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Here, Ca5Mn4−xNixV6O24 (CMNVO, x = 0.00–0.08) ceramics are successfully prepared by the solid-phase reaction method, and the connection between the physical phase information, microscopic morphology, Raman spectroscopy, and microwave dielectric properties is explored. The experimental results show that Ni2+ occupies the Mn2+ sites without altering the crystal structure and is effectively solid-solvated into the lattice. The relative density reaches a maximum value of 95.9% when the temperature (Tem.) = 900°C and x = 0.06. The trend of the dielectric constant (εr) depends on the ionic polarization rate, and the quality factor (Q×f values) are correlated with the microstructure and relative density. The maximum value of 43,800 GHz is reached at Tem. = 900°C and x = 0.06, and the temperature coefficient of resonant frequency (τf values) is enhanced from −75 ppm/°C to −52 ppm/°C. The CMNVO (x = 0.06) ceramic obtains better microwave dielectric properties (εr = 11.4, Q×f = 43,800 GHz, and τf = −52 ppm/°C). This ceramic material is expected to be a candidate for low-temperature co-fired ceramic (LTCC) microwave devices. [ABSTRACT FROM AUTHOR]

Microwave communication for 5 G signals is the preferred solution in modern communication networks where fiber optic cables are difficult to deploy or base stations operate incorrectly. Here, a novel Zn 1- x (Li 0.5 Bi 0.5) x MoO 4 (ZLBMO∼ x LB, x = 0.09) ceramic with excellent microwave dielectric properties (ε r = 10.5, Q× f = 43,001 GHz, τ f = −21.5 ppm/°C) is developed using solid-state reaction method. The sintering temperature is successfully reduced from 850 °C to 725 °C. For the first time, an all-ceramic device for multichannel transmission of 5 G signals is designed using this ceramic material. This device exhibits transverse dual-channel, longitudinal dual-channel, and four-channel transmission under x -, y - and 45°-polarized waves incidence, respectively. The number of channels can be changed by switching the polarization state of the incident wave. This functionality is verified by simulation results of the electric field and phase. This work provides new ideas for the combination of dielectric ceramics and communication devices. [ABSTRACT FROM AUTHOR]

A novel Li 2 Mg 2- x Na 2 x Mo 3 O 12 (x = 0.09) ceramic with ultra-low sintering temperature is prepared by the solid-state reaction method. This ceramic (625 °C) exhibits excellent microwave dielectric properties (ε r = 7.9, Q× f = 43844 GHz, τ f = −48.3 ppm/°C), terahertz transmission properties (ε r 1 = 7.4, tan σ 1 = 0.0158, T coefficient = 0.598), and chemical compatibility with Ag. For the first time, two polarization selective devices are designed in the microwave and terahertz regions by using this ceramic substrate, respectively. The transmission amplitudes of the right- and left-handed circularly polarized waves of the microwave device at 9.7 GHz are 0.895 and 0.019, respectively. The transmission coefficients of the y - and x -polarized waves of the terahertz device at 0.45 THz are 0.598 and 0.075, respectively. Both functions are verified by the overall far-field radiation pattern. This work promotes the application of dielectric ceramics and ULTCC technology in the microwave and terahertz regions. [ABSTRACT FROM AUTHOR]

To meet the polarization adaptation in communication systems, it is necessary to improve the performance of polarization converters. Microwave dielectric materials are very promising to optimize the response speed, operating frequency, conversion efficiency, and transmission stability of polarization converters, which puts higher demands on ceramic materials. In this paper, the microwave dielectric properties of Ca5Mn4(VO4)6 ceramics are improved by using Cu2+ instead of Mn2+. The effects of Cu2+ substitution and sintering temperature on microwave dielectric properties are also investigated. The substituted ceramics have excellent microwave dielectric properties of εr = 11.4, Q × f = 42709 GHz, and τf = − 65 ppm/°C. As a concept demonstration, a new 5G polarization converter between linear polarization and left-handed circularly polarized (LCP) waves is designed by using this ceramic substrate. By observing the surface electric field and surface current, it can be judged that the principle of the polarization converter is the difference in the electric dipole resonance absorption between the LCP and the right-handed circularly polarized (RCP) waves. The simulation results of normalized reflectivity and far-field (electric field and phase) show good performance of the polarization converter. [ABSTRACT FROM AUTHOR]

In this work, a new Zn 1- x Ni x MoO 4 (ZNMO) (x = 0.03) ceramic with low-dielectric constant, low-loss, and low-sintering temperature for X-band two-dimensional (2D) beam splitting is developed by solid-state reaction method. This ceramic has excellent microwave dielectric properties of ε r = 8.5, Q × f = 28192 GHz, τ f = −60.2 ppm/°C. The effects of Ni2+ substitution on the microwave dielectric properties of the ZnMoO 4 ceramic are studied in detail through crystal structure analysis, Raman spectroscopy, and first-principles calculations. For the first time, an array antenna for X-band 2D electromagnetic beam splitting is designed by using this ceramic as a substrate. The effects of the dielectric constant and dielectric loss on the radiation efficiency of the array antenna are revealed. The normalized reflection amplitude and reflection phase of the unit cell exceed 0.97 and cover 360°, respectively. The function of 2D electromagnetic beam splitting is verified by the overall far-field pattern of the array antenna. This work has the opportunity to promote the development of LTCC and microwave dielectric ceramics. [ABSTRACT FROM AUTHOR]

A novel Zn 1- x Co x MoO 4 (ZCMO) (x = 0.03) ceramic with low-dielectric constant, low-loss, and low-sintering temperature for 5G electromagnetic beam splitting is developed by solid-state reaction method. This ceramic exhibits excellent microwave dielectric properties with ε r = 8.0, Q × f = 57682 GHz, τ f = − 54.9 ppm/°C at a sintering temperature of 825 °C. An array antenna for electromagnetic beam splitting at 5.4 GHz is designed by using this ceramic for the first time. The highest efficiency and the best electromagnetic beam splitting effect can be jointly controlled by the dielectric constant and dielectric loss of the ceramic. The normalized reflection amplitude of each array unit cell is above 98 %, and the reflection phase covers 360°. The function of electromagnetic beam splitting is verified by the far-field pattern of the electric field. This work helps to promote the development of LTCC and broaden the application scope of microwave dielectric ceramics. [ABSTRACT FROM AUTHOR]

With the development of modern communication technology, all kinds of wireless communication devices are developing rapidly toward miniaturization, lightweight, and integration, which puts forward higher requirements for the size and volume of the antenna. In recent years, magneto-dielectric ferrite materials have been widely studied because of their good performance in magnetic and dielectric properties. In this work, a series of Ba1.5Sr1.5Co2−xFe24+xO41 (x = 0, 0.2, 0.4, 0.6) materials were successfully synthesized through the traditional solid-state reaction method. The influences of Fe substitution on the phase formation, microstructure, high-frequency dielectric, and magnetic properties were studied. It is found that, with the increase of substitution amount, the real permeability decreases from 8.8 to 4.2, and the real permittivity increases from 7.6 to 9.8. When the amount of substitution is relatively low (x = 0, 0.2), the real permeability and permittivity of the materials are almost equivalent at the frequency of 500 MHz to 1.0 GHz. The sample of x = 0.2 with permeability (7.1 to 8.2) and permittivity (7.8), and low losses (tanδµ ≤ 0.22, tanδε ≤ 0.02) could be used for antenna miniaturization in UHF band in the future. [ABSTRACT FROM AUTHOR]

[Display omitted] • The novel ceramic with excellent microwave dielectric properties is developed. • The improvement of the dielectric properties of ceramics by W6+ is revealed. • An all-ceramic patch for 5G signal enhancement is designed using this ceramic. • The device compensates for the attenuation of 5G signals within the wall. • This work provides a new idea for LTCC device design. In modern wireless communication systems, the transmission of 5G signals is substantially attenuated by obstacles, resulting in indoor receivers not receiving signals at all. To overcome this thorny problem, a novel Zn 0.97 Co 0.03 Mo 0.92 W 0.08 O 4 ceramic material with excellent microwave dielectric properties (ε r = 8.432, Q × f = 64096 GHz, τ f = -41.9 ppm/°C) sintered at 850 °C is developed by the solid-state reaction method. For the first time, an all-ceramic array patch for 5G signal enhancement is designed and demonstrated using this ceramic. This all-ceramic-based device not only effectively avoids the problem of matching co-fire between metal electrodes and ceramics, but also compensates for the attenuation loss of 5G signals in the wall. The intensity of the 5G signal is greatly improved from 0.02 to 1.62 by the focusing effect of the device. This function is verified by the intensity and phase of the near-field electric field. This work provides a new idea for the design of all-ceramic-based LTCC devices and broadens the application of microwave dielectric ceramics. [ABSTRACT FROM AUTHOR]

Microwave imaging has the advantages of high accuracy, non-contact and damage-free, but this puts forward higher requirements on the materials of imaging devices. Here, a novel Zn 0.96 Cu 0.04 MoO 4 ceramic is reported using a solid-state reaction process. The substitution behavior and microwave dielectric properties of the ceramic are systematically investigated by the crystal structure, microscopic morphology, and Raman spectroscopy. It exhibits excellent microwave dielectric properties (ε r = 8.66, Q× f = 32024 GHz, and τ f = −58.1 ppm/◦C) sintered at 825 °C. A 40 × 40 microstructure array for static microwave imaging is designed and demonstrated based on this ceramic substrate. The maximum spin-selective reflection difference of the LCP and RCP waves at 9.6 GHz is 0.926. The image of a Chinese character presented has a recognizable resolution, both from intensity differences and three-dimensional (3D) electric field arrows. The pair of mutually chiral microstructures have an angular space of 6° for experimental manipulation. This work opens up the application of microwave dielectric ceramics in the imaging field. • The Zn 1- x Cu x MoO 4 (x = 0.04) ceramic (825 °C) can obtain excellent microwave dielectric properties (ε r = 8.66, Q× f = 32024 GHz, τ f = −58.1 ppm/◦C). • According to microstructural analysis and Raman spectroscopy, an appropriate amount of Cu2+ substitution can regulate the ε r and improve the Q× f and τ f values. • Based on this ceramic, a 40 × 40 microstructure array for static microwave imaging is designed and demonstrated. • The pair of mutually chiral microstructures have an angular space of 6° for experimental manipulation. • This work opens up the application of microwave dielectric ceramics in the imaging field. [ABSTRACT FROM AUTHOR]

A novel low-loss and low-sintering temperature Zn 3- x Co x (VO 4) 2 (ZCVO) (x = 0.25) ceramic for enhanced polarization converters is developed by solid-state reaction methodology. This ceramic has excellent microwave dielectric properties (ε r = 13.6, Q× f = 32173 GHz (@10.1 GHz), τ f = −74.5 ppm/℃) and good chemical compatibility with Ag. According to microstructural analysis, Raman spectroscopy, and first-principles calculations, it is revealed that an appropriate amount of Co2+ substitution can enhance the density, regulate the dielectric constant (ε r), and improve the Q× f and τ f values. Based on this ceramic, an enhanced polarization converter is designed. The maximum efficiency is as high as 90.38%. And the performance of this polarization converter can be regulated by the ε r and dielectric loss of ZCVO ceramics. The mechanism and function of the polarization converter are revealed according to the electric field strength, current direction, and far-field pattern. This work expands the application of microwave dielectric ceramics. • The Zn3-xCox(VO4)2 (x = 0.25) ceramic has excellent microwave dielectric properties (εr = 13.6, Q×f = 32173 GHz, τf = −74.5 ppm/℃). • An appropriate amount of Co2 + substitution can improve the microwave dielectric properties. • Based on this ceramic, an enhanced polarization converter between linear polarization and circular polarization is designed. • The performance of this polarization converter can be regulated by the εr and Q×f of ZCVO ceramics. • This work provides a new idea for LTCC device design and expands the application range of microwave dielectric ceramics. [ABSTRACT FROM AUTHOR]

The core of this research is to elucidate the effect of the particle size of the starting oxide on the dielectric properties of Zn 0.7 Mg 0.3 TiO 3 ceramics. The study was carried out using a conventional solid-state reaction route. The microstructure optimization of Zn 0.7 Mg 0.3 TiO 3 ceramics was achieved by introducing nanoscale particles. The distortion of octahedral [TiO 6 ] and the effect of crystal structure led to significant changes in the dielectric properties. Stability analysis shows that usage of nanoparticles decreases the temperature stability of Zn 0.7 Mg 0.3 TiO 3 ceramics. This work will offer a well-defined guideline for the selection of raw materials to prepare ceramics in the practical production process. [ABSTRACT FROM AUTHOR]

Beam scanning devices in the X-band allow spatial reorientation of the beam, but this poses challenges for material and device design. To meet such challenges, the development of microwave dielectric materials and the design of special structures are crucial. Here, the microwave dielectric properties of Ca 5 Mn 4 V 6- x Nb x O 24 (x = 0.00–0.08) ceramics are systematically investigated by using first-principles calculations and microstructural analysis. The ceramic has the best microwave dielectric properties (ε r = 10.92 ± 0.14, Q × f = 50032 ± 1795 GHz (@10.52 GHz), τ f = −59.58 ± 3.81 ppm/°C) when x = 0.04 and T = 875 °C. As a concept demonstration for device applications, a frequency-controlled beam scanning device in the X-band is designed by using this ceramic and copper electrode. This device has a beam scanning space of 3.248° (from 27.143° to 32.371°) in the frequency range of 10–11 GHz while maintaining high reflectivity (≥0.6). This function is verified by simulation results for far-field amplitude and far-field phase. This work contributes to the application of microwave dielectric ceramics. [ABSTRACT FROM AUTHOR]

In this work, a new low loss Ba 3 Ti 4- x (Mn 1/3 Nb 2/3) x Nb 4 O 21 (MN-BTN, 0 ≤ x ≤ 12 mol%) ceramics configuration was presented through preparing by the solid-state route. The XRD patterns, Rietveld refinement, microstructure, and microwave properties were systematically analyzed. All the fabricated MN-BTN ceramics belonged to the hexagonal structure with a P 6 3 / mcm space group. More specifically, the 6MN-BTN ceramic exhibited a high relative density of ~92.3 %, homogeneous grains distribution with an average size of ~71.95 µm, and several excellent microwave dielectric properties: ε r = 59.67, Q× f = 16,226 GHz, τ f = +103.9 ppm/℃ sintered at 1220 ℃. The incorporation of 1.5 wt % BaCu(B 2 O 5) (BCB) compound within the 6MN-BTN ceramic not only effectively reduced the sintering temperature from 1220 ℃ to 950 ℃, but also the excellent microwave dielectric properties were maintained: ε r = 42.33, Q× f = 11,300 GHz, τ f = +24.7 ppm/℃. Interestingly, the 6MN-BTN + 1.5 wt % BCB ceramic showed better chemical compatibility with Ag. The proposed 6MN-BTN + 1.5 wt % BCB ceramic configuration could be regarded as a promising material for LTCC applications. • Adapting composite (Mn 1/3 Nb 2/3)4+ ions and adding BCB compound to realize low temperature co-firing BTN ceramics. • 6MN-BTN ceramic had excellent microwave dielectric properties: εr=59.67, Q×f=16226 GHz, τf=+103.9 ppm/℃ sintered at 1220℃. • Enhanced microwave properties were related to bulk density, uniform grain size, packing fraction, octahedral distortion. • BCB compound was an effective sintering aid, not only matched with Ag co-firing, but also validly improved τf. [ABSTRACT FROM AUTHOR]