Search

This letter proposes a unit integrating reflectarray and transmitarray functions together. The proposed units can form multifunctional metasurface (MS), which can realize both focusing (with required focus points and point numbers) and multiple pencil beams (with required direction, and beam numbers) based on x - and y -polarizations, respectively. The developed MS has the following advantages: low sidelobe, high focusing efficiency, high aperture efficiency, multibeam, dual-band and less layer number. The MSs formed by the units have multifunctional applications, such as multibeam communication splitter, and point to point or point to multipoint in near field communication and wireless and power transmission.

In this letter, a high-efficiency planar reflectarray with a small size of 3.87λ0 × 3.87λ0 is designed, which can effectively convert arbitrary polarized waves to orbital angular momentum (OAM) waves with a desired mode number and a beam direction. The two concentric rings with a small size of 0.38 λ 0 × 0.38 λ 0 compose the unit, which can cover the phase-shifting range 360° by adjusting the ring radius. Though the developed reflectarray is much smaller than that of published ones, it can produce beams with the similar performance as large antennas. The advantages are as follows: high efficiency 22.6%, which is superior to published OAM reflectarrays, high gain 15.4 dBi, narrow divergence angle 9°, high purity, good stability, polarization insensitivity, planar structure, and easy fabrication. Using this reflective metasurface, we designed the following OAM beams: first, OAM mode l = 1, 2, 3, 4 at ( θ = 0°, ϕ = 0°); second, l = 1 at ( θ = 45°, ϕ = 180°); and third, l = 1 at ( θ = 45°, ϕ = 270°). The above advantages are proved by the following analysis: the magnitude and phase distributions in the near field, the purity analysis, and the radiation pattern in the far field.

We present a new wideband single-layer reflectarray based on polarization rotating (PR) unit cells. These PR unit cells convert a linearly polarized incident electromagnetic wave to an orthogonal polarization upon reflection wave. Each unit cell consists of a pair of L-shaped patches and a metallic strip tilted at 45° from the x-axis in the xy plane. By adjusting the dimension of this unit cell, a pair of 90° phase difference unit cells were achieved. And we used these two unit cells and their mirror images to achieve a 2 bit phase shifter, which provides a phase shift of 0°/90°/180°/270° from 11 GHz to 17 GHz. Based on the proposed element, a wideband reflectarray is designed, fabricated and measured. The measured results show that the reflectarray's maximum gain is 25.6 dBi, with a 1 dB gain bandwidth of 30.4 % and an aperture efficiency of 35%, which agree well with the simulated results.

In this paper, an electromagnetic induced transparency (EIT) metamaterial is proposed. The EIT structure are developed with low frequency metamaterial, which has high Q value and can lead to small Joule heat loss. Bright-bright mode is used to produce EIT. Both structures can be excited by X-polarized electromagnetic waves, and then transparent windows are generated by weak hybridization. Current distribution and electric field distribution are simulated to demonstrate the intrinsic mechanism. The EIT metamaterial works near 14.38 MHz with two transmission valleys at 14.32 MHz and 14.50 MHz respectively.

In this paper, a wideband coding metamaterial (CDM) is proposed for radar cross-section (RCS) Reduction. The proposed coding units have three advantages: (1) Simple design. Dual-polarized ‘0’ and ‘1’ coding elements (CEs) are realized by a pair of rectangle patch over 7-14.6 GHz (bandwidth 70%). The ‘0’ and ‘1’ CEs represent reflected phases 0° and 180°, respectively. (2) The proposed metamaterial is insensitive to dielectric and metal environment. The above advantages are explained by the following analysis: the key parameters for the 180° phase difference, the bistatic RCS reduction, and the environment effect. This metasurface may achieve potential applications on low-scattering vehicle.

A single-layer planar reflectarray with compact size 3.87λ 0 × 3.87λ 0 is proposed to produce vortex beam with high efficiency and good quality in 5.8GHz. The required phase shift in the reflected metasurface is realized by simply adjusting the radius of dual-ring elements. Thanks to the symmetric structure of the proposed unit-cell, the vortex waves operation can be obtained with arbitrary polarization. A set of reflectarrays producing OAM beams with mode l=1, 2, 3, 4 respectively, are designed and verified using full-wave simulations. Furthermore, the reflectarray with mode l=1 is fabricated and measured for experimental verification. The aperture efficiency of the reflectarray reaches to 22.6%, which is superior to homogeneous antennas. Both the simulated and measured results demonstrate the good performance of the proposed reflectarray.

A wideband circular polarization (CP) near-field focused (NFF) antenna array operating at 2.45 GHz is reported. The antenna array consists of 16 patches placed on two concentric circles. The proposed antenna array can use fewer elements to achieve smaller size of focal point and a controllable focal distance can be realized by adjusting the phase excitation distribution.

In this paper, a single-layer wideband dual-linearly polarized reflective element is developed operating from 13GHz to 15.5GHz. The developed reflective metasurface can produce orbital angular momentum (OAM) vortex waves with required modes, beam numbers, direction, x-, y- or both x- and -y polarizations. To demonstrate this versatility, three reflectarrays with multiple modes, multiple beams, and both x- and -y polarizations are designed, and one is fabricated and measured to validate the design. The measured peak gain, aperture efficiency, divergence angle is 19dBi, 11.54%, 6°, respectively. The designed reflectarray has potential applications for high communication rate.

This letter presents a compact dual-polarized chipless tag. The chipless tag consists of nested concentric coplanar square loops, and adjacent loops are connected by two stub lines at the center of the opposite sides, respectively. There are two critical factors in achieving small size. One is due to the integration of multiple square loops in a nested structure, sharing the same sides. The structure is designed to obtain the following function relationship between the loop number $n$ and resonant mode number $N: N\,= \,2(n- 1)$ . The other critical factor for minimization is that it is the coupling of adjacent loops that responds to resonances. The gap size only influences the coupling strength, and shifts resonance frequency a little, and does not influence the sharp-edged resonance in spite of small gap. This is one highlight. The other highlight is that four variations can be independently adjusted on the basis of the proposed reference tag, and a lot of different encoding identifications can be obtained. In addition, the proposed tag also has the following advantages. The proposed tag is magnetic, and the radar cross section (RCS) magnitude is insensitive to the medium where it is pasted. High RCS magnitude is realized at the condition of minimization. The connected coplanar square loop resonators are reused in both vertical and horizontal polarizations to double the encoding capacity within a fixed bandwidth. The RCS curve keeps unchanged until the orientation angle rotates up to 35°. An 18-bit tag is developed by the proposed nested loops, and ${\text{19bits/cm}}^{2}$ data density is obtained.

A multiple-input–multiple-output (MIMO) antenna with high frequency selectivity and controllable bandwidth, is proposed for band-notched ultrawideband (UWB) applications. In other words, it has a bandstop-filter-like response (second-order notched band) at the aimed rejected band. It consists of two rectangular printed monopole (PM) elements and a simple stepped ground stub to enhance wideband isolation. For achieving the second-order rejected band of the IEEE 802.11 wireless local area network (WLAN) band from 5.15 to 5.85 GHz centered at 5.5 GHz, two parasitic modified split-ring resonators (PMSRRs) and two inverted L-shaped branches (ILBs), are utilized. Measured results prove a bandwidth of S11

This letter presents a technique for designing left-handed material (LHM) unit cell, and a minimized 2-D low-loss LHM square spiral unit cell ( $38~ \text {mm} \times 38 ~\text {mm} \times 1.6 ~\text {mm}$ ) with rotation symmetry is developed in the frequency band 13.56–14 MHz. Two LHM slabs with $5 \times 5$ unit cell array are added to the transmission and receiving antennas, respectively, and the power transfer efficiency has increased greatly.

This Letter presents a single-layer, dual-frequency unit for generating orbital angular momentum (OAM) in the microwave range. The unit cell consists of a square frame and two concentric rings with branches. The developed units can produce multifunctional OAM with required OAM mode, beam number, and direction. To demonstrate this versatility, three reflectarrays operating at dual frequencies are designed, and one is fabricated and measured to validate the design. The reflectarray has the following advantages: high gain (15.4dBi at 10 GHz, 20.3dBi at 20 GHz), high aperture efficiency (13.53% at 10 GHz, 10.33% at 20 GHz), low divergence angle (7.5°at 10 GHz, 6° at 20 GHz), small size, and compactness in the form of a single-layer structure. The designed multifunctional reflectarray has potential applications in remote sensing, point-to-point communication, satellite communications, and others.

In this paper, a simple broadband circular polarization (CP) monopole antenna is developed. Off-center feeding technique has been applied to monopole antenna to excite CP radiation. The CP antenna consists of a tilted elliptical monopole, ground with an arc-shaped edge, and folded feedline. Placing the elliptical monopole off-center is the key factor for producing wide CP and impedance bandwidth. The measured -10 dB impedance bandwidth is 122% (1.14-4.7 GHz) and 3-dB axial ratio (AR) bandwidth reaches 90.4% (1.31-3.47 GHz).

This paper presents a novel high encoding capacity and bending-insensitive chipless tag. The chipless tag consists of nested concentric coplanar split rings, and adjacent rings are connected by two stub lines at the center of the opposite sides, respectively. There exist four highlights. First is minimization. The first key factor for minimization: The structure of nested split rings is designed to obtain the following function relationship between the ring number n and resonant mode number $\mathrm{N}:\mathrm{N}=3(\mathrm{n}- 1)$ . The second key factor for minimization is small gap between adjacent split rings. The resonance modes are magnetic and it is the current coupling of adjacent loops that contribute the magnetic resonances. The gap size only influences the coupling strength, shift resonance frequency a little, and does not influence the sharp-edged resonances in spite of small gap. The second highlight is that five variations can be independently adjusted on the basis of the proposed reference tag, and a lot of encoding identifications (IDs) can be obtained. The third light spot is that the tag is bending-insensitive. There still exist sharp-edged resonances and high RCS magnitude when the tag is mounted on cylinder surface. The fourth highlight is environment dielectric insensitivity because of magnetic resonance.

An innovative design of spiral electrically small magnetic antenna (ESMA) with high radiation efficiency is proposed for wireless power transfer (WPT). The achievable wireless power transfer efficiency (PTE) by the proposed ESMA is far beyond than that of the traditional spiral shape with the same size. The operation frequency for the proposed ESMA is 13.56 MHz, and $ka = 0.04$ , where $k$ and $a$ are wavenumber in free space and radius of a minimum sphere enclosing the antenna, respectively. The ESMA consists of an embedded multiloop feed and an innovative spiral resonator. In order to increase the radiation efficiency, conductor strip is used instead of the wire to reduce loss, and the internal and external turns stagger in the axial direction in order to confine the electric current to the outermost surface of the occupied volume. The input impedance is made closer to $50 \Omega$ by the embedded multiloop feed. The radiation efficiency for the single proposed ESMA is 93.5%, and the PTE between two symmetric proposed ESMAs are 92.4%, 77.4%, and 61% at distances 60 cm (3 times the maximum side length), 70 cm (3.5 times the maximum side length), and 80 cm (4 times the maximum side length), respectively.

In this article, a small-size seven-band antenna covering GSM850/900/1800/1900/UMTS2100/LTE2300/2500 bands for wireless wide area network/long term evolution mobile handset is presented. The developed antenna only occupies a planar size of 15 × 25 mm2. The capacitive coupling feed is used to generate fundamental resonant λ/8 mode and high-order λ/4 mode to reduce the size. Electromagnetic (EM) coupling between the radiation strips is used to widen the operation band. The antenna consists of a feed strip and two radiation strips (RS1, RS2). RS2 is in the same side of the ground. RS1 is in the other side of substrate. Two λ/8 modes (at 850 and 925 MHz) and two λ/4 modes (at 1850 and 2200 MHz) are generated by the capacitive feed. Strip RS1 contributes to 850 and 1850 MHz modes, and strip RS2 contributes to 925 and 2200 MHz modes. In the mean time, there exists EM coupling between the two radiation strips (RS1, RS2), then dual-resonance mode at 845 and 925 MHz form a wide lower band covering GSM850/900, two high order resonant modes at 1850 and 2200 MHz form a wide upper band covering GSM1800/1900/UMTS2100/LTE2300/2500. Design mechanics is analyzed and main parameters are studied. The proposed antenna is fabricated, and the simulated and measured results agree well. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1029–1033, 2015

In this letter, a wideband printed dual-antenna for mobile terminals is presented. The dual-antenna consists of two symmetric antenna elements, a connecting line (CL), and three slots. The antenna element is an L-like monopole with a grounded branch, and the two antennas are connected by a narrow line. The three slots and connecting line not only reduced the mutual coupling, but also improved the reflection coefficient within a wide frequency band. Different slot can adjust different frequency band independently. The working mechanism of the three slots is analyzed based on the S-parameters and surface current distributions. A prototype shows that the measured $-\hbox{10~dB}$ impedance bandwidth is 1.01 GHz (1.71–2.72 GHz), and the measured mutual coupling is lower than $-\hbox{15~dB}$ at 1.68–2.7-GHz bands, which covers the GSM1800, GSM1900, UMTS, LTE2300, LTE2500, and 2.4-GHz WLAN bands. The radiation patterns are measured, and the diversity performance is presented.

This work presents a planar handset antenna having a small size 47 × 15 × 0. 8m m 3 and providing four wide operating bands of at least 698–960, 1710–2690, 3100–3900 and 5150–5850 MHz for the 11band LTE700/GSM850/900, GSM1800/1900/UMTS/LTE2300/LTE2500, WiMAX 3.5 GHz/5.4 GHz

In this paper, a very compact ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna, with a high isolation and triple notched bands, is proposed. Its size is dramatically decreased to 30× 26× 0.8mm3 on a cost-effective FR4 substrate. It consists of two rectangular printed monopole (PM) elements and a simple stepped ground stub to enhance wideband isolation. For two different rejected bands of the wireless local area network (WLANs) covering 5.15–5.35 and 5.725– 5.825GHz, four parasitic C-shaped split-ring resonators (PCSRR) are placed on either side of the feed line. By etching two inverted U-shaped slots on the center of the patch, the notched frequency at 4GHz C-band (3.7–4.2 GHz) of satellite communication systems is obtained. The results of simulation and measurement prove a bandwidth of S11 < −10 dB and S12 < −21 dB over the whole band (3.1– 11.2GHz) excluding the three independently adjustable rejection bands. Hence, the proposed UWB MIMO antenna has a very small size, simple structure, higher isolation and three narrower notched bands which effectively save more useful frequencies. Moreover, it is a good candidate for wireless portable UWB MIMO applications.

In this paper, a simple broadband circular polarization (CP) V-shaped slot antenna is developed. The CP antenna consists of Z-shaped feedline with a stub, a patch and symmetrically etched two right-angled V-shaped slots (an open slot and a closed slot) along the center line. The stub is introduced for multi-resonances to obtain broadband. The broad CP and impedance bandwidths overlap by the symmetrically etched right-angled V-shaped closed slot along the center line and the Z-shaped feedline placed in a proper position. The measured results show that the proposed antenna has a broad overlapped 3-dB axial ratio (AR) bandwidth and −10 dB impedance bandwidth of 71% (2.19–4.6 GHz).

This paper presents a technique for designing left hand material (LHM) unit cell, and a minimized 2D low loss LHM square spiral unit cell (38mm×38mm×1.6mm) with rotation symmetry is developed in the frequency band 13.56MHz-14MHz. The mechanics for double negative (DNG) magnitudes and evanescent wave magnification are analyzed. Two LHM slabs with 5×5 the unit cell array are added to the transmission and receiving antennas, respectively, and the power transfer efficiency (PTE) has been increased greatly.

In this paper, a three-band antenna with small size 50 × 15 × 0.8mm3 is developed. The multi-broadband antenna consists of strip-1, strip-2, Br-1, Br-2 and S-strip. The lengths of strip-1, strip-2 are close to λ/4 at 680MHz, 850MHz and λ3/4 at 2.04GHz, 2.55GHz, respectively. S-strip is close to λ at 5.2GHz and λ3/4 at 3.7GHz. In addition, two tuning stubs Br1 and Br-2 connected to strip-2 can further improve the impedance matching. Then six key resonances are excited: 680MHz, 850MHz, 2.04GHz, 2.55GHz, 3.7GHz and 5.2GHz. There exists electromagnetic coupling (EMC) among them. As a result of the effect of the structure, three wide-bands are produced: 660–1050MHz, 1.60–3.75 GHz, and 5.25–6.50 GHz. That is, the operation band covers full LTE700/2300/2500(1710–2690 MHz)/GSM850/900/(680 MHz–960MHz) GSM1800/1900/WiMAX3.5 GHz (3400 ∼ 3650MHz)/5.4-GHz (5250 ∼ 5850MHz)/UMTS (1710– 2170MHz). The return loss is better than −6 dB. The peak gains also satisfy the requirement for practical application.

A compact printed dual-band antenna for WiMAX/WLAN applications is proposed in this paper. The dual-band monopole antenna consists of a triangular patch and two folding arms shorted to the ground plane. The proposed antenna features a low proflle and compact dimension. To avoid via process in the fabrication, the triangular patch and two folding arms are separately constructed on the two sides of a FR4 substrate. By employing this structure, flve difierent resonances can be yielded. The triangular patch provides two resonant modes (4.62GHz and 7.05GHz). The two folding arms produces three resonances at 2.43GHz, 3.43GHz, and 6.59GHz. A prototype of the dual-band antenna is experimentally fabricated and tested. The measured results shows good impedance bandwidth and radiation pattern.

This paper introduces a method for canceling the parasitic capacitance of integrated common mode (CM) fllter by optimizing the layout of ground winding. Firstly, the CM fllter with positive or negative coupling between the ground and inductor winding is researched, respectively. Then, the two coupling polarizes are combined to form the bi-directional coupling, simulation and measured results show bi-directional coupling ground can efiectively improve the high frequency (HF) flltering performance. The equivalent circuits are given to demonstrate the cancellation mechanism, and modelling is derived for the design of ground winding. To further validate the application of proposed technique, CM noise and input/output signals for PFC (Power Factor Correction) converter with bi-directional coupling ground CM fllter are simulated. The noise spectrums show conductive interference at high frequencies is efiectively suppressed and meets the required electromagnetic interference (EMI) standard.

In this paper, a small-size ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna with triple notched bands and a high isolation, is proposed. Its size is dramatically decreased to 30×26×0.8 mm3 on a cost-effective FR4 substrate. It consists of two rectangular printed monopole (PM) elements and a simple stepped ground stub to enhance wideband isolation. For two different rejected bands of the wireless local area network (WLANs) covering 5.15–5.35 and 5.725–5.825 GHz, four parasitic C-shaped split-ring resonators (PCSRR) are placed on either side of feed line. By etching two inverted U-shaped slots on the center of radiators, the notched frequency at 4 GHz C-band (3.7–4.2 GHz) of satellite communication systems is obtained. Simulated and measured results prove a bandwidth of S 11 12

A wideband printed dual-antenna for mobile terminals is presented. The antenna array consists of two symmetric antenna elements, A T-shape protruded ground(TP) and three slots. The antenna element consists of a feed strip and two radiation strips(RS1, RS2), which only occupies a planar size of 15 × 25mm2. The three slots and T-shape metal strip are utilized to reduce the mutual coupling. Different slot can adjust different frequency band independently. The working mechanism of the three slots is analyzed based on the S-parameters and surface current distributions. A measured impedance bandwidth with S11 lower than 6 dB over 824 960MHz and 1710–2690 MHz is obtained. Within the operating bands, the measured S21 is lower than −15dB. The radiation patterns are measured, and the diversity performance is presented.

In this article, a small-size seven band antenna covering GSM850/900/1800/1900/ UMTS2100/LTE2300/2500 bands for WWAN/LTE mobile handset is presented. The developed antenna only occupies a planar size of 15×25mm2. The capacitive coupling feed is used to generate fundamental resonant λ/8 mode and high-order λ/4 mode to reduce the size. EM coupling between the radiation strips is used to widen the operation band. The antenna consists of a feed strip and two radiation strips(RS1, RS2). RS2 is in the same side of the ground. RS1 is in the other side of substrate. Two λ/8 modes(at 850 and 925MHz) and two λ/4 modes(at 1850 and 2200 MHz) are generated by the capacitive feed. Strip RS1 contributes to 850 and 1850 MHz modes, and strip RS2 contributes to 925 and 2200MHz modes. In the mean time, there exists electromagnetic(EM) coupling between the two radiation strips (RS1, RS2), then dual-resonance mode at 845 and 925 MHz form a wide lower band covering GSM850/900, two high order resonant modes at 1850 and 2200MHz form a wide upper band covering GSM1800/1900/UMTS2100/LTE2300/2500. Design mechanics is analyzed and main parameters are studied. The proposed antenna is fabricated, and the simulated and measured results agree well.

A simple analytical model of odd and even mode external inductance and kinetic inductance for coupled high-temperature superconducting (HTS) microstrip lines is developed. The kinetic inductance model is derived with the extended incremental inductance rule which is applied in a different way for different conductor thickness. The odd and even mode inductance, self- and mutual inductance, characteristic impedance, and attenuation constant are computed with the presented model expressions and the results agree well with that in published literature.

In this paper the capacitance equivalent circuits of quasi-TEM HTS microstrip have been presented for thick and thin conductors according to the distribution of magnetic field and current density in superconducting thick and thin films, and the basic capacitance expressions have been given. The expressions are verified by using them to analyze three examples.

A superconducting microwave ring resonator whose resonant frequency can be tuned is designed and simulated. The structure is a ring resonator directly coupled to two low inductance open loops with Josephson junctions fabricated in a thin film format. The frequency tuning is accomplished by changing the nonlinear equivalent inductance of the Josephson junctions. The designed resonator works with higher Q value than that from other tuning approaches and with a frequency tuning range of 18%.

Microstrip multi-band bandstop filters using tri-mode equilateral triangular patch resonator are developed, and the rules of resonant frequency and patch defection dimension are obtained by calculation. With fractal patch defection and a higher substrate permittivity, higher order modes of resonator are activized for the multi-band implementation, and the dominant mode TM 1,0,−1 , and the higher order modes TM 1,1,−2 and TM 2,−2,0 are fully applied, and filter performances are greatly enhanced. The design is demonstrated by experiment. The proposed filters have advantages of simple topology, compact size and nicer performances, and all these features are well popular for wireless communication systems.

New equilateral triangular patch resonator bandpass filters using fractal defection are presented to implement high performances of wide passband, transmission zeros, and low passband insertion losses. Using fractal defection acts as perturbation, filter performances are greatly enhanced, and the validity of the design is demonstrated by measurement. Compared with some reported dual-mode or multi-mode filters, the new filters still have nicer performances even though operate at a single mode, simultaneously, have more compact and simple structures for having single patch resonator without coupling gaps.

Multi-mode technique has very important application in microwave filter design for implementing miniaturization, wide band and nicer performances. This report presents a new multi-mode bandpass filter with wide passband by using single isosceles right-angled triangular resonator which with much less attention, and transmission zeros and low passband insertion losses are obtained. The new filter has a novel, compact and simple structure as well as nicer performances, and can be quite useful in modern RF/microwave circuits and systems.

New microstrip low pass filters with low insertion loss, ultra-wide stopband and transmission zero are presented by using triangular and trapezoidal patch resonators with fractal defection. With such defection and a certain parallel feed method, undesired responses and harmonics are effectively suppressed and wide band, sharp attenuation obtained. The new filters have simpler and more compact configurations even better filter properties than the traditional line based ones.