This study investigates a high-gain, miniaturized antenna array featuring metamaterial-based semicircular Defected Ground Structures (DGSs) based metamaterial designed for wideband smartphone applications. The antenna array, measuring 49 × 25 mm², is constructed on an FR4 substrate with a dielectric constant of 4.3 and a thickness of 1.6 mm. The design incorporates two orthogonal antennas, each with a U-shaped radiating patch and a semicircular DGS to control bandwidth and reduce size. A T-shaped stub is positioned at the center of the U-shaped radiating area, with a star-shaped element attached to the leg of the T-shaped stub to enable wideband operation. The antenna demonstrates strong S11 performance, achieving approximately -38 dB at 5.8 GHz and -42 dB at 8.1 GHz, making it ideal for Sub-6 GHz and C-band applications. The proposed antenna array operates across a frequency range from 4 GHz to beyond 10 GHz, reaching a peak gain of 11 dBi and an efficiency of 95%. A time-domain analysis was conducted to verify radiation efficiency, and the specific absorption rate (SAR) is approximately 0.0475 for 1g of tissue and 0.0101 for 10g of tissue at 4.5 GHz, confirming the array's suitability for wideband smartphone devices within the target frequency band. The simulated and experimental results of the proposed antenna array show excellent agreement.

A right-hand circularly polarized (RHCP) crossed dipole antenna with wide impedance and axial ratio bandwidth is developed. The antenna is composed of a pair of crossed dipoles, four parasitic patches, a metal reflecting cavity and 12 metal support posts. The four parasitic patches and 12 metal support posts together constitute two pairs of magneto-electric dipoles. By using a quarter wavelength phase delay ring on the crossed dipole, the 90° phase difference between the upper and lower arms is obtained, thereby realizing circularly polarized radiation. By adding slotted parasitic patches, grounded metal posts, and modifying the cavity structure, the circular polarization performance of the antenna is improved. The measurement results show that the antenna with a compact size, low cost obtains 64.5% of impedance bandwidth (1.85-3.61 GHz) and 59.6% of axial ratio bandwidth (1.92-3.55 GHz), and has stable pattern and gain in the operating bandwidth, highlighting significant potential for future applications in sub-6 GHz 5G applications.

This paper presents a highly miniaturized self-quadplexing antenna based on a quarter-mode substrate integrated waveguide. The miniaturization of the antenna is achieved by utilizing a pair of complementary split-ring resonator-inspired slots. The quadplexing characteristics of the antenna are achieved by varying the width of the inner CSRR-shaped slot. The antenna is designed to resonate at four distinct frequencies: 2.09 GHz, 2.18 GHz, 2.26 GHz, and 2.36 GHz. It demonstrates a minimum port isolation exceeding 32.6 dB between the ports. Additionally, this self-quadplexing antenna offers frequency tunability and maintains a unidirectional radiation pattern across the designated operating frequencies. The antenna's simulated and measured gains are 5.32 dBi (5.44 dBi), 5.58 dBi (5.42 dBi), 5.41 dBi (5.15 dBi), and 5.18 dBi (5.26 dBi). The design supports independent frequency tunability through the activation of four ports, with a compact size of 0.037 λ₀², where λ₀ is determined at lowest resonant frequency. These features indicate the antenna's suitability for S-band applications.

A new dual-band antenna is presented for use in space-based passive energy harvesting. This antenna is based on elliptical dipole antennas, whose inner metallization is removed, leaving an outline antenna and room for a second set of antenna arms. This will in turn result in an interleaved structure to tune each set of dipole arms to two different frequencies. Due to the close proximity of the dipole arms there exists strong mutual coupling, which is lessened by adding decoupling elements to the design. The proposed antenna is supported by a partial ground plane to improve the front-to-back ratio of the radiation patterns. The ground plane is extended with an exponential taper, and additional parasitic elements are added to improve antenna performance. The dual-band elliptical outline design was fabricated and measured, and the results are found in good agreement with simulation. This antenna design provides 14 dB return loss, 3.4 dBi peak gain, and 12 dB front-to-back ratio for both the 0.915 GHz and 2.45 GHz bands, making it a useful antenna for applications such as passive energy harvesting that require lightweight dual-band designs.

In this work, a novel circularly polarized antenna with four ports and loaded with complementary split ring resonator (CSRR) for beam steering applications without phase shifters or PIN diodes is presented. The single antenna loaded with CSRR is arranged in a rotational manner forming a 4-port structure. The separation distance among the four antennas is optimized for achieving a steering angle of 29° with an isolation level greater than 25 dB over the whole bandwidth. When one of the four antennas is excited, the others either open-circuited or terminated to a 50-Ω impedance, the antenna has a resonant frequency of 5.8 GHz and produces a left-hand circularly polarized (LHCP) tilted beam in the elevation plane. The introduction of the CSRR leads to achieving a small design and also to get circular polarization characteristics. The proposed structure has a radiation efficiency of 90 % and a gain of 6 dBi over the whole bandwidth. This characteristic can be tuned which makes the proposed design suitable for many modern communication systems.

This paper proposes a magneto-electric dipole antenna with broadband, good directivity, and high gain. By changing the shape of the radiating patch and loading the T-slot to improve the impedance matching ability of the antenna, the bandwidth is effectively expanded. Low cross-polarization and high gain are achieved by using a square metal reflective cavity and a hollow metal cylinder loaded on top of the antenna. Test results show a relative impedance bandwidth (|S₁₁|<-10 dB) of 94.40% (1.32 GHz-3.68 GHz) with a maximum gain of 10.7 dBi. The antenna has excellent performance and has applications in wireless communication systems.

This paper presents a novel, thin, circularly polarized microstrip antenna optimized for radar applications, designed to operate within the 7.5-7.7 GHz frequency band. The antenna is compact, with overall dimensions of 1.97λ x 1.08λ x 0.0025λ (where λ is wavelength calculated at 7.5 GHz) printed on a flexible polyimide substrate, offering advantages in terms of mechanical flexibility and integration into conformal systems. Circular polarization is achieved with an axial ratio of less than 3 dB across the operating bandwidth, while a peak gain of 6.25 dBi ensures adequate signal strength for radar detection and communication. Performance improvements are realized by introducing inverted C-shaped slots in the radiating element, effectively manipulating the surface current distribution and enhancing polarization purity and radiation efficiency. A prototype of the antenna was fabricated and tested, with experimental results closely matching simulation data, confirming the reliability of the design methodology. The results demonstrate that the proposed antenna is highly suitable for compact radar systems, offering an optimal balance among size, performance, and fabrication simplicity.

A compact size, dual band rectangular spiral antenna with an inset feed is simulated and tested for S-band applications. Feeding of an antenna is given through a 50 Ω microstrip transmission line. The proposed design consists of a rectangular spiral radiating patch in the top plane and a Z-shaped structure in the bottom plane. Ansoft HFSSv13 has been utilised to design the rectangular spiral antenna, and parametric analysis has been done to verify the characteristics of an antenna. The rectangular spiral antenna is fabricated by utilising chemical etching, and it is tested by utilising MS2037C Anritsu combinational analyzer. Reflection coefficients of -16.5 dB and -16.2 dB, and fractional bandwidths of 8% (2.35-2.55 GHz) and 6.7% (3.22-3.44 GHz) are obtained at 2.4 GHz and 3.3 GHz respectively. Maximum gains of 3.1 dBi and 3.34 dBi are obtained at the two resonating frequencies. Omnidirectional and dipole type radiation patterns are obtained for different values of θ and Φ. The rectangular spiral antenna occupies an area of 16 × 16 × 1.6 mm³, and it is fabricated by using FR4 material. Simulated results are in good agreement with the measured ones. These results make the antenna suitable for many Zigbee/IEEE 802.15.4-based wireless data networks that operate in the 2.4-2.4835 GHz band, and it is also suitable for a wide range of applications including FWA systems.

Deep learning neural network (DLNN) has enormous potential in solving electromagnetic inverse design problem, and thus meet the growing demand for rapid high gain antenna design in current industrial applications and other complex questions. Here, we propose a wideband near-zero refractive index high gain antenna based on dual band near zero refractive index frequency selective surface (DB-NZRI FSS) with the aid of Fourier transform neural network (FTNN). FTNN employs a Fourier transform-based data simplification algorithm to address the prevalent issue of long training time in neural network for antenna design. We verify the universal adaptive and effectiveness of FTNN by rapid designing near-zero refractive index metamaterial working in adjacent bands. The proposed DB-NZRI FSS unit has transmission zeros at the magnetic resonance point and electric resonance point, and a stopband with high reflectivity exists between the two points. By integrating the initial highly directional radiation effect of zero refractive index metamaterial with the planar parallel cavity principle, the proposed lens antenna obtains the maximum gain of 12.64 dBi at 8.2 GHz. The FTNN has high accuracy and low loss of 0.0407. The designed DB-NZRI FSS has relatively low profile of 3 mm (8% wavelength at the central frequency of 8.2 GHz). Besides, the designed antenna has the characteristics of dual polarizations and wideband with the relative 3 dB gain bandwidth of 19.35% (7.56-9.18 GHz).

With the rapid development of various intelligent scenarios, the demand for low latency, efficient processing, and energy optimization is increasing. In smart communities, intelligent transportation, industrial environments, and other scenarios, a large amount of data is generated that needs to be processed in a short time. Traditional cloud computing models are difficult to meet the requirements for real-time and computing efficiency due to the long data transmission distance and high latency. Therefore, this paper introduces Intelligent Reflecting Surfaces (IRS) into the optimization model of Device-to-Device (D2D) communication and Mobile Edge Computing (MEC) collaborative offloading to enhance system performance and minimize total latency. This paper proposes a latency minimization problem for joint offloading mode selection, computing resource allocation, and IRS phase beamforming. The original problem is decoupled into three subproblems using the Block Coordinate Descent (BCD) algorithm. Through precise potential game theory, the Nash equilibrium (NE) is achieved, and multi-objective optimization is realized using the Lagrangian multiplier method and KKT conditions. Finally, a phase shift optimization problem is solved using the gradient descent algorithm. Simulation results show that the proposed algorithm outperforms other benchmark schemes in terms of performance.

This paper presents the design, discussions, and characterization of a low-cost printed slotted substrate integrated waveguide traveling wave antenna. The antenna exhibits an omnidirectional pattern in the azimuth plane and a cosecant squared pattern in the elevation plane. This synthesized pattern enables application in 5G mm-wave systems by providing a defined signal equipotential region, thereby increasing coverage areas in locations such as stadiums, exhibition centers, arenas, and parks. Additionally, the proposed design method facilitates the easy implementation of new designs tailored to specific installation sites.

To improve surface current distribution and give dual polarizations, a petal-shaped array antenna with slots was presented. We analyze the surface current of petal-shaped array antenna, study the working modes of each part, and use defect structures to remove surface reverse currents to reduce sidelobes and achieve high gain characteristics. By changing the radiation length of the antenna, the designed antenna operates in the target frequency band. Then, strip defects are introduced to improve surface current and enhance isolation. Finally, antenna prototype was fabricated and measured to demonstrate our ideas. The measured results show that the proposed antenna has a 10 dB impedance bandwidth from 5.74 to 5.82 GHz with a relative bandwidth of 1.4%, and achieves a peak gain of 11.3 dBi at 5.8 GHz. The isolation of the two ports is more than 26.4 dB in the passband. The overall size of the proposed antenna is only 1.47λ₀×1.47λ₀×0.015λ₀.

This paper addresses the susceptibility of motor parameters to external disturbances during the operation of three-vector model predictive current control (TV-MPCC) for permanent magnet-assisted synchronous reluctance motors (PMA-SynRMs), which leads to increased current fluctuations and reduced tracking precision. To enhance the control system's stability, a step-by-step parameter identification approach is proposed. First, the proposed method devises six switching configurations, considers eight potential current prediction points generated by voltage vectors, and reformulates the value function. Next, a model reference adaptive system (MRAS) is employed to incrementally identify the motor's d and q axis inductances, resistance, and flux linkage. These identified parameters are used to update the model in real time. In this study, a 3kW PMA-SynRM serves as the control object for simulation verification. Results indicate that the TV-MPCC based on step-by-step parameter identification has obvious improvement in current tracking static error and peak value of current fluctuation.

The performance of surface plasmon resonance (SPR) sensor modified with chitosan-graphene quantum dots (CS-GQDs)/Au bilayer thin film for dopamine (DA) detection was evaluated in this work. The sensor's selectivity to DA was evaluated in the presence of various interfering substances. The sensor's stability was examined over three weeks. Additionally, the repeatability of this sensor was assessed through nine successive measurements, and its reproducibility was evaluated using six different sensor films. The sensor demonstrated excellent selectivity to DA when 1 pM of DA was introduced to a 100 pM mixture of epinephrine, ascorbic acid, and uric acid. Furthermore, the storage stability of the sensor was found to be excellent. The sensor showed good repeatability as well as reproducibility with relative standard deviation (RSD) values of 0.343% and 0.229%, respectively, while detecting 1 fM of DA. The real-time DA detection showed that obtained response signals were stable after roughly 10 minutes of injection of all concentrations. By fitting the experimental data to Pseudo-first-order (PFO) kinetic model, the equilibrium SPR angular shift was 0.318° with adsorption rate constant of 0.240 min-1 for 1 fM DA contacting the sensor surface. AFM images revealed that DA influenced the surface morphology of the sensor film, changing its average roughness by 0.710 nm, and FTIR spectra showed changes in the spectral bands and peaks intensities. These findings showed that CS-GQDs/Au based SPR sensor is an advantageous option for rapidly and economically diagnosing DA deficiency with high selectivity and sensitivity.

Two compact substrate-integrated waveguide (SIW) filters with hybrid coupling of eighth-mode substrate integrated waveguide (EMSIW) resonators and microstrip are proposed in this paper. Hybrid coupled filters were achieved by etching two half-wavelength microstrip resonators (BPF I) or two quarter-wavelength microstrip resonators (BPF II) on top of traditional second-order EMSIW filters. The topology of the two filters was analyzed. Due to the cross coupling between resonator 1 and resonator 4, two transmission zeros were achieved outside the band of BPF I, which increased the selectivity of the filter. Due to the mixed electromagnetic coupling between resonator 2 and resonator 3, a transmission zero is realized in the stopband of BPF II. To confirm the validity of the two filter models, two filters were designed, produced and measured. Based on the findings of the measurements, the central frequency of BPF I is recorded at 7.7 GHz, with a fractional bandwidth (FBW) of 18.2%. The insertion loss (IL) within the passband is minimal at 0.8 dB, and the size of the filter is only 8 mm * 4 mm (0.53λ_g * 0.26λ_g). The filter exhibits enhanced out-of-band suppression due to the presence of two transmission zeros located at frequencies of 6.4GHz and 10GHz. The center frequency of BPF II is 19.5 GHz; the FBW is 20.5%; the IL within the passband is only 0.49 dB; and the size of the filter is only 2 mm * 2 mm (0.34λ_g * 0.34λ_g). As a result of the mixed electromagnetic coupling effects, a transmission zero occurs at a frequency of 26.7 GHz. The simulation outcomes are consistent with the experimental findings. Compared with other reported SIW filters, the two filters introduced in this study exhibit favorable characteristics such as reduced insertion loss and compact dimensions.

The electromagnetic environment effect test of UAV airborne equipment is commonly completed in anechoic chambers. Due to the influence of platform on antenna radiation characteristics, it is necessary to move the large platform with a antenna to anechoic chambers. However, testing costs even make this case impossible. To evaluate the electromagnetic effect of platform-free antenna ports, this study proposes an antenna platform virtualization technique. The FIT (Finite Integration Technique) is employed to calculate the antenna gain corresponding to different frequencies with and without an antenna platform. Subsequently, the difference in antenna gain under these two cases is obtained. By compensating for this variation at the interference source, the frequency domain response of the interference signal at the antenna port can be predicted, disregarding the platform. To validate the effectiveness of the proposed technique, a UAV's airborne antenna is employed for simulation analysis. The root-mean-square error of the proposed technique is less than 0.5 dB. Moreover, in terms of time domain transient interference, the effect of the platform on the transient interference signal at the antenna port is equivalent to a transfer function. The root-mean-square error for the transient response prediction method is less than 0.1%. The results demonstrate that the proposed antenna platform virtualization technique makes it possible to test the electromagnetic effect of antenna in anechoic chambers without a platform.

In this Letter, a miniaturized U-shaped microstrip filter based on a load-coupled open line is proposed. It is composed of a step impedance resonator and parallel coupled open stub line. Interfinger feed is used to enhance coupling. This configuration and coupled open stub lines form four transmission zeros between two passbands as part of open coupled stub lines to increased out-of-band rejection. The analysis of formation reason of transmission zero is conducted using lossless transmission line theory and even-odd mode analysis techniques. A filter operating at 2.53 GHz and 5.53 GHz is simulated and fabricated. The insertion loss of first passband is 1.30 dB, and return loss is -18.60 dB. The insertion loss of the second passband is 0.70 dB, and return loss is 22.89 dB. The out-of-band rejection is maintained below -20.00 dB. The final model size is 0.20λ_g x 0.23λ_g. The final physical measurement results confirm theoretical results.

In this paper, a compact and reconfigurable radiation pattern dipole antenna based on the Yagi-Uda antenna principle and operating at 2.5 GHz is designed. Controlling the switching states of three loaded switches allows for pattern reconfigurability. Three modes can be chosen based on the results of the simulations and measurements. In the first mode M1, a high directive- beam can be achieved by turning ON all the RF switches, and a measured peak gain of 6.7dBi is obtained with a corresponding half-power beamwidth (HPBW) of 44°. In the second mode, only the director is required to enable a less directive beam. This allows for a larger HPBW of 62° and a lower peak gain of 5.47 dBi. Finally, by disabling the reflector and director in the third mode, M3, we get an omnidirectional radiation pattern around the y-axis with a maximum measured gain of 3.8 dBi. The comparison with other prior art antennas shows that the proposed reconfigurable antenna has compact size, high gain, and simple design, making the structure a good candidate for new wireless applications.

The Global Navigation Satellite System Reflected (GNSS-R) Signal adopts a heterogeneous observation mode and utilizes the globally shared GNSS constellation as a multisource microwave signal transmission source, providing the opportunity signals for radar measurements. As a basis for GNSS-R bistatic remote sensing simulations, this paper analyzes wave spectrum model of sea surfaces, GNSS signal scattering model, and GNSS signal scattering power model. The modified Zavorotny and Voronovich (Z-V) model combined with two-scale method (TSM) for sea surface scattering is utilized to simulate delay Doppler map (DDM), with emphasis on the analysis of the effects of wave polarizations, delay Doppler interval, and sea states on DDM of GNSS signal scattered from sea surfaces. The correlated power model of GNSS scattering signal is validated by comparison with measured Cyclone Global Navigation Satellite System (CYGNSS) DDM data in L1 level 2.1 version. The DDM waveforms obtained from Z-V model combined with TSM are basically consistent with the CYGNSS actual data, in which strong scattering spots can be observed clearly from both simulated and measured DDMs. The modeling and analysis of DDM for spaceborne GNSS-R signal from sea surface is of great value in ocean remote sensing applications, particularly for the interpolation and utilization of various spaceborne GNSS measured data.

A hybrid continuous extended-mode inverse class-F power amplifier is designed with band-pass filtered matching networks to match transistor inputs. This design methodology increases the impedance space by incorporating free factors into the current equation of the traditional inverse class-F power amplifier (PA). The suggested matching network in this article is a reliable alternative to the commonly used low-pass structured matching network, and this synthesis method simplifies the deployment of the distributed network compared to the LC low-pass network. High efficiency is guaranteed by the constructed output band-pass matching network. To verify the validity and superiority of this design method, a broadband power amplifier operating at 2.6-4.0 GHz was designed and fabricated. Largesignal measurement results indicate that the drain efficiency (DE) ranges from 60% to 81%, 40-42.3 dBm output power, and 10.5-11.5 dB power gain across this frequency range.