal‐shaped graphene antenna through a machine learning (ML) approach for terahertz (THz) application is presented. The proposed THz antenna is designed on a polyamide () substrate with a thickness of 10 μm, and graphene is used as an antenna radiator. The size of the substrate is 38 × 46 μm2. The FT is achieved by changing the chemical potential of graphene material. The performance of the proposed THz antenna has been investigated, and the impacts of several conducting materials like gold, aluminum, copper, and graphene and dielectric materials like Rogers RT/duroid 5880, polyamide, quartz, and SiO2 are explored. The proposed THz antenna provides three operating bands. The frequency of operation in Band‐1 is 2.51–5.05 THz, Band‐2 is 5.99–7.43 THz, and Band‐3 is 7.94–9.63 THz. The bandwidth in Band‐1, Band‐2, and Band‐3 are 2.54, 1.44, and 1.69 THz, respectively. The % of impedance bandwidth in Band‐1, Band‐2, and Band‐3 are 67.19%, 24.02%, and 21.28% respectively. The proposed antenna has a maximum peak gain of 5 dBi. The proposed antenna is optimized through various ML algorithms like random forest (RF), extreme gradient boosting (XGB), K‐nearest neighbor (KNN), decision tree (DT), and artificial neural network (ANN). The RF algorithm gives more than 99% accuracy compared to other ML algorithms and accurately predicts the S11 of the proposed antenna. The proposed THz antenna would be suitable for applications related to imaging, medical, sensing, and ultra‐speed short‐distance communication applications in the THz region.

High-order-mode cavity fed 45° linear polarized antenna for 5G applications

Abstract In this paper, a high-order-mode (HOM) (TE330) cavity-fed 45° linear polarized 6×6 slot array antenna is proposed. The 45° linear polarization is achieved by introducing asymmetric cross slots on the HOM cavity, resulting in low profile and wide bandwidth. The antenna array was verified using standard printed circuit board technology. Measured results show that the impedance bandwidth ( $|S_{11}|\le$ −10 dB) is 13.9% (36.98–42.92 GHz), and the peak gain is 19.3 dBi with a 3-dB gain bandwidth of 13.6%. Attributed to its simple structure, low profile, and wide bandwidth, the presented antenna is a good candidate for 5G applications.

Flexible dual-band antenna for ISM/5G enabled MIMO systems with pattern diversity for wireless body area networks

Abstract This paper outlines the design of a six-element multiple-input–multiple-output (MIMO) antenna with pattern diversity for industrial scientific medical (ISM)/5G-enabled wireless body area networks (WBANs). Within the MIMO configuration, each element has a quasi-yagi antenna configuration implemented on an ultrathin microwave laminate. The proposed quasi-yagi antenna has a small form factor of 25 × 25 mm, featuring a dipole-like radiator excited through a microstrip-line to tapered slot-line transition. The antenna’s radiators are patterned to ensure a dual-narrow impedance bandwidth. The conventional strip-line director in the planar yagi is replaced with a semicircular loop-like director, enhancing directional radiation patterns. This proposed flexible antenna offers versatile functionality by operating at both ISM standards of 2.45 GHz and the 5G wireless local area network standard at 3.5 GHz. The quasi-yagi elements are strategically distributed in a hexagonal formation to construct the six-element MIMO scheme with pattern diversity, resulting in a tangential radiation pattern suitable for on-body communication. Following fabrication, the prototype MIMO antenna’s simulation results are validated through real-time measurements. The proposed antenna exhibits an average gain exceeding 3.5 dBi across both operating bands. Furthermore, the proposed MIMO antenna exhibits promising performance metrics suitable for densely cluttered WBAN environments.

Design of a Multiband Antenna Using Auxiliary Classifier Wasserstein Generative Adversarial Network for IoT Applications

ABSTRACTThe rapid expansion of Internet of Things (IoT) applications presents unprecedented challenges for antenna design, demanding solutions that are versatile, efficient, and capable of operating across multiple frequency bands. This paper addresses these challenges through the development of a design of a multiband antenna using Auxiliary Classifier Wasserstein Generative Adversarial Network for IoT applications (DMA‐ACWGAN‐IoT). Here, the Auxiliary Classifier Wasserstein Generative Adversarial Network (ACWGAN) is employed to generate synthetic data representing electromagnetic field distributions and antenna characteristics across various frequencies. The proposed metamaterial‐based Multiple‐Input Multiple‐Output (MIMO) antenna contains four discrete elements, each provided by a micro strip feed. The structures overall width and length are 60 and 52 mm. The metamaterial is printed on a patch and dispersed from the fields with the most effective coupling. The proposed structures strong impedance bandwidth works at 8.3 GHz, 10.8 GHz, 12.3 GHz, 13.7 GHz, 16.1 GHz, and 18.1 GHz, fabricating the proposed antenna prototype using a substrate made of FR‐4 material. The proposed DMA‐ACWGAN‐IoT design provides 6.5 dB maximum gain and 25.40%, 21.60%, and 20.05% higher efficiency compared to existing dual band antenna design with resonance frequency prediction under machine learning models (DBA‐PRF‐ML), machine learning verification depending on a distinctive SWB multiple slotted four‐port high isolated MIMO antenna loaded with metasurface for the applications of IoT (SWB‐MIMO‐IOT‐ML), and dual‐band miniaturized composite right–left‐handed transmission line ZOR antenna along machine learning method for microwave communication (DB‐ZORA‐MC‐ML).

A miniature capsule endoscope based on spiral antenna with wireless sensing capabilities

Abstract In this paper, a capsule endoscopy system with a sensing function is proposed for medical devices. A single-arm spiral antenna is designed for data transmission and is combined with the voltage controlled oscillator to achieve sensing capabilities. The designed antenna operates at a 900 MHz industrial scientific medical band. By establishing a three-layer cylindrical model of the stomach, it was concluded that the antenna in the stomach has a high peak gain of −1.1 dBi. Additionally, the antenna achieved a −10 dB impedance bandwidth of 5%. The capsule endoscopy was experimentally measured in both actual stomach and simulated environments. The maximum working distance of the capsule endoscope was measured to be 6.8 m. Additionally, the proposed capsule endoscope was tested for its sensing function using solutions with different dielectric constants. Finally, it was confirmed through link analysis that it has good communication capabilities. The results and analysis confirm that the proposed capsule endoscope can be used for examining gastric diseases.

A beam-reconfigurable probe-fed mm-wave SIW slot array antenna using cavity-backed U-slot SIW switch

ABSTRACT A beam-reconfigurable millimeter-wave (mm-wave) antenna is proposed, constructed with a dodecagonal substrate integrated waveguide (SIW) structure and a cavity-backed U-slot SIW switch. The SIW switch consists of a U-shaped slot in the ground plane, a p-i-n diode, and a pair of metallic vias, primarily operated by controlling the impedance of the U-shaped slot. Six SIW switches are employed to enable six-beam switchable reconfiguration. Correspondingly, six 4 × 4 SIW slot subarrays are equiangularly arranged along the periphery of the dodecagonal substrate, acting as the main radiators. By carefully controlling the excitation phase and magnitude of the slot elements in the subarrays, a tilted beam of approximately θ = 19° can be produced in measurement with switchable reconfigurable beams 1‒6 steering along the azimuth plane at discrete angles of approximately ϕ = 90°, 150°, 210°, 270°, 330°, and 30°, respectively. The measured results indicate that the overlapped impedance bandwidth (|S11|<-10 dB) of the proposed antenna is across 25.63‒26.08 GHz with a relative bandwidth of 3.7%. The measured antenna peak gains for beams 1‒6 can reach up to 8.0 dBi.

Statement of Removal: Knowledge-based heuristic optimisation technique for mm-wave 5G antenna

ABSTRACT This work presents a knowledge-based decision-making robust antenna design (KDRAD) method that employs a heuristic-optimisation technique for antenna design. The method is used to create and scale a single-element antenna to operate at multiple frequencies within the 5 G range. In this study, a low-profile planar four-element microstrip antenna of 14.8 mm × 14.8 mm × 0.508 mm gives simulated and measured impedance bandwidths of about 1.18 GHz (26.43–27.61 GHz) and 1.08 GHz (26.42–27.50 GHz), respectively, with a centre frequency of 27 GHz. The mm-wave planar four-port antenna has a maximum gain of 7.2 dBi; isolation of 33.2 dB; and multiple antenna matrices with minimal ECC (0.000000109), high diversity gain (10 dB) and channel capacity loss of 0.00110 bits/s/Hz.

A wideband circularly polarized four port microstrip MIMO antenna with high gain and enhanced isolation for 5G millimeter frequency applications

Abstract In this article, a MIMO antenna system featuring wide bandwidth, high gain, and circular polarization for 5G communication networks is presented. The proposed antenna enables high data rates, enhanced signal reliability, and improved performance in dynamic and challenging 5G environments. Wide bandwidth ensures compatibility with various 5G frequency bands, while circular polarization allows for better signal propagation and reception, particularly in non-line-of-sight scenarios. In that regard, the present endeavor exhibits an enhanced bandwidth 4-port circularly polarized MIMO antenna to encounter polarization mismatch along with high data rates. The presented MIMO antenna comprises four identical patches strategically positioned in orthogonal orientations in such a way as to provide the circular polarization direction. Meanwhile, the bandwidth is extended by inserting straightforward defected ground structure (DGS) and L slots. The MIMO antenna anticipated in this work offers an impedance bandwidth covering from 24 GHz to 28.5 GHz and an axial ratio bandwidth of 62% within the overall band. It demonstrates excellent performance with a high peak gain of approximately 14.84 dB. Additionally, it exhibits strong isolation of more than 20dB among the closely packed antennas, ensuring reliable communication and minimizing interference. The combination of these features in a MIMO antenna system is crucial for meeting the demanding requirements of 5G communication, including increased data capacity, low latency, and reliable connectivity. The simulated and measured outcomes exhibit robust concurrence, signifying a high level of accuracy. Consequently, the suggested MIMO antenna appears well-suited for encompassing the 5G bands designated for deployment in the USA (27.50–28.35 GHz) and Europe (24.25 - 27.5 GHz).&amp;#xD;

Research on impedance measurement based on Gallium Nitride Transistor

Abstract Impedance measurement has broad applications in fields such as electrochemistry, biology, medicine, and food safety. Typically, frequency response analyzers are used for small signal disturbance measurements, but they come with drawbacks such as high cost, large size, and limited excitation capabilities. To address the need for wide-band, large-signal, and portable impedance measurement in electrochemical applications, a novel scheme based on a Gallium Nitride device excitation circuit and amplitude-phase discrimination module is proposed. A multiphase cascade frequency-doubling buck circuit is used to inject disturbance signals into the impedance under test, and impedance parameters are obtained using discrete fourier transformafter signal sampling. By varying the frequency of the disturbance signal, impedance information across different frequencies can be captured. In this approach, the amplitude-phase discrimination module replaces the frequency response analyzer, reducing the overall size of the measurement system, while the power device-based excitation circuit enables large signal disturbances.

Compact size and wideband 4 × 4 MIMO antenna for 5G NR networks

Abstract In this paper, a crescent-shaped four-port MIMO is proposed to deploy in 5 G wireless network coverage with the advantages of wide bandwidth. The MIMO antenna is printed on an RO4003 substrate (ε r = 3.55) with a thickness of 0.203 mm and a rectangular slot in the ground plane to obtain the desired performance. The antenna is duplicated two times in an orthogonal arrangement to achieve 4 ports MIMO antenna for capacity improvement purposes. The antenna satisfies an impedance bandwidth of 20 GHz (20.5–40.5 GHz) with an isolation of ≥22 dB. Furthermore, the suggested 4-port MIMO antenna is fabricated and tested to validate the simulated outcomes, and good consistency between results is achieved in terms of scattering parameters, radiation patterns, gain, and diversity parameters. The presented 4-port MIMO antenna is considered a good candidate for future 5 G NR networks due to its competitive advantages.

Dual-Wide Multi-Band (DWMB) four-port flexible MIMO antenna for on-body multiple wireless applications including high diversity performance.

The single-input-single-output technology experiences loss of data in the communication channel due to the receiving antenna undergoing fading of the signal impinged on it. Today's need is faster data transfer with multiple applications in the single antenna with multiple-identical radiating elements, leading to multiple-input-multiple-outputDWMB (MIMODWMB) technology. The MIMODWMB configuration with multi-band capability is the objective of the proposed work with applications ranging between microwave-millimeterWave bands. The four-port Dual-Wide Multi-Band (DWMB) MIMODWMB antenna radiating electro-magnetic-energy is proposed, which generates measured bandwidths of 7.27GHz-34.32GHz (Band 1) and 46.54GHz-71.52GHz (Band 2) including applications Up-link/Down-link Satellite System, X-Band, Ku-Band, ISM 24.0GHz (24.0GHz-24.25GHz), 24.0GHz UWB Band (21.65GHz-26.65GHz), n258, n257/n261 and n263 V-band. The proposed antenna technology is printed on Rogers's low permittivity substrate with a hexagon patch etched with dual merged-elliptical slot and three identical circular slots to achieve high impedance matching for Band 1. The partial-ground is etched by a rectangular slot for better impedance matching, and two-thin-etched rectangular slits generate 60.0GHz Band 2. The thin substrate, thickness 0.254mm, is utilized for flexible applications without compromising the operation of dual wide bandwidths. The flexible antenna is also subjected to analysis of Specific-Absorption-Rate (SAR) analysis at key frequencies within both the bands and found to be within the standard limit of 1.60W/Kg for 1g of the human tissue model and corresponds to 1.01W/Kg at 10.0GHz, 0.280W/Kg at 15.0GHz, 0.475W/Kg at 26.0GHz, 0.588W/Kg at 28.0GHz & 0.301W/Kg at 60.0GHz. The high diversity performance with Envelope Correlation Coefficient<0.50, Diversity Gain≈10.0dB, Total Active Reflection Coefficent<0dB, Channel Capacity Loss<0.40b/s/Hz and multi-band capability for mobile users make the proposed work suitable for flexible on-body applications in a wireless environment. The proposed work MIMODWMB antenna offers advantages such as reduced size (20mm×24mm: 0.61λ0×0.74λ0 at λ0 = 7.27GHz) and a wide range of impedance bandwidths, which are useful for several applications. Also, due to the flexible nature of the design, they can be used for future on-body wearable applications.

Design of four-port antenna with two sets of orthogonal CO-CP performance

This work presents a four-port in-band full-duplex (IBFD) antenna that allows transmitting and receiving two sets of orthogonal co-circularly polarized signals, facilitating IBFD system applications. The single-element antenna is constructed using a six-port isolation network (SPIN) without the need for circulators, helping to reduce cost and facilitate integration. The transmit-receive isolation is accomplished via the isolation of power dividers and the cancellation guided by the coupling path of SPIN. The microwave network analysis method perfectly analyzes the operating mechanism of isolation and orthogonal co-circular polarization. The measured results confirm that this design achieves excellent two sets of orthogonal co-circular polarization. The measured results show that the 10-dB impedance bandwidth is 24.2%, the 3-dB axial-ratio bandwidth is 23.5%, and the measured 30-dB isolation bandwidth is 3.52-4.15 GHz (16.4%) with a maximum isolation of 53.2 dB.

Flexible Impedance Matching in a Self‐Diplexing Patch Antenna

ABSTRACTThis study introduces a new approach to achieve flexible impedance matching in a self‐diplexing conventional patch antenna by using paired vias for impedance bandwidth tunability. The antenna design incorporates a rectangular radiating patch, an orthogonal arrangement of a couple of paired vias, and a bottom ground plane. The patch is excited with the help of two orthogonal microstrip feeds aligned along the centerline of the broadside and narrow sides of the patch. The orthogonal vias set enables dynamic impedance matching in two frequency bands, lower and upper ranging from 2 to 3 GHz. Optimized via placement achieves high decoupling between input ports, facilitating the self‐diplexing phenomenon. To validate the proposed concept, a prototype with patch dimensions of has been analyzed, fabricated, and subjected to comprehensive experimental study. The experimental results demonstrate the successful realization of two distinct operating frequency bands, centered around 2.47 and 2.66 GHz, each exhibiting peak gain values of 5.75 and 6.31 dBi, respectively. The input port isolation values are noteworthy, measuring at −34B and −29.5 dB for lower and upper operating frequency bands, respectively. The design offers a low‐profile, minimally coupled structure with independent band control and the unique ability to simultaneously transmit and receive signals.

A split ring resonator slot based fabricated crescent microstrip patch antennas for UWB wireless system applications

This paper clarifies significant bandwidth and optimum gain for a split ring resonator slot based fabricated microstrip patch antenna for ultra wide band (UWB) wireless telecommunication system applications. The antenna has a circular slot partially cut into a circular patch and radiates in the UWB frequency range. The design system features a steady radiation pattern and an impedance bandwidth of 3.3 to 10.96 GHz. The proposed UWB notch antenna is at 4.6 GHz, 7.29 GHz, and 9.36 GHz, with an impedance bandwidth of 3.3 to 10.96 GHz. The UWB notch antenna offers linear phase response and a group delay of fewer than 1 ns. It is practical for UWB applications due to less group delay and stable radiation patterns. FR4 material with a 4.4 relative permittivity. The reported antenna is measured following the manufacturing of the prototype design using HFSS simulations. The suggested fabricated antenna minimizes return loss. The findings demonstrate that when combined with VSWR 2, the reflection coefficient covers the band ranges from 3.3-10.96 GHz.

CPW fed optically transparent ultrawideband fractal MIMO terahertz antenna with meshed ground plane

Abstract An optically transparent UWB antenna element and its two-element pattern diversity MIMO configurations are presented in this paper. Three iterations of the quarter elliptical coplanar waveguide ground plane, rectangular microstrip feedline, and octagonal annular rings make up the antenna element. By metal meshing the ground planes and loading the radiator with several octagonal slots, the optical transparency is improved. It has a maximal achieved gain of 6.78 dBi and operates with steady radiation characteristics over the frequency spectrum of 4.52–28.64 THz (145.48%). The dimensions of the antenna element are 18 × 20.5 μm2. A metallic stub is positioned between two identical antenna components that are positioned orthogonally to one another to create a two-element pattern diversity MIMO antenna arrangement. The MIMO antenna is 20.5 × 42.5 μm2 in total. Its impedance bandwidth is 23.72 THz for port 2 and 22.68 THz for port 1. Using a rectangular stub results in an intraport isolation of &gt;19 dB. Between the two ports, the planes in the radiation patterns have switched places. The diversity performance characteristics, which are considerably below the permissible limitations, are as follows: ECC &gt; 0.01, CCL &lt; 0.3 b/s/Hz, DG ∼ 10, TARC &lt; 0 dB, MEG ∼ −3 dB, and 1≤VSWR_MIMO≤2. Compared to previously published structures, the suggested antenna structures have the advantages of smaller dimensions, a larger bandwidth, and improved optical transparency.

Dual band four port MIMO antenna with dual circular polarization for Wi-Fi/WiMAX applications

The planar compact four port circularly polarized printed MIMO antenna described in this article is small and intended to support Wi-Fi and WiMAX applications. Suggested four E-shaped monopole elements make up the dual circularly polarized (CP) MIMO antenna that has two left hand CP (LHCP) elements and two right hand CP (RHCP) elements. An I shaped strip is used to join separate ground planes of designed E shaped monopole antenna to have same voltage levels. A good diversity performance is achieved with an envelope correlation coefficient (ECC) of less than 0.15. The 60 mm × 60 mm antenna is designed from FR4 material, which is inexpensive and has a 1.6 mm thickness. Using a high-frequency structure simulator (HFSS), the suggested MIMO antenna is designed and optimized. The measured findings demonstrate the circular polarization, 3-dB axial ratio beamwidth, impedance bandwidth of 2.11 GHz −2.42 GHz and 3.40 GHz-3.51 GHz, adequate axial ratio bandwidth (ARBW) of the suggested MIMO antenna along with high isolation of −17 dB, gain of 3.43 and 2.09 dBic at 2.4 GHz and 3.5 GHz respectively, TARC (Total active reflection coefficient) of less than 0 dB, a CCL (Channel capacity loss) of lesser than 0.4 bits/sec/Hz, and an MEG (Mean effective gain) value of less than 3 dB.

Compact circularly polarized metasurface antenna based on characteristic mode analysis

AbstractThis article introduces a novel, single‐layer, low‐profile, circularly polarized metasurface antenna. Through characteristic mode analysis, the optimization of a 33 rectangular metasurface structure was performed. Two orthogonal modes were selected as the operating modes, and improvements to the metasurface structure were made to achieve a 90 phase difference between these modes. The adoption of a coplanar waveguide structure enables the excitation of the metasurface, facilitating circularly polarized radiation performance for the two selected modes. The antenna's dimensions are 40 mm 40 mm 3 mm (0.67 0.67 0.05 ), featuring a −10 dB impedance bandwidth of 27.8% (4.49–5.94 GHz). The 3 dB axial ratio bandwidth is 14.2% (5.25–6.05 GHz), with a maximum gain of 7.26 dBi.

Miniaturized circularly polarized wearable array antenna for medical device applications

Antenna miniaturization is essential for healthcare applications, and numerous studies have tackled the challenge of presenting miniaturized, reliable designs while maintaining performance. This paper presents a small circularly polarized (CP) sequential wearable array antenna with overall dimensions of only 110 mm × 95 mm × 1.8 mm. It comprises four novel designs of circular-shaped elements arranged sequentially in an array configuration measured only 24 mm×24 mm×1 mm. It is fed by a separate cascade feeding network incorporating a single rat-race and two branch-line couplers. The antenna is designed for medical device applications within the 2.4 GHz Industrial Scientific Medical (ISM) frequency band. The proposed design is fabricated and experimentally tested, demonstrating wide impedance bandwidths of 21.24% (2.2–2.72 GHz) and an Axial Ratio (AR) bandwidth (AR < 3 dB) covering the entire 2.4 GHz ISM frequency band. At 2.43 GHz, the antenna achieves a gain of -14.9 dBi. Both simulation and experimental results confirm excellent performance in impedance matching, gain pattern, and circular polarization, making it promising for wearable wireless communication in medical applications. The link margin was calculated, and the specific absorption rate of the antenna was analyzed, the result revealing that it aligns with the safety limits of IEEE C95.1-1999 standards.

A compact dual‐band omnidirectional antenna with folded microstrip lines and slotlines for 5G applications

AbstractA compact dual‐band omnidirectional antenna with folded microstrip lines and slotlines is proposed. The antenna is composed of a substrate and a superstrate. The superstrate is employed to broaden the antenna bandwidth. The radiating patch is situated on the upper surface of the substrate and consists of folded microstrip lines. The performance of the high‐frequency band can be optimized based on the analysis of the current distribution intensity. The bottom of the substrate is composed of a ground plane with slotlines. The introduction and improvement of the low‐frequency band are achieved by modifying the ground plane structure with characteristic modal analysis. The antenna demonstrates omnidirectional radiation characteristics across both frequency bands. The dimensions of the antenna are π × 0.178 λ0 × 0.178 λ0 × 0.049 λ0 (π × 22 × 22 × 6 mm). The antenna achieves a maximum gain of 3.37 dBi at 2.5 GHz and 2.74 dBi at 5.8 GHz. The measured impedance bandwidths for the two frequency bands are 17.3% and 21.7%, respectively.