A differentially fed dual-polarized antenna with low cross-polarization is proposed for sub-6 GHz applications. The main patch is fed through two pairs of symmetrical ports, and annular-ring slits are etched around the feedings. The broadband 180° phase shifter provides a stable differential feeding structure, and a 1 mm thick radome with a parasitic patch printed on its inner surface is utilized to

This paper presents a close-spaced dual-band 2 × 2 multiple-input multiple-output (MIMO) antenna with high isolation based on half-mode substrate integrated waveguide (HMSIW). The dual-band operation of the antenna element is achieved by loading a rectangular patch outside the radiating aperture of an HMSIW cavity. The HMSIW cavity is excited by a coaxial probe, whereas the rectangular patch is energized

Lens antennas with multibeam, high gain, and low sidelobe level are potential candidates for base station antennas in 5G mobile communication. In this paper, the authors perform simulation and parametric analysis of a lens antenna with positive and negative refractive indexes (NRI) using the modern electromagnetic field simulation software ANSYS HFSS. The simulation results of structures and theoretical

In order to reduce the path loss of the wireless communication signal in the underground tunnel, a scheme for configuring the antenna polarization of wireless systems based on a zone-division method is proposed. A multimodal method is used to estimate the effect of antenna polarization on the wireless propagation. When the optimal polarization of the antenna leading to low path loss is different in

The purpose of this paper is to investigate a large radio telescope support point number effect on its pointing accuracy and provide a useful guideline for the large radio telescope design engineer. In a large radio telescope system, the azimuth track is used to support the whole telescope structure and the mounting error as well as the telescope wheel-track contact in a long term can cause unevenness

Synthetic aperture radar (SAR) was originally exploited to image stationary scenes. However, it is important to derive target information of velocity for many applications. The fractional Fourier transform (FrFT) is a generalization of the classical Fourier transform and is well-known as a useful tool to estimate the chirp rate of linear frequency-modulated (LFM) signals. Motion compensation is critical

When using Gaussian process (GP) machine learning as a surrogate model combined with the global optimization method for rapid optimization design of electromagnetic problems, a large number of covariance calculations are required, resulting in a calculation volume which is cube of the number of samples and low efficiency. In order to solve this problem, this study constructs a deep GP (DGP) model by

The spoof surface plasmon polaritons (SSPPs) structure can be used as a sensor in THz region for the biosensing. The accuracy of resonance and amplitude for sensor is very important for biosensing. The momentum matching of SSPPs determines the resonance position and the gap distance determines the amplitude. For the biomolecular sensing, the sample is positioned between the prism base and the SSPPs

A dipole antenna based on a balun bandpass filter (BPF) is developed in this paper. The balun BPF employs two U-shaped resonators settled on the left side of the open-circuited transmission line and two L-shaped stubs to produce signals with equal amplitude and inverse phase. In this way, the volume of the balun BPF is reduced by half, and the distance between two output ports is dramatically decreased

ICPT is one of the most influential solutions in the field of wireless power transmission, but it is also very susceptible to the working environment. The complicated marine environment has a great influence on the performance of ICPT. In the deep-sea high-pressure environment, due to the piezomagnetic effect, the magnetic core in the coupling structure will suddenly change the permeability, and the

The propagation channel around human body will fluctuate due to the body effects, so it is essential to investigate the body channel. As an important method of channel modeling, ray-tracing (RT) is affected by the human body model. In this paper, a realistic human body is modeled with the idea of greedy algorithm. Based on the RT simulation and measurement results of path loss (PL), we derive the approximate

Suppressing higher-order modes up to sixth harmonics of the fundamental working frequency in a single-layer microstrip line-fed patch antenna has been successfully demonstrated. Higher-order modes of the antenna are suppressed by simultaneously employing a circular head open stub connected to the feed line and a novel defected ground structure (DGS) beneath the feed line. The filtering property of

A compact substrate integrated waveguide (SIW) antenna array that operates at 28 GHz and 38 GHz is proposed for fifth generation (5G) applications. The proposed array consists of four SIW cavities fabricated on one single layer of substrate. Each cavity implements a rhombic slot and a triangular-split-ring slot, resonating on TE101 and TE102 modes at 28 GHz and 38 GHz, respectively. In comparison with

A new strategy of density tapering called the partial density tapering (PDT) accompanied with the algorithm of differential evolution (DE) is proposed to suppress the peak sidelobe level (PSL) of uniform excited concentric ring arrays (UECRA) with isotropic elements. Through performing the PDT, a sound starting solution for DE can be generated. Then, the ring filling factor (RFF) is introduced so that

This article presents the design, fabrication, and measurement of a square Koch fractal slot antenna for UHF band using both the FR4-G10 and Cuclad 250 substrates. Conveniently, this 56.56 cm full-length antenna possesses a geometry that allows it to be incorporated into the standardized 10 cm × 10 cm faces of the CubeSats. Furthermore, it is shown that both selected substrates exhibit an acceptable

This research proposes a single-fed broadband circularly polarized (CP) bidirectional antenna operable in 840–960 MHz frequency band for readers of universal UHF-RFID applications. The proposed antenna is comprised of upper-layer conductor, lower-layer conductor, and wall patches. The upper-layer conductor consists of two diagonally aligned rectangular copper plates with a feeding gap at the center

Space target identification is key to missile defense. Micromotion, as an inherent attribute of the target, can be used as the theoretical basis for target recognition. Meanwhile, time-varying micro-Doppler (m-D) frequency shifts induce frequency modulations on the target echo, which can be referred to as the m-D effect. m-D features are widely used in space target recognition as it can reflect the

A backward to forward scanning periodic microstrip leaky wave antenna (MLWA) is presented. The proposed antenna consists of a long rectangular patch with alternating shorting pin on each side, which connects the antenna patch and the ground plane to form periodic shorting circuits. There are two pairs of slots alternately spaced on the long patch to suppress the open stop band (OSB). The OSB problem

Apart from interfering in the communication system of an aircraft, electromagnetic pulses (EMPs) radiated from spark discharge plasma, which is generated during high-speed flight, can also be utilized in passive detection. In order to validate this idea, an experiment on direction of arrival (DOA) estimation of a spark discharge plasma target using its radiated EMPs is carried out in this paper. A

In this study, a phased array radar was used to accurately image stationary and moving ship targets on the vast sea surface. To solve the challenge in real-time processing of the massive amount of data generated by phased array synthetic-aperture radar imaging, this study leveraged the block sparse characteristics of ships on the sea surface and adopted the joint block orthogonal matching pursuit algorithm

This paper presents the low profile, planar, and small-size antenna design for WWAN, LTE, and 5G (5th generation wireless systems) for use in portable communication equipment. The antenna occupies only 65 × 13 × 0.4 mm3, and the antenna is combined with a 200 × 260 mm2 copper plate to simulated system ground plane. In the low band, a direct-fed right-side arm and a coupled-fed arm implemented can excite

Electromagnetic metasurface lenses with the characteristic of being conformal to a cylindrical geometry are presented in this study. Based on the formulated principle of the cylindrical metasurface lens operating with transmission or reflection mode, the transmission or reflection phase gradient varying along the circumferential direction of a cylinder is implemented. A focused beam is observed at

This paper presents a new design of a compact, high-gain coplanar waveguide-fed antenna and proposes a multielement approach to attain enhanced characteristics. The proposed method overcomes the simulation and geometrical complexity and achieves optimal performance features. The antenna prototype is carefully designed, and simulation results have been analyzed. The proposed antenna was fabricated on

The rapid development of high-speed train and Metro communications has provided new challenges for the application of MIMO technologies. Therefore, we propose a three-dimensional (3D) multiple-input multiple-output (MIMO) channel model using leaky coaxial cable (LCX) in a rectangular tunnel. The channel model is based on geometry-based single-bounce (GBSB) channel model and the electric field distribution

In this paper, we consider the joint angle-range estimation in monostatic FDA-MIMO radar. The transmit subarrays are first utilized to expand the range ambiguity, and the maximum likelihood estimation (MLE) algorithm is first proposed to improve the estimation performance. The range ambiguity is a serious problem in monostatic FDA-MIMO radar, which can reduce the detection range of targets. To extend

This paper introduces a 2D angle-of-arrival (AoA) estimator, which has a 6–18 GHz 7-element nonuniformly spaced array (NSA) and a Direct Data Domain- (D3-) based AoA algorithm for a 2D isotropic-element planar array (IEPA). A 2D calibration and data-transformation method is developed to convert the NSA data to the output of the IEPA, so that the NSA-measured data can be used in the D3 algorithm. Using

For the traditional target localization algorithms of frequency diverse array (FDA), there are some problems such as angle and distance coupling in single-frequency receiving FDA mode, large amount of calculation, and weak adaptability. This paper introduces a good learning and predictive method of target localization by using BP neural network on FDA, and FDA-IPSO-BP neural network algorithm is formed

Fast factorized backprojection (FFBP) takes advantage of high accuracy of time-domain algorithms while also possessing high efficiency comparable with conventional frequency domain algorithms. When phase errors need to be compensated for high-resolution synthetic aperture radar (SAR) imaging, however, neither polar formatted subimages within FFBP flow nor the final Cartesian image formed by FFBP is

This paper presents two novel UHF RFID near-field reader antennas with uniform vertical electric field distribution. The two antennas have the following common characteristics. First, the radiating parts of the two antennas are simulated and fabricated by the microstrip lines and work using the leakage wave principle of microstrip lines. Second, the end of microstrip lines match the load to form a

Antenna array synthesis is one of the most popular topics in the electromagnetic field. Since achieving a desired antenna radiation pattern is a mathematical problem, in the literature, there are various optimization algorithms applied to the synthesis process of different kinds of antenna arrays. In this study, Multiverse Optimizer (MVO) and modified MVO (MMVO) are used to perform circular antenna

In high-frequency (HF) hybrid sky-surface wave radar, the first-order sea clutter broadening is severe under the action of ionospheric phase disturbance and bistatic angles. In this paper, a cascaded method is described to suppress the spread sea clutter. Firstly, the radar configuration and sea clutter broadening model are introduced based on the newly developed integrated HF sky-surface wave experimental

The performance of wireless optical MIMO system with multiple pulse position modulation (MPPM) over correlated fading channel is investigated. The combined effects of atmospheric attenuation, atmospheric turbulence, and pointing error are taken into consideration. The bit error rate (BER) and the ergodic channel capacity are analyzed by utilizing the Poisson counting model and the exponential correlation

A compact hybrid-mode antenna is proposed for sub-6 GHz communication. The proposed antenna is composed of a slotted rectangular patch, a feeding dipole, and a balun. Three modes are sequentially excited in a shared patch to achieve a compact size. A prototype antenna with a major size of 0.48 λ0 × 0.31 λ0 × 0.16 λ0 (λ0 is the wavelength in the free space at the center of the operating frequency band)

This paper presents a dual-band step impedance resonator (SIR) antenna based on metamaterial-inspired periodic structure of coupled complementary split-ring resonators substrate-integrated waveguide (CSRR-SIW). The antenna supports wireless local area networks (WLAN) bands at 2.4/5.2/5.8 GHz. The CSRRs and two branches of the SIR element are etched on the top and bottom metal surfaces of the substrate

This paper presents a broadband band-pass filter with cross-coupled line structure. The cross-coupled line structure is composed of the parallel coupled lines and an open stub. It can be analyzed by the odd- and even-mode method due to its symmetric structure. There are three transmission poles in the passband and two transmission zeros out of passband. Then, the influence of the impedance parameters

A multiwideband bandpass filter (MW-BPF) using a quad cross-stub stepped impedance resonator (QC-SSIR) was simulated, fabricated, and measured. The proposed QC-SSIR is designed on a four-series arrangement of crossed open stub (COS) structures where each open stub is developed with a step impedance resonator (SIR) structure to generate a wide bandwidth. Compared to the COS resonator, the QC-SSIR has

System analysis is a powerful tool for researching modern wireless systems. This includes breaking such systems into parts that make them up and studying how these parts work together. All these parts can be represented as “black boxes” in the form of two-port or multiport networks with the common system of parameters. Antenna is an integral part of any wireless system, so it should be also represented

This paper presents a compact Multiple Input Multiple Output antenna with high isolation and low envelope correlation (ECC) for fifth-generation applications using spatial diversity technique. The proposed MIMO antenna consists of two single antennas, each having size of 13 × 12.8 mm2, symmetrically arranged next to each other. The single and MIMO antennas are simulated and analyzed. To verify the

In this work, the numerical steepest descent path (NSDP) method is proposed to compute the highly oscillatory physical optics (PO) scattered fields from the concave surfaces, including both the monostatic and the bistatic cases. Quadratic variations are adopted to approximate the integrands of the PO type integral into the canonical form. Then, on involving the NSDP method, we deform the integration

This paper studies optimal resource allocation in the wireless powered communication networks (WPCN) combined with time reversal (TR) in which one hybrid access point (H-AP) broadcasts constant wireless energy to a set of distributed users in the downlink (DL) and receives information from the users via space division multiple access (SDMA) in the uplink (UL). Inevitable interferences will occur when

Two hypotheses for the blocking effect mechanisms under the electromagnetic radiation are presented, and the corresponding dual-frequency interference prediction models are proposed, which can be used to predict the working state of equipment under the condition that the single-frequency susceptibility is known. By taking a radar and a communication radio as the EUT, the experiments of dual-frequency

The performance of direction-of-arrival (DOA) estimation for sparse arrays applied to the distributed source is worse than that applied to the point source model. In this paper, we introduce the coprime array with a large array aperture into the DOA estimation algorithm of the exponential-type coherent distributed source. In particular, we focus on the fourth-order cumulant (FOC) of the received signal

A radio frequency identification reader antenna having multitag identification for medical systems is presented, which consists of four PIFAs, two hybrid couplers, and four power dividers. The high isolation is achieved by the symmetric design of the antenna geometry and four power dividers, which are fed by two hybrid couplers. The experimental results show an isolation of more than 40 dB in the North

This paper introduces a wideband rectenna that can scavenge ambient wireless power to a range of frequency band from 0.91 GHz to 2.55 GHz efficiently. The proposed rectenna is based on a wideband 2 × 2 fractal monopole antenna array with omnidirectional radiation patterns and high gains of 5 to 8.3 dBi at the desired bands. An improved two-branch impedance matching technique is presented which is designed

This paper proposes a trifrequency reconfigurable antenna (FRA), which can work in the X-band, Ku-band, and Ka-band, by controlling only two RF MEMS switches. The antenna element has a frequency ratio beyond 3 : 1 and provides a good candidate for the frequency reconfigurable antenna array, since the size of the antenna is reduced by loading multiple metal shorting holes between the antenna radiating

Polarized smart antenna array has attracted considerable interest due to its capacity of matched reception or interference suppression for active sensing systems. Existing literature does not take full advantage of the combination of polarization isolation and smart antennas and only focuses on uniform linear array (ULA). In this paper, an innovative synthesis two-dimensional beampattern method with

A wideband circularly polarized (CP) antenna is presented to achieve enhanced impedance, axial ratio (AR), and gain bandwidths. The antenna consists of two circular patches, a split-ring microstrip line with six probes, and a circular ground plane. By using these six probes which are placed in sequence on the split-ring microstrip line, the operating bandwidth of the proposed antenna is increased.

A triband patch antenna with monopole-like and patch-like radiation patterns for multifunctional wireless systems is proposed. The antenna consists of a single square radiation patch with an annular slot, a ground plane, and a top-loaded metal sheet. The top-loaded metal sheet is shorted to the ground plane for producing a zeroth-order resonant (ZOR) mode, which has an omnidirectional radiation pattern

The rheology and evolution of the polar ice sheet are deeply influenced by the anisotropy of ice crystals. Studying the anisotropy of ice crystals can help to well understand and predict the behavior of the polar ice sheet and then the sea level rising and global climate change. In this paper, firstly, we deduce the expression of eigenvalues and eigenvectors of anisotropic media, which are determined

This study proposes a method for designing and calibrating a millimeter-wave (mm-wave) multiple-input multiple-output (MIMO) antenna module. Herein, we adopt a design example involving a 64-element MIMO antenna array arranged in a triangular lattice (instead of the commonly used rectangular lattice) to achieve a 3°dB enhancement in effective isotropic radiated power. Analyzing a grating lobe diagram

In order to realize the miniaturization of quasi-Yagi antenna array, an antenna array with split-ring resonators (SRRs) based on two 7 units quasi-Yagi elements is designed in this paper. The radiation performance of the quasi-Yagi antenna array degrades significantly when array element spacing is reduced. After embedding SRRs on both sides of the miniaturized dielectric substrate surface, the S parameters

A method for designing a dual-polarized wideband absorber with low profile by using dual-resistor-loaded metallic strips is proposed in this paper. Each unit cell consists of a resistive sheet with dual-resistor-loaded metallic strips and an underlying conducting plate. Two-dimensional arrays of two unequal metallic strips are printed on the dielectric substrate, and two resistors are embedded in the

This paper presents a quad-band, 3D mountable rectenna module for ambient energy harvesting. With the aim of powering up Internet of Things (IoT) nodes in practical ambient environments, a hybrid approach of combining power, both at RF and DC, is adopted using 98 MHz FM band, GSM900 (Global System for Mobile Communications), GSM1800, and Wi-Fi 2.4 GHz band. A dual polarized cross-dipole antenna featuring

In order to counter active jamming, an adaptive polarization filtering method based on dual polarization radar is put forward. First, the signal flow principle of the dual polarization radar and its signal model are introduced. Then, the weighted coefficient matrices of the polarization filter are calculated adaptively according to the actual work situation of the current radar. Finally, the specific

The existing sparse imaging observation error estimation methods are to usually estimate the error of each observation position by substituting the error parameters into the iterative reconstruction process, which has a huge calculation cost. In this paper, by analysing the relationship between imaging results of single-observation sampling data and error parameters, a SAR observation error estimation

In some frequency-sharing studies between fixed service and space radiocommunication services, including fixed-satellite, broadcasting-satellite, and space science services, it is necessary to estimate the apparent elevation angle of a space station, taking into account the atmospheric refraction. Recommendations ITU-R (International Telecommunication Union—Radiocommunication) P.834-9 and F.1333-1

In this paper, a flexible microstrip patch antenna sensor is proposed for monitoring of the moisture content of lubricating oil. The sensor identifies liquids having different effective dielectric constants by detecting changes in the resonance frequency. The proposed antenna comprises a radiation patch, a metal ground plane, and a PDMS substrate with microchannels. The microchannels are etched on

In this paper, an improved propagator method (PM) is proposed by using a two-parallel array consisting of two uniform large-spacing linear arrays. Because of the increase of element spacing, the mutual coupling between two sensors can be reduced. Firstly, two matrices containing elevation angle information are obtained by PM. Then, by performing EVD of the product of the two matrices, the elevation

The paper proposes a simple four-element microstrip patch array antenna fed with corporate-series technique. The paper compares the proposed design with four-element antennas fed with only series-fed and corporate-fed microstrip antennas. All three antenna designs use rectangular microstrip patch elements with two insets and slots on both sides of the patch. The patch elements are accompanied by Yagi

This study aimed to explore a metallic striped grid array planar antenna, analyze it numerically in terms of its parameters, and optimize it for best performance. It may be an appropriate candidate for long-range point-to-point connectivity in wireless sensor networks. Antenna gain and frequency impedance bandwidth are two important performance parameters. For an efficient antenna, its gain should