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Flexible inkjet-printed antenna is presented. The proposed antenna is designed on a synthetic paper substrate with an area of 35 × 40 mm2 to provide frequency bands for many popular wireless applications. Simulation and measurement are used to study the performances, including the frequency bands, radiation patterns, peak gains and efficiency, of the antenna in two severely bending conditions with a curvature radius of 20 mm in the forward and backward directions. The antenna printed in photo papers material could not be fully flexible due to cracks introduced to the coating material on the surface of the photo paper. Hence, the resin coated material was only suitable for curved devices. The synthetic paper material used in this paper does not have a resin coating, therefore, the antenna does not lose its flexibility and can be bent in both the forward and backward directions without any cracks. Results show that bending in these two conditions has insignificant effects on the performances of the antenna. With a curvature radius of 20 mm in the forward direction, the measured peak gain and efficiency of the antenna are in the ranges from −3 to +2 dBi and 40% to 60%, respectively. The results together with the low cost make the antenna most suitable for many flexible 5G communications devices. [ABSTRACT FROM AUTHOR]

A flexible paper based and dual-band antenna is designed for UMTS service (1.9 GHz) and WiMAX services (5.8 GHz). Flexible paper is used as a substrate for the printed antenna. Expanded graphite ink is used to enable printing the antenna on the substrate. The antenna has been designed, simulated, fabricated, and measured. Steps of preparing the conductive printed ink and fabrication of the antenna have been discussed. The conductivity of the printed antenna is measured to be 1 × 104 S/square and the thickness is also measured with an average of 30 µm. Through the whole paper, good agreement between simulated and measured results is satisfied. In addition to the achieved flexibility, the antenna has demonstrated good measurement results. First, the antenna has a bandwidth of 300 MHz at 1.9 GHz and 400 MHz at 5.8 GHz with fractional bandwidth of 15.7% and 6.8% at the both bands, respectively. Second, the measured antenna radiation pattern has indicated that it is omnidirectional at 1.9 GHz and approximately omnidirectional at 5.8 GHz. Third, The antenna gain is 1.266 dB and 0.512 dB at the two bands, respectively. Finally, the antenna's efficiency at the both bands is 35% and 55%. [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 primary contribution of this paper is to investigate the effect of mechanical errors on the electromagnetic (EM) performance of the generalized deployable log-period dipole (GDLPDA) antenna. The concept of the "GDLPDA" is introduced first. Additionally, an electromechanical error analysis model is developed to assess the effects of dipole machining errors and deformations on the EM performance of GDLPDA. Based on this model, positional errors in two directions along the feedline are considered. Furthermore, an electromechanical error analysis model considering dipole rotational errors on cross-polarized electric fields is established. The actual positional and rotational errors are simulated to analyze the EM performance of GDLPDA. The simulation results show that the dipole positional and rotational errors can degrade the EM performance. Specifically, positional errors reduce gain and pointing accuracy, along with an increase in the 3 dB beamwidth. Rotational errors generate cross-polarization fields, decreasing the level of the co-polarization amplitude. This insight can help antenna design engineers to optimize GDLPDA to minimize the adverse effects of error on performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel antenna design with metasurface layer is presented. • The evaluation of the antenna array in various dusty atmosphere demonstrates its effective. • The proposed antenna exhibits a minor phase shift in the main beam, with a half-power beamwidth. • The proposed antenna can be adapted in many milieus different from that in which it is designed. The unique interaction between sand and wireless communication components in a dusty environment requires fundamental communication ideas that must be revisited from a different viewpoint. This paper introduces a 4 × 4 microstrip antenna array designed for a 24 GHz radar system, exhibiting high gain and a narrow beamwidth. A metasurface layer, employing a parasitic patch array, serves as a superstrate to enhance the array antenna's performance and safeguard it against deterioration from direct contact with sand. The paper conducts a theoretical study on the sand model to assess the antenna's performance in the sand environment, including an analysis of wave attenuation. The proposed antenna, loaded with the metasurface, demonstrates an impedance bandwidth from 23.08 to 24.9 GHz with a peak gain of 16.57 dBi. Evaluating its performance in various dusty atmospheres, the antenna proves effective in such environments, showing an impedance bandwidth of 23.04 to 24.73 GHz and a peak gain of 15.61 dBi. Additionally, the proposed antenna exhibits a minor phase shift in the main beam, with a half-power beamwidth of 15 degrees. [ABSTRACT FROM AUTHOR]

Reflector antennas, operating at high frequencies, require a high surface accuracy: deviations from the target geometry accuracy result in a loss of RF performance (e.g., antenna gain and efficiency). As a result, the aperture may need to be larger, or a more complex backing structure must be engineered to achieve the reflector surface accuracy to deliver the equivalent gain of an efficient solid reflector. This would typically increase the mass, the stowed volume, and the design complexity. The design of larger aperture deployable antennas (e.g., Cassegrain, Offset) for SAR (Synthetic Aperture Radar) applications can be challenging for missions where platform size and payload mass are limited. Inspired by the Origami based techniques, Oxford Space Systems (OSS) is currently developing an innovative SAR Reflectarray antenna, targeting the X-Band frequency range, with the aim of achieving a relatively large aperture from a small, stowed volume suitable for a small satellite. The Reflectarray antenna architecture has several potential advantages over other antenna designs. It is a cost-competitive technology with excellent stowage efficiency, which can be further improved with origami-based folding mechanisms/kinematics. It requires a simplified deployment mechanism and in contrast to conventional parabolic reflectors, it does not need a separate backing structure. Until now, work on space deployable Reflectarray antennas (e.g., MARCO, OMERA and ISSARA missions from NASA) have focused on multi-degree of freedom structures, i.e., independent self-actuated hinge driven architectures. This paper presents an elegant single degree of freedom, origami-inspired Reflectarray architecture that does not require actuation on all the hinges. Thanks to its Hold-Down Release Mechanism (HDRM) and spring-loaded hinges, the OSS Reflectarray antenna is self-deployable. It maintains the required flatness accuracy achieved through its novel hinge integrated latching system. The OSS Reflectarray antenna has an 8:1 footprint stowage ratio, which enables installation on small satellite platforms (between 50 kg and 100 kg). The reflectarray has been designed to work in the X-band frequency with dual linear polarization for the concept study. However, the architecture can be scaled up or down to suit other frequency bands, making the OSS Reflectarray compatible with many applications and platforms. • Rigid origami folding ensure high deployed/stowed volume ratio. • OSS Origami Reflectarray design ensure high Performances/mass ratio. • OSS Reflectarray simulations results ensure a good correlation with tests. • Target for SAR applications in the design. • Kinematics and RF tests successfully prove the design of such antenna. [ABSTRACT FROM AUTHOR]

With the increasing maturity of the power Internet of things (pIoT), radio frequency identification technology (RFID), is more applied to the fault monitoring of power equipment, of which the temperature monitoring of power equipment is one of the focuses of fault monitoring. When the traditional RFID temperature measurement tag is applied to high-voltage electrical equipment, it often produces metallic interference to the RFID temperature measurement tag antenna because it is attached to the surface of metal conductor, such as large synchronous machine and high-voltage transmission line, which greatly shortens the identification range of the traditional RFID temperature measurement tag on the metal surface and even cannot work normally. To solve the problems above, a new anti-metal RFID temperature tag antenna is designed in this paper. The internal antenna of the RFID temperature measurement tag adopts the anti-metal design based on the short-circuit stub structure, so that the temperature measurement tag can achieve the purpose of good anti-metal performance. Finally, through the simulation of HFSS, this paper verifies that the designed RFID temperature measurement tag can not only resist metal effect, but also be well applied to complex metal environment. [ABSTRACT FROM AUTHOR]

• The research paper conducts an in-depth comparison of graphene's conventional and GA-based optimised designs for THz antennas. • The proposed research examines four graphene and copper combinations, identifying the extremely explosive compound trinitrotoluene (TNT) at a resonance frequency of 5.6 THz. • Among the four designs, the entire graphene design demonstrates higher performance than the other three combinations, with a smaller size. • The optimised graphene antenna is altered to operate as a tri-band antenna with frequencies of 3.37 THz, 4 THz, and 5.2 THz. • The proposed tri-band antenna can detect drugs like l-histidine and explosives like ammonium nitrate (NH4NO3) and PETN in PE with lower, middle and higher resonant frequencies, respectively. The proposed research paper introduces a novel design of THz graphene-based antennas capable of countering terrorism by detecting explosive materials and drugs. The research work is subdivided into three distinct sections; the initial research entails conducting a comparative analysis of conventional and genetic algorithm-based optimised designs of terahertz antennas utilising graphene material. Subsequently, three supplementary designs are evaluated in comparison to the optimum design: one integrating a copper ground with a graphene patch, another integrating a copper patch with a graphene ground, and a third incorporating both a copper patch and ground. All four optimised designs, each resonating at a frequency of 5.6 THz, are used to detect explosive compounds like Trinitrotoluene (TNT). The optimised graphene-based antenna outshines the rest of the designs in terms of radiation efficiency, with a value of 90.03 %. It also exhibits superior performance regarding S 11 parameters, with a value of −53.38 dB, and VSWR, with a value of 1.004, at the resonant frequency. The optimised antenna demonstrates superior performance concerning gain (dB) and directivity (dBi), measuring 6.56 dB and 7.02 dBi, respectively. During the final phase of the proposed research, a graphene antenna was modified to function as a tri-band antenna by incorporating a 180° mirrored f-shaped slot within the antenna's patch. The tri-band antenna functions at resonant frequencies of 3.37 THz, 4 THz, and 5.2 THz. These frequencies detect explosives and narcotics, notably l-histidine, ammonium nitrate (NH 4 NO 3), and PETN in PE. These resonant frequencies hold the potential to be utilised in future applications of 6G technology worldwide. [ABSTRACT FROM AUTHOR]

This paper discusses a review of frequency reconfigurability through switches for 5G applications. A new switching technique (varying values of lumped parameters) for frequency reconfiguration is analysed and validated by investigation a difference between a simple (non-reconfigurable) and a reconfigurable antenna for 60 GHz resonant frequency. Different switching techniques for frequency Reconfigurable Antenna (RA) and formulations for the parameters of Microstrip Patch Antenna and slot insertion. Generic interconnections of switches for antenna array is addressed for RA design. important aspect of this paper is that these techniques have been discussed for the frequency switching of Reconfigurable microstrip antennas designed for 5G applications i.e. their frequency of operation is in millimetre-wave range (>6GHz). [ABSTRACT FROM AUTHOR]

This paper presents a planar CPW-fed Ultrawideband (UWB) antenna with two independently tunable notch bands. The proposed design consists of a modified Rhombus-shaped monopole structure that is integrated with a dual band-stop filter based on hexagonal split ring resonators (HSRR). The antenna is capable of suppressing multiple frequency bands within ultrawideband range (3.1–11 GHz) such as WLAN and X-band downlink satellite communication frequency bands with an independent tunable mechanism to fulfill the on-demand band rejection. The frequency reconfigurability of the two notch bands is obtained by loading the hexagonal filter arms with two varactor diodes (for each band). Details of antenna design steps and reconfigurability mechanism are illustrated. The notch band element is explained using equivalent circuit model and surface current distribution at lower and higher notch frequency bands. A prototype of the proposed design is printed on the RO4003C (ϵ r = 3.55) substrate printed circuit board (PCB) and tested to authenticate the performance. The proposed antenna volume is 21.5 ▪ 48 ▪ 1.524 mm3 and demonstrates an omnidirectional radiation pattern in E and H planes with an average gain of 3.7 dBi across the operational passbands, while a sharp reduction in gain of -6.8 dBi and -3.5 dBi is achieved at the lower and higher notch bands, respectively. Continuous tuning is achieved experimentally from 5.08 to 5.77 GHz and 7.75 to 8.52 GHz for the lower and higher notch bands, respectively. Excellent agreement is observed between the simulated and measured results. Application areas include radio-frequency identifications, ground-penetrating radar, and wireless communications. [ABSTRACT FROM AUTHOR]

In this paper, a high gain circularly-polarized antenna array with a flat panel structure for low Earth orbit (LEO) satellite communication systems is proposed. This new CP structure can efficiently achieve high directivity and can easily be integrated with beamforming ICs (BFIC) when designing an antenna module, resulting in a good candidate for Ka-band satellite communications. Furthermore, the proposed FPAA can easily be extended to a larger scale array from a base unit in a 2 × 2 sub-array structure. Each sub-array is configured by four high-gain planar segmented antenna (PSA) elements with a sequentially rotating arrangement, where a single 4-channel BFIC can drive CP radiation. Unlike previously reported PSA elements that have limited CP performance, the proposed PSA-CP configuration adopts additional conductors and ground-via structures to further improve the CP gain, axial-ratio (AR), and cross-polarization (XPD) characteristics. To verify the performance of the proposed PSA-CP, a 2 × 2 left-hand circular polarization (LHCP) sub-array was fabricated at 28 GHz and tested with a BFIC. The measured 10-dB impedance and 3-dB AR bandwidths of the proposed 2 × 2 array were 13.92% and 12.5%, respectively. In addition, the measured peak gain was 15.2 dBic at 28.5 GHz with an XPD level of less than 15 dB. [ABSTRACT FROM AUTHOR]

Multiple-input multiple-output (MIMO) antennas are essential for modern wireless communication systems that require high data rates, reliability, and quality. However, designing MIMO antennas poses several challenges, such as achieving high isolation, low mutual coupling, low envelope correlation coefficient (ECC), high gain, and high efficiency in a compact size. In this paper, we propose a novel MIMO antenna design that can overcome these challenges and support various wireless applications, such as WiFi-6, 5G (n77/n78/n79), and satellite communications. The proposed design consists of four spanner-shaped radiating elements that are etched on an FR-4 substrate with a tapered feeding line. The spanner-shaped antenna is derived from an octagonal ellipse that is cut by another octagonal ellipse to form the shape of the antenna. The proposed design achieves dual operating bands of 3.3–3.8 GHz and 4.5–8.4 GHz with low mutual coupling (<−10 dB), low ECC (less than0.05), high gain (up to 4 dBi), and high efficiency (>80%). The proposed design is compared with other MIMO antenna designs in the literature and shows its advantages in terms of size, performance, and applicability. [ABSTRACT FROM AUTHOR]

A novel passive frequency beam-steering linear antenna array is proposed in this paper to be utilized at the transmit side of a long-range wireless power transfer (WPT) system. To assure high power handling for a long-range transfer, the proposed antenna is designed based on stripline technology. Moreover, unlike other reported designs, the antenna array in this paper uses parallel feed while frequency beam-steering. This permits to apply a special synthesis at the radiating elements to minimize the energy wasted at the side lobes. The antenna array uses common-fed dipoles as radiating elements to eliminate the surface current at the ground planes that is considered a critical issue in high power applications. The antenna covers the frequency band from 1.1 to 1.5 GHz with a reflection coefficient better than −10 dB (VSWR < 2). Consequently, steers its main lobe from 60° to 90° respectively. Being passive, the efficiency of the WPT system is improved as no active component is needed to steer the antenna beam. The antenna is capable of radiating simultaneous, sequential or selective (shuffled) multiple beams for multiple receivers with a half-power beamwidth of 6°, a peak-to-side lobe level better than 20 dB and an average realized gain of 13 dBi. The antenna array handles a peak power reaches 1.6 MW which makes it an excellent candidate for a long-range WPT system. [ABSTRACT FROM AUTHOR]

Surrogates are essential in surrogate-assisted evolutionary algorithms (SAEAs) for solving expensive optimization problems. Gaussian processes (GPs) are often used as surrogates for their accuracy in prediction and ability to quantify prediction uncertainty. However, calculating the inverse and determinant of the covariance matrix in GPs is computationally expensive because of its cubic complexity. To tackle the issue, this paper proposes a scalable GP with hyperparameters sharing based on transfer learning. A linear predictor adaptively transfers the hyperparameters knowledge from the source full GPs (FGPs) to the target GP. The transfer is performed probabilistically based on the similarity between the distributions of the training data of FGPs and target GP. In this way, the number of building FGPs is significantly reduced. As a result, the optimization cost of the algorithms is also reduced. The scalable GP can be used in SAEAs to solve expensive optimization problems. The effectiveness of the proposed method is confirmed through testing on expensive benchmark problems and a real-world antenna design problem. • The computational cost of full GPs (FGPs) is high with cubic complexity. • This paper proposes a scalable GP to reduce the number of building FGPs. • The knowledge from source FGPs is transferred to target GP by a linear predictor. • The number of building FGPs and algorithmic optimization cost are markedly reduced. [ABSTRACT FROM AUTHOR]

Theoretical photoelectric conversion efficiency is higher in energy conversion using nano-rectifying antennas compared to traditional photovoltaic cell conversion technology. This paper presents the design of a wide-band metal rectifying antenna based on a concave bow tie structure to achieve efficient and wide-band solar energy collection. Firstly, the concave bow tie nanoantenna's structure is designed using the finite difference time domain method. The optimization of the antenna structure considers the influence of parameters such as antenna gap, concave corner radius, thickness, and substrate thickness on absorption efficiency. The resulting absorption efficiency is 94.6% within the wavelength range of 400 nm–1600 nm. Subsequently, the design, preparation, and experiment of the metal–insulator–insulator–metal​ ( Ag-Al 2 O 3 − HfO 2 − Au) rectification based on Ag particle antenna are carried out, and a rectification system test platform is established. The correctness of the proposed transfer matrix method tunneling model and rectification antenna design approach in this paper is verified, yielding a photoelectric conversion efficiency of 5.14 × 10−9. • Design of a wide-band metal rectifying antenna based on a concave bow tie structure for efficient and wide-band solar energy collection. • Optimization of the concave bow tie nanoantenna structure,Achieved absorption efficiency of 94.6% within the wavelength range of 400 nm–1600 nm. • Design, preparation, and experimental validation of a metal–insulator–insulator–metal (MIIM) rectification system. • Establishment of a rectification system test platform to evaluate the performance of the proposed design. • Verification of the proposed transfer matrix method tunneling model and rectification antenna design approach. • Demonstration of a photoelectric conversion efficiency of 5.14×10-9 using the developed rectification system. [ABSTRACT FROM AUTHOR]

Pigments with unique optical features are always sought after in realizing superior security features to protect authentic documents/products against forgery. The present study reports the synthesis of triphenylamine-naphthalene chalcone (TPA-NC) with fascinating optical features: solvato-fluorochromism, mechano-fluorochromism, and aggregation-induced emission. The flexo print obtained on UV dull paper using water-based eco-friendly UV fluorescent ink with TPA-NC as pigment displayed good adhesion, resistance to abrasion, light fastness, and favourable electrical parameter values, which could be well utilized in security documents and developing OTFTs in banknotes to prevent them from being forged. Moreover, the printed paper samples could impart superior features including solvent fugitiveness, penetrating fluorescence, and mechanical stimuli responsive variations in emission color for achieving multilevel security. The security ink prepared using the thermally stable and biocompatible TPA derivative could generate a robust platform for tamper-detection, validation of genuine documents/products and in marking technology. Moreover, an ultra-high radio frequency identification (RFID) antenna is designed to resonate at 2.35 GHz. The hybrid arrangement has steady radiation characteristics for electronic anticounterfeiting applications. [Display omitted] • Synthesis and characterization of triphenylamine-naphthalene chalcone: TPA-NC. • Mechano- and solvato-fluorochromic TPA-NC with aggregation induced emission. • Water-based flexo ink with multiple security features for document authentication and tamper detection. • Ink film with good light fastness, rub resistance, and colorimetric values. • Prints on paper for flexible electronics and RFIDs as electronic anticounterfeit solutions. [ABSTRACT FROM AUTHOR]

In this paper a novel reconfigurable H-plane horn Multiple Input Multiple Output (MIMO) leaky wave substrate integrated waveguide (SIW) antenna is proposed. The antenna is operating at two resonant frequencies, 22.8 GHz and 26.32 GHz. The transverse periodic leaky wave slots are radiating power in the broadside direction at 22.8 GHz and pattern diversity is achieved at 26.32 GHz. Dielectric loading and an array of meta -material structures are used, which further improve gain of the antenna. The antenna achieves better matching with a return loss of –33.5 dB at 22.8 GHz and maximum isolation of −38.7 dB at 26.32 GHz is achieved between antenna elements. A 2x2 and 4x4 MIMO SIW antenna is designed and analyzed in this paper. All the MIMO performance measurement parameters have values within limits. The antenna achieves a maximum gain of 7.3 dBi and 8.1 dBi. The proposed antenna operates in the K band (18 GHz–27 GHz) region, making it suitable for automotive radars and short-range applications. [ABSTRACT FROM AUTHOR]

This paper surveys a new class of electromagnetic materials. The emphasis is on the bianisotropic medium; a complex material which has never been applied in antenna design. In this context, we investigate the behavior of the magnetoelectric elements of the gyrotropic reciprocal bianisotropic medium used as a grounded substrate by studying their effects on the input impedance and mutual coupling of a printed dipole antenna. Numerical integrative equation calculations are carried out using the spectral method of moments (SMoM) based on the analytical derivation of the appropriate spectral Green's functions for the considered dipole configuration. The obtained results reveal a change in the sign of the real part of the input impedance. This is mainly due to the complex property of the considered medium. The medium has also minimized the input impedance ∼4 times (1kΩ); this can help in device matching. This medium has shown a significant impact on the input impedance as well as the antenna array coupling. The design miniaturization possibility is an important result of this research in the design of antenna arrays. [ABSTRACT FROM AUTHOR]

Antenna arrays have various applications, such as radar, military systems, and wireless communications. The performance of the communication system depends heavily on the antenna array design process. The major challenges in designing such arrays are the high sidelobe levels and the enormous number of elements. Recently, optimization techniques that exploit the evolutionary algorithms have been used extensively for thinning the antenna arrays to reduce power consumption and improve the radiation pattern by decreasing the sidelobe levels. However, due to the stochastic nature of the resolution algorithms, achieving a global optimal for such algorithms is not assured. Based on the combination theory, this paper adopts an element-by-element removing strategy for thinning planar arrays. Without loss of generality, a uniformly excited 25 elements rectangular array with isotropic elements is investigated as an example. The proposed thinning method examines all the possible arrangements of the placements of 25 elements in the phased array aperture. The optimum position of elements is selected to achieve the desired characteristics of the radiation pattern. The results show that with the 40% thinning percentage, the same radiation pattern for the full array (without thinning) can be witnessed. Consequently, a considerable reduction in resource utilization can be achieved in terms of power consumption, the number of phase shifters, and the number of attenuators. [ABSTRACT FROM AUTHOR]

Two textile-based printed inspired Folded Dipole Antennas (FDAs) are presented in this paper for health monitoring of Covid-19 infected patients. The first antenna has an overall size of 80 mm × 20 mm and is mounted on the human's chest, while the second one is backed by a 2 × 4 textile Artificial Magnetic Conductor (AMC) array structure and is mounted on a surgical mask that covers the human's mouth. The first antenna is designed to work at center frequency, bandwidth, and gain of 2.45 GHz, 116.6 MHz and −2.45 dB, respectively. The second antenna works at 2.4 GHz with bandwidth of 76.6 MHz and gain of 2.71 dB. The SAR results equal 0.524 W/Kg and 0.255 W/Kg at 1 g and 10 g, respectively, for the first antenna and 0.0174 W/Kg and 0.0091 W/Kg, respectively, for the second one. The previous specifications of the two antennas enable them to be utilized in wearable applications and Wi-Fi services. [ABSTRACT FROM AUTHOR]

Body centric Networks (BCNs) are the most important and attractive part of the next generation (5G and beyond) wireless technologies having a plethora of applications in day to day life. However the design of antennas for BCNs is a challenging task. Such antennas should have small size, light weight, higher gain and larger bandwidth besides having a stable radiation pattern under the influence of human body effects. This paper presents a miniaturised Ka/V dual band mmWave microstrip antenna for 5G BCN applications. The antenna has very small dimensions of 2.28 × 3.06 × 0.14 mm3 and operates at 33.5 GHz (Ka band) and 60.8 GHz (V band). The performance of the antenna is examined for "Off-body, On-body and In-body" BCN application scenarios. The radiation pattern, return loss, peak gain and −10 dB bandwidth results reveal that the antenna performs quite well at all interested frequencies. A comparative study with state of art mmWave antennas also shows the effectiveness of the proposed antenna. [ABSTRACT FROM AUTHOR]

This paper describes the optimal design and analysis of compact multiband Hybrid Fractal Antenna using Invasive Weed Optimization (HFAIWO). The configured structure involves the fusion of Minkowski, Sierpinski carpet and Giuseppe Peano in a coherent manner. The two-iterative conglomerated fractal antenna is realized physically by considering FR4 epoxy material (dielectric constant, ε r = 4.4 and mass density = 1,900 kg/m3). The volumetric dimensions of the fabricated prototype are 36 x 36 x 1.6 mm3. In the designing process, the geometrical descriptors, namely, feedline width 'W F ' and ground plane dimension 'L G ' are optimized specifically using Invasive Weed Optimization (IWO) and Harmony Search Algorithm (HSA) strategies. The optimal solution is searched by changing the descriptor values under a set of practical constraints. The examined values of 'W F ' and 'L G ' using IWO and HSA are 3 and 31 mm, and 2.6 and 28.7 mm, respectively. Comparative results reveal that IWO offers superior solution quality and convergence than HSA. Afterwards, experimentation of the Projected HFAIWO is done to justify the recommended fractal hybridization approach. Measurements reveal that for VSWR ≤ 2, the fabricated structure produces nine resonance points (1.84, 3.99, 5.15, 5.55, 6.30, 6.58, 8.00, 9.29, and 12.01 GHz) with appreciable gain values. At the respective resonance points, the −10 dB impedance bandwidth is 3.9 %, 3.1 %, 2.1 %, 2.2 %, 1.4 %, 1.2 %, 6.9 %, 1.2 %, and 12.23 %. The provided radiation patterns are arbitrary bidirectional/omnidirectional. By applying the above-said approaches, the radiator size is reduced by 54 %. Importantly, the constructed structure covers two important bands i.e. 1.84 GHz (GSM 1800 band, downlink) and 5.55 GHz (WLAN (Lower) 5.150–5.725 GHz) associated with energy harvesting applications. The practical outcomes suggest that the introduced prototype is a proficient candidate for energy harvesting systems, Satellite communication for downlink, Long range tracking, Battlefield surveillance, Digital broadcast satellite service, Weather Radar, and Maritime navigation radar. [ABSTRACT FROM AUTHOR]

This paper presents a new proximity-coupling mechanism between a rectangular patch and a microstrip line with an open circuit terminal. The patch is located to cover both adjacent maximum-voltage (capacitive coupling) and maximum-current (inductive coupling) points of the standing wave on the feedline, and consequently, two orthogonal resonant modes with 90° phase difference are excited on the patch for generating a circularly polarized (CP) radiation. Based on this feeding mechanism, a dual-band dual-sense CP antenna is designed, which is composed of two linear rectangular patch arrays coupled to an open-ending microstrip line. It is realized on a single-layer substrate and its CP rotating sense in each band is opposite to each other. For verification, the antenna operating at 5.0 and 8.0 GHz are designed, fabricated, and tested. Noting that the design concept can be easily implemented to other frequency bands. The measurements result in an impedance-matching bandwidth of 4.72 – 5.10 GHz and 7.50 – 8.20 GHz. The antenna is left-hand CP for the lower band and right-hand CP for the upper band. In addition, the prototype shows a 3-dB axial ratio bandwidth of 4.93 – 5.02 GHz and 7.40 – 8.10 GHz and peak gains of 11.4 and 12.7 dBic at the lower and upper bands, respectively. [ABSTRACT FROM AUTHOR]

This paper presents a butler matrix-based microstrip hexagonal patch antenna with a direction of arrival (DOA) estimation approach for mm-wave application. The hexagonal-shaped patch antenna had been designed with a Z-shaped slot with an eight-port butler matrix. The DOA estimation is also done for the switched beam antenna using a novel direction of arrival (DOA) estimation algorithm known as Cramer-Rao lower bound (CRLB). The proposed design leads to significant size reduction and loss minimization. In addition to this, the design had the advantages of being low-cost, lightweight, and small-volume. The entire proposed design provides an operating frequency range of 28 GHz to 39 GHz with a center frequency of 33 GHz. The proposed work makes use of two butler matrices with two 45° phase shifters and 120° phase shifters. The effectiveness of the proposed algorithm and antenna design using the Butler matrix is evaluated for various performance metrics separately. The antenna is designed using Rogers RT/duroid 5880(tm) substrate, and the fabricated prototype is studied. The designed antenna attains high radiation efficiency, and it ranges between 97 and 98 % under both the measures and simulated scenarios under the operating frequency range of 28 GHz to 39 GHz. [ABSTRACT FROM AUTHOR]

In recent times, the Multiple-Input Multiple-Output (MIMO) system has played a vital role in wireless communication. MIMO antenna uses multiple antennas on both the sides of the transmitter and receiver. Mutual coupling occurs between two antenna elements to reduce the performance. The passage of current in the same direction on both neighbouring sides of the antennas increases the rate of mutual coupling. To decrease the mutual coupling, Split Ring Resonators (SRR) are located on the MIMO antenna. In this research paper, a MIMO antenna with SRR for Ultra Wide Band (UWB) applications with different frequency notches is proposed. Also, bandwidth and isolation are considered essential metrics for MIMO antennas. In the proposed 4 × 4 MIMO antenna design, SRR is located at the antenna's two sides, and the defected ground structure is on the bottom portion with a permittivity of 4.4 (FR4 substrate). The defected ground structure is proposed with stubs to enhance the characteristics of bandwidth and create notch bands in the frequency range of 3.1 GHz to 10.6 GHz. Placing SRRs adjacent to the feed line enhances the gain performance. The experimental results show that the ECC of the proposed antenna is less than 0.25, DG is higher than 9.8 dB, and the peak realized gain for 9.38 GHz is 11.3 dB, which is more reliable than other antenna designs. Therefore, experimental outcomes of the proposed antenna design enhance the applicability of band notching for wideband communication. [ABSTRACT FROM AUTHOR]

A new Graphene nano-antenna has been designed and proposed in this paper for optical frequency applications with optimized gain performance. The proposed design uses a Silicon Lens and subsequent layers to match the dielectric constant between the antenna and air. The different patch materials are taken and studied for better results. The proposed antenna has been simulated upon a Highly resistive silicon substrate having a high dielectric constant of 11.9. The base of the proposed antenna is designed on a square substrate of 6000 μ m length and 300 μ m height. The slotted "bow-tie" antenna is placed on it with an aperture area of 156. 8 μ m × 42 μ m. A silicon layer is placed over it for improved performance. Further, it has been optimized by placing 16 stacked aligning layers to match the dielectric constants. The gain and efficiency improvement are achieved after each layer or coating over the lens. The resonant frequencies obtained are 0.4THz, 1THz, and 2.2THz having triple bands. The maximum gain obtained is 36.89 dB and the maximum radiation efficiency is 97%. HFSS 21.0 software is the used environment for the simulation and optimization. [ABSTRACT FROM AUTHOR]

The widespread use of graphene patch antennas is escalating as evidence of their applicability in areas like 6 G communications and THz spectroscopy. Geometric uncertainty and fabrication issues while downsizing makes terahertz antenna design problematic. Graphene's electromagnetic and mechanical qualities make it ideal for miniaturizing antennas for Terahertz use. In the THz spectrum, a graphene antenna requires careful dielectric material selection since performance fall, especially efficiency. This paper compares dual band multi-layered genetic algorithm-based optimized antennas for the THz applications, especially spectroscopy and 6 G utilizing sole layer duple substrates concept, i.e., two distinct substrates at the same level between the ground and patch. Different antennas are designed using various substrates like Rogers RO3010, RO3210, RT5880, RT5880LZ, TMM 13i, Taconic TLY-3, RF-10, Silicon, & Teflon. Two segments of four antennas are planned; one has silicon as a common substrate with four additional materials, and another has Teflon. The proposed antenna's performance is assessed in terms of bandwidth, beamwidth, directivity, efficiency, gain, radiation pattern, return loss, and VSWR. The results reveal that Silicon and Rogers RT5880 LZ substrates-based antenna perform better in a segment I, with bandwidth (GHz) of 150.1 and 156.9, directivity (dBi) of 5.93 and 4.23, efficiency (%) of 76.65 and 78.98, and gain (dB) of 4.97 and 3.3. While in segment II, Teflon and Taconic RF-10-based antenna perform better with features 158 and 198 bandwidth, 6.43 and 4.43 directivity, 74 and 83 efficiency, and 4.67 and 3.65 gain. [ABSTRACT FROM AUTHOR]

For a radar antenna working in an open air environment, wind load is a typical load that cannot be ignored, and it has a greater impact on the rigidity, strength and servo drive capability of the antenna.And it will indirectly affect the use accuracy of the radar antenna, resulting in the pointing deviation and defocusing of the radar antenna. Therefore, the wind load research of radar is one of the important links in radar antenna design. This paper designs an antenna wind load coefficient simulation model by using the standard k-ɛ turbulence numerical solution method, the author studies the wind load coefficient of the polyhedral phased array antenna relative to different shaft positions, compares the trend of the wind load coefficient under the offset of the axis δ= 70, 100, 120,140,170. And explores the influence of shaft offset on the wind load coefficient. The feasibility of the turbulence model was verified through industrial wind tunnel tests, and the wind load coefficients of similar-shaped polyhedral antennas were given for reference in engineering design. [ABSTRACT FROM AUTHOR]

UWB systems provide a distinctive solution for short-range wireless communication due to large bandwidth and low power consumption in transmission and reception. However, for these systems, designing an antenna with optimal characteristics is a major challenge, because it needs to avoid interference with existing narrowband systems (e.g., WLAN, Wi-MAX, HIPERLAN, ITU-R, etc.) in the UWB spectrum. To achieve this, different techniques (e.g., Slot, parasitic element and stub loading, Using fractals, metamaterials and electromagnetic band gap (EBG) structures) have been reported in the literature and this paper provides a comprehensive review of the mentioned techniques for achieving band notch characteristics in UWB antennas. Moreover, the challenges, future perspectives, simulated and measured results, different notched bands and their applications are also discussed in this paper to make it useful for future research. [ABSTRACT FROM AUTHOR]

This paper describes a conceptual ICRH system for the tokamak T-15MД, in construction at the Nuclear Fusion Institute of the Kurchatov Research Centre for Atomic Energy in Moscow. The proposed system consists of a number of Travelling Wave Antenna sections, located below the equatorial plane of the tokamak. This antenna system, loaded by a simulated density profile provided by the T-15MД team, is modelled including its resonant ring feeding system. Resonant ring feeding allows the recirculation of the RF power that is not radiated to the plasma and the termination of the TWA section on its iterative impedance. The paper describes the antenna design, the feeding ring tuning algorithm and expected performances of this antenna concept. The chosen geometry of the TWA sections is compatible with that of a future reactor and therefore this ICRH antenna system for T-15MД represents also a test bed for DEMO. [ABSTRACT FROM AUTHOR]

This paper is a continuation and extension of a previous work [1]. In this paper, an enhanced UWB microstrip-fed quasi self-complementary fractal (QSCF) antenna with triple band notches is presented. These band notches are allocated at 3.5, 5.5 and 7.8 GHz. The proposed design supports coexistence with narrow band applications IEEE 802.16 WiMAX, IEEE 802.11 WLAN and X-band of satellite communications, respectively. Both slot and parasitic loading techniques are utilized to achieve this goal. A guided half wavelength U-shape slot is etched in the ground for creating band rejection at the WiMAX frequency band. To attain the WLAN band rejection, another half wavelength U-shape slot is inserted to the feed line. A split ring resonator (SRR) is embedded to the left and right of the feed line for avoiding interference with X-band. The prospective antenna is designed using low cost FR4 substrate of miniaturized size 32 × 16.5 × 1.5 mm3 which empowers it to be embedded in assorted portable devices. Nearly omnidirectional radiation patterns and stable gain are accomplished over the operating bandwidth from 2 to 11 GHz. For further clarification of the operating principle, an equivalent circuit model is considered showing good agreement with CSTMWS, HFSS and experimental results. Furthermore, a time domain analysis is investigated presenting satisfactory distortion performance between excited and received pulse validating it for diversified UWB applications. [ABSTRACT FROM AUTHOR]

In this paper, a dual band graphene square patch antenna is designed for operation in 4 THz and 7.75 THz. The main idea of this paper is partitioning the graphene patch into pieces to have more degrees of freedom to reconfigure the polarization of antenna. Antennas polarization is controlled by partitioning the patch into 9 elements, resizing them and changing their chemical potential. The main operation mode of antenna has linear polarization in its boresight. Circular polarization is reached in five different modes; each mode has its own advantages. The main purpose is to achieve minimum efficiency loss modes among all chemical potential combination modes. Each mode has two separate types, one type will have RHCP and the other one will have LHCP, switching types will change RHCP to LHCP or LHCP to RHCP. [ABSTRACT FROM AUTHOR]

This paper proposes a symmetric 3 × 4 non-uniform metasurface-based patch antenna to achieve broadband circular polarization. The metasurface consists of rectangular meta-elements symmetrically placed along the vertical axis. To increase the impedance and 3 dB axial ratio bandwidth (ARBW), a shorting post is used in the antenna. The design analysis of the antenna uses the characteristic mode analysis (CMA) of CST MWS. The antenna achieves 39.7% (5.81–8.69 GHz) impedance bandwidth, 33% (5.34–7.45 GHz) 3 dB ARBW, and a peak gain of 7.43 dBi. It is a low-profile antenna with a size of 34 × 34 × 3.04 mm 3 (0.73 λ × 0. 73 λ × 0. 06 λ , where λ is free space wavelength with an operational frequency of 6.4 GHz). A prototype is fabricated on an I-Tera MT40 substrate. The experimental results agree well with the measured results. [ABSTRACT FROM AUTHOR]

[Display omitted] • A high-gain circularly polarized magnetoelectric dipole antenna array for millimeter-wave is proposed. • An antenna array design method of trade-off between high gain and low profile is proposed in this paper. • The 4 × 4 antenna array achieves 20.4 dBic peak right-handed circularly polarized gain. A high-gain circularly polarized (CP) magnetoelectric (ME) dipole antenna with metallic radiating structure is presented. The proposed CP antenna element consists of two pairs of metallic posts with a supporting metallic plate, a metallic air-filled elliptical cavity, and a feeding slot on the bottom substrate integrated waveguide (SIW). The two pairs of modified rectangular metallic posts combined with the gaps between them act as radiating ME-dipoles which are surrounded by a metallic air-filled elliptical cavity. The above-mentioned radiating structures are fed by a modified cross-shaped coupling slot etched on the bottom feeding SIW to generate CP radiation, where loading the elliptical metallic cavity significantly improve the CP performance of the antenna element. Then, a 4 × 4 antenna array with full-corporate feeding network is designed, fabricated, and measured, which has an impedance bandwidth of 18.9 % from 37.4 to 45.2 GHz and a 3-dB axial ratio (AR) bandwidth of 14.2 % from 36 to 41.5 GHz. Thanks to the all-metal radiating structures, a maximum measured gain of 20.4 dBic has been achieved. The measured and simulated results are in good agreement. [ABSTRACT FROM AUTHOR]

The paper introduces a self-isolated quad-port multi input multi output antenna system designed for fifth-generation wireless communication. The reported antenna structure possesses an overall dimension of 12.4 × 12.4 × 0.508 mm3 and is derived from a single-element antenna, featuring a circular patch accompanied by a sectoral slot. To achieve the desired frequency band, an additional circular patch is purposefully placed over the main radiator. The development of each design stage in the antenna structure is investigated using the theory of characteristic mode. This configured multi-element antenna structure achieves a broad operational bandwidth spanning 4.5 GHz, encompassing frequencies from 26.1 GHz to 30.6 GHz, rendering the antenna well-suited for deployment in the millimeter-wave frequency bands of n257, n258, and n261 respectively. A total gain of 6.27 dBi is achieved with port isolation of −24 dB. Furthermore, the antenna undergoes validation for diversity metrics, including envelope correlation coefficient, diversity gain, channel capacity loss, total active reflection coefficient, and mean effective gain. The antenna is fabricated and experimentally validated with the simulated counterpart. Later, a comparative analysis has been conducted which revealed that the proposed antenna demonstrates > 80 % increase in compactness compared to existing antenna designs documented in the literature. [ABSTRACT FROM AUTHOR]

Dual-function radar and communications (DFRC) systems based on multiple-input multiple-output (MIMO) arrays have received considerable attention in recent years due to their excellent ability to alleviate spectrum congestion. The MIMO DFRC systems enable high-resolution detection of multiple targets while communicating with multiple users simultaneously. However, MIMO arrays require numerous radio frequency (RF) units and suffer a strong mutual coupling among antennas, resulting in significant system overhead and performance degradation, respectively. In light of this, this paper investigates the joint optimization of transmit precoding and antenna selection for MIMO DFRC systems, aiming to improve the angular ambiguity function with a guaranteed communication quality of service (QoS) using a small number of antennas. To address the resultant non-convex optimization problem, both the indirect and direct precoding methods are proposed. In the former, the waveform covariance and antenna selection vector are first jointly optimized via a promoted sparsity along the covariance diagonal, followed by the precoding matrix indirectly derived from the optimal covariance. In the latter, the precoding matrix is directly optimized via an imposed group sparsity under the communication QoS and power constraints. Simulation results demonstrate that the proposed sparse MIMO DFRC system with fewer active antennas can achieve comparable dual-functional performance to that of the full array system. • The joint design of precoding and antenna selection for MIMO DFRC is proposed. • The indirect precoding method is proposed to address the joint optimization problem. • The direct precoding method is proposed to directly optimize the precoding matrix. • The proposed sparse system achieves comparable performance to that of a full system. [ABSTRACT FROM AUTHOR]

In this paper, a reconfigurable multibeam antenna with switchable polarization and wide/narrow beam tunability is presented. The antenna consists of a reconfigurable power splitter and a 2 × 2 patch antenna array. The curved patch, as part of the periphery of the antenna unit, is used to switch grounded and ungrounded, so as to achieve wide and narrow beam radiation, respectively. By embedding p-i-n diodes in the power splitter and switching the ON/OFF state, the selection of the output ports and the phase difference between them are achieved. In the process of function selection, polarization switching can be realized by exciting the antenna units at different positions. Beam deflection can be achieved by controlling the phase difference between output ports. To ensure stable and fast switching between beam states, the antenna is controlled by an external micro-control system, which has the advantages of simplicity, stability, and speed. The experimental results show that the antenna can generate 12 beam states, which are in good agreement with the simulation results. [ABSTRACT FROM AUTHOR]

This paper proposes an array antenna with high isolation for MIMO application. Two tightly coupled microstrip patch pairs are proposed as array element with two rectangular stubs connected. By adjusting the position and width of the stubs, good resonant frequency matching can be achieved, and isolation can be effectively improved across the operating frequency band. Furthermore, 1 × 2 and 1 × 4 arrays with only 0.04 wavelength space between the edges are constructed for MIMO application. By adding an open-loop resonators (OLR) and slots in the metal reflector, the isolation between adjacent ports can be improved to 26 dB. In order to verify the feasibility of the proposed array antenna, the array antenna has been simulated, processed and tested, respectively. The simulation and measurement agree well and show the isolation more than 25 dB for all ports. The proposed structure has great potential in practical MIMO applications. [ABSTRACT FROM AUTHOR]

This paper presents a high-gain and ultra-wideband antipodal Vivaldi antenna (AVA) with vias-loaded linearized edges for 5G millimeter-wave applications. By replacing the traditional exponential tapered edge by linear tapered slot (LTS), the side-lobe is obviously descended. Moreover, metal vias are loaded on radiation edges, more energy in the main radiation direction is constrained and the antenna directivity and gain performance are improved. A prototype of the proposed antenna was designed, fabricated and measured. The measurements agree well with the simulations, which certify the new way for miniaturization and easier fabrication of the propose antenna. The measured results show that the antenna achieves a peak gain up to 12.1 dBi at 36 GHz and gain of 10.8 ± 1.3 dBi in the operating range from 22 to 40 GHz, where the reflection coefficient is less than −10 dB. The gain increment is up to 2 dB compared with the conventional AVA. Due to characteristics like high-gain, ultra-wideband, and compact size, it is highly well-suited for 5G millimeter-wave applications. [ABSTRACT FROM AUTHOR]

Very large antennas are a key infrastructure for advanced space systems, but their size is limited by the size of the launching rocket's nose-fairing. This paper proposes an innovative phased-array antenna with foldable panels that overcomes this limitation through a combination of mechanical engineering and electrical engineering design. The antenna includes steps between the panels in contrast to traditional flat antenna designs, so as to fold panels of finite thickness without mechanical interference using ordinary, simple hinges (which are very reliable). As a result, excellent deployment efficiency and two-dimensional deployment have been achieved. However, the mechanical steps need to be compensated electronically in order to preserve the radiated beam characteristics, so the excitation phase of each radiator on the panels is precisely adjusted depending on the step size, radiation frequency and desired beam direction. The feasibility of both the deployment and phase-compensation methods was verified by both simulation and experiment, using a deployable mechanical model and an electrical model. Moreover, this technique is suitable for scaling up to very large antennas. • A huge antenna can be realized avoiding the size constraint of the rocket fairing • Panel steps are permitted in a multi-panel array antenna, contrary to tradition • Enables efficient and 2D deployment of multiple panels of finite thickness • Adjust radiators' phase on panels to compensate for steps and improve performance • Verified by simulation and experiment using both mechanical and electrical models [ABSTRACT FROM AUTHOR]

This paper introduces a design and analysis of a four directional radiation pattern antenna operating at 5.1 GHz. The proposed antenna consists of four center-fed copper arms placed over a substrate of relative permittivity ε r = 2.2. The substrate is backed with copper ground sheet. The design of this antenna is then modified to be frequency reconfigurable antenna by placing transformer oil (liquid which is operated at high frequency) within a container between the substrate and the ground. The modified antenna can be operated at different frequency ranges from 5.21 GHz to 6.56 GHz by varying the oil height in the container. Four PIN diodes are then added between the antenna's four arms and the feeding point in order to add beam reconfigurability feature to the modified antenna. Finally, multiple reconfigurable antennas are obtained to radiate in different directions at different operating frequencies with different gain and HPBW values. [ABSTRACT FROM AUTHOR]

In this paper, a novel spatial support mechanism for planar deployable antennas is designed based on the motion principle of planar deployable antennas and the spatial mechanism theory. The composition principle of the novel mechanism and its geometric characteristics are analyzed, and its degrees of freedom are calculated based on the constraint topological diagram. Subsequently, kinematic analysis is conducted, and the angular velocity, linear velocity, and linear acceleration of each component in the mechanism are calculated. Then, numerical calculation and simulation are performed to verify the correctness of the theoretical analysis results. The performance analysis of the spatial support mechanism is completed. A prototype of the proposed support mechanism is developed and tested to validate the feasibility of the mechanism principle. The present work can provide reference for the design and engineering application of this type of mechanisms. • 1.Propose a novel support mechanism for planar deployable antennas. • 2.Analyze the DOFs, kinematics, dynamics based on the constraint topological diagram. • 3.Develop a prototype of the proposed support mechanism and validate the motion principle. [ABSTRACT FROM AUTHOR]

High- Q antennas are highly sought after for their narrow bandwidth and compact size, enabling them to occupy minimal volume in a given structure. In this paper, we present a new ultra-narrow band filter/antenna designed for LoRa applications. The filter/antenna consists of an elliptical slot loaded with a high permittivity rectangular dielectric resonator, excited by a coupled microstrip line. The proposed antenna serves not only as a radiating element but also as a filter, offering the significant benefit of eliminating loss between the filter and the antenna. To assess the influence of the SMA power cable on miniature antennas, we conducted a comparison of the antenna with and without a radio frequency (RF) module, focusing on radiation pattern. Our proposed filter/antenna provides a compact profile of 25 × 40 mm 2 (λ / 13 × λ /8), an omnidirectional radiation pattern, and remarkable rejection in the stop-band. The validity of the proposed design is accomplished by comparing the electromagnetic simulation with fabrication and measurement results, achieving a high level of agreement between simulation and measurement. Thanks to its exceptional performance, small size, low cost, and low-power characteristics, this innovative structure is suitable for IoT applications at UHF band with a stop-band outside this frequency to avoid potential interference from adjacent bands. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel design approach for multi-mode antenna radiation patterns using characteristic mode (CM) theory. Specifically, we observe that the response of the multi-mode radiation pattern is a superposition of modal current responses, which can be controlled through port excitation. By combining the port excitations, we achieve the desired multi-mode radiation pattern. The feed structure can also be designed using CM theory. The validity of this intuition is confirmed through CM analysis. Subsequently, we use the proposed theory to design an antenna structure with a profile height of 0.07 λ 0 (λ 0 is the wavelength of the electromagnetic wave at 2.8 GHz in vacuum). This antenna is capable of achieving four orthogonal radiation patterns. Simulation and measurement of the antenna demonstrate that the four radiation patterns can operate simultaneously within a bandwidth of 17% (| S 11 | < −10 dB), with worst-case port isolation of −24 dB. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel approach to address the challenge posed by large datasets in the context of antenna optimization through machine learning (ML). The approach involves a modified artificial neural network (ANN) technique. To tackle the issue of training with limited data, we introduce a method that leverages prior knowledge to create initial small datasets. Throughout the training process, these datasets are iteratively enhanced by incorporating new simulation data obtained from optimization results. In the applications presented here, ANN is used to establish a relationship model between antenna geometric variables and transmission coefficients (S 21). Subsequently, a genetic algorithm (GA) is used to optimize the decoupling of the antenna array. By implementing wideband and narrowband optimization of the S 21 between two antennas, the accuracy and efficiency of this method are verified. The initial design and optimized antennas were fabricated and measured. In summary, this proposed method not only can effectively mitigate the expenses associated with design but also generates antenna optimization solutions of high quality. [ABSTRACT FROM AUTHOR]

To establish a stable, effective and reliable communication systems between unmanned aerial vehicle (UAV) and mobile vehicles, the propagation characteristics of air-ground (AG) wireless channels need to be better understand. In this paper, a narrowband multi-link channel measurement for UAV to mobile vehicles at 2.4 and 5.9 GHz is presented. Based on the measured data, some essential channel characteristics such as large-scale fading (LSF) including path loss, shadow fading (SF), and small-scale fading (SSF) including fading depth (FD), magnitude distribution and Rician distribution K-factor are analyzed. Then the cross-correlation characteristics of different channel parameters and receiving antenna numbers at 2.4 GHz and 5.9 GHz are systematically investigated. These researches provide some references to optimize antenna design and multi-link channel modeling of UAV to mobile vehicle communication systems in future intelligent transportation system (ITS). [ABSTRACT FROM AUTHOR]

Design of contemporary antennas is an intricate endeavor involving multiple stages, among others, tuning of geometry parameters. In particular, re-designing antennas to different operating frequencies, makes parametric optimization imperative to ensure the best achievable system performance. If the center frequency at the current design is distant from the target one, local tuning methods generally fail, whereas global algorithms (e.g., nature-inspired procedures) incur prohibitive computational expenses, especially when antenna evaluation is performed using full-wave electromagnetic (EM) analysis. In this paper, a novel technique involving automated decision-making has been developed, whose main objective is low-cost and precise re-design of antenna structures over wide ranges of operating frequencies. The employed methodology involves knowledge-based simultaneous scaling of antenna dimensions and gradient-based performance improvements. The two stages are automatically interleaved, and embedded into an iterative optimization procedure. The problem-specific knowledge allows for carrying out the scaling phase, in which fast relocation of the center frequency of the antenna is performed, based on a single EM analysis of the structure. The gradient-based tuning phase enhances the design quality with regard to the assumed objectives. The process defaults to local optimization after the antenna center frequency becomes sufficiently close to the target. The main novelty of the proposed algorithm consists in development of an automated knowledge-based framework of quasi-global search capabilities linking brute-force scaling and design refinement. Our technique has been demonstrated with the use of three microstrip antennas, optimized for best matching and maximum in-band gain. The main findings are that for all structures, satisfactory designs have been identified despite poor starting points, with operating frequencies being away from the assumed targets. At the same time, the computational cost is comparable to conventional local search. The proposed approach is versatile, simple to implement and easy to handle, in particular, its control parameters do not require tailoring to a specific antenna structure at hand. [ABSTRACT FROM AUTHOR]

5G NR (new radio) FR1 range refers to as Sub-6 GHz band (410–7125 MHz and 3.4–6 GHz). In this paper, the frequency range of interest is from 3.4 to 6 GHz, as many cellular companies are focusing on this Sub-6 GHz band. A wideband circularly polarized (CP) antenna radiator is designed with diamond shape patches, fed by a microstrip line at the bottom through a rectangular shape wide slot on a ground plane. The proposed CP antenna covering a −10 dB bandwidth of 21.52 % (5.0–6.3 GHz) with 3-dB axial ratio (AR) bandwidth of 12.48 % (5.1–5.8 GHz). Furthermore, a metasurface-based lens (metalens) is designed for gain enhancement and fed by 3 × 1 array of the proposed CP antennas for multibeam operation. The lightweight dual-layer metasurface structure consisting of circular shape unit cell elements are used to implement the lens. For the proof-of-concept, the array of radiating elements is implemented and experimentally validated, which gives a ±18° beam scanning range with a maximum gain of 13dBic at 5.6 GHz. [ABSTRACT FROM AUTHOR]

In this paper, a modified Pharaonic Ankh-Key antenna is proposed to support modern technologies and enhance the usage of 5G and next generations applications providing better performance compared to the previously designed Ankh-Key antenna [3]. The multiband antenna can operate in 28GHz band, 37 GHz band, and all bands from 49 GHz to beyond 140 GHz with peak gain between 6.9 dBi to 10.2 dBi along the operating spectrum. The single layer antenna is simply designed with dimensions 12.75 mm x 18.7 mm x 0.787 mm using Rogers/Duroid RT 5880 of ε r = 2.2 and tanδ = 0.0009 promising a lower cost and easy-to-fabricate antenna compared to the existing commercial antennas. The antenna is simulated using Ansys HFSS and CST suite simulators and the results where compared to the previously designed Ankh-Key antenna achieving much better performance and wider bandwidths. [ABSTRACT FROM AUTHOR]