In the past twenty years, electromagnetic metamaterials represented by left-handed metamaterials（LHMs） have attracted considerable attention due to the unique properties such as negative refraction, perfect lens, an...In the past twenty years, electromagnetic metamaterials represented by left-handed metamaterials（LHMs） have attracted considerable attention due to the unique properties such as negative refraction, perfect lens, and electromagnetic cloaks. In this paper, we present a comprehensive review of our group＇s work on metamaterials and metasurfaces. We present several types of LHMs and chiral metamaterials. As a two-dimensional equivalent of bulk three-dimensional metamaterials, metasurfaces have led to a myriad of devices due to the advantages of lower profile, lower losses, and simpler to fabricate than bulk three-dimensional metamaterials. We demonstrate the novel microwave metadevices based on metamaterials and metasurfaces： perfect absorbers and microwave patch antennas, including novel transmission line antennas,high gain resonant cavity antennas, wide scanning phased array antennas, and circularly polarized antennas.展开更多
The spectral domain integral equation(SDIE) provides an accurate and efficient method for computing the resonant frequency, radiation patterns, etc . Using continuous Fourier transform, the formulation utilizes the...The spectral domain integral equation(SDIE) provides an accurate and efficient method for computing the resonant frequency, radiation patterns, etc . Using continuous Fourier transform, the formulation utilizes the singular integral equations via the Glerkin's method to derive the deterministic equation with fewer mathematical manipulations. In contrast, discrete Fourier transform(DFT) requires intricate mathematical labor. The present scheme requires a small size, i.e ., (2×2) matrix, and it is possible to extract higher order modal solutions conveniently. Moreover, computation is reduced with the same convergence properties. Based on the present scheme, some results for resonant frequency and radiation patterns compared with available data and computed current distribution on the patch are presented.展开更多
The patch antennas with an array of pins （pin array patch antennas） with excellent radiation characteristics are investigated for various substrate thicknesses. The radiation in the horizontal plane of a pin array p...The patch antennas with an array of pins （pin array patch antennas） with excellent radiation characteristics are investigated for various substrate thicknesses. The radiation in the horizontal plane of a pin array patch antenna is very small compared to that of a conventional patch antenna. And the increase of forward radiation and the decrease of backward radiation of a pin array patch antenna are obtained than those conventional one＇s. Also the half-power beamwidth of E -plane radiation pattern of a pin array patch antenna is narrower compared to that of the conventional so that the directivity is improved.展开更多
The property of multi-band operation has been studied and investigated analytically through the design of a rectangular patch microstrip antenna having different numbers of wide slots arranged at both the radiating ed...The property of multi-band operation has been studied and investigated analytically through the design of a rectangular patch microstrip antenna having different numbers of wide slots arranged at both the radiating edges. The analyses were carried out using the method of moments simulation software. It is shown that a patch with three slots has a multi-band feature with four resonant frequencies at 1.6, 1.8, 2.65, and 4.83 GHz and adequate values of return loss and gain. It is also shown that a patch with two pairs of wide slots arranged at both the radiating edges has the dual band feature with resonant frequencies at 1.64 and 1.8 GHz and good values of return loss and gain.展开更多
Wireless interrogation of a rectangular microstrip patch antenna for strain measurement is investigated by simulations.To analyze the antenna performance,a microstrip line-feeding patch antenna at 10 GHz is designed.A...Wireless interrogation of a rectangular microstrip patch antenna for strain measurement is investigated by simulations.To analyze the antenna performance,a microstrip line-feeding patch antenna at 10 GHz is designed.A patch antenna wirelessly fed by a horn is proposed to measure the strain.The direction information of strain detected by the patch antenna is also considered.The strain can be detected both in the width and length directions.It is shown that the strain can be measured wirelessly using a standard horn antenna.This kind of wireless strain-sensing technique offers significant potential for wireless structural health monitoring(SHM),especially for high-end equipment.展开更多
Antenna is very crucial to radiotelemetry capsules which can measure the physiological parameters of the gastroin- testinal (GI) tract. The objective of this paper is to design a novel spiral slots microstrip patch an...Antenna is very crucial to radiotelemetry capsules which can measure the physiological parameters of the gastroin- testinal (GI) tract. The objective of this paper is to design a novel spiral slots microstrip patch antenna for the radiotelemetry capsules communicating with external recorder at 915 MHz located in ISM (Industry, Science, and Medical) bands. The microstrip patch antenna is designed and evaluated using the finite-difference time-domain (FDTD) method. Return loss characteristics and the effect of the human body on resonant frequency are analyzed, and the performances of radiation patterns at different positions of the human alimentary tract are also estimated. Finally, specific absorption rate (SAR) computations are performed, and the peak 1-g and 10-g SAR values are calculated. According to the peak SAR values, the maximum delivered power for the designed antenna was found so that the SAR values of the antenna satisfy the ANSI (American National Standards Institute) limitations.展开更多
A new design of reconfigurable single-feed circular patch microstrip antenna for dual-band circular polarization application is proposed. The dual-band functionality is realized through incorporating cross-slots of eq...A new design of reconfigurable single-feed circular patch microstrip antenna for dual-band circular polarization application is proposed. The dual-band functionality is realized through incorporating cross-slots of equal slot length in the circular patch and utilizing two PIN diodes to switch the slots on or off. A pairs of tuning stubs are used to tune the circular polarization performance. The design process is presented and good results were obtained.展开更多
In this study,Ge^(4+)-substituted cordierite,Mg_(2)Al_(4)(Si_(1-x)Ge_(x))_(5)O_(18)ceramics,were successfully prepared by the traditional solid-state method to broaden its application potential.Notably,the excellent d...In this study,Ge^(4+)-substituted cordierite,Mg_(2)Al_(4)(Si_(1-x)Ge_(x))_(5)O_(18)ceramics,were successfully prepared by the traditional solid-state method to broaden its application potential.Notably,the excellent dielectric properties withεr=4.90,Q·f=128,200 GHz,andτf=−21.01 ppm℃^(-1) were achieved.The increase inεr value is mainly due to the heightened content of Ge^(4+)with high polarizability.The Q·f value im-proved by 2.21 times compared to the cordierite matrix,which can be primarily attributed to enhanced lattice energy,bond covalency,and hexagonal ring symmetry.The alteration inτf value arises from the variation of bond energy,bond strength,and distortion in the[MgO6]octahedra.These conclusions pro-vide valuable insights for the design of silicate ceramics with higher Q·f values.In addition,the dielectric properties in the microwave and terahertz bands were compared.The higher Q·f and lowerεr values in the terahertz band mainly result from the withdrawal of partial polarization mechanisms and differences in measurement methods.Mg_(2)Al_(4)(Si_(0.92)Ge_(0.08))_(5)O_(18)ceramics,demonstrating an ultra-lowεr value of 4.54 and an ultra-high Q·f value of 286,533 GHz in the terahertz band,emerge as formidable contenders for future terahertz communications materials.Finally,a microstrip patch antenna was fabricated,achiev-ing a bandwidth of 150 MHz at 4.78 GHz,which confirms the application in the n79 band for wireless communication.展开更多
Circularly polarized antennas are used in communications between ground stations and satellites to achieve reliable communication links.The right-hand circular polarization and left-hand circular polarization are two ...Circularly polarized antennas are used in communications between ground stations and satellites to achieve reliable communication links.The right-hand circular polarization and left-hand circular polarization are two types of circular polarization in satellite communications,they are used to support uplink and downlink communications.Circularly polarized antennas are used also in radar system for target detection,tracking and identification.The“three-element circularly polarized microstrip array antenna”is designed to produce left-handed circular polarization,make its size compact,make its bandwidth wider than 3.7-4.2GHz and achieve high gain.Circular polarization element antenna and three-element circularly polarized microstrip array antenna are designed and simulated in software HFSS,and the circular polarization element antenna is manufactured and tested in anechoic chamber.For circular polarization element antenna and three-element circularly polarized microstrip array antenna,the study analyzed these parameters:AR,S(1,1),VSWR,bandwidth,normalized impedance,gain and realized gain,radiation efficiency.After optimized,the study get the required results of them.展开更多
This paper presents a flexible and wearable textile array antenna designed to generate Orbital Angular Momentum(OAM)waves with Mode+2 at 3.5 GHz(3.4 to 3.6 GHz)of the sub-6 GHz fifth-generation(5G)New Radio(NR)band.Th...This paper presents a flexible and wearable textile array antenna designed to generate Orbital Angular Momentum(OAM)waves with Mode+2 at 3.5 GHz(3.4 to 3.6 GHz)of the sub-6 GHz fifth-generation(5G)New Radio(NR)band.The proposed antenna is based on a uniform circular array of eight microstrip patch antennas on a felt textile substrate.In contrast to previous works involving the use of rigid substrates to generate OAM waves,this work explored the use of flexible substrates to generate OAM waves for the first time.Other than that,the proposed antenna was simulated,analyzed,fabricated,and tested to confirm the generation of OAMMode+2.With the same design,OAM Mode−2 can be generated readily simply by mirror imaging the feed network.Note that the proposed antenna operated at the desired frequency of 3.5 GHz with an overall bandwidth of 400 MHz in free space.Moreover,mode purity analysis is carried out to verify the generation of OAM Mode+2,and the purity obtained was 41.78%at free space flat condition.Furthermore,the effect of antenna bending on the purity of the generated OAM mode is also investigated.Lastly,the influence of textile properties on OAM modes is examined to assist future researchers in choosing suitable fabrics to design flexible OAM-based antennas.After a comprehensive analysis considering different factors related to wearable applications,this paper demonstrates the feasibility of generating OAMwaves using textile antennas.Furthermore,as per the obtained Specific Absorption Rate(SAR),it is found that the proposed antenna is safe to be deployed.The findings of this work have a significant implication for body-centric communications.展开更多
Antennas are an indispensable element in wireless networks. For long-distance wireless communication, antenna gains need to be very strong (highly directive) because the signal from the antenna loses a lot of str...Antennas are an indispensable element in wireless networks. For long-distance wireless communication, antenna gains need to be very strong (highly directive) because the signal from the antenna loses a lot of strength as it travels over long distances. This is true in the military with missile, radar, and satellite systems, etc. Antenna arrays are commonly employed to focus electromagnetic waves in a certain direction that cannot be achieved perfectly with a single-element antenna. The goal of this study is to design a rectangular microstrip high-gain 2 × 1 array antenna using ADS Momentum. This microstrip patch array design makes use of the RT-DUROID 5880 as a substrate with a dielectric constant of 2.2, substrate height of 1.588 mm, and tangent loss of 0.001. To achieve efficient gain and return loss characteristics for the proposed array antenna, RT-Duroid is a good choice of dielectric material. The designed array antenna is made up of two rectangular patches, which have a resonance frequency of 3.3 GHz. These rectangular patches are excited by microstrip feed lines with 13 mm lengths and 4.8 mm widths. The impedance of the patches is perfectly matched by these transmission lines, which helps to get better antenna characteristics. At a resonance frequency of 3.3 GHz, the suggested antenna array has a directivity of 10.50 dB and a maximum gain of 9.90 dB in the S-band. The S parameters, 3D radiation pattern, directivity, gain, and efficiency of the constructed array antenna are all available in ADS Momentum.展开更多
Genetic algorithm(GA)is utilized to design microstrip patch antenna shapes for broad bandwidth.A new project based on GA and high frequency simulation software(HFSS)is proposed to perform optimization.Reasonable agree...Genetic algorithm(GA)is utilized to design microstrip patch antenna shapes for broad bandwidth.A new project based on GA and high frequency simulation software(HFSS)is proposed to perform optimization.Reasonable agreement between simulated results and measured results of the GA-optimized design is obtained.The optimized patch design exhibits a three-fold enhancement in bandwidth when contrasted with a standard square microstrip antenna,showing the validity of this project.展开更多
The development of dielectric materials with low permittivity and low loss is a great challenge in wireless communication.In this study,LiLn(PO_(3))_(4)(Ln=La,Sm,Eu)ceramic systems were successfully prepared using the...The development of dielectric materials with low permittivity and low loss is a great challenge in wireless communication.In this study,LiLn(PO_(3))_(4)(Ln=La,Sm,Eu)ceramic systems were successfully prepared using the traditional solid-state method.X-ray diffraction analysis indicated that the LiLn(PO_(3))_(4)ceramics crystallized in a monoclinic structure when sintered at 850–940℃.The characteristic peak shifted to higher angles with variations in the Ln element,which was ascribed to a reduction in the cell volume.Further analysis by structure refinement revealed that the reduction in the cell volume resulted from the decrease in chemical bond lengths and the compression of[LiO_(4)]and[PO_(4)]tetrahedra.Remarkably,the LiLn(PO_(3))_(4)ceramic system displayed exceptional performance at low sintering temperatures(910–925℃),including a high quality factor(Q·f)of 41,607–75,968 GHz,low temperature coefficient of resonant frequency(τ_(f))ranging from−19.64 to−47.49 ppm/℃,low permittivity(ε_(r))between 5.04 and 5.26,and low density(3.04–3.26 g/cm^(3)).The application of Phillips–van Vechten–Levine(P–V–L)theory revealed that the increased Q·f value of the LiLn(PO_(3))_(4)systems can be attributed to the enhanced packing fraction,bond covalency,and lattice energy,and the stability of τ_(f) was associated with the increase in the bond energy.Furthermore,a prototype microstrip patch antenna using LiEu(PO_(3))_(4) ceramics was fabricated.The measurement results demonstrated excellent antenna performance with a bandwidth of 360 MHz and a peak gain of 5.11 dB at a central frequency of 5.08 GHz.Therefore,low-εr LiLn(PO_(3))_(4)ceramic systems are promising candidates for microwave/millimeter-wave communication.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11674267,51272215,11874301,and 11204241)the National Basic Research Program of China(Grant No.2012CB921503)+2 种基金the National Aerospace Science Foundation of China(Grant No.2016ZF53061)the Fundamental Research Funds for the Central Universities,China(Grant No.3102017jghk02004)the Natural Science Basic Research Plan in Shaanxi Province of China(Grant No.2017JM1009)
文摘In the past twenty years, electromagnetic metamaterials represented by left-handed metamaterials（LHMs） have attracted considerable attention due to the unique properties such as negative refraction, perfect lens, and electromagnetic cloaks. In this paper, we present a comprehensive review of our group＇s work on metamaterials and metasurfaces. We present several types of LHMs and chiral metamaterials. As a two-dimensional equivalent of bulk three-dimensional metamaterials, metasurfaces have led to a myriad of devices due to the advantages of lower profile, lower losses, and simpler to fabricate than bulk three-dimensional metamaterials. We demonstrate the novel microwave metadevices based on metamaterials and metasurfaces： perfect absorbers and microwave patch antennas, including novel transmission line antennas,high gain resonant cavity antennas, wide scanning phased array antennas, and circularly polarized antennas.
文摘The spectral domain integral equation(SDIE) provides an accurate and efficient method for computing the resonant frequency, radiation patterns, etc . Using continuous Fourier transform, the formulation utilizes the singular integral equations via the Glerkin's method to derive the deterministic equation with fewer mathematical manipulations. In contrast, discrete Fourier transform(DFT) requires intricate mathematical labor. The present scheme requires a small size, i.e ., (2×2) matrix, and it is possible to extract higher order modal solutions conveniently. Moreover, computation is reduced with the same convergence properties. Based on the present scheme, some results for resonant frequency and radiation patterns compared with available data and computed current distribution on the patch are presented.
文摘The patch antennas with an array of pins （pin array patch antennas） with excellent radiation characteristics are investigated for various substrate thicknesses. The radiation in the horizontal plane of a pin array patch antenna is very small compared to that of a conventional patch antenna. And the increase of forward radiation and the decrease of backward radiation of a pin array patch antenna are obtained than those conventional one＇s. Also the half-power beamwidth of E -plane radiation pattern of a pin array patch antenna is narrower compared to that of the conventional so that the directivity is improved.
文摘The property of multi-band operation has been studied and investigated analytically through the design of a rectangular patch microstrip antenna having different numbers of wide slots arranged at both the radiating edges. The analyses were carried out using the method of moments simulation software. It is shown that a patch with three slots has a multi-band feature with four resonant frequencies at 1.6, 1.8, 2.65, and 4.83 GHz and adequate values of return loss and gain. It is also shown that a patch with two pairs of wide slots arranged at both the radiating edges has the dual band feature with resonant frequencies at 1.64 and 1.8 GHz and good values of return loss and gain.
基金supported by the National Natural Science Foundation of China (Nos. 51575015,51235001,51505013)
文摘Wireless interrogation of a rectangular microstrip patch antenna for strain measurement is investigated by simulations.To analyze the antenna performance,a microstrip line-feeding patch antenna at 10 GHz is designed.A patch antenna wirelessly fed by a horn is proposed to measure the strain.The direction information of strain detected by the patch antenna is also considered.The strain can be detected both in the width and length directions.It is shown that the strain can be measured wirelessly using a standard horn antenna.This kind of wireless strain-sensing technique offers significant potential for wireless structural health monitoring(SHM),especially for high-end equipment.
基金Project (No. 2006AA04Z368) supported by the Hi-Tech Researchand Development Program (863) of China
文摘Antenna is very crucial to radiotelemetry capsules which can measure the physiological parameters of the gastroin- testinal (GI) tract. The objective of this paper is to design a novel spiral slots microstrip patch antenna for the radiotelemetry capsules communicating with external recorder at 915 MHz located in ISM (Industry, Science, and Medical) bands. The microstrip patch antenna is designed and evaluated using the finite-difference time-domain (FDTD) method. Return loss characteristics and the effect of the human body on resonant frequency are analyzed, and the performances of radiation patterns at different positions of the human alimentary tract are also estimated. Finally, specific absorption rate (SAR) computations are performed, and the peak 1-g and 10-g SAR values are calculated. According to the peak SAR values, the maximum delivered power for the designed antenna was found so that the SAR values of the antenna satisfy the ANSI (American National Standards Institute) limitations.
文摘A new design of reconfigurable single-feed circular patch microstrip antenna for dual-band circular polarization application is proposed. The dual-band functionality is realized through incorporating cross-slots of equal slot length in the circular patch and utilizing two PIN diodes to switch the slots on or off. A pairs of tuning stubs are used to tune the circular polarization performance. The design process is presented and good results were obtained.
基金supported by the National Natu-ral Science Foundation of China(No.52272126)The authors are thankful to Professor Zeming Qi and Chuansheng Hu in the IR beamline workstation of the National Synchrotron Radiation Labo-ratory(NSRL)for the IR measurement.Thanks zkec(www.zkec.cc)for XRD and SEM examination。
文摘In this study,Ge^(4+)-substituted cordierite,Mg_(2)Al_(4)(Si_(1-x)Ge_(x))_(5)O_(18)ceramics,were successfully prepared by the traditional solid-state method to broaden its application potential.Notably,the excellent dielectric properties withεr=4.90,Q·f=128,200 GHz,andτf=−21.01 ppm℃^(-1) were achieved.The increase inεr value is mainly due to the heightened content of Ge^(4+)with high polarizability.The Q·f value im-proved by 2.21 times compared to the cordierite matrix,which can be primarily attributed to enhanced lattice energy,bond covalency,and hexagonal ring symmetry.The alteration inτf value arises from the variation of bond energy,bond strength,and distortion in the[MgO6]octahedra.These conclusions pro-vide valuable insights for the design of silicate ceramics with higher Q·f values.In addition,the dielectric properties in the microwave and terahertz bands were compared.The higher Q·f and lowerεr values in the terahertz band mainly result from the withdrawal of partial polarization mechanisms and differences in measurement methods.Mg_(2)Al_(4)(Si_(0.92)Ge_(0.08))_(5)O_(18)ceramics,demonstrating an ultra-lowεr value of 4.54 and an ultra-high Q·f value of 286,533 GHz in the terahertz band,emerge as formidable contenders for future terahertz communications materials.Finally,a microstrip patch antenna was fabricated,achiev-ing a bandwidth of 150 MHz at 4.78 GHz,which confirms the application in the n79 band for wireless communication.
文摘Circularly polarized antennas are used in communications between ground stations and satellites to achieve reliable communication links.The right-hand circular polarization and left-hand circular polarization are two types of circular polarization in satellite communications,they are used to support uplink and downlink communications.Circularly polarized antennas are used also in radar system for target detection,tracking and identification.The“three-element circularly polarized microstrip array antenna”is designed to produce left-handed circular polarization,make its size compact,make its bandwidth wider than 3.7-4.2GHz and achieve high gain.Circular polarization element antenna and three-element circularly polarized microstrip array antenna are designed and simulated in software HFSS,and the circular polarization element antenna is manufactured and tested in anechoic chamber.For circular polarization element antenna and three-element circularly polarized microstrip array antenna,the study analyzed these parameters:AR,S(1,1),VSWR,bandwidth,normalized impedance,gain and realized gain,radiation efficiency.After optimized,the study get the required results of them.
基金This work was supported by Ministry of Higher Education through the Fundamental Research Grant Scheme(FRGS)under a grant number of FRGS/1/2020/ICT09/UNIMAP/02/2.
文摘This paper presents a flexible and wearable textile array antenna designed to generate Orbital Angular Momentum(OAM)waves with Mode+2 at 3.5 GHz(3.4 to 3.6 GHz)of the sub-6 GHz fifth-generation(5G)New Radio(NR)band.The proposed antenna is based on a uniform circular array of eight microstrip patch antennas on a felt textile substrate.In contrast to previous works involving the use of rigid substrates to generate OAM waves,this work explored the use of flexible substrates to generate OAM waves for the first time.Other than that,the proposed antenna was simulated,analyzed,fabricated,and tested to confirm the generation of OAMMode+2.With the same design,OAM Mode−2 can be generated readily simply by mirror imaging the feed network.Note that the proposed antenna operated at the desired frequency of 3.5 GHz with an overall bandwidth of 400 MHz in free space.Moreover,mode purity analysis is carried out to verify the generation of OAM Mode+2,and the purity obtained was 41.78%at free space flat condition.Furthermore,the effect of antenna bending on the purity of the generated OAM mode is also investigated.Lastly,the influence of textile properties on OAM modes is examined to assist future researchers in choosing suitable fabrics to design flexible OAM-based antennas.After a comprehensive analysis considering different factors related to wearable applications,this paper demonstrates the feasibility of generating OAMwaves using textile antennas.Furthermore,as per the obtained Specific Absorption Rate(SAR),it is found that the proposed antenna is safe to be deployed.The findings of this work have a significant implication for body-centric communications.
文摘Antennas are an indispensable element in wireless networks. For long-distance wireless communication, antenna gains need to be very strong (highly directive) because the signal from the antenna loses a lot of strength as it travels over long distances. This is true in the military with missile, radar, and satellite systems, etc. Antenna arrays are commonly employed to focus electromagnetic waves in a certain direction that cannot be achieved perfectly with a single-element antenna. The goal of this study is to design a rectangular microstrip high-gain 2 × 1 array antenna using ADS Momentum. This microstrip patch array design makes use of the RT-DUROID 5880 as a substrate with a dielectric constant of 2.2, substrate height of 1.588 mm, and tangent loss of 0.001. To achieve efficient gain and return loss characteristics for the proposed array antenna, RT-Duroid is a good choice of dielectric material. The designed array antenna is made up of two rectangular patches, which have a resonance frequency of 3.3 GHz. These rectangular patches are excited by microstrip feed lines with 13 mm lengths and 4.8 mm widths. The impedance of the patches is perfectly matched by these transmission lines, which helps to get better antenna characteristics. At a resonance frequency of 3.3 GHz, the suggested antenna array has a directivity of 10.50 dB and a maximum gain of 9.90 dB in the S-band. The S parameters, 3D radiation pattern, directivity, gain, and efficiency of the constructed array antenna are all available in ADS Momentum.
基金This work was supported by the Specialized Research Fund for the Doctoral Program of Higher Education(No.200700130046)the National Natural Science Foundation of China(Grant Nos.60771060 and 60971078).
文摘Genetic algorithm(GA)is utilized to design microstrip patch antenna shapes for broad bandwidth.A new project based on GA and high frequency simulation software(HFSS)is proposed to perform optimization.Reasonable agreement between simulated results and measured results of the GA-optimized design is obtained.The optimized patch design exhibits a three-fold enhancement in bandwidth when contrasted with a standard square microstrip antenna,showing the validity of this project.
基金National Natural Science Foundation of China(Nos.52272117 and 52171141)the National Key R&D Program of China(Nos.2022YFB3505104 and 2022YFB3706604)The authors are thankful to Professors Zeming Qi and Chuansheng Hu in IR beamline workstation of National Synchrotron Radiation Laboratory(NSRL)for the IR measurement.The authors thank Professor Lanling Zhao and Shiyanjia Lab(www.shiyanjia.com)for the support of first-principles calculations.
文摘The development of dielectric materials with low permittivity and low loss is a great challenge in wireless communication.In this study,LiLn(PO_(3))_(4)(Ln=La,Sm,Eu)ceramic systems were successfully prepared using the traditional solid-state method.X-ray diffraction analysis indicated that the LiLn(PO_(3))_(4)ceramics crystallized in a monoclinic structure when sintered at 850–940℃.The characteristic peak shifted to higher angles with variations in the Ln element,which was ascribed to a reduction in the cell volume.Further analysis by structure refinement revealed that the reduction in the cell volume resulted from the decrease in chemical bond lengths and the compression of[LiO_(4)]and[PO_(4)]tetrahedra.Remarkably,the LiLn(PO_(3))_(4)ceramic system displayed exceptional performance at low sintering temperatures(910–925℃),including a high quality factor(Q·f)of 41,607–75,968 GHz,low temperature coefficient of resonant frequency(τ_(f))ranging from−19.64 to−47.49 ppm/℃,low permittivity(ε_(r))between 5.04 and 5.26,and low density(3.04–3.26 g/cm^(3)).The application of Phillips–van Vechten–Levine(P–V–L)theory revealed that the increased Q·f value of the LiLn(PO_(3))_(4)systems can be attributed to the enhanced packing fraction,bond covalency,and lattice energy,and the stability of τ_(f) was associated with the increase in the bond energy.Furthermore,a prototype microstrip patch antenna using LiEu(PO_(3))_(4) ceramics was fabricated.The measurement results demonstrated excellent antenna performance with a bandwidth of 360 MHz and a peak gain of 5.11 dB at a central frequency of 5.08 GHz.Therefore,low-εr LiLn(PO_(3))_(4)ceramic systems are promising candidates for microwave/millimeter-wave communication.
