Optical responses in dilute composites are controlled through the local dielectric resonance of metallic clusters. We consider two located metallic clusters close to each other with admittances ε1 and ε2. Through va...Optical responses in dilute composites are controlled through the local dielectric resonance of metallic clusters. We consider two located metallic clusters close to each other with admittances ε1 and ε2. Through varying the difference admittance ratio η[= (ε2 - ε0)/(ε1 - ε0)], we find that their optical responses are determined by the local resonance. There is a blueshift of absorption peaks with the increase of η- Simultaneously, it is known that the absorption peaks will be redshifted by enlarging the cluster size. By adjusting the nano-metallic cluster geometry, size and admittances, we can control the positions and intensities of absorption peaks effectively. We have also deduced the effective linear optical responses of three-component composites εe=ε0 (1+∑^n n=1[(γn1+ηγn2)/(ε0(s-sn))]) and the sum rule of cross sections:∑^n n=1(γn1+ηγn2)=Nh1+Nh2,, where Nh1and Nh2 are the numbers of εl and ε2 bonds along the electric field, respectively. These results may be beneficial to the study of surface plasmon resonances on a nanometre scale.展开更多
Dielectric resonator magnetoelectric dipole(DRMED)arrays with enhanced isolation,reduced cross-polarization,and backward radiation are proposed for base station(BS)applications.The proposed antenna comprises an elevat...Dielectric resonator magnetoelectric dipole(DRMED)arrays with enhanced isolation,reduced cross-polarization,and backward radiation are proposed for base station(BS)applications.The proposed antenna comprises an elevated dielectric resonator antenna(DRA)on a small metal plate above a sizeable common ground plane.The DRA is designed in its T Eδ11 mode,acting like a magnetic dipole.The surface current excited by the differential probes flowing on the small ground plane is equivalent to an electric dipole.Since these two equivalent dipoles are orthogonal,they have the magnetoelectric dipole characteristics with reduced backward radiation.Meanwhile,the small ground planes can be treated as decoupling structures to provide a neutralization path to cancel the original coupling path.A linearly-polarized 4-element prototype array was verified experimentally in previous work.Here,a dual-polarized DRMED antenna is presented to construct a 2-element and 4×4 array for BS applications.To investigate its MIMO performance,sophisticated multi-cell scenario simulations are carried out.By using the proposed dualpolarized DRMED array,the cellular system capacityis improved by 118.6%compared to a conventional DRA array.This significant MIMO system improvement is mainly due to the reduced backward radiation and,therefore,reduced inter-cell interferences.Measurements align well with the simulations.展开更多
This paper proposes a new dielectric resonator antenna(DRA)design that can generate circularly polarized(CP)triple-band signals.Atripleband CP DRA antenna fed by a probe feed system is achieved with metal strips struc...This paper proposes a new dielectric resonator antenna(DRA)design that can generate circularly polarized(CP)triple-band signals.Atripleband CP DRA antenna fed by a probe feed system is achieved with metal strips structure on side of DRA structure.The design start with conventional rectangular DRA with F shaped metal strips on DRA structure alongside the feed.Then,the F metal strip is enhanced by extending the length of the metal strip to obtain wider impedance bandwidth.Further improvement on the antenna performance is observed by improvised the conventional DRA structure.The method of removing part of DRA bottom resulted to higher antenna gain with triple band CP.The primary features of the proposed DRA include wide impedance matching bandwidth(BW)and broadband circular polarization(CP).The primary features of the proposedDRAinclude wide impedance matching bandwidth(BW)and broadband circular polarization(CP).The CP BW values recorded by the proposed antenna were∼11.27%(3.3–3.65 GHz),12.18%(4.17–4.69 GHz),and 1.74%(6.44–6.55 GHz)for impedance-matching BW values of 35.4%(3.3–4.69 GHz),1.74%(5.36–5.44 GHz),and 1.85%(6.41–6.55 GHz)with peak gains of 6.8 dBic,7.6 dBic,and 8.5 dBic,respectively,in the lower,central,and upper bands.The prototype of the proposed antenna geometry was fabricated and measured.A good agreement was noted between the simulated and the measured results.展开更多
This paper presents an overview of dielectric patch(DP)antennas developed in recent years.The employed DP resonator composed of a DP and a bottom substrate is analyzed comprehensively here,enabling the easy realizatio...This paper presents an overview of dielectric patch(DP)antennas developed in recent years.The employed DP resonator composed of a DP and a bottom substrate is analyzed comprehensively here,enabling the easy realization of a quasi-planar DP antenna.It combines the dual advantages of the conventional microstrip patch(MP)antenna and dielectric resonator(DR)antenna in terms of profile,gain,bandwidth,radiation efficiency,and design freedom.Furthermore,the DP antenna inherits the multi-mode characteristic of the DR antenna,thus it has a large number of high-order modes,including TMmn mode and TEmn mode.The high-order modes are widely applied,for example,by combining with the dominant TM10 mode to expand the bandwidth,or selecting multiple higher-order modes to implement a high-gain antenna.Additionally,the non-radiation high-order modes are also utilized to produce natural radiation null in filtering antenna design.In this paper,the design theories and techniques of DP antenna are introduced and investigated,including calculation and control methods of the resonant mode frequencies,analysis of the radiation mechanism,and applications of the multi-mode characteristic.This overview could provide guidance for the subsequent antenna design,thus effectively avoid time-consuming optimization.展开更多
In this paper, a low-profile wideband dielectric resonator antenna(DRA) with a very compact planar size is investigated. The antenna consists of a high permittivity dielectric sheet on the top, a low permittivity subs...In this paper, a low-profile wideband dielectric resonator antenna(DRA) with a very compact planar size is investigated. The antenna consists of a high permittivity dielectric sheet on the top, a low permittivity substrate in the middle, and a probe feeding structure at the bottom. By digging an annular slot in the designated area of the square dielectric sheet, the resonant frequency of fundamental TE111 mode can be effectively increased to be close to the high-order TE131 mode. The two modes can be finally merged together, yielding a wide impedance bandwidth of16.6%. Most importantly, the combination of the two modes is done on the premise of a fixed antenna planar size, which can be very compact and suitable for beam-scanning applications. A probe feeding structure is used to excite the DRA, making the antenna simple and practical to be integrated with other RF circuits. For verification, antenna prototypes with singlefeed linear polarization and differential-feed dual polarization were fabricated and measured. Reasonable agreement between the measured and simulated results is observed.展开更多
The synthesis, structure and properties of a new A5B4O15-type cation-deficient perovskite Ba3La2Ti2Ta2O15 were discribed. The compound was prepared by the conventional solid-state reaction route. The phase and structu...The synthesis, structure and properties of a new A5B4O15-type cation-deficient perovskite Ba3La2Ti2Ta2O15 were discribed. The compound was prepared by the conventional solid-state reaction route. The phase and structure of the ceramics were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The results reveal that the compound is successfully synthesized. The compound crystallizes in the trigonal system with unit cell parameter a=5.6730(2) A, c=11.6511(2) A, V=324.93(1) A^3 and Z=1. The microwave dielectric properties of the ceramic are studied using a network analyzer, and it shows a high dielectric constant of 45.1, a high quality factors with Q×fof21 029 GHz, and a positive τf of 5.3 ppm℃^-1.展开更多
In this article an ultra-wideband rectangular Dielectric Resonator Antenna is designed for millimeter wave 5G frequency band applications.Indoor 5G communications require antenna system with wide bandwidth and high ef...In this article an ultra-wideband rectangular Dielectric Resonator Antenna is designed for millimeter wave 5G frequency band applications.Indoor 5G communications require antenna system with wide bandwidth and high efficiency to enhance the throughput in the channel.To fulfill such requirements a Dielectric Resonator Antenna(DRA)is designed here which has achieved an ultra-wide bandwidth of 20.15%(22.32–27.56 GHz)which is 5.24 GHz of bandwidth centered at 26 GHz as resonating frequency.This covers the complete band 30(24.3–27.5 GHz)of 5G spectrum.26 and 28 GHz are considered as most popular frequencies in millimeter wave 5G communications.The aperture fed DRA designed here has also achieved an efficiency of 96 percentage with maximum radiation in the broadside direction(Phi=0,Theta=0).The measured gain of the DRA is 6.3 dB.The DRA designed here has dimensions of 0.25λ0×0.22λ0×0.12λ0.under the characteristic’s mode.The DRA is placed over a substrate with dimensions 0.5λ0×0.5λ0×0.02λ0.A cross slot aperture has been made on the ground plane which is placed above to the substrate.Here a full ground plane is used to resonate the antenna and is of similar dimension to the substrate.A microstrip line with two concentric rings makes an annular feed structure is used to excite the DRA and is placed below the substrate.The DRA is excited here in characteristics mode TE1Y1 and is the only mode of excitation.The DRA is linearly polarized,and the characteristic mode of excitation is maintained with 50 Ohm input impedance of the antenna.The DRA also gives here a good difference between the co-pol and cross pol approximately 15 to 20 dB.This antenna is more suitable for 5G indoor applications in millimeter wave frequency band centered at 26 GHz.展开更多
Nowadays, the high-critical-temperature radio frequency superconducting quantum interference device (high-Tc rf SQUID) is usually coupled to a dielectric resonator that is a standard 10× 10×1 mm^3 SrTiO3 ...Nowadays, the high-critical-temperature radio frequency superconducting quantum interference device (high-Tc rf SQUID) is usually coupled to a dielectric resonator that is a standard 10× 10×1 mm^3 SrTiO3 (STO) substrate with a YBa2Cu3O7-δ (YBCO) thin-film flux focuser deposited on it. Recently, we have simulated a dielectric resonator for the high-Tc rf SQUID by using the ANSOFT High Frequency Structure Simulator (ANSOFT HFSS). We simulate the resonant frequency and the quality factor of our dielectric resonator when it is unloaded or matches a 50-Ω impedance. The simulation results are quite close to the practical measurements. Our study shows that ANSOFT HFSS is quite suitable for simulating the dielectric resonator used for the high-Tc rf SQUID. Therefore, we think the ANSOFT HFSS can be very helpful for investigating the characteristics of dielectric resonators for high-Tc rf SQUIDs.展开更多
Dipoles with Lorentz-type resonant electromagnetic responses can realise negative effective parameters in their negative resonant region. The electric dipole and magnetic dipole can realise, respectively, negative per...Dipoles with Lorentz-type resonant electromagnetic responses can realise negative effective parameters in their negative resonant region. The electric dipole and magnetic dipole can realise, respectively, negative permittivity and negative permeability, so both the field distribution forms of electric and magnetic dipoles are fundamentals in designing left-handed metamaterial. Based on this principle, this paper studies the field distribution in high-permittivity dielectric materials. The field distributions at different resonant modes are analysed based on the dielectric resonator theory. The origination and influence factors of the electric and magnetic dipoles are confirmed. Numerical simulations indicate that by combining dielectric cubes with different sizes, the electric resonance frequency and magnetic resonance frequency can be superposed. Finally, experiments are carried out to verify the feasibility of all-dielectric left-handed metamaterial composed by this means.展开更多
High gain antennas are highly desirable for long-range wireless communication systems.In this paper,a compact,low profile,and high gain dielectric resonator antenna is proposed,fabricated,experimentally tested,and ver...High gain antennas are highly desirable for long-range wireless communication systems.In this paper,a compact,low profile,and high gain dielectric resonator antenna is proposed,fabricated,experimentally tested,and verified.The proposed antenna system has a cylindrical dielectric resonator antenna with a height of 9 mm and a radius of 6.35 mm as a radiating element.The proposed dielectric resonator antenna is sourced with a slot while the slot is excited with a rectangular microstrip transmission line.The microstrip transmission line is designed for a 50impedance to provide maximum power to the slot.As a result,the proposed antenna operates at 5.15 GHz with a 10-dB absolute bandwidth of 430 MHz(4.98–5.41 GHz).It is important to mention that the gain of the dielectric resonator antenna is enhanced by the introduction of an electromagnetic bandgap(EBG)structure.In fact,EBG units are placed below the antenna,which enhances the realized peak gain from 5.32 dBi to 8.36 dBi at 5.15 GHz.More specifically,a gain enhancement of 3.04 dB is observed with the introduction of the EBG array.This antenna has several good features such as high gain,compact size,large bandwidth,and lower losses which make it a suitable choice for long-range wireless communication systems.展开更多
In this study,a compact 2×2 interlaced sequentially rotated dual-polarized dielectric-resonator antenna array is proposed for 5.8 GHz applications.The array is composed of a novel unit elements that are made of r...In this study,a compact 2×2 interlaced sequentially rotated dual-polarized dielectric-resonator antenna array is proposed for 5.8 GHz applications.The array is composed of a novel unit elements that are made of rectangular dielectric resonator(RDR)coupled to an eye slot for generating the orthogonal modes,TEδx 21 and TE1yδ1 to acquire circular polarization(CP)radiation.For the purpose of miniaturization and achieving dual polarized resonance,the array is fed by two interlaced ports and each port excites two radiating elements.The first port feeds horizontal elements to obtain left hand circular polarization(LHCP).The second port feeds vertical elements to obtain right hand circular polarization(RHCP).A quarter-wave length transformer is employed to reduce the attenuation and consequently increase the array gain performance.The 35×35 mm2(0.676λ0×0.676λ0)gains were 8.4 and 8.2 dBi for port 1 and port 2,respectively,with port isolations of−33.51 dB.The design achieves a voltage standing-wave ratio(VSWR)<−10 dB and an axial ratio(AR)<−3 dB bandwidth of 2.48%(5.766 to 5.911 GHz)for LHCP at port 1 and a VSWR<−10 dB and AR<−3 dB bandwidth of 2.28%(5.788 to 5.922 GHz)for RHCP at port 2.The findings of the proposed design validate its use for ISM band applications.展开更多
In this work,we propose an all-dielectric frequency selective surface(FSS) composed of periodically placed highpermittivity dielectric resonators and a three-dimensional(3D) printed supporter.Mie resonances in the...In this work,we propose an all-dielectric frequency selective surface(FSS) composed of periodically placed highpermittivity dielectric resonators and a three-dimensional(3D) printed supporter.Mie resonances in the dielectric resonators offer strong electric and magnetic dipoles,quadrupoles,and higher order terms.The re-radiated electric and magnetic fields by these multipoles interact with the incident fields,which leads to total reflection or total transmission in some special frequency bands.The measured results of the fabricated FSS demonstrate a stopband fractional bandwidth(FBW)of 22.2%,which is consistent with the simulated result.展开更多
A wideband polarization reconfigurable dielectric resonator antenna excited by quasilumped quadrature coupler( QLQC) is proposed. By adjusting the value of varactor diode on the QLQC feed network,both the wideband L...A wideband polarization reconfigurable dielectric resonator antenna excited by quasilumped quadrature coupler( QLQC) is proposed. By adjusting the value of varactor diode on the QLQC feed network,both the wideband LP and CP dielectric resonator antennas( DRA) modes can be achieved. By selecting a different feed port,left-and right-handed CP conversion can be realized.It is found that the 10 dB impedance bandwidth of the LP and CP modes are 10. 1% and 44. 9%,respectively.For the CP mode,a very wide 3 dB axial ratio bandwidth of 37. 7% can be obtained which is much larger than that of the microstrip patch counterpart( 3. 8%). It is worth mentioning that the wideband CP DRA has a stable broadside radiation pattern across the whole operating band where the boresight gain is larger than 3 dBi.展开更多
A ceramic dielectric resonator antenna excited by a corner-cut square patch for the circularly-polarized operation is introduced. The effect of patch size and cut size is investigated, showing that the resonant freque...A ceramic dielectric resonator antenna excited by a corner-cut square patch for the circularly-polarized operation is introduced. The effect of patch size and cut size is investigated, showing that the resonant frequency of the antenna can be changed by simply changing the patch size. The reflection, axial ratio, and radiation characteristics of the antenna are found. Measurements were carried out to verify the design. The antenna is compact in structure, which is attractive in the application as the satellite communication terminals.展开更多
In this paper, the resonant frequency of a dual\|mode dielectric resonator is calculated using a finite difference time\|domain method. A new type of bandpass filter is designed with the calculated coupling coefficien...In this paper, the resonant frequency of a dual\|mode dielectric resonator is calculated using a finite difference time\|domain method. A new type of bandpass filter is designed with the calculated coupling coefficient. The filter designed in this paper has reached the design goal, verified by simulation with Ansoft HFSS.展开更多
The design of a 5.305 GHz series feedback free running dielectric resonator oscillator (DRO) is presented. Its simulation and optimization are realized by obtaining the unloaded Q factor of the cavity dielectric res...The design of a 5.305 GHz series feedback free running dielectric resonator oscillator (DRO) is presented. Its simulation and optimization are realized by obtaining the unloaded Q factor of the cavity dielectric resonator (DR) and analyzing the linear and nonlinear models of the DRO. CAD packages of DR_Rez and Agilent Advance Design System (ADS) are used and the best tradeoff among the output power, phase noise, and frequency stability is achieved. With the result of simulation, a physical oscillator prototype is constructed. The measured results show the good agreement with those of simulation.展开更多
The theory and application of resonances and vibrational modes are part of the foundation of science.In this contribution,examples of acoustical resonators are highlighted,and compared to electromagnetic modes.As an e...The theory and application of resonances and vibrational modes are part of the foundation of science.In this contribution,examples of acoustical resonators are highlighted,and compared to electromagnetic modes.As an example from architecture,we describe the phenomenon of whispering galleries;such modes are nowadays known in dielectric and optical resonators.A specimen of a semicircular whispering bench in Park Sanssouci in Potsdam is acoustically investigated and demonstrated to show low losses for sound propagation.A special acoustical bug is discussed which was used for the espionage of the U.S.ambassador in Moscow.The Sovyets could interrogate this passive device by radio waves.Its working principle was based on the electromagnetic resonance of the cavity that the sound-sensitive membrane was part of.The underlying relation between excitation and resonance is compared to the sound production in flue organ pipes.A stopped flue organ pipe was investigated using a piezoelectric film sensor inside the pipe body.The results show that even-numbered modes,which are usually suppressed in the radiated sound of a stopped pipe,are still present in the vibrations inside the resonator.展开更多
Microwave dielectric ceramics should be improved to advance mobile communication technologies further.In this study,we prepared Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics with nonstoichiometric Sr^(2+)ratios based on our ...Microwave dielectric ceramics should be improved to advance mobile communication technologies further.In this study,we prepared Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics with nonstoichiometric Sr^(2+)ratios based on our previously reported SrY_(2)O_(4) microwave dielectric ceramic,which has a low dielectric constant and an ultrahigh quality factor(Q value).The ceramic exhibited a 33.6% higher Q-by-frequency(Q×f)value(Q≈12,500)at x=0.02 than SrY_(2)O_(4).All Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics exhibited pure phase structures,although variations in crystal-plane spacings were observed.The ceramics are mainly composed of Sr-O,Y1-O,and Y_(2)-O octahedra,with the temperature coefficient of the resonant frequency(τ_(f))of the ceramic increasing with Y_(2)-O octahedral distortion.The ceramic comprises uniform grains with a homogeneous elemental distribution,clear grain boundaries,and no obvious cavities at x=0.02.The Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics exhibited good microwave dielectric properties,with optimal performance observed at x=0.02(dielectric constant(εr)=15.41,Q×f=112,375 GHz,and τ_(f)=-17.44 ppm/℃).The τ_(f) value was reduced to meet the temperaturestability requirements of 5G/6G communication systems by adding CaTiO_(3),with Sr_(1.02)Y_(2)O_(4.02)+2wt% CaTiO_(3) exhibiting ε_(r)=16.14,Q×f=51,004 GHz,andτf=0 ppm/℃.A dielectric resonator antenna prepared using Sr_(1.02)Y_(2)O_(4.02)+2wt%CaTiO_(3) exhibited a central frequency of 26.6 GHz,with a corresponding gain and efficiency of 3.66 dBi and 83.14%,respectively.Consequently,Sr_(1.02)Y_(2)O_(4).02-based dielectric resonator antennas are suitable for use in 5G millimeter-wave band(24.5-27.5 GHz)applications.展开更多
Conventionally, metallic nanostructures are used for surface-enhanced Raman spectroscopy(SERS), but recently there has been increasing interest in the enhancement of Raman scattering from dielectric substrates due to ...Conventionally, metallic nanostructures are used for surface-enhanced Raman spectroscopy(SERS), but recently there has been increasing interest in the enhancement of Raman scattering from dielectric substrates due to their improved stability and biocompatibility compared with metallic substrates. Here, we report the observation of enhanced Raman scattering from rhodamine 6 G molecules coated on silica microspheres. We excite the whispering gallery modes(WGMs) supported in the microspheres with a tapered fiber coupler for efficient WGM excitation, and the Raman enhancement can be attributed to the WGM mechanism. Strong resonance enhancement in pump laser intensity and modified Raman emission from the Purcell effect in the microsphere resonator are observed from the experiment and compared with theoretical results. A total Raman enhancement factor of 1.4 × 10~4 is observed, with contribution mostly from the enhancement in pump laser intensity. Our results show that, with an efficient pumping scheme, dielectric microspheres are a viable alternative to metallic SERS substrates.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos 10304001, 10334010, 10521002, 10434020, 10328407 and 90501007).
文摘Optical responses in dilute composites are controlled through the local dielectric resonance of metallic clusters. We consider two located metallic clusters close to each other with admittances ε1 and ε2. Through varying the difference admittance ratio η[= (ε2 - ε0)/(ε1 - ε0)], we find that their optical responses are determined by the local resonance. There is a blueshift of absorption peaks with the increase of η- Simultaneously, it is known that the absorption peaks will be redshifted by enlarging the cluster size. By adjusting the nano-metallic cluster geometry, size and admittances, we can control the positions and intensities of absorption peaks effectively. We have also deduced the effective linear optical responses of three-component composites εe=ε0 (1+∑^n n=1[(γn1+ηγn2)/(ε0(s-sn))]) and the sum rule of cross sections:∑^n n=1(γn1+ηγn2)=Nh1+Nh2,, where Nh1and Nh2 are the numbers of εl and ε2 bonds along the electric field, respectively. These results may be beneficial to the study of surface plasmon resonances on a nanometre scale.
基金supported by the National Key Research and Development Program of China under Grant 2020YFA0709800.
文摘Dielectric resonator magnetoelectric dipole(DRMED)arrays with enhanced isolation,reduced cross-polarization,and backward radiation are proposed for base station(BS)applications.The proposed antenna comprises an elevated dielectric resonator antenna(DRA)on a small metal plate above a sizeable common ground plane.The DRA is designed in its T Eδ11 mode,acting like a magnetic dipole.The surface current excited by the differential probes flowing on the small ground plane is equivalent to an electric dipole.Since these two equivalent dipoles are orthogonal,they have the magnetoelectric dipole characteristics with reduced backward radiation.Meanwhile,the small ground planes can be treated as decoupling structures to provide a neutralization path to cancel the original coupling path.A linearly-polarized 4-element prototype array was verified experimentally in previous work.Here,a dual-polarized DRMED antenna is presented to construct a 2-element and 4×4 array for BS applications.To investigate its MIMO performance,sophisticated multi-cell scenario simulations are carried out.By using the proposed dualpolarized DRMED array,the cellular system capacityis improved by 118.6%compared to a conventional DRA array.This significant MIMO system improvement is mainly due to the reduced backward radiation and,therefore,reduced inter-cell interferences.Measurements align well with the simulations.
文摘This paper proposes a new dielectric resonator antenna(DRA)design that can generate circularly polarized(CP)triple-band signals.Atripleband CP DRA antenna fed by a probe feed system is achieved with metal strips structure on side of DRA structure.The design start with conventional rectangular DRA with F shaped metal strips on DRA structure alongside the feed.Then,the F metal strip is enhanced by extending the length of the metal strip to obtain wider impedance bandwidth.Further improvement on the antenna performance is observed by improvised the conventional DRA structure.The method of removing part of DRA bottom resulted to higher antenna gain with triple band CP.The primary features of the proposed DRA include wide impedance matching bandwidth(BW)and broadband circular polarization(CP).The primary features of the proposedDRAinclude wide impedance matching bandwidth(BW)and broadband circular polarization(CP).The CP BW values recorded by the proposed antenna were∼11.27%(3.3–3.65 GHz),12.18%(4.17–4.69 GHz),and 1.74%(6.44–6.55 GHz)for impedance-matching BW values of 35.4%(3.3–4.69 GHz),1.74%(5.36–5.44 GHz),and 1.85%(6.41–6.55 GHz)with peak gains of 6.8 dBic,7.6 dBic,and 8.5 dBic,respectively,in the lower,central,and upper bands.The prototype of the proposed antenna geometry was fabricated and measured.A good agreement was noted between the simulated and the measured results.
基金supported by the Natural Science Foundation of Jiangsu Province under Grant BK20201438by the Natural Science Research Project of Jiangsu Provincial Institutions of Higher Education under Grant 20KJA510002by the Postgraduate Research and Practice Innovation Program of Jiangsu Province under Grant KYCX202825.
文摘This paper presents an overview of dielectric patch(DP)antennas developed in recent years.The employed DP resonator composed of a DP and a bottom substrate is analyzed comprehensively here,enabling the easy realization of a quasi-planar DP antenna.It combines the dual advantages of the conventional microstrip patch(MP)antenna and dielectric resonator(DR)antenna in terms of profile,gain,bandwidth,radiation efficiency,and design freedom.Furthermore,the DP antenna inherits the multi-mode characteristic of the DR antenna,thus it has a large number of high-order modes,including TMmn mode and TEmn mode.The high-order modes are widely applied,for example,by combining with the dominant TM10 mode to expand the bandwidth,or selecting multiple higher-order modes to implement a high-gain antenna.Additionally,the non-radiation high-order modes are also utilized to produce natural radiation null in filtering antenna design.In this paper,the design theories and techniques of DP antenna are introduced and investigated,including calculation and control methods of the resonant mode frequencies,analysis of the radiation mechanism,and applications of the multi-mode characteristic.This overview could provide guidance for the subsequent antenna design,thus effectively avoid time-consuming optimization.
基金supported by the National Natural Science Foundation of China under Grant 62071256National Natural Science Foundation of Jiangsu under Grant BK20201438+1 种基金supported by State Key Laboratory of Millimeter Waves (Nanjing) and Nantong Research Institute for Advanced Communication Technologies (Nantong)sponsored by Qing Lan Project of Jiangsu Province。
文摘In this paper, a low-profile wideband dielectric resonator antenna(DRA) with a very compact planar size is investigated. The antenna consists of a high permittivity dielectric sheet on the top, a low permittivity substrate in the middle, and a probe feeding structure at the bottom. By digging an annular slot in the designated area of the square dielectric sheet, the resonant frequency of fundamental TE111 mode can be effectively increased to be close to the high-order TE131 mode. The two modes can be finally merged together, yielding a wide impedance bandwidth of16.6%. Most importantly, the combination of the two modes is done on the premise of a fixed antenna planar size, which can be very compact and suitable for beam-scanning applications. A probe feeding structure is used to excite the DRA, making the antenna simple and practical to be integrated with other RF circuits. For verification, antenna prototypes with singlefeed linear polarization and differential-feed dual polarization were fabricated and measured. Reasonable agreement between the measured and simulated results is observed.
基金Funded by the National Natural Science Foundation of China(No.20571059 and No.50572078)Opening Foundation of Key Laboratory of New Processing Technology for Nonferrous Metals and Materials,Ministry of Education
文摘The synthesis, structure and properties of a new A5B4O15-type cation-deficient perovskite Ba3La2Ti2Ta2O15 were discribed. The compound was prepared by the conventional solid-state reaction route. The phase and structure of the ceramics were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The results reveal that the compound is successfully synthesized. The compound crystallizes in the trigonal system with unit cell parameter a=5.6730(2) A, c=11.6511(2) A, V=324.93(1) A^3 and Z=1. The microwave dielectric properties of the ceramic are studied using a network analyzer, and it shows a high dielectric constant of 45.1, a high quality factors with Q×fof21 029 GHz, and a positive τf of 5.3 ppm℃^-1.
基金This work was supported by Universiti Teknologi Malaysia under TDR grant vote 05G20 and HiCOE grant vote 4J415.
文摘In this article an ultra-wideband rectangular Dielectric Resonator Antenna is designed for millimeter wave 5G frequency band applications.Indoor 5G communications require antenna system with wide bandwidth and high efficiency to enhance the throughput in the channel.To fulfill such requirements a Dielectric Resonator Antenna(DRA)is designed here which has achieved an ultra-wide bandwidth of 20.15%(22.32–27.56 GHz)which is 5.24 GHz of bandwidth centered at 26 GHz as resonating frequency.This covers the complete band 30(24.3–27.5 GHz)of 5G spectrum.26 and 28 GHz are considered as most popular frequencies in millimeter wave 5G communications.The aperture fed DRA designed here has also achieved an efficiency of 96 percentage with maximum radiation in the broadside direction(Phi=0,Theta=0).The measured gain of the DRA is 6.3 dB.The DRA designed here has dimensions of 0.25λ0×0.22λ0×0.12λ0.under the characteristic’s mode.The DRA is placed over a substrate with dimensions 0.5λ0×0.5λ0×0.02λ0.A cross slot aperture has been made on the ground plane which is placed above to the substrate.Here a full ground plane is used to resonate the antenna and is of similar dimension to the substrate.A microstrip line with two concentric rings makes an annular feed structure is used to excite the DRA and is placed below the substrate.The DRA is excited here in characteristics mode TE1Y1 and is the only mode of excitation.The DRA is linearly polarized,and the characteristic mode of excitation is maintained with 50 Ohm input impedance of the antenna.The DRA also gives here a good difference between the co-pol and cross pol approximately 15 to 20 dB.This antenna is more suitable for 5G indoor applications in millimeter wave frequency band centered at 26 GHz.
基金Project supported by the National Basic Research Program of China (Grant No.2006CB601007)the National Natural Science Foundation of China (Grant No.10674006)+1 种基金the National High Technology Research and Development Program of China (Grant No.2007AA03Z238)the Foundation of the State Key Laboratory of Information Control Technology for Communication System,China (Grant No.9140C1304010803)
文摘Nowadays, the high-critical-temperature radio frequency superconducting quantum interference device (high-Tc rf SQUID) is usually coupled to a dielectric resonator that is a standard 10× 10×1 mm^3 SrTiO3 (STO) substrate with a YBa2Cu3O7-δ (YBCO) thin-film flux focuser deposited on it. Recently, we have simulated a dielectric resonator for the high-Tc rf SQUID by using the ANSOFT High Frequency Structure Simulator (ANSOFT HFSS). We simulate the resonant frequency and the quality factor of our dielectric resonator when it is unloaded or matches a 50-Ω impedance. The simulation results are quite close to the practical measurements. Our study shows that ANSOFT HFSS is quite suitable for simulating the dielectric resonator used for the high-Tc rf SQUID. Therefore, we think the ANSOFT HFSS can be very helpful for investigating the characteristics of dielectric resonators for high-Tc rf SQUIDs.
基金Project supported in part by the National Natural Science Foundation of China(Grant Nos.50632030,60871027 and 10804130)in part by the National Basic Research Program of China(Grant No.2009CB613306)the Natural Science Foundation of Shaanxi Province,China(Grant No.SJ08F01)
文摘Dipoles with Lorentz-type resonant electromagnetic responses can realise negative effective parameters in their negative resonant region. The electric dipole and magnetic dipole can realise, respectively, negative permittivity and negative permeability, so both the field distribution forms of electric and magnetic dipoles are fundamentals in designing left-handed metamaterial. Based on this principle, this paper studies the field distribution in high-permittivity dielectric materials. The field distributions at different resonant modes are analysed based on the dielectric resonator theory. The origination and influence factors of the electric and magnetic dipoles are confirmed. Numerical simulations indicate that by combining dielectric cubes with different sizes, the electric resonance frequency and magnetic resonance frequency can be superposed. Finally, experiments are carried out to verify the feasibility of all-dielectric left-handed metamaterial composed by this means.
基金The author would like to thank the Deanship of Scientific Research at Majmaah Universty,Kingdom of Saudi Arabia for supporting this work(R-2021-211).
文摘High gain antennas are highly desirable for long-range wireless communication systems.In this paper,a compact,low profile,and high gain dielectric resonator antenna is proposed,fabricated,experimentally tested,and verified.The proposed antenna system has a cylindrical dielectric resonator antenna with a height of 9 mm and a radius of 6.35 mm as a radiating element.The proposed dielectric resonator antenna is sourced with a slot while the slot is excited with a rectangular microstrip transmission line.The microstrip transmission line is designed for a 50impedance to provide maximum power to the slot.As a result,the proposed antenna operates at 5.15 GHz with a 10-dB absolute bandwidth of 430 MHz(4.98–5.41 GHz).It is important to mention that the gain of the dielectric resonator antenna is enhanced by the introduction of an electromagnetic bandgap(EBG)structure.In fact,EBG units are placed below the antenna,which enhances the realized peak gain from 5.32 dBi to 8.36 dBi at 5.15 GHz.More specifically,a gain enhancement of 3.04 dB is observed with the introduction of the EBG array.This antenna has several good features such as high gain,compact size,large bandwidth,and lower losses which make it a suitable choice for long-range wireless communication systems.
基金The author would like to thank the Deanship of Scientific Research at Majmaah University for supporting this work under Project Number R-2022-71.
文摘In this study,a compact 2×2 interlaced sequentially rotated dual-polarized dielectric-resonator antenna array is proposed for 5.8 GHz applications.The array is composed of a novel unit elements that are made of rectangular dielectric resonator(RDR)coupled to an eye slot for generating the orthogonal modes,TEδx 21 and TE1yδ1 to acquire circular polarization(CP)radiation.For the purpose of miniaturization and achieving dual polarized resonance,the array is fed by two interlaced ports and each port excites two radiating elements.The first port feeds horizontal elements to obtain left hand circular polarization(LHCP).The second port feeds vertical elements to obtain right hand circular polarization(RHCP).A quarter-wave length transformer is employed to reduce the attenuation and consequently increase the array gain performance.The 35×35 mm2(0.676λ0×0.676λ0)gains were 8.4 and 8.2 dBi for port 1 and port 2,respectively,with port isolations of−33.51 dB.The design achieves a voltage standing-wave ratio(VSWR)<−10 dB and an axial ratio(AR)<−3 dB bandwidth of 2.48%(5.766 to 5.911 GHz)for LHCP at port 1 and a VSWR<−10 dB and AR<−3 dB bandwidth of 2.28%(5.788 to 5.922 GHz)for RHCP at port 2.The findings of the proposed design validate its use for ISM band applications.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61201030,61372045,61472045,and 61401229)the Science and Technology Project of Jiangsu Province,China(Grant No.BE2015002)+1 种基金the Open Research Program of the State Key Laboratory of Millimeter Waves,China(Grant Nos.K201616 and K201622)the Nanjing University of Posts and Telecommunications Scientific Foundation,China(Grant No.NY214148)
文摘In this work,we propose an all-dielectric frequency selective surface(FSS) composed of periodically placed highpermittivity dielectric resonators and a three-dimensional(3D) printed supporter.Mie resonances in the dielectric resonators offer strong electric and magnetic dipoles,quadrupoles,and higher order terms.The re-radiated electric and magnetic fields by these multipoles interact with the incident fields,which leads to total reflection or total transmission in some special frequency bands.The measured results of the fabricated FSS demonstrate a stopband fractional bandwidth(FBW)of 22.2%,which is consistent with the simulated result.
基金Supported by the National Natural Science Foundation of China(61771055,61527805)
文摘A wideband polarization reconfigurable dielectric resonator antenna excited by quasilumped quadrature coupler( QLQC) is proposed. By adjusting the value of varactor diode on the QLQC feed network,both the wideband LP and CP dielectric resonator antennas( DRA) modes can be achieved. By selecting a different feed port,left-and right-handed CP conversion can be realized.It is found that the 10 dB impedance bandwidth of the LP and CP modes are 10. 1% and 44. 9%,respectively.For the CP mode,a very wide 3 dB axial ratio bandwidth of 37. 7% can be obtained which is much larger than that of the microstrip patch counterpart( 3. 8%). It is worth mentioning that the wideband CP DRA has a stable broadside radiation pattern across the whole operating band where the boresight gain is larger than 3 dBi.
基金Project supported by the National High-Technology Research and Development Project of China (Grant No.2007AA12Z125)the Innovation Foundation of Shanghai University (Grant No.SHUCX092130)
文摘A ceramic dielectric resonator antenna excited by a corner-cut square patch for the circularly-polarized operation is introduced. The effect of patch size and cut size is investigated, showing that the resonant frequency of the antenna can be changed by simply changing the patch size. The reflection, axial ratio, and radiation characteristics of the antenna are found. Measurements were carried out to verify the design. The antenna is compact in structure, which is attractive in the application as the satellite communication terminals.
文摘In this paper, the resonant frequency of a dual\|mode dielectric resonator is calculated using a finite difference time\|domain method. A new type of bandpass filter is designed with the calculated coupling coefficient. The filter designed in this paper has reached the design goal, verified by simulation with Ansoft HFSS.
文摘The design of a 5.305 GHz series feedback free running dielectric resonator oscillator (DRO) is presented. Its simulation and optimization are realized by obtaining the unloaded Q factor of the cavity dielectric resonator (DR) and analyzing the linear and nonlinear models of the DRO. CAD packages of DR_Rez and Agilent Advance Design System (ADS) are used and the best tradeoff among the output power, phase noise, and frequency stability is achieved. With the result of simulation, a physical oscillator prototype is constructed. The measured results show the good agreement with those of simulation.
文摘The theory and application of resonances and vibrational modes are part of the foundation of science.In this contribution,examples of acoustical resonators are highlighted,and compared to electromagnetic modes.As an example from architecture,we describe the phenomenon of whispering galleries;such modes are nowadays known in dielectric and optical resonators.A specimen of a semicircular whispering bench in Park Sanssouci in Potsdam is acoustically investigated and demonstrated to show low losses for sound propagation.A special acoustical bug is discussed which was used for the espionage of the U.S.ambassador in Moscow.The Sovyets could interrogate this passive device by radio waves.Its working principle was based on the electromagnetic resonance of the cavity that the sound-sensitive membrane was part of.The underlying relation between excitation and resonance is compared to the sound production in flue organ pipes.A stopped flue organ pipe was investigated using a piezoelectric film sensor inside the pipe body.The results show that even-numbered modes,which are usually suppressed in the radiated sound of a stopped pipe,are still present in the vibrations inside the resonator.
基金supported in part by the Innovation and Technology Support Programme(ITSP)of the Innovation and Technology Commission(ITS/210/19)in part by the Young Scientists Fund of the National Natural Science Foundation of China(62001409)+1 种基金in part by Shenzhen-Hong Kong-Macao Science and Technology Project(Category C)(SGDX20210823104002018)in part by 2022 Guangdong-Hong Kong-Macao Joint Innovation Funding Scheme(2022A0505030021).
基金supported by the National Natural Science Foundation of China(Nos.61761015 and 11664008)the Natural Science Foundation of Guangxi(No.2018GXNSFFA050001)the High Level Innovation Team and Outstanding Scholar Program of Guangxi Institutes.
文摘Microwave dielectric ceramics should be improved to advance mobile communication technologies further.In this study,we prepared Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics with nonstoichiometric Sr^(2+)ratios based on our previously reported SrY_(2)O_(4) microwave dielectric ceramic,which has a low dielectric constant and an ultrahigh quality factor(Q value).The ceramic exhibited a 33.6% higher Q-by-frequency(Q×f)value(Q≈12,500)at x=0.02 than SrY_(2)O_(4).All Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics exhibited pure phase structures,although variations in crystal-plane spacings were observed.The ceramics are mainly composed of Sr-O,Y1-O,and Y_(2)-O octahedra,with the temperature coefficient of the resonant frequency(τ_(f))of the ceramic increasing with Y_(2)-O octahedral distortion.The ceramic comprises uniform grains with a homogeneous elemental distribution,clear grain boundaries,and no obvious cavities at x=0.02.The Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics exhibited good microwave dielectric properties,with optimal performance observed at x=0.02(dielectric constant(εr)=15.41,Q×f=112,375 GHz,and τ_(f)=-17.44 ppm/℃).The τ_(f) value was reduced to meet the temperaturestability requirements of 5G/6G communication systems by adding CaTiO_(3),with Sr_(1.02)Y_(2)O_(4.02)+2wt% CaTiO_(3) exhibiting ε_(r)=16.14,Q×f=51,004 GHz,andτf=0 ppm/℃.A dielectric resonator antenna prepared using Sr_(1.02)Y_(2)O_(4.02)+2wt%CaTiO_(3) exhibited a central frequency of 26.6 GHz,with a corresponding gain and efficiency of 3.66 dBi and 83.14%,respectively.Consequently,Sr_(1.02)Y_(2)O_(4).02-based dielectric resonator antennas are suitable for use in 5G millimeter-wave band(24.5-27.5 GHz)applications.
基金National Science Foundation(NSF)(CBET1264750,CBET 1264997)Army Research Office(ARO)(W911NF-16-1-0339)
文摘Conventionally, metallic nanostructures are used for surface-enhanced Raman spectroscopy(SERS), but recently there has been increasing interest in the enhancement of Raman scattering from dielectric substrates due to their improved stability and biocompatibility compared with metallic substrates. Here, we report the observation of enhanced Raman scattering from rhodamine 6 G molecules coated on silica microspheres. We excite the whispering gallery modes(WGMs) supported in the microspheres with a tapered fiber coupler for efficient WGM excitation, and the Raman enhancement can be attributed to the WGM mechanism. Strong resonance enhancement in pump laser intensity and modified Raman emission from the Purcell effect in the microsphere resonator are observed from the experiment and compared with theoretical results. A total Raman enhancement factor of 1.4 × 10~4 is observed, with contribution mostly from the enhancement in pump laser intensity. Our results show that, with an efficient pumping scheme, dielectric microspheres are a viable alternative to metallic SERS substrates.