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Unlike popular multiband antenna array radiation based on either electric or magnetic surface currents, the use of mutually interleaved and tightly coupled electric and magnetic currents results in an aperture-reuse space-efficient multiband radiating surface for highly integrated antenna-frontend architecture and spatial power combining design scenarios. In this work, slot and dipole modes corresponding to magnetic and electric currents are effectively interleaved and excited in a surface to develop a space-efficient dual-wideband aperture-shared radiating surface. In this case, due to an effective reuse of the antenna aperture over both frequency bands, a high aperture-reuse efficiency is achieved. First, we devise a planar magneto-electric (ME)-dipole-alike antenna and analyze it in both the frequency and time domain. The antenna is then studied by the characteristic mode theory and the findings are validated using full-wave simulations. The developed planar ME-dipole-alike antenna is used to realize a dual-wideband radiating surface in which electric and magnetic currents are mutually coupled and interlaced, which is excited by properly oriented and distributed sources on the antenna's surface. Eventually, a highly isolated dual-wideband prototype was developed and fabricated using a cost-effective multi-layer Printed Circuit Board (PCB) process that operates in the Ku-band with both impedance and gain bandwidth of approximately 42% and in the Ka-band with respective impedance and gain bandwidth of 29% and 16.32%. [ABSTRACT FROM AUTHOR]

In WiFi 7 (IEEE 802.11be), Multiple Input Multiple Output (MIMO) technology plays a crucial role in enhancing throughput. This combination enables numerous applications for wearable WiFi devices. For instance, WiFi can be utilized for tracking and fall detection purposes. Additionally, wearable devices used in gaming, vital signal monitoring, and tracking can benefit from the implementation of wearable MIMO antennas. Despite the demand for wearable WiFi antennas, specifically in the new 6 GHz band, a significant gap exists in the investigation of antennas that are completely made of textile, are low profile, and provide vertical polarization and omnidirectional patterns. Addressing this gap, in this paper, a wearable planar antenna is introduced, which is specifically designed to offer an omnidirectional pattern and linear polarization. To ensure its practicality and ease of use, the antenna utilizes lightweight and wearable textile material. The design details and performance of the proposed antenna are presented. The antenna covers all three bands of WiFi, namely, 2.4 GHz, 5 GHz, and 6 GHz bands. The 10-dB return loss bandwidth is 2.4 GHz-2.5 GHz, and 4.6 GHz-7.2 GHz. The maximum Specific Absorption Rate (SAR) for an input power of 500 mW is calculated at 1.053 W/Kg for a 2 mm air gap between the antenna and tissue surface. The size of the antenna is given by a circular area of π x (50 mm)², and a thickness of 6 mm. [ABSTRACT FROM AUTHOR]

This article presents a systematic design and optimization process for a compact 0.27λ0 × 0.31λ0 multiband monopole antenna for Internet of Vehicles (IoV) applications, including navigation, Vehicle to Infrastructure (V2I), Wi-Max, and 5G. The antenna's modified ground plane enables installation within a shark-fin module on a car roof, aligning with its low-profile dimensions and high performance. Structural modifications to the initial antenna element, including the T-shaped structure and integrated stub between quad rings, enable circular polarization in the GPS L1 band. With simulated total radiation efficiency exceeding 60% at four bands, numerical simulations and physical fabrication on an FR-4 substrate are followed by antenna radiation measurement in an anechoic chamber. The measured gain at 1.575 GHz, 2.6 GHz, 4.8 GHz, and 8 GHz is 1 dBi, 2.2 dBi, 3.2 dBi, and 3.8 dBi, respectively. Additionally, ray tracing techniques evaluate the antenna's performance when mounted on a car, considering interactions with other vehicular antennas and infrastructure in urban propagation scenarios. Urban propagation analysis illustrates efficient operation, characterized by minimal delay time, favorable line of sight, and controlled path loss at frequencies 2.6 GHz and 4.8 GHz. These findings demonstrate the antenna's potential for adoption in the automotive industry. [ABSTRACT FROM AUTHOR]

The proposed surface‐mountable self‐isolated MIMO antenna covers n78 and n79 5G frequency bands. The presented design has two semicircular slots with engineered geometry to get the desired frequency spectrum. Antenna presents the bandwidth in the order of 8.77% and 2.81% at frequency resonance of 3.42 GHz and 4.98 GHz, respectively, covering FR1 5G and WLAN applications. The design presents an acceptable gain of 2.95 dBi and 2.42 dBi. The elements of MIMO antennas are kept an adequate distance apart to achieve self‐isolation in order of 19 dB. It aids further in achieving optimal MIMO diversity parameters. The 2D electrical size of the presented self‐isolated planar antenna is 0.97λ × 0.65λ at the lowest resonance. The MIMO antenna parameters were examined for the stated antenna design. The optimal envelope correlation coefficient (ECC) is near to 0.02, channel capacity loss (CCL) is around 0.2 bits/sec/Hz, directivity gain (DG) is around 9.98 dB, and the MEG ratios are near to unity. The computed performance of the resonator is validated through fabrication and experimentally tested using VNA 9912A in an anechoic chamber environment. [ABSTRACT FROM AUTHOR]

Summary In this research work, the design and analysis of a compact microstrip antenna having a monopole structure with 64.86% of wide bandwidth is presented. The main radiator of the structure is a fractal‐based geometry with the shape of a half‐Koch snowflake, and the ground plane is partial (defected ground). The design methodology of the antenna is presented using analytical modeling, and the structure prototype is fabricated to verify the performance. Measurement outcomes confirm the −10 dB bandwidth in range of 4–7.84 GHz, thus covering approximately the C‐band with omnidirectional radiation patterns. The proposed antenna shows a peak realized gain of 3.4 dBi at 7.2 GHz and has an overall dimension of 0.33λ × 0.49λ × 0.03λ, at 5.8 GHz. The structure is found compact compared to some recently reported designs and the read range is found to be 1.98 cm at 5.8 GHz. The read range and validation of the propagation test indicate the suitability of the compact and wideband planar antenna in various short‐range reader applications. [ABSTRACT FROM AUTHOR]

Summary: A band‐notched super wideband (SWB) planar monopole antenna with improved notch characteristics is proposed in this article. A hexagonal SWB antenna operating in the frequency range from 3.04 to 36 GHz is initially designed on Arlon substrate. The hexagonal patch is then loaded with optimum sized U‐shaped slot to eliminate WLAN band (5.15–5.85 GHz). The notch band's characteristics are further improved by incorporating a frequency selective surface (FSS) of a square array at a specific distance below the antenna to introduce a phase delay of 180° between the back radiation reflected by the FSS with the front radiation at the notched frequency. Improvement of notch band gain, efficiency, and antenna front‐to‐back ratio (FBR) are studied. The antenna without embedding an FSS exhibits working spectrum from 3.1 to 33.6 GHz with notch frequency gain of −2.6 dBi and efficiency 53%. The inclusion of an FSS layer at 25.2 mm behind the antenna results in notch frequency gain of −7.6 dBi with an efficiency of 23%. FBR improvement of about 16 dB is achieved at 8 GHz, and FBR is reduced by about 5 dB at the notch frequency. 169% fractional bandwidth with bandwidth dimension ratio (BDR) of 1622 is achieved in this proposed FSS integrated antenna. The inclusion of FSS to improve the band elimination performance represents the novelty of this proposal. The data are validated by electromagnetic simulation and physical measurement techniques. [ABSTRACT FROM AUTHOR]

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Two-dimensional leaky-wave antennas (LWAs) are a class of planar, traveling-wave radiators with attractive features of a low profile, ease of feeding, frequency reconfigurability of the radiation pattern, and polarization agility. Their use in conjunction with array feeders has been the subject of various investigations in recent decades, thanks to the additional degrees of freedom provided by the presence of multiple independent sources. Here, we provide a review of some of the most recent and promising array-fed two-dimensional (2-D) LWAs, selecting a couple of the most significant structures in application, namely Fabry–Perot cavity antennas and bull's-eye antennas, and discussing some of their recently proposed advanced features. [ABSTRACT FROM AUTHOR]

A rectenna designed for wireless power transfer at 900 MHz focuses on conjugate impedance matching and image impedance matching for improved efficiency. To do them, a voltage doubler rectifier circuit (VD) and a planar monopole antenna (PMA) were engineered with the same pure resistance value and integrated into the rectenna. The input impedance of the VD with 30 Ω load resistance indicated a pure resistance of approximately 73 Ω. This value closely matches the input impedance of a dipole antenna operating as a pure resistor. Since the prototype rectifier circuit is unbalanced, the authors constructed a PMA, an unbalanced antenna similar to a dipole antenna, on a double‐sided circuit board. In this setup, a microstrip line was created by extending the radiating element, achieving the impedance matchings. Measurements indicated a voltage standing wave ratio of approximately 1.03. A rectenna efficiency of 37.4% was observed for a transmission distance of 50 cm. The rectification efficiency of the VD is nearly 0% when the input power is less than −20 dBm, and the received power of the PMA is less than −20 dBm when the transmission distance is 60 cm or more. It is predicted that the rectenna efficiency will be 0% when the transmission distance is 60 cm or more. However, the rectenna efficiency was 24.6% when the transmission distance was 60 cm. This over 20% improvement is due to the connection between the PMA and the VD using pure resistance. Key Points: This study introduces the development of an integrated rectenna for RF WPT focus on achieving impedance matching to enhance efficiencyPure resistance was employed in both a voltage doubler rectifier circuit and a planar monopole antenna designMeasurements revealed that an efficiency enhancement is achieved by approximately 20% [ABSTRACT FROM AUTHOR]

This letter proposes a novel planar endfire circularly polarized antenna with widened half‐power beamwidth. Widened azimuth beamwidth mechanism of 2D sectorial electric dipole is theoretically revealed, thus it is able to combine with a rectangular magnetic dipole to yield a half‐power beamwidth widened planar endfire circularly polarized antenna. Finally, a prototype planar endfire circularly polarized antenna with sectorial flared angle of α = 270° is fabricated, simulated, and implemented to validate the design approach. As investigated, the antenna exhibits broadened azimuth half‐power beamwidth of 150° over a frequency range of 2.40–2.45 GHz. [ABSTRACT FROM AUTHOR]

This article proposes a Ka‐band substrate integrated waveguide (SIW) quasi‐Yagi array antenna with the advantages of thinness, compactness, wide bandwidth, and higher gain. Analyzing the microstrip‐to‐SIW transition structure to confirm that the designed structure provides the best performance, the optimum reflectance coefficient bandwidth can be obtained. With the optimized rectangular etched slot structure at the antenna end, the impedance matching can be tuned to improve the bandwidth. The designed array antenna is fabricated and measured for verification. The substrate is based on Al2O3 ceramic and the antenna size is 23.3 mm × $\times $ 13 mm × $\times $ 0.5 mm. The measurement results indicate that the antenna achieves an impedance bandwidth of 13.59% below −10dB, with an average gain of approximately 7 dBi and a peak gain of 7.4 dBi in 28.1–32.2 GHz. Therefore, the 1*2 antenna proposed in this paper has the advantages of compact and planar structure, easy fabrication, and easy integration into RF circuits, which is very suitable for Ka‐Band applications. [ABSTRACT FROM AUTHOR]

In this paper, we propose a printed circuit board (PCB)-based planar antenna pair, operating at 2.4 GHz and 5.0 GHz frequency bands, respectively, for dual-band routers. The antennas are both rectangular and consist of twisted radiating elements and microstrips etched on an FR4 dielectric substrate. Etching slots on the radiating elements and adjusting the serpentine microstrips influence surface current distribution and therefore effectively reduce antenna size and enhance antenna gain. The proposed antenna features a compact size compared to general router antennas and demonstrates high gain characteristics compared to dipole antennas. In the 2.3–2.5 GHz band, the simulated S11 of the 2.4 GHz antenna was lower than -10 dB, while the gain was 3.9 dBi at 2.4 GHz. In the 5.1–5.9 GHz band, the simulated S11 of the 5.0 GHz antenna was lower than -10 dB, and the gain was greater than 4.8 dBi. The proposed antenna has potential for application to router antennas. [ABSTRACT FROM AUTHOR]

This work presents a new compactly printed ultrawideband antenna for mobile satellites (8.025 GHz), metrological aids (9.5 GHz), and aeronautical radio navigation (9-9.2 GHz) applications. The proposed antenna is made up of four straightforward radiating rectangular-shaped strips, the overall geometry of which resembles two U-shaped in the radiating patch, fed by a 50O microstrip feed line. Two exponential patches, along with a rectangular patch, are implemented in the ground part of the structure, which can be effectively constructed by varying the sizes and geometries of these two U-shaped strips. The proposed antenna is compact overall. The proposed antenna is designed, simulated, fabricated, and tested minutely. The measured values of 10 dB return loss absolute/fractional BW of 10 GHz/142 % at the center frequency, minimum/maximum gain of 2/6.1 dBi, and maximum/minimum radiation efficiency of 92/70 % are achieved from the 2 to 12 GHz frequency range. These bandwidths are also well suited for 2.5/3.5/5.5-GHz WiMAX bands and 2.4/5.2/5.8-GHz WLAN bands. In addition, a comparison table is provided to prove the state-of-the-art design of the antenna. [ABSTRACT FROM AUTHOR]

In a highly integrated analog radio-over-fiber transceiver, seamless integration of the antenna-frontend is crucial as an antenna is generally implemented on a high-κ material, which is set to highly degrade the antenna's performance. This work is concerned with the radiation behavior improvement of a planar leaky-wave antenna with an inductive partially reflecting surface (PRS) on a high-κ substrate for the development of a highly directive antenna. To begin with, we show how a thin and single-mode resonance (SMR) inductive PRS on high-κ materials in a planar leaky-wave antenna is set to provoke two resonance frequencies (i.e., PRS and cavity resonances) to converge, thereby diminishing the antenna's broadside directivity. By applying an equivalent circuit model, we explain how a multi-mode resonance (MMR) PRS can adequately be applied to address the underlying challenges. Subsequently, the leaky-wave radiation behavior of an antenna with a heterogeneous substrate is investigated and analytical equations are derived and verified with a full-wave simulation. The effects of material permittivity and thickness in a heterogeneous-cavity antenna on leaky-wave performance are investigated using these approximate yet accurate-enough equations. To justify the findings, two 9 × 9 planar leaky-wave antennas are prototyped on heterogeneous substrates based on SMR and MMR PRS and the radiation performances are compared. Our investigations reveal that in the proposed scenario, an MMR PRS can significantly enhance the antenna's broadside directivity by over 4 dBi at the resonance frequency (27.5 GHz), which is also set to improve radiation pattern compared to a SMR-based antenna. Finally, a single-fed dual-band aperture-shared antenna with a large frequency ratio (S-band and Ka-band) is developed and fabricated on a high-κ substrate based on the proposed MMR PRS. [ABSTRACT FROM AUTHOR]

Integrated quantum photonic circuits require the efficient coupling of photon sources to photonic waveguides. Hybrid plasmonic/photonic platforms are a promising approach, taking advantage of both plasmon modal confinement for efficient coupling to a nearby emitter and photonic circuitry for optical data transfer and processing. In this work, we established directional quantum dot (QD) emission coupling to a planar TiO2 waveguide assisted by a Yagi-Uda antenna. Antenna on waveguide is first designed by scaling radio frequency dimensions to nano-optics, taking into account the hybrid plasmonic/photonic platform. Design is then optimized by full numerical simulations. We fabricate the antenna on a TiO2 planar waveguide and deposit a few QDs close to the Yagi-Uda antenna. The optical characterization shows clear directional coupling originating from antenna effect. We estimate the coupling efficiency and directivity of the light emitted into the waveguide. [ABSTRACT FROM AUTHOR]

• A novel parabolic rigid deployable antenna based on origami was designed; • The optimization framework of parabolic rigid deployable antenna structure was estU:\ES\DTD560\JASR\17318\S5ablished; • Connection nodes and rotating axis were designed to circumvent collision during the process of deploying and folding. This paper introduces a novel approach for optimizing the packing and design of deployable parabolic rigid antenna structures based on origami, tailored to meet specific requirements related to the number of solid-surface blocks and the size of the folded antenna. The study begins by selecting a single-vertex four-crease configuration with one degree of freedom from the origami pattern, guided by mobility analysis, to optimize block arrangement. Subsequently, a planar model is employed to qualitatively examine the impact of geometric parameters on the stowage efficiency of the antenna. Building upon the insights gained from the planar model, an optimization framework for the parabolic rigid deployable antenna structure is established. The objective function of the optimization is the stowage volume, while simultaneously adhering to stiffness, collision, and mobility constraints. The design parameters of the antenna structure are thoroughly analyzed. To mitigate collision risks during folding, design considerations are applied to placement of support nodes, location of rotating axes, and block division, leveraging the optimized parameters. The practicality of the proposed method is successfully demonstrated through the folding of a simulated 3D model and of a physical 3D printed model. These tangible representations show the feasibility of the presented approach, affirming its potential applicability in the optimization and design of deployable parabolic rigid antenna structures. [ABSTRACT FROM AUTHOR]

The letter presents a low‐windage omnidirectional antenna for high‐speed aircraft in the UHF and L bands. It combines a planar biconical antenna with a printed tape parasitic branch monopole antenna. Upgrading the traditional restricted‐length biconical antenna to a double‐layer planar design meets the compact, lightweight, and low windage requirements of airborne use. To enhance bandwidth and meet the lightweight, compact criteria of high‐speed aircraft, the planar‐printed monopole antenna integrates parasitic stubs and loop antenna concepts. Experimental results exhibit excellent isolation between antenna elements, with over 15 dB segregation and operational spectrum return loss of 27% and 18% at 10 dB. The voltage standing wave ratio is below 2, with less than 5 dB variation in the horizontal radiation pattern across frequency bands. The antenna, measuring 20 mm × 190 mm × 270 mm and weighing around 0.5 kg, holds great promise for high‐speed aircraft applications. [ABSTRACT FROM AUTHOR]

Summary: The investigations related to the planar antenna array have attracted much attention due to their vast applications in the areas of advanced wireless communication and electromagnetics. This article presents an effective synthesis method of a sparsely thinned symmetric planar antenna array using three well‐known meta‐heuristics including symbiotic organism search (SOS) algorithm, moth fly optimization (MFO), and multi‐verse optimization (MVO) algorithms. The main aim of this work is to optimize the positions of the switched‐on antenna elements on the array aperture in order to reduce the value of side‐lobe levels in the radiation field pattern in multiple planes for a desired first null beam width and subsequently to obtain the maximum reduced number of array‐elements in the antenna array. Two different cases are performed to optimize the radiation pattern in different azimuth angles with two different examples. The proposed methods can constrain the total number of array elements, inter‐element distance, and aperture area of the array. The radiation pattern characteristic and computation time linked with each example and each algorithm are recorded and compared with each other as well as with a fully populated planar symmetric rectangular array antenna of same aperture size for arriving at the conclusion. The simulation‐based results demonstrate the effectiveness of the proposed design and the efficiency of the performance using the SOS algorithm. [ABSTRACT FROM AUTHOR]

In this manuscript, the design of a compact-size circular patch Ultra-Wideband (UWB) antenna with enhanced fractional bandwidth (BW), peak realized gain (PRG), and proper impedance matching is presented. The modified antenna has three circular slots etched from the circular path (top), fed by a 50O microstrip feed line. These circular slots play a significant role in improving the impedance bandwidth. Additionally, the partial ground plane with a slot integrated with a rectangular stub is used in order to achieve a bandwidth for an operating range of 3.25 GHz - 27 GHz. The proposed antenna is designed, fabricated, and tested in the laboratory in order to validate with simulation data. The designed antenna size is 25 mm? 20 mm × 0.508 mm. The experimental value of 10 dB return loss absolute/fractional BW of 23.75 GHz/157.08% at the center frequency, minimum/maximum gain of 5.90/12.05 dBi, and maximum/minimum radiation efficiency of 85/97 % are achieved from the 3.25 GHz to 27 GHz frequency range. In addition, a comparison table is provided to prove the state-of-the-art of the antenna's design. The proposed antenna is suitable for wireless services, radar, and satellite communication. [ABSTRACT FROM AUTHOR]

To tackle the challenge of keeping 5G mobile devices compact while supporting millimeter-wave bands, we've created an ultra-compact 4-port dual-band MIMO antenna with a defected ground structure (DGS). This design minimizes mutual coupling and covers a broad frequency range. Built on a Rogers TMM4 substrate with dimensions of 17.76×17.76 mm2, the antenna includes four planar patch antennas positioned perpendicularly at the corners. Each antenna operates at 28/38 GHz and features a rectangular patch with four rectangular slots and a full ground plane. The patches are separated by 0.5 λo, with the DGS further reducing mutual coupling. Both simulations and measurements indicate a significant reduction in mutual coupling (−39 to −60 dB), improving ECC, TARC, MEG, and DG. Time-domain and SAR analyses confirm the antenna's efficiency and its suitability for 5G devices. [ABSTRACT FROM AUTHOR]

A novel compact dual-band antenna based on dual-cap metasurface (MS) is proposed. By etching circumferential circular ring slots on one side of the substrate and a large cruciform slot on the other side, the dual-cap MS operates in two frequency bands. In addition, by placing the dual-cap MS at the back of a circular ring planar antenna which serves as a reflector, the impedance characteristic of the antenna in lower band and gain both in two bands are improved. The results show that this dual-cap MS antenna operates in the Wireless Local Area Network (WLAN) bands of 2.43-2.6 GHz and 5.48-6.05 GHz. Moreover, the maximum gains in lower and upper bands can reach 6.9 and 5.8 dBi, respectively. [ABSTRACT FROM AUTHOR]

In this paper, a novel input impedance analysis methodology based on Babinet's principle to broaden bandwidth is proposed, and a broadband multiple-input and multiple-output (MIMO) antenna system is designed, fabricated, and measured for fifth-generation (5G) and Wireless Fidelity (Wi-Fi) 6E/7 mobile applications. By analyzing the input impedance of open-slot antennas and planar monopole antennas using numerical calculations, the characteristics of the input impedance can be obtained. We find that combining the two antenna types in parallel can significantly enhance the bandwidth. Then, the four-dimensional image calculated by MATLAB based on the parallel impedance formula is processed to validate the methodology. Thus, a broad antenna element based on the impedance property analysis methodology is achieved, which operates ranging from 2.6 GHz to 7.46 GHz. Moreover, the equivalent circuit of the antenna element is established to further verify the validity of the methodology. Finally, a broadband MIMO antenna system consisting of eight antenna elements is designed, fabricated, and measured, and the isolation performance is better than 12 dB. Acceptable total efficiency higher than 45% is also obtained with envelope correlation coefficients (ECCs) lower than 0.05. The proposed impedance property analysis methodology innovatively proposes a new way to increase bandwidth, which can be widely applied in various antenna designs. Also, reasonable results show that the proposed MIMO antenna system is a good candidate for 5G and Wi-Fi 6E/7 mobile applications. [ABSTRACT FROM AUTHOR]

A compact planar self-quadruplexing antenna backed with the SIW technology with high isolation between the input ports is designed and demonstrated for the simultaneous quad-band operation of the antenna. The SIW cavity is integrated with a Swastik shaped slot and two metallic vias to generate four distinct frequency bands with high gain and low cross polarization. Utilizing four distinct orthogonal patches with different lengths, each independently connected to a 50- Ω microstrip feed line, makes the antenna operate at four frequency bands of 4.8, 5.5, 6.6, and 7.6 GHz. The minimum value of Front-To-Back-Ratio (FTBR) is 18 dB, and the minimum isolation between the input ports is 28.4 dB. The measured values of peak gains in the frequency bands 4.8, 5.5, 6.6, and 7.6 GHz are 5.05, 6.20, 6.45, and 6.32 dBi, respectively. Hence, a single antenna consists of four signals transmitting or receiving simultaneously from four individual input ports without interfering with each other and with high isolation between the input ports confirms the selfquadruplexing property of the antenna. This antenna configuration enables the independent tuning of each resonant frequency according to specific application needs by manipulating a single parameter, that is the length of the patch and without disturbing other performance parameters of the antenna. To validate the simulation results, the antenna is fabricated and tested. The measurement findings match the simulation results closely, which confirms the quad-band operation of the antenna design. Simple configuration, compact size, high gain, and low cross polarization of the antenna make the proposed planar antenna suitable for practical multiband applications and for handheld transceivers with high isolation between the input ports. [ABSTRACT FROM AUTHOR]

This study introduces a groundbreaking antenna system, the directive Metasurface Half-Maxwell Fish-Eye (MHMF) lens antenna, tailored specifically for Internet-of-Things (IoT) networks. Designed to operate at 60 GHz, this antenna ingeniously integrates a dipole antenna within a parallel-plate waveguide to illuminate a Half-Maxwell Fish-Eye (HMFE) lens. The HMFE lens serves as a focal point, enabling a crucial high gain for IoT operations. The integration of metasurface structures facilitates the attainment of the gradient refractive index essential for the lens surface. By employing commercial Ansys HFSS software, extensive numerical simulations were conducted to meticulously refine the design, focusing particularly on optimizing the dimensions of unit cells, notably the modified H-shaped cells within the parallel waveguides housing the beam launchers. A functional prototype of the antenna was constructed using a standard PCB manufacturing process. Rigorous testing in an anechoic chamber confirmed the functionality of these manufactured devices, with the experimental results closely aligning with the simulated findings. Far-field measurements have further confirmed the effectiveness of the antenna, establishing it as a high-gain antenna solution suitable for IoT applications. Specifically, it operates effectively within the 60 GHz range of the electromagnetic spectrum, which is crucial for ensuring reliable communication in IoT devices. The directive HMFE lens antenna represents a significant advancement in enhancing IoT connectivity and capabilities. Leveraging innovative design concepts and metasurface technology, it heralds a new era of adaptable and efficient IoT systems. [ABSTRACT FROM AUTHOR]

The presented research aims to analyze in detail the characteristics of broadband matching antennas specifically designed for 5G mobile communications applications, with an emphasis on innovative composite materials. The study focuses on a compact planar loop antenna designed for use on smartphones, covering the LTE/WWAN frequency bands 824 to 960 MHz, 1,710 to 2,690 MHz, and 3,300 to 3,600 MHz for full coverage of modern 5G networks. Experimental and numerical methods are used to broadly analyze the frequency range associated with 5G networks. The features of the use of composite materials in the implementation of antenna devices in 5G technologies are noted. A broadband matching circuit (BMC) with elements with lumped parameters and a reduced sensitivity invariant has been synthesized. A 3D model of the adaptive selective surface controller (SSC) was developed using CST Studio. The study results highlight the benefits of new composite materials in improving the performance of 5G antennas. This research makes a significant contribution to the development of 5G technologies by optimizing antenna design for efficient data transmission in modern mobile networks and can be a valuable resource for engineers and designers working in this field. [ABSTRACT FROM AUTHOR]

Phase gradient metasurfaces (PGMs) have demonstrated powerful capacities for manipulating light waves freely. However, PGMs have limitations of bulky size and narrow bandwidth that hinder further applications. In this work, we present the design and analysis of a reflection-type PGM by utilizing the phase choice freedom in the supercell. It is found that in this well-designed PGM, perfect negative reflection including perfect retro-reflection can be observed not only at the initially designed frequency f1 = f0, but also at its double frequency, i.e., f2 = 2f0, which is named as the frequency-doubling perfect negative reflection. As a proof of concept, we design and fabricate a reflection-type PGM with 4π phase coverage in a supercell, with experimental results in perfect agreement with the theoretical ones. Our work offers an approach to design planar optical devices at multiple operating frequencies, holding potential applications for frequency division multiplexing communication, remote sensor technology, laser tracking, and more. [ABSTRACT FROM AUTHOR]

A wideband planar microstrip antenna with good horizontally polarized omnidirectional radiation performance is presented. Using tightly coupled structures, six planar dipole elements are deployed in a circular pattern, and radiation is synthesized into a horizontal omnidirectional radiation pattern by superposing the far‐field pattern of the six dipoles. Owing to the tight coupling between radiating elements, the proposed antenna has a wide operating band. The radiating elements are printed on a printed circuit board and excited by a balun with uniform magnitude and synchronized current. A prototype is manufactured and measured. The measurement results show that the impedance bandwidth of the proposed antenna is 102% $ \% $. The gain variation of the horizontal omnidirectional pattern is less than 1.2 dB in the 1.27–3.89 GHz band. Within the operating frequency band, the total efficiency and radiation efficiency are greater than 82% and 88%, respectively. The diameter of the antenna is 0.48λL ${\lambda }_{L}$, where λL ${\lambda }_{L}$ is the wavelength corresponding to the lowest frequency in the operating band. [ABSTRACT FROM AUTHOR]

The authors design and experimentally analyse an anisotropic metasurface for the simultaneous conversions of linear cross and circular polarisations in the C and partial X bands. The proposed compact structure utilises a dual‐cut square‐ring resonator and a square patch on an FR4 substrate above a ground plane. The full‐wave simulations exhibit over 92% efficiency in cross‐conversion over a fractional bandwidth (BW) of 52.3%. The proposed metasurface efficiently converts linear to circular polarisation in two different bands, achieving left‐hand circularly polarised and right‐hand circularly polarised efficiencies exceeding 93% and 89%, respectively. The compact unit‐cell with dimension 0.22λ × 0.22λ attains stable polarisation transformation efficiency rates exceeding 80% up to 40° incident angles. The design is adaptable for efficient wide BW across both lower and higher (millimetre‐wave) frequencies through scaling. A prototype of the proposed polarisation converter (PC) was realised and validated effectively in measurements, aligning well with simulations. This PC features a novel and simple structure with multifunctional wideband operation, stable incident angle output, polarisation insensitivity, and scalability, making it an efficient front‐end for various radio frequency applications, including polarisation control and polarisation transformers. [ABSTRACT FROM AUTHOR]

BACKGROUND: Implantable medical devices are being valued as one of the developments of wireless biomedical technology. OBJECTIVE: This paper presents a mid-field wireless power transmission (WPT) system, which is designed for implantable applications and operates at the 2.40–2.48 GHz band of Industrial, Scientific, and Medical (ISM). METHODS: A new compact transmitter structure is proposed, and a small 4-C planar ring antenna is designed as the receiving element. A measurement setup is fulfilled on porcine tissues to verify the power transmission system. RESULTS: The experimental results show that the operating bandwidth is 2.2–2.62 GHz and the transmission coefficient can reach - 26.32 dB at a distance of 50 mm. The effects of tissue differences, placement depth, and different transmission distances were also measured. The displacement and deflection tolerances between the transmitter and the implant receiver also have good performance. In the safety standard of specific absorption rate, for the 1 W output power from the mid-field transmitter, the receiving power of the implantable antenna at the mid-field distance can reach 79.6 mW. CONCLUSION: With measurements of different implantation and transmission distance on pork, the mid-field power transmission efficiency is proven and shows the high performance of the system. [ABSTRACT FROM AUTHOR]

An electrically small multiband planar antenna is presented by using rectangular split ring resonator (RSRR) metamaterial element for LTE, WiMAX and WLAN applications. The designed antenna possesses asymmetric coplanar strip (ACS)-fed Hilbert Curve Fractal Antenna (HCFA) loaded with RSRR metamaterial for multiband radiation at 1.44 GHz, 3.76 GHz and 5.27 GHz. ACS-fed HCFA is responsible for creating the first (at 1.44 GHz) and second (at 3.76 GHz) resonance frequencies owing to the coupling between ACS-fed HCFA and ground plane. Moreover, the RSRR yields upper resonance at 5.27 GHz owing to the metamaterial transmission line. The stop band and pass band nature of the RSRR and its negative permeability characteristics are described using an effective medium theory. An equivalent circuit model of the proposed antenna is investigated with the help of Agilent ADS to validate the operating frequencies. Also, the geometrical parameters have been optimized using the artificial neural network (ANN), which is performed by MATLAB. The proposed antenna has been fabricated on a 18 × 16.5 × 1.6 mm3 FR-4 dielectric having ε r = 4.4 and tan δ = 0.02. It provides multiband response at 1.4 GHz, 4.4 GHz and 5.3 GHz with a − 10 dB impedance bandwidth of 330 MHz, 570 MHz, and 340 MHz, respectively, which is usable for LTE, WiMAX and WLAN band applications. [ABSTRACT FROM AUTHOR]

The interest in precise point positioning techniques using smartphones increased with the launch of the world's first dual-frequency L1/L5 GNSS smartphone, Xiaomi Mi 8. The smartphone GNSS antenna is low-cost, sensitive to multipath, and limited by physical space and design. The main purpose of this work is to determine the mechanical location and antenna performance in terms of radiation pattern in an anechoic chamber using a Vector Network Analyzer (VNA) and robotic positioning platform by varying the elevation and azimuth angles between the transmitter and smartphone GNSS antennas; the power received and satellite visibility are developed in an outdoor scenario. The results show a Planar Inverted-F Antenna with an omnidirectional radiation pattern without gain. The L1/E1/B1 and L5/E5a/B2a GNSS antennas are physically located at the top face of the screen, with dimensions of 48 × 17 mm and 60 × 13 mm, respectively. With the screen with line-of-sight toward the sky, L5 satellites have a better signal–noise ratio (SNR), unlike the back side, which loses 99% of the data in the PPP solution. Under multipath scenarios, the L1 GNSS smartphone antenna works with 25% less power than the GPS user segment recommendation, showing high sensitivity to track weak signals. [ABSTRACT FROM AUTHOR]

The growing interest of the scientific community in surveying and monitoring submerged assets is motivated by the increasing demand for high-resolution products with certified accuracies. While many instrumental and methodological solutions for documenting, monitoring, and studying archaeological and cultural heritage through geomatics techniques are already available for the terrestrial environment, the challenge remains open to the underwater context. High-resolution capability and accurate positioning are still difficult to achieve in these environments. This paper discusses the limitations of positioning and georeferencing techniques in the underwater environment. It explores how existing methods and new instruments can be used to perform accurate topographic surveys of ground control points (GCPs) in very shallow waters (within 5 m depths), which can support the photogrammetric reconstruction of underwater assets. This research presents two innovative prototypes: a self-built plastic marker for topographic use in the underwater environment and a self-built aluminum pole for topographic use in the marine environment. The prototypes are tested and validated with a tilt-compensating smart antenna to reduce planar and altimetric errors when the pole is not perfectly level and to work independently of the shore proximity required when using a total station to perform said measurements. [ABSTRACT FROM AUTHOR]

Purpose: Propagation characteristics of millimeter wave (mmW) frequencies that are being explored for implementing 5G network are quite different from sub 3GHz frequencies in which 4G network is operating, and hence antenna design for mmW 5G network is going to be significantly different. The purpose of this paper is to bring forth the unique challenges and opportunities of planar antenna design for mmW 5G network. Design/methodology/approach: A lot of notable contemporary work has been investigated for this study and reported in this paper. A comparison of 4G and 5G technologies has been carried out to understand the difference between the air interface of two technologies that governs the antenna design. Important research gaps found after collating the work already done in the field have been bullet pointed for the use by many researchers working in this direction. Findings: Several antenna design considerations have been laid out by the authors of this work, and it has been claimed that mmW 5G antenna design must satisfy these design considerations. In addition, prominent research gaps have been identified and thoroughly discussed. Originality/value: As research in the field of mmW antenna design for 5G applications is still evolving, a lot of work is currently being done in this area. This study can prove to be important in understanding different challenges, opportunities and current state-of-art in the field of mmW planar antenna design for 5G cellular communication. [ABSTRACT FROM AUTHOR]

Summary: Wireless sensor networks (WSNs) are used to monitor the real‐time parameters of remote/restricted access areas of automation industries which are tightly sealed. In such scenarios, the main challenge is signal transmission in sealed environments. An omnidirectional radiation pattern is preferred as a control link for receiving packets or periodic updates from its neighbouring nodes. However, the gain and directivity of omnidirectional antenna should be sufficient enough to transfer the data to the collecting node. This paper proposes a high‐gain horizontally polarised omnidirectional radiation pattern planar antenna resonating at the 2.45 GHz. The developed microstrip planar antenna offers a very simple and compact structure printed on either side of FR4 epoxy substrate (ε = 4.4) suitable for WSN nodes. A printed dipole director is arranged orthogonally and offers horizontal polarisation. A pair of parasitic elements is placed parallel to dipole radiators to improve the total gain of the antenna. A parallel pair of parasitic elements is placed on an inclination of 45° in antenna design plane for uniform distribution of surface current to achieve the omnidirectional antenna. The symmetrical structure of the radiating element on either side of the substrate avoids the design of the traditional balun structure to reduce the complexity of feeding network. The developed antenna is simulated, fabricated, measured and tested using WSN. The measured radiation (directivity = 3.9 dBi) is maximum at Ⴔ = 0° and Ⴔ = 90°. The frequency response of the antenna indicates a −10 dB fractional bandwidth of 380 MHz (2.24 GHz–2.62 GHz). The measured far‐field response shows a stable average gain of 3.9 dBi over the ISM band. The real‐time received signal strength indicator (RSSI) of the antenna installed in the sensor node observed a success rate of 79.46% with a transmission error of 10%. The observed response of an antenna makes it well‐suitable for WSN in industrial automation. [ABSTRACT FROM AUTHOR]

A novel design for Vivaldi antenna is introduced to operate in more than one frequency band in the millimeter-wave spectrum range with high gain. The proposed Vivaldi antenna is planar and printed on both sides of Rogers 3003C flexible substrate. A parasitic annular ring is added to each arm of the Vivaldi antenna to adjust the impedance matching and maximize the gain. The dimensions of the antenna are optimized using the CST microwave simulator to obtain the best impedance matching bandwidths and highest gain in a compact-size antenna. The 28-GHz band is then selected due to its importance to enhance the gain and improve the operating bandwidth for the 5G applications. A gain of 10 dBi and bandwidth of 6.1 GHz are obtained at 28 GHz. A multiple-input multiple-output (MIMO) antenna system is then designed for pattern diversity for the fifth-generation mobile applications. The performance of the MIMO system is evaluated regarding the envelope correlation coefficient and the diversity gain showing good results. The optimized antenna is fabricated and its return loss and radiation patterns are measured showing good consent between the simulations and the practical work. The MIMO antenna system is also fabricated, and its performance is measured regarding the reflection and coupling coefficients showing good agreement between the measurements and simulations. [ABSTRACT FROM AUTHOR]

This paper presents the results of a numerical study of a planar antenna with a complex form factor. The antenna is based on a combination of two resonators, a disc resonator and a ring resonator. The feeding of the ring resonator is performed using a coplanar structure: pointwise by galvanic contact between the central conductor of the coplanar line and the ring resonator and by distributed electromagnetic coupling of the ring resonator and the aperture of the outer conductor of the coplanar line. The antenna was placed over a metal plane whose geometric dimensions were significantly larger than those of the antenna to exclude the influence of edge diffraction effects. In numerical simulation a complex approach including the method of semi-open resonator and the finite element method (FEM) implemented within the commercial package HFFS was used. The dependences of spectral, energy and polarization characteristics on material constants and frequency parameter have been investigated. It was found that within the framework of single-parameter optimization it is impossible to simultaneously achieve a high level of all important parameters. The values of frequencies of spectral lines in the spectral characteristics of the antenna are found with a relative error not worse than 1200 Hz. Frequency ranges within which there is no degeneration of oscillation types are established. The distributions of surface currents on the metal elements of the antenna, allowing to determine the position of phase centers of excitation, are presented. It is shown that the proposed antenna can provide an acceptable level of matching both at fixed frequencies and in sufficiently wide local frequency bands, reaching 11% with respect to the center frequency of the sub-band. The boundary values of gain coefficients in frequency bands are established. The simulation results allow to predict effective radiation with formation of practically single-lobe radiation pattern and presence of elliptical polarization. [ABSTRACT FROM AUTHOR]

In this paper we describe a class of printed patch antennas that involve 3 metal layers completely integrated within a single dielectric, which are of very high efficiency and significant gain. The antennas presented have dual linear polarization and sufficient impedance matching bandwidth to be suited for sub-6 5G applications, producing advantageous antenna arrays monolithically integrated into a single planar PCB that are thin and lightweight. The feeding mechanism of the antennas is through an intermediate dedicated metal layer designed appropriately as a coupler, coupling the input power at the feeding ports of the structure to the antenna without a direct metal contact to the radiating patch. The multilayer design allows monolithic integration of multi-element combiners and phase shifters within the PCB of antenna arrays and results in compact monolithic scanning arrays. Theoretical full-wave simulations and measurements of fabricated prototypes are in very good agreement and validate the proposed designs. [ABSTRACT FROM AUTHOR]

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Planar feedback micro-nanoscale cavities, shaped by advances in nanofabrication, have revolutionized laser technology, giving rise to chip-scale, low-threshold lasers with wide-ranging applications, spanning from atmospheric investigation to incorporation into central devices such as smartphones and computer chips. The complicated designs of these cavities, shaped by the physics of periodic and quasiperiodic structures, empower efficient manipulation of light-matter interaction and coherent light coupling, minimizing losses. This review thoroughly explores the underlying concepts and crucial parameters of planar feedback microcavities, shedding light on the photophysical behavior of recent gain materials pivotal for realizing optimal lasing properties. The examination extends to photonic crystal bandgap (PhC BG) microcavity lasers, specifically with periodic and quasiperiodic architectures. In-depth assessments probe into the principles and designs of each architecture, exploring features such as wavelength selectivity, tuneability, lasing patterns, and the narrow linewidth characteristics inherent in distributed feedback (DFB) microcavity lasers. The review highlights the intriguing characteristics of non-radiative bound states in the continuum (BIC) within periodic architectures, emphasizing trends toward high-quality factors, low thresholds, and directional and vortex beam lasing. It also explores the nascent field of Quasiperiodic (QP) microcavity lasers, addressing challenges related to disorder in traditional periodic structures. Comparative inquiries offer insights into the strengths and limitations of each architecture, while discussions on challenges and future directions aim to inspire innovation and collaboration in this dynamic field. [ABSTRACT FROM AUTHOR]

This paper proposes a genetic algorithm for the design of passive components operating at THz frequencies and its experimental validation using an exemplar patch antenna. The patch antenna is based on an SU8 substrate, with a binary array describing the placement of metal "bits" replacing the conventional patch. These "bits" are constrained at 25 × 25 μm2, ensuring ease of fabrication. Optimal configurations of this array are determined using a finite-difference time-domain solver coupled to the genetic algorithm, which simulates and optimizes for maximum power collection in the frequency range of 0.10–5.0 THz. The aim was to produce an evolved patch antenna design with double the power collection efficiency across the majority of the frequency range compared to a reference, plain patch antenna of the same size. This was successful with a 5.3 dB mean improvement in simulated power collection compared to a plain reference patch. A vector network analyzer in conjunction with 0.80–1.0 THz frequency extenders was used to validate the simulation results. The antennas were arranged in pairs with variable feed length to determine the feedline attenuation and validate the simulated antenna directionality. [ABSTRACT FROM AUTHOR]

Abstract A planar antenna with dual‐linearly polarised end‐fire radiation is proposed. A tapered double‐sided symmetrical spoof surface plasmon polariton (SSPP) transmission line (TL) with tilted unit cells is proposed. The SSPP TL can operate in two types of first high‐order modes: the first high‐order even mode and the first high‐order odd mode. A two‐port feeding structure is designed to feed the SSPP TL. When the signal is fed from port 1, the energy travels through the substrate integrated waveguide and eventually excites the even mode on the SSPP TL, leading to vertically polarised radiation. Conversely, when the signal is input from port 2, the energy travels through the stripline‐to‐slotline transition and eventually excites the odd mode on the SSPP TL, generating horizontally polarised radiation. According to the measured results, a 54.6% overlapping bandwidth is obtained. The horizontal and the vertical polarisations achieve a maximum gain of 14.7 and 12.2 dBi, respectively.

Summary: A small size, dual‐band and dual‐sense monopole antenna is proposed to improve the axial ratio bandwidth (ARBW). The proposed antenna is considered on a low‐cost lossy FR4 substrate with parasitic strips (PSs) and partial ground plane of half guided wavelength dimensions. The dimension of the antenna in terms of wavelength is 0.27λ0×0.29λ0×0.02λ0, where λ0 is the wavelength at the lowest resonant frequency. The circularly polarized (CP) mode is created for strong orthogonal electric fields EX and EY. The obtained phase difference (PD) between two electric fields EX and EY is varied from 86° to 96° under ARBW. The achieved ARBW is 3.68–3.8 GHz, 4.84–12.58 GHz, and impedance bandwidth (IBW) is 3.51–3.82 GHz and 4.28–15 GHz. The applications of the proposed antenna are International Telecommunication Union (ITU) for 5G, C‐band IEEE 802.11a wireless local area network (WLAN) at 5 GHz (5.15–5.825 GHz) and X‐band wireless systems. [ABSTRACT FROM AUTHOR]

The process of spectrum sensing in cognitive radio (CR) networks plays a critical role as it identifies frequencies that are not utilized, hence saving on bandwidth and energy. For spectrum sensing in CR systems, the design of multi-input multi-output (MIMO) antenna system for a small super-wideband (SWB) diversity antenna system with three band-notches is suggested. Four identical semi-elliptical monopole antennas, positioned perpendicularly with feed lines tapered CWG type, make up a MIMO antenna. Every antenna for the SWB characteristics has a cross-slot carved on the bottom that is comparable to the radiator. The antenna radiator features two connected slits that produce the image of the split ring resonator and a staircase-like slit to ensure that there is no negative impact on SWB. The antenna has a bandwidth ratio of 36:1 and resonates between 1.2 and 43 GHz. Isolation of up to 18dB and envelop correlation coefficient less than 0.01 is implemented within a resonating band for the MIMO antenna that have orthogonally placed antenna elements. At 3.5 GHz, 5.5 GHz, and 8.5 GHz, there is a drop in gain for a maximum gain of 4 dBi offered by the antenna. A small antenna comprising of 52 mm × 52 mm MIMO has been proposed for this research. The proposed antenna provides higher bandwidth ratio, which makes it simple to integrate into modern RF equipment. This SWB, MIMO antenna surpasses those previously discussed in the literature possessing multiple notched bands. Likewise, the three notches of small super-wideband (SWB) are obtained and implemented without incorporating any filter, thus, the antenna design is quite feasible. [ABSTRACT FROM AUTHOR]

Beam-switching antennas based on quasi-optical beamformers can provide cost-effective solutions for high-frequency communication applications. Here, we propose a wide-angle beam-switching planar lens antenna based on the recently presented virtual image lens. The antenna operates from 24 to 28 GHz and produces a beam that can be steered in a 100-degrees range in one plane with less than 2 dB simulated gain variation over the angular range and operational band. The performance of the presented antenna is similar to reported lens antennas with stable gain, but the proposed lens requires a smaller refractive index range to be realized, which alleviates the manufacturing. [ABSTRACT FROM AUTHOR]

This paper proposes a broadband optical transparent antenna using a transparent conductor film on a transparent polyethylene terephthalate (PET) substrate. The planar wide‐slot antenna coupling fed by microstrip has a wide impedance bandwidth, so it is selected to design the transparent antenna. The upper surface of the PET substrate is a microstrip line with a fork‐shaped tuning branch, and the lower surface is a wide slot. They were made of transparent conductor film. Finally, a new capacitive coupling method is used to feed the transparent antenna. The transparent conductor film used in the antenna is metal mesh, which was developed by 3M company. The metal mesh with an open area greater than 80% to achieve high transmittance. The measured results show that the impedance bandwidth is 177% (0.30–5.0 GHz), and the gain of the antenna varies from 5.06 to 7.8 dBi over the entire frequency band. Therefore, it can be well applied to the current indoor mobile communication system. [ABSTRACT FROM AUTHOR]

This paper presents a small‐sized, planar antenna fabrication for ultra‐wideband (UWB) and vehicle‐to‐everything (V2X) applications. The design is inspired by a hexagonal ring, providing an UWB bandwidth of 16.61 GHz (from 3.33 to 19.94 GHz) and a fractional bandwidth of 142.75%. A suitably placed inverted‐U slot in the feed line helps in achieving the WLAN notch band (from 5.04 to 6.01 GHz). The overall design footprint is 0.17 × 0.23 λ02 in size, provides stable radiation characteristics, and a gain of 4 dBi in the pass‐band with stable time‐domain performance. The proposed antenna also covers both 3.5 GHz (LTE‐42 Band) and 5.9 GHz (DSRC Band), therefore being suitable for modern UWB frontends and V2X communication. [ABSTRACT FROM AUTHOR]

In this paper, a planar reflectarray antenna is designed. The designed structure consists of new types of metamaterial unit cells. Two different flower-like shaped unit cells were studied at the center frequency of 12.5 GHz. The reflectarray contains multi cells with varying sizes of flowers. A metal plate and an air gap layer are placed behind the metamaterial sheet. A standard Ku band horn antenna feeds the structure. The F/D ratio is unity for the designed reflect array. Compared to previous reflectarray antennas, the designed reflect array consists of a limited number of cells, i.e. 121. Also, a new method without any try-and-error process is presented. The width of the designed reflector is so compact. This proposed method can be used for a reflectarray antenna with gain in the range of 20 to 30dBi with acceptable radiation efficiency. The CST software is performed to simulate and optimize the proposed structure. There is a good agreement between simulation and measurement results. [ABSTRACT FROM AUTHOR]

Designing antennas for vehicular communication systems presents several unique challenges due to the dynamic nature of vehicular environments, mobility, and the need for reliable connectivity. A wider bandwidth is a critical requirement of vehicular antennas. In this paper, a super-wideband FR4 epoxy-based low-cost meander line patch antenna is designed for fifth-generation (5G) vehicular mobile frequency applications. The proposed antenna is excited through a microstrip feedline on top of the substrate with a continuous ground plane. The meander line is implemented through a theoretical formula to cover upper-5G frequency range 1 (FR1) and frequency range 2 (FR2). The proposed antenna has 7.5 dBi peak gain when operated at 28 GHz. The simulated bandwidth ratio (BWR) is 9.09:1 for a −10 dB reflection coefficient covering a 53.4 GHz (6.6 GHz to 60 GHz) frequency range. The proposed antenna has a linear meander line planar structure, occupies a small area of 34 mm × 20 mm × 1.6 mm, and satisfies the bandwidth requirements of 5G millimeter-wave and sub-bands of the sixth generation for vehicular applications. [ABSTRACT FROM AUTHOR]

The demand for wideband circularly polarized (CP) antennas in wireless communication applications has been increasing, given that it offers reliable signals with reduced interference. In particular, planar monopole antennas are a popular choice for use in CP applications due to their compact size and ease of integration. However, achieving CP characteristics often requires complex modifications, an increased antenna size, and design complexity. To address these challenges, this study proposes a simplified radiator structure modification for CP planar monopole antennas and validates the performance of the proposed antenna for ultra-wideband (UWB) applications by conducting both frequency-domain and time-domain analyses. The size of the proposed antenna is 34 mm × 41 mm × 1.6 mm, with FR-4 as the substrate. Both the -10 dB S11 bandwidth and 6 dB axial ratio axial ratio is 3.46-5.5 GHz, with the radiation patterns in the frequency range of interest being omni-directional. The proposed UWB CP antenna also yields decent antenna performance in time-domain analyses, such as the antenna fidelity factor and the system fidelity factor. [ABSTRACT FROM AUTHOR]