In this letter, the scattering of a nondiffractive Bessel beam (BB) incident field by a perfect electric conducting circular cylinder is investigated and compared with the standard scattering solution by a plane wave. It is proven that the BB incident field improves the validity of standard physical optics approximation and possibly extends its range of applicability to cylinders, or more general scatterers

A low-profile microstrip patch antenna with pattern diversity is proposed. In our design, even- and odd-order modes are employed to enhance the impedance bandwidth for the conical and broadside radiation beams, respectively. Initially, an array of concentric shorting pins is introduced to reallocate the resonant frequencies of TM 01 , TM 11 , and TM 02 modes closely to each other. Then, a longitudinal

In this letter, we develop an accurate and effective analytical framework to arbitrarily manipulate the frequency response of magnetic metasurfaces. In particular, we demonstrate the possibility to homogenize the response of the unit cells constituting a finite slab, avoiding undesired truncation effects and, consequently, performance degradation. In addition, we also show that the control over the

An S-/Ka- band shared-aperture antenna with frequency switching function for 5G applications is proposed in this letter. The proposed antenna comprises a thick patch containing a slotted cavity array (TPCSCA), S- band feeding structure, and coaxial cables for Ka- band. The TPCSCA is designed using 16 Ka -band slotted cavity antennas inside an S- band thick patch. Half of these Ka -band antenna elements

To expedite the design process of metasurface, an improved transfer function (TF)-based artificial neural network (ANN) model is proposed, which can directly generate structure parameters to match the customer-expected electromagnetic (EM) response. Compared with the existing inverse design techniques, poles and residues of TF instead of the EM responses at discrete points are input into the proposed

This letter proposes a method based on primary-dual iteration to address the array pattern synthesis problem of minimizing the peak sidelobe level (PSL) under the constraints of controlled mainlobe ripples and dynamic range ratio (DRR) of current excitations. Especially, when DRR = 1, the phase-only beampattern synthesis problem is solved. Simulation examples are presented to verify the effectiveness

It was difficult to solve the conflict of integrating the lightweight property, mechanical resistance, and broadband microwave absorption into one composite structure. Herein, the glass fiber (GF)/carbon fiber (CF) reinforced lightweight multifunctional metastructure with mechanical resistance and broadband microwave absorption was designed and optimized through the genetic algorithms and fabricated

A novel method based on alternating linear programming optimization is presented to synthesize sparse linear arrays with sum and difference patterns. This method can find the optimized element positions and excitations shared for both sum and difference patterns with accurate control of multiregion sidelobe distribution and difference pattern null slope. In addition, the constraints on the minimum

A high-permittivity dielectric material-filled substrate integrated suspended line (SISL) antenna with size reduction is proposed, which provides a novel fixing method for dielectric resonator antenna (DRA). The proposed antenna is based on five substrate layers with two air cavities while the high-permittivity dielectric material is filled with the upper air cavity of the hollowed substrate. So the

In this letter, a new polarization-insensitive, low profile frequency-selective rasorber (FSR) is presented with a switchable transmission band. This FSR consists of a lossy layer, a bandpass layer, and a switchable layer where p-i-n diodes are mounted and parallel fed. The lossy layer is composed of compact fractal elements with lumped resistors, which miniaturizes the unit dimensions. The bandpass

The design of a shared-aperture dual-band differentially fed array antenna with microstrip grid and patches is presented in this letter. The patches as high-frequency elements operating at 38 GHz are inserted into microstrip grid array antenna (MGAA) operating at the low-frequency band of 28 GHz. The impedance bandwidth of MGAA can be enhanced from 3% to 16% at 28 GHz due to the introduced resonance

A wideband and compact Fabry–Perot resonator antenna (FPRA) employing two layers of partially reflective surfaces (PRSs) is presented in this letter. The proposed PRSs with regular hexagonal units are used in wideband FPRA for the first time. Based on the compact arrangement of regular hexagon units and the addition of tripod branches, the size of FPRA is greatly reduced. Furthermore, the regular hexagonal

In this letter, a tunable quasi-reflectionless filtering antenna is proposed. The device consists of a reflective microstrip bandstop filter (BSF) and a radiating patch antenna connected in a complementary-duplexer fashion. By terminating the output port of the BSF with another antenna and employing the patch antenna (antenna channel) as the radiator, a tunable quasi-reflectionless antenna is obtained

A low-profile broadband folded dipole antenna with high gain is presented in this letter. Folded dipole antenna is utilized to reduce the height of the reflector to 0.1 $\lambda$ , without degrading the impedance bandwidth. Parasitic patches shorted to the reflector are employed to reduce the gain variation of the antenna. The $|S_{11}|$ $\leq$ $-$ 10 dB bandwidth of the antenna is from 1.18 to 4.08 GHz

The conventional calibration methods only took into account the mutual coupling (MC) and the gain/phase error. However, the antenna element pattern could also be an important factor in calibration as the antenna element pattern could be direction-dependent. This letter proposes a calibration method to jointly estimate array errors and antenna element patterns for the uniform circular array (UCA). The

Substrate integrated E-plane waveguide (SIEW) is a recently invented transmission line type that is able to guide two orthogonally polarized waves, one perpendicular and one parallel to the circuit board. This is accomplished by emulating an intact vertical metallic wall using a row of copper plated through holes as well as a copper strip that passes through all the through holes at the middle height

This letter presents a filtering substrate integrated waveguide slot antenna design with multiple radiation nulls based on a double slot coupling scheme. It consists of a dual-layer cavity resonator, a slot in the first layer, and two coupling slots inserted in the middle layer. The slot in the first layer functions as the antenna radiator. This radiator is etched in the first cavity instead of the

Point cloud data (PCD) can record a high-resolution model of the environment much more efficiently than the conventional geometrical mesh. This feature makes PCD suitable for the radio channel prediction of a new environment, especially for the millimeter-wave (mmWave). Since the multiple propagations and visibility computation using PCD are time consuming, progressive processing on PCD is introduced

Dynamic modification of the pattern of a reflector antenna system traditionally requires an array of feeds. This letter presents an alternative approach in which the scattering from a fraction of the reflector around the rim is passively modified using, for example, an electronically reconfigurable reflectarray. This facilitates flexible sidelobe modification, including sidelobe canceling, for systems

Array antennas with multipolarization function have important research value to improve the stable transmission of communication systems by supporting antenna diversity technology. In this letter, a millimeter-wave (mm-wave) quadri-polarization array antenna based on folded C-type substrate integrated waveguide is proposed. The operating principle is that the proposed differential feeding network can

In this letter, a millimeter-wave (mm-wave) nondiffracting Airy orbital angular momentum (OAM) beam is experimentally demonstrated by using a single-layer hexagonal lattice reflectarray based on an Airy-OAM-phase modulation method. To reduce the design time, a near-field synthesis technique is used to theoretically analyze the nondiffracting characteristics of the Airy OAM beam. A hexagonal dual-resonance

A simple compact circularly polarized (CP) cross slot antenna with a wide frequency tuning range has been presented in this letter. Four identical varactors are loaded at the ends of the cross slot for varying the operating frequency, and only one voltage is adopted to control the varactors. Distributed inductors and capacitors are employed to realize CP radiation. By varying the value of varactors

A frequency-diverse metamaterial cavity antenna (FDMCA) that can be used for the microwave coincidence imaging is proposed in this letter. The proposed FDMCA is a slot antenna array excited by a metamaterial-based cavity, which can generate diverse radiation patterns at different frequencies. The average electric-field variation (AEV) is introduced to forecast the correlation coefficients of radiation

In this letter, a paradigm for designing tunable frequency selective surfaces (FSSs) with angular stability is presented. The tunable FSS is implemented by nonresonant subwavelength unit cells loaded with varactor diodes, which can be applied in a dynamic and efficient compensation mechanism. The red shifts introduced by varactor diodes are used to compensate the deviation under oblique incident angles

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A new method for detecting microwave harmonic Doppler signatures of held objects in cluttered environments is presented. Based on a passive harmonic tag combined with a pulsed microwave radar, the motion of tagged objects held by a person can be detected in high-clutter environments. In this letter, we present a new derivation of the dynamic harmonic signal response of a harmonic tag in motion. Based

This letter proposes a novel antenna structure for 60 GHz band 3-D coverage beamforming. By using the proposed antenna structure, the coverage area can be expanded in an elevation plane. Dipole and patch subarray antennas were packaged into one structure by using the copper balls interconnection technique. A simple idea to utilize dipole and patch elements enables endfire and broadside radiations resulting

A simple numerical solution for electromagnetic scattering from a 2-D homogeneous chiral cylinder of arbitrary cross section placed above a dielectric half-space (DHS) is presented. A modified surface equivalence principle is used to obtain coupled electric field integral equations. For feasible application of method of moments, a perturbation method is used where a strip of finite width approximates

A number of real-life applications involve the determination of scattered field of an unchanged large object and several varying small scatterers in its vicinity. Integral equation methods based on free-space Green's function (FSGF) are usually applied to solve this problem. In this letter, we propose an artificial neural network (ANN) accelerated numerical Green's function (NGF) to reduce the computational

In this letter, a novel concept for the dielectric resonator functioning as a differential antenna and as an independently controllable dual-band filter simultaneously is proposed for the first time. The multifunctional design takes full advantage of the virtual and reflection grounds of the differential dielectric resonator antenna (DDRA). The antenna and filter functions share a single module and

This letter presents a novel phase-cancellation and absorptive metasurface (PCAM) with ultralow scattering and broadband features. The PCAM is formed by two circular frequency selective surface elements with lumped resistors, which can not only reduce reflection amplitudes by transforming the incident waves into heat but also adjust reflection phase responses simultaneously. The two electromagnetic

In this letter, a broadband 1 bit reconfigurable transmitarray antenna (RTA) based on polarization rotation element is proposed. The transmitarray element is composed of two split circular rings connected by two narrow strips and sandwiched by two orthogonal polarizers. As phase shift and polarization conversion structure, the two patches are separated by the air layer, and the p-i-n diodes are soldered

This letter presents a design of reflectarray for near-field (NF) shaped focusing, and a synthesis method is proposed to generate desired shaped pattern in the NF zone. The orthogonally arranged tridipoles structure is used to realize the dual-polarized reflectarray. The unit cell has continuous reflection phase-shift ranges (more than 360°) under x -polarized and y -polarized incident E-fields. A

Multibeam antennas have found more and more applications in current and future communication systems. In this letter, a low-profile multibeam fully planar folded transmitarray antenna (FTA) based on the bifocal principle is proposed. It consists of a reflectarray, a transmitarray, and a group of identical planar feeding antennas. The transmitarray is developed with the metasurface and achieves high

A low-profile aperture-coupled microstrip patch antenna (MPA) under multiresonant modes for wide half-power beamwidth (HPBW), high gain and enhanced-bandwidth is proposed. Firstly, the radiation patterns of the MPA are studied to improve the radiation performance. It demonstrates that the HPBW of the lower TM 10 mode could be progressively widened by properly selecting the dielectric constant of the

We put forward an improved ray-tracing algorithm to obtain a fast prediction of the radar cross section (RCS) for electrically large complex targets using the shooting and bouncing ray (SBR) method. Our algorithm employs a rope-based kd-tree data structure together with the neighbor-facet-tree based backward ray-tracing technique. The proposed algorithm shows excellent performance in the evaluation

A new method to miniaturize patch antennas is presented by using coupled microstrip patches. A design example is given at 8.45 GHz. The resultant patch antenna has an electrical size of 0.146 × 0.146 × 0.04 λ 0 3 , which is about 60% area reduction with respect to a conventional patch antenna. The miniaturized patch antenna shows similar broadside radiation patterns and a lower cross-polarization level

A compact structure with slot splitting meandered lines defected ground is proposed to reduce the mutual coupling between two microstrip antennas with a center-to-center distance of 0.38λ. The meandered line defected ground structure is symmetrically etched on the ground between the microstrip antennas. The proposed structure is optimized and explained by the common/differential mode theory. For experimental

In this letter, we present a dual-polarized orbital angular momentum multiple-input.multiple-output (OAM-MIMO) with uniform circular arrays (UCAs) that achieves a transmission rate of over 200 Gb/s. We design and evaluate the properties of microstrip antennas on 28 GHz band and then fabricate the antennas and implement them on a transmitter and receiver with four UCAs disposed concentrically. Each

The synthesis and design methods of a novel filtering antenna with flexible passband and radiation null based on parallel scheme are presented in this letter. The filtering antenna is constructed by parallelly connecting two inverted-fed resonant antenna elements to a common feed point. The two resonant antenna elements can be separately designed and adjusted. A specific filtering performance with

This letter proposes a dielectric superstrate to reduce the couplings between copolarized and cross-polarized antenna elements in realistic base station (BS) arrays. The mutual couplings are reduced by adjusting the permittivity and profile of the dielectric superstrate to create “reflected” waves to neutralize the original coupling wave. The dielectric superstrate is a simple structure that is easy

A compact implantable antenna is proposed for wireless health monitor microsystem, which is operated in frequency of the Industrial, Scientific, and Medical (ISM) band. A circular radiator is cut four L-shaped slots and loading a shortpin between the radiator and ground plane to implement the circular polarization. Two crossed rectangle slots are etched on the ground plane so that the impedance and

Classical microstrip patch antenna fabricated on a dielectric substrate suffers from poor gain, efficiency, and high cross polarization due to the automatic excitation of TM 0 surface wave. It also radiates strong fields along the horizon which is susceptible to multiple-input–multiple-output (MIMO) or array configurations. In view of this, a separate class of circular microstrip antenna known as the

A leapfrog scheme for the unconditionally stable complying-divergence implicit (CDI) finite-difference time-domain (FDTD) method is presented. The leapfrog CDI-FDTD method is formulated to comprise distinctive implicit and explicit update procedures. The implicit update procedures are in the fundamental form with operator-free right-hand sides (RHS), whereas the explicit ones are compatible and correspond

A full-wave leaky-wave analysis of 1-D periodically corrugated metallic surfaces with wide gaps is presented. Such wide gaps, in the order of half-wavelength, are employed in the most cited designs for corrugated metallic antenna implementation due to the high attainable gain performance. A full-wave periodic unit cell method is described and implemented on a corrugated metal surface design for the

With the ability to increase the gain of the millimeter-wave antenna system effectively, lenses have attracted wide attention. Researchers proposed a large number of lens-based array systems. When each array element works alone, the system can transmit beams in different directions. However, it is difficult to adjust the scanning angle flexibly. In this letter, we propose a method to synthesize the

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In this letter, the use of flat-top broad beams is proposed for the improvement of the robustness against direction-of-arrival (DoA) ambiguities in amplitude-monopulse systems, if compared to the conventional use of narrow tilted beams. Oscillations of the monopulse function outside the field-of-view are eliminated, thus suppressing false detections created by signals coming from outside the angular

This letter proposes a compact 435 MHz telemetry, tracking, and command (TT&C) CubeSat antenna, which does not require an in-orbit deployment mechanism for proper operation. It uses characteristic modes on spacecraft's body to increase the radiating aperture, resulting in a λ/4 sized antenna (as calculated along diagonal of the cube). The antenna aims to provide reliable communication, operating independently

Although the 60 GHz band meets the higher data rate demands for various wireless applications, large path losses and small size of 5 mm free-space wavelength makes the design, fabrication, packaging, and measurement of 60 GHz antenna arrays challenging. In this letter, we present a low-cost and high-efficiency patch antenna array fabricated using a printed circuit board (PCB) process. As the mini-connector

This letter presents a high-gain 32 × 32-element full corporate-feed array antenna using a simplified assembly of only two split blocks. This is made possible by a new feeding configuration which eliminates the cavity-backed layer used in conventional designs. E-plane T-junctions, as well as the single-ridge waveguide output structure, are used in the full corporate-feed network to reduce its size

The near-field ultrahigh-frequency (UHF) quadruple-loop antenna (QLA) with uniform field distribution for item-level tagging is proposed. The proposed antenna consists of quadruple fan-shaped small loops and the middle feeding lines of each loop located at the top and bottom of the substrate using vias. The currents flowing through feeding lines are cancelled due to opposite directional currents (ODCs)

This letter presents a broadband 3-D-printed circularly polarized (CP) spherical Luneburg lens (LL) with the linearly polarized feed antenna for the X -band. In order to implement spatially continuous varying effective refractive index (RI), the proposed LL is divided to many unit cells and their effective RI is simulated and calculated by effective medium theory. Since the effective RI of unit cells

A novel wideband circularly polarized microstrip patch antenna (MPA) with multimode resonance is proposed in this letter. The TM 1/2,0 mode, the zeroth-order mode, and the TM 1,0 mode are excited by inserting the shorting pins underneath the driven patch and the parasitic patch. Therefore, a wide impedance bandwidth is achieved under triple-mode resonance. By sequentially rotating the triple-mode elements

Solving the combined field integral equation (CFIE) for the large-scale scattering problem is computationally expensive. In this letter, we investigate the feasibility of applying deep learning to solve the CFIE for 2-D perfect electrically conducting objects. Inspired by the conjugate gradient method, an iterative deep neural network is designed to learn the manner of solving the surface current density

In this letter, a dielectric resonator antenna (DRA) with an engraved groove and a comb-like metal wall for beamwidth enhancement in both E- and H-planes is proposed. First, with an engraved groove, the radiation intensity on the top wall of the rectangular DRA can be enhanced, which significantly broadens the half-power beamwidth (HPBW) in the E-plane. Second, by placing a regular notched metal wall

A reconfigurable antenna with a compact size and quad-polarization reconfigurability is presented. By employing a switchable feed scheme, the antenna can operate at single-fed and dual-fed modes. At single-fed mode, the feed structure allows output ports switching to produce the excitations for either slant +45° or −45° linear polarization (LP). At dual-fed mode, it serves as a switchable phase-shifting

We present an algorithm for designing and manipulating pulsed caustic (accelerating) beams that propagate along a predefined planar curved beam-axis trajectory in free space. These pulsed beams are localized time-dependent wave packets. We evaluate the pulsed aperture field (source) distribution that radiates the beam along the desired trajectory. The aperture field is evaluated by setting its delay