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Novel LiCa(PO 3) 3 and LiSr(PO 3) 3 phases were produced by conventional solid-state synthesis and formed into ceramic pellets followed by conventional sintering. The crystal structure, ceramic microstructure, microwave dielectric properties and ac conductivity were investigated. A triclinic space group P1- was obtained from Rietveld refinements, and the lattice vibration modes were determined by Raman spectroscopy. The optimum sintering conditions for LiCa(PO 3) 3 and LiSr(PO 3) 3 ceramics were 700 ℃ and 625 ℃, respectively, both for 10 h. Dense glass-free ceramic microstructures were confirmed by SEM. High relative densities of 94.6 % and 93.8 %, low microwave ε r values of 5.85 and 5.62 at 14 GHz, and high quality factors Q×f of 25,200 and 23,450 GHz at 14 GHz were detected. Large negative τ f of − 105 and − 106 ppm/°C were obtained, which are uncommon but highly valuable for offsetting positive τ f values of other systems. Moderate Li+-ion conduction was detected in both compounds by ac impedance spectroscopy. [ABSTRACT FROM AUTHOR]

Microwave dielectric ceramics with low dielectric permittivity ε r combined with low ceramic sintering temperatures have raised considerable research interest recently due to their potential application in LTCC technology for 5G wireless communications. Here in this study, ceramic processing, crystal structure, and microwave dielectric properties of LiM(PO 3) 3 (M = Mg2+, Zn2+) ceramics were comprehensively investigated. Optimized LTCC compatible ceramic sintering processes were developed at 725 °C and 625 °C for 10 h, respectively, leading to high relative densities of 96.27 % and 94.09 %. Low microwave ε r values of 5.74 and 6.30 and Q × f values of 16,660 GHz and 9629 GHz (at 14 GHz) were obtained, where such values were found to be affected by the grain microstructure. LiMg(PO 3) 3 exhibited a small τ f of −11 ppm/°C, while LiZn(PO 3) 3 showed −58 ppm/°C. Complementary impedance spectroscopy measurements indicated modest Li+-ion conductivity with a higher value of 2.92·10−7 (Ωcm)−1 at 560 K (287 °C) in LiZn(PO 3) 3. Both ceramics were found to be dielectrically homogeneous without any perceptible contributions from the grain boundaries. [ABSTRACT FROM AUTHOR]

The main aim of this work was to estimate the dielectric constant of electrospun BaTiO 3 nanofibers (BT NF s) using theoretical models. The effect of calcination temperatures on morphology and crystal structure of BT NF s was also investigated by using SEM, TEM, XRD and Raman spectroscopy. The dielectric constant of BT NF s was calculated by applying modified Maxwell Garnett and Yamada models on polymer nanocomposite films comprising stearic acid modified BT NF s in Polyvinylidene difluoride (PVDF) matrix. The results showed that although it was detected low tetragonality (1.0041) at lowest calcination temperature (850 °C), the better crystallization of BT and high tetragonality could be achieved at a calcination temperature of 1000 °C and above. Based on both theoretical models, the dielectric constant of BT NF s calcined at 850 °C (around 830) is lower than those calcined at 1000 °C (about 1300), which is the result of different tetragonality and grain size. [ABSTRACT FROM AUTHOR]

BaTiO 3 (BT) nanotubes (NT s) were synthesized using a co-axial electrospinning process. BT precursor/PVP-ethanol and heavy mineral oil were used as the shell solution and core liquid, respectively. The rheological studies indicated that NT s could be formed by a stable jet at a range of viscosities of the shell solution. Due to the shear thinning behavior of the shell solutions, their actual viscosity values at the time of jet formation will be lower than the viscosity of the core liquid. The morphology of the obtained NT s was strongly influenced by the viscosity of the shell solution. By increasing the concentration of BT precursor, the morphology of the BT NT s was changed from porous to more dense structure. XRD analysis revealed that the crystallization of BT NT s occurs at 550–630 °C calcination temperature range. Raman spectra confirmed the presence of tetragonal phase at early stage of crystallization. [ABSTRACT FROM AUTHOR]

The structural, vibrational, densification, and microwave properties of Ba(Co 1/3 Nb 2/3 )O 3 ceramics with small compositional variations along several tie lines in the ternary BaO CoO Nb 2 O 5 diagram were studied. The results showed that very small deviation from stoichiometric Ba(Co 1/3 Nb 2/3 )O 3 composition has profound effect on Q × f , degree of ordering, densification, and phase assemblage. The 0.94 Ba(Co 1/3 Nb 2/3 )O 3 –0.06 Ba 5 Nb 4 O 15 ceramic has the highest Q × f value (71 THz) – a value two times larger than that of stoichiometric Ba(Co 1/3 Nb 2/3 )O 3 (36 THz). Transformation from the (partial) disordered distribution of Co and Nb cations to 1:2 ordered arrangement in the octahedral sites was found to increase the Q factor of the high density and single phase ceramics. It was also observed that formation of very small amount of Ba 9 CoNb 14 O 45 second phase degraded Q × f value severely for the dense and highly ordered Nb-rich and Ba-deficient ceramics. [ABSTRACT FROM AUTHOR]

A nanostructured carbon film was deposited on carbon fiber fabrics by plasma assisted chemical vapor deposition (PACVD) to overcome the limitations of carbon fibers and improve the interface with the composites in the carbon fiber fabrics. The main process parameters investigated were the intensity of the pulsed direct current and deposition time on the chemical and structural features of the coating. Methane gas was used as the reactant gas in PACVD. FESEM images revealed good uniformity of the deposited coating. The thickness of the coating varied from 40 to 320 nm for different specimens and the thickness increased as the intensity of the pulsed direct current and deposition time increased. Raman spectroscopy results showed that increasing the magnitude of the pulsed direct current increased the fraction of sp 3 bonds and the residual stress. Diamond nanoparticles 10–20 nm in size were revealed after etching. Increasing the pulsed direct current created a smoother surface with 45.59 nm of average roughness. Depositing a thin coating (40 nm) increased fracture strength 27.6%; however, the fracture strength decreased significantly with further increases in the thickness of the coating. [ABSTRACT FROM AUTHOR]

Micro-porous yttria doped silica membrane, fabricated on alpha-alumina substrate and gamma-alumina interlayer, has been prepared via the polymeric sol–gel method. In order to investigate the hydrothermal stability of the membrane, silica sols with different amounts of 5, 15 and 25wt% yttria were prepared. These sols showed particle size distributions in the range of 0.6–3nm. It was found that the hydrothermal stability of the unsupported silica–15% yttria membrane heat treated at 500°C is the highest according to the results of FTIR analysis showing the formation of Si–O–Y bonds. XRD data showed thermal stability up to around 800°C for the unsupported silica membrane with 15% yttria. N2 adsorption–desorption isotherm confirmed the existence of micro-porous structure for this membrane as BET surface area and average pore size of the unsupported membrane was 286m2g−1 and 1.9nm, respectively. Modified substrate surface reduced average roughness and a layer with similar roughness and pore size was achieved. Cross sectional images by FESEM showed the thickness of 680nm for the obtained membrane. [ABSTRACT FROM AUTHOR]

Abstract: The mechanical properties and permeability of cement-based composites containing nano-MgO were studied and the experimental results indicated that the mechanical strength of the composites mixed with the nano-MgO, measured at different ages, were higher than those of a plain composite. The results from the treated composites compared to those of the plain composite indicated that the compressive strength of sample containing 1% nano-MgO of binder by weight (MGC1) increased by 103% and 80% at 7days and 28days, respectively, and that the flexural strength of MGC1 equaled 4.66 and 5.1MPa, which were 95% and 70% higher than those of the plain composite (PC), respectively. SEM revealed that the microstructure of the composites with nano-MgO were more compact and homogeneous than that of plain composite because of expansive effect of nano-MgO. This paper describes the mechanism of the nano-MgO effects on composites’ nanostructure. [Copyright &y& Elsevier]

Abstract: The effects of Al addition on pressureless-sintering of B4C–TiB2 composites were studied. Different amounts of Al from 0% to 5wt.% were added to B4C–TiB2 mixtures (containing up to 30wt.% TiB2) and the samples were pressureless sintered at 2050°C and 2150°C under Ar atmosphere. Physical, microstructural and mechanical properties were analysed and correlated with TiB2 and Al additions and sintering temperature. Addition of Al to B4C–TiB2 results in increased shrinkage upon sintering and final relative density and lower porosity, the effect is being more evident when both Al and TiB2 are present. Fracture strength, elastic modulus and fracture toughness of 450MPa, 500GPa and 6.2MPa.m1/2, respectively were measured. [Copyright &y& Elsevier]

Abstract: The effect of small Al addition on pressureless-sintering and mechanical properties of B4C ceramic was analyzed. Different amounts of aluminium powder, from 0% to 5wt%, were added to the base material and pressureless-sintering was conducted at 2050 and 2150°C under argon atmosphere. Microstructure, crystalline phases, density evolution, fracture strength, elastic modulus, hardness and fracture toughness were analyzed and correlated to Al additions and firing temperature. Density and grain size of sintered samples increased significantly with Al load while the effect of sintering temperature was less evident; 94% dense material was obtained by adding 4wt% Al. Bending strength, hardness and fracture toughness of sintered B4C samples were shown to increase for Al content up to 4wt% while further additions resulted in a decrease of the mechanical resistance. Conversely, elastic modulus showed an increase with Al load especially between 1 and 3wt%. [Copyright &y& Elsevier]

Abstract: The effect of Al addition on pressureless sintering of B4C ceramic was analyzed in the present work. Different amounts of Al, from 0 to 5wt.% were added to the base material and pressureless sintering was conducted at 2050 and 2150°C under argon atmosphere. Microstructure, crystal phases and density evolution were studied and correlated to Al additions and firing temperature. Density and grain size of sintered samples, increased significantly with Al load while less evidence is the effect of sintering temperature; 94% dense material was obtained by adding 4wt.% Al regardless of the maximum firing temperature. [Copyright &y& Elsevier]

In this study, high-entropy Mg 1.8 R 0.2 Al 4 Si 5 O 18 (R Ni, Ni 1/2 Co 1/2 , Ni 1/3 Co 1/3 Zn 1/3 , Ni 1/4 Co 1/4 Zn 1/4 Cu 1/4 , Ni 1/5 Co 1/5 Zn 1/5 Cu 1/5 Mn 1/5) cordierite ceramics based on equimolar ratios were designed and synthesized through the solid-state reaction technique at high temperatures. The effect of various R-ionic substitutions at the octahedral site and their relationship with ionic polarization, chemical bonding, and configurational entropy were explored. These factors have greatly affected the microwave dielectric properties of Mg 1.8 R 0.2 Al 4 Si 5 O 18 ceramics. The presence of cation radius mismatch and electronegativity mismatch at [MgO 6 ]-octahedron lattice sites revealed lattice distortion resulting from multiple cation substitutions. As the entropy values increased, the temperature stability of microwave dielectric properties of Mg 1.8 R 0.2 Al 4 Si 5 O 18 ceramics improved. For R Ni 1/2 Co 1/2 , a higher Q×f of approximately 73,658 GHz @ 13 GHz, with ɛ r ∼4.44 and τ f ∼ −23.9 ppm/°C was obtained. In the case of R Ni 1/5 Co 1/5 Zn 1/5 Cu 1/5 Mn 1/5 , a near zero τ f (−10.7 ppm/°C), ɛ r = 4.68 and Q×f = 35,478 GHz @13 GHz were achieved, making it potentially suitable for practical applications. [ABSTRACT FROM AUTHOR]

In this paper, different divalent ions (X = Ni, Cu, Mg, Co, Zn) are doped to replace Mg2+ at the tetrahedral sites in mixed spinel Mg 0.95 X 0.05 Al 2 O 4. These substitutions induce variations in the degree of inversion/preferential occupation at the A/B lattice site in MgAl 2 O 4 ceramics because the octahedral stabilization energies change as a function of dopant. According to crystal field theory, the number of d -orbital electrons has a significant impact on the stability of octahedral sites. Therefore, OSPE values vary between 0 Dq and 0.845 Dq for different elements. The higher the OSPE value, the greater the degree of inversion, and the higher the quality factor (Q × f). The dielectric constant (ε r) and temperature coefficient of resonant frequency (τ f) of Mg 0.95 X 0.05 Al 2 O 4 ceramics changes as a function of the ionic polarizability and B -site bond valence. Mg 0.95 Ni 0.05 Al 2 O 4 with a higher OSPE (8.45 Dq) and degree of inversion of A/B sites (λ = 0.221), has the better set of microwave dielectric properties (ε r = 8.39, Q × f = 78,338 GHz, τ f = −66.8 ppm/°C). The adjustment of stability energy of octahedral sites is favorable to improve the microwave dielectric properties of MgAl 2 O 4 spinel. [ABSTRACT FROM AUTHOR]

Non-stoichiometric Ba (Co 1 / 3 Nb 2 / 3) O 3 (BCN) ceramics were synthesized using the solid-state method at 1150 ℃. The heat treatment process was then followed by sintering at 1400–1550 ℃ and annealing at 1300 °C. Systematically varying the extent of the non-stoichiometry and the heat treatment conditions resulted in the division of the BaO − CoO − Nb 2 O 5 system into two categories of compounds: (A) high-order Co / Ba -deficient and Co / Nb -excess ceramics and (B) completely disordered Nb -deficient and Ba -excess ceramics. It was found that a slight deviation from stoichiometry toward the group (A) and subsequent annealing led to a significant improvement in the ordering from 82% to 100% accompanied with the formation of non-equidistant Nb − O bonds. The crystal structure based on the ultra-high order BCN − 0.02 Ba 5 Nb 4 O 15 was also designed to display non-equidistant Nb − O bonds. The dielectric characteristics demonstrated that high Q correlates with the 1:2 ordering and the highest Q × f values obtained from BCN − x Ba 5 Nb 4 O 15 ceramics (x = 0.02, 0.04, 0.06): 83, 84.95, and 79.71 THz, respectively. [ABSTRACT FROM AUTHOR]

In garnet phase ceramics Y 2.9 M 0.1 Al 4.9 Si 0.1 O 12 (M = Mg2+, Co2+, Zn2+, Mn2+, Ca2+, Sr2+, Ba2+), rattling effects occur when M = Mg2+, Co2+, Zn2+, Mn2+ ions with smaller ionic radius (<1Å) occupy the dodecahedron lattice lattices. This results in an abnormally high dielectric constant, in contrast to the larger ionic radius (>1 Å) of M = Ca2+, Sr2+ and Ba2+, which deviate from the theoretical values calculated using the Clausius-Mosotti formula according to each ion's polarizability. The optimal microwave dielectric properties for Y 2.9 Mg 0.1 Al 4.9 Si 0.1 O 12 was obtained by sintering at 1575 °C for 5 h (Q × f = 51,382 GHz, ε r = 9.74, and τ f = −30.12 ppm/°C). Additionally, a thermal stable Y 2.9 Mg 0.1 Al 4.9 Si 0.1 O 12 -6 wt%TiO 2 composite ceramic was developed. Based on this composite, a Wifi6E/7 patch antenna operating at 6.3 GHz and a millimeter-wave resonant antenna functioning at 27.1 GHz were designed and validated. This indicates the potential application prospects of garnet ceramics in 5G/6G radio communication technologies. [ABSTRACT FROM AUTHOR]

This study first reports the synthesis of Li 2 ZnTi 3 O 8 (LZTO) system by microwave (MW) and conventional (CS) sintering techniques. The effects of both synthesis and sintering technique on the structure, degree of ordering and microwave dielectric properties of LZTO ceramics were investigated. Based on XRD data analysis, a single phase Li 2 ZnTi 3 O 8 is obtained for both synthesis techniques. However, fully ordered LZTO system can only be obtained by the CS method. All the samples display nearly non-homogenous grain growth with an average grain size of 7 μm (MW sintering) and 38 μm (CS sintering), respectively. The calculated activation energy of the grain growth for LZTO ceramics was reduced from 329 kJ/mol (MW process) to 233 kJ/mol (CS process). The LZTO ceramics finally densified at 1075 °C display dielectric constants of ε r C S = 25.26 and ε r M W = 25.65, temperature coefficient of resonant frequencies of τ f C S = -13.6 ppm/°C and τ f M W = -12.0 ppm/°C and Q×f values of 76,000 GHz and 65,000 GHz for CS and MW samples, respectively. It is clear, therefore, that the synthesis and thermodynamics (sintering) can both play an important role in shaping the physical properties of LZTO materials. [ABSTRACT FROM AUTHOR]

New ultra-low loss, temperature-stable composite ceramics, (1- x) Mg 1.99 Ga 0.01 Si 0.99 Al 0.01 O 4 - x CaTiO 3 , have been developed with a view to expanding the portfolio of low-cost, MW dielectrics available for 5 G/6 G telecommunications, currently dominated by 95 wt%MgTiO 3 -5 wt%CaTiO 3 , (Mg,Ca)TiO 3 (relative permittivity, ε r ∼ 21, quality factor, Q × f ∼ 56,000 GHz and temperature coefficient of resonant frequency, τ f ∼ 0 ppm/°C). Compared with (Mg,Ca)TiO 3 , 89 wt%Mg 1.99 Ga 0.01 Si 0.99 Al 0.01 O 4 -11 wt%CaTiO 3 ceramics are also temperature stable (τ f = −2.72 ppm/°C) but have lower ε r (∼8.55) and a higher Q × f (∼ 72,900 GHz @ 12 GHz and 80,900 GHz @ 26 GHz), better suited to the higher frequencies earmarked for 6 G millimeter-wave (mm-wave) applications. To demonstrate its potential for 5 G/6 G telecommunications, a waveguide filter with novel negative coupling structure was fabricated based on simulated results. The filter had low insertion loss (0.43 dB) at the center frequency (4.8 GHz) and high selectivity with a roll-off rate of 576/375 dB/GHz. The S-parameters matched well at 25 °C and 85 °C, demonstrating that the filter had excellent temperature stability and was therefore suitable for future 5 G/6 G microwave and mm-wave communication devices. [ABSTRACT FROM AUTHOR]

Y 3- x R x Al (Oct)2 Al (Tet)3- x Si x O 12 (x = 0.1–0.5; R = Mg, Ca) ceramics were prepared via solid-state reaction method. The effects of Mg2+ (∼0.89 Å) and Ca2+ (∼1.12 Å) substitution at the dodecahedral site for Y3+ (∼1.019 Å) on the microstructure, crystal structure and microwave dielectric properties of Y 3- x R x Al (Oct)2 Al (Tet)3- x Si x O 12 garnet ceramics were investigated and discussed using the P–V-L theory, Raman spectrum, bond valence theory, Terahertz time-domain spectroscopy and infrared reflectance spectrum. Different from normal garnet structure of ceramics, the dielectric constant is abnormally increased in Y 3- x Mg x Al (Oct)2 Al (Tet)3- x Si x O 12 (x = 0.1–0.5) ceramics due to the increase of ion polarizability caused by the rattling effect. There is a dependence of bond energy, bond valence and dodecahedral distortion on τ f value, which provides new possibility for tuning the temperature coefficient of garnet ceramics. There are strong effects of grain size distribution, average lattice energy, packing fraction, FWHM of Raman peak on their Q×f values of Y 3- x R x Al (Oct)2 Al (Tet)3- x Si x O 12 isostructural ceramics caused by the difference of Mg2+ and Ca2+ ionic radius. Above work provides deeper insights into the understanding of the microstructural characteristics and performance relationship of garnet-type microwave ceramics, and lays a foundation for future applications in the 5G/6G frequency bands. [ABSTRACT FROM AUTHOR]

In this paper, a strategy for preparing MgAl 2- x (Mg 0.5 Ge 0.5) x O 4 (0 ≤ x ≤ 0.12) solid solution ceramics through the substitution of (Mg 0.5 Ge 0.5)3+ for Al3+ in the octahedral lattice of spinel crystal structure A(tetra)B 2 (octa)O 4 via traditional high-temperature solid-state reaction method is presented. The intrinsic and extrinsic factors influencing their microwave dielectric properties, including the inversion degree of A/B lattice sites (lattice occupancy), bond length and bond valence, as well as grain sizes, were investigated using Rietveld refinement of X-ray powder diffraction data and scanning electron microscopy. To verify the applicability for the next-generation 5 G-n257/n258 millimeter wave frequency band, the Q × f values were tested within the frequency range of 12–25 GHz. Notably, MgAl 1.91 (Mg 0.5 Ge 0.5) 0.09 O 4 ceramics exhibited a high Q × f value of 105, 384 GHz @11.83 GHz, low ε r of 8.7, and τ f of −66.4 ppm/℃. SrTiO 3 was added to tune the τ f to a near-zero value of +2.6 ppm/℃ with high Q × f value of 51, 152 GHz @11.53 GHz and ε r of 9.91. Finally, a microstrip filter with a center frequency of 3.6 GHz was designed using this composite ceramic, successfully demonstrating its practical application in the low-frequency band of 5 G networks. [ABSTRACT FROM AUTHOR]

Cordierite-based dielectric ceramics with a lower dielectric constant would have significant application potential as dielectric resonator and filter materials for future ultra-low-latency 5G/6G millimeter-wave and terahertz communication. In this article, the phase structure, microstructure and microwave dielectric properties of Mg 2 Al 4–2 x (Mn 0.5 Zn 0.5) 2 x Si 5 O 18 (0 ≤ x ≤ 0.3) ceramics are studied by crystal structure refinement, scanning electron microscope (SEM), the theory of complex chemical bonds and infrared reflectance spectrum. Meanwhile, complex double-ions coordinated substitution and two-phase complex methods were used to improve its Q×f value and adjust its temperature coefficient. The Q×f values of Mg 2 Al 4–2 x (Mn 0.5 Zn 0.5) 2 x Si 5 O 18 single-phase ceramics are increased from 45,000 GHz@14.7 GHz (x = 0) to 150,500 GHz@14.5 GHz (x = 0.15) by replacing Al3+ with Zn2+-Mn4+. The positive frequency temperature coefficient additive TiO 2 is used to prepare the temperature stable Mg 2 Al 3.7 (Mn 0.5 Zn 0.5) 0.3 Si 5 O 18 - y wt%TiO 2 composite ceramic. The composite ceramic of Mg 2 Al 3.7 (Mn 0.5 Zn 0.5) 0.3 Si 5 O 18 - y wt%TiO 2 (8.7 wt% ≤ y ≤ 10.6 wt%) presents the near-zero frequency temperature coefficient at 1225 °C sintering temperature: ε r = 5.68, Q×f = 58,040 GHz, τ f = −3.1 ppm/°C (y = 8.7 wt%) and ε r = 5.82, Q×f = 47,020 GHz, τ f = +2.4 ppm/°C (y = 10.6 wt%). These findings demonstrate promising application prospects for 5 G and future microwave and millimeter-wave wireless communication technologies. [ABSTRACT FROM AUTHOR]

Garnet-typed ceramics of Y 3 Mg 1- x Mn x Al 3 SiO 12 (0 ≤ x ≤ 0.2) have been synthesized using the traditional solid-state reaction method. The optimal microwave dielectric properties (ε r = 10.73, Q׃ = 62,824 GHz, τ f = −34.8 ppm/°C) are obtained for Y 3 Mg 0.9 Mn 0.1 Al 3 SiO 12 (x = 0.1) sintered at 1575 °C for 5h. A millimeter-wave dielectric resonator antenna is designed and fabricated using Y 3 Mg 0.9 Mn 0.1 Al 3 SiO 12 as a dielectric unit due to its excellent characteristics of low dielectric constant and high Q׃. The designed DRA resonates at 24.94 GHz with a bandwidth ∼2.20 GHz (S 11 < −10 dB). The simulated gain and efficiency are 6.64 dBi and 91.08%, respectively. The results indicate that the Y 3 Mg 0.9 Mn 0.1 Al 3 SiO 12 ceramic has a potential application as an antenna for the 5G/6G millimeter wave frequency band. [ABSTRACT FROM AUTHOR]

In this work, the effects of divalent ions on the phase structure, microstructure, and microwave dielectric properties of Mg 1.8 R 0.2 Al 4 Si 5 O 18 (R = Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu, Zn) cordierite ceramics were investigated. Complex chemical bond theory, Raman spectrum and infrared reflectance spectrum were employed to understand the relationship among structural characteristics, vibration modes and microwave dielectric properties for alkaline earth and transitional metal divalent elements doped cordierite ceramics. The optimal microwave dielectric properties were obtained for Mg 1.8 Ni 0.2 Al 4 Si 5 O 18 with ε r of 4.53, Q× f of 61,880 GHz and τ f of -32 ppm/℃. Finally, a 5G-Sub 6GHz patch antennas with a central frequency of 4.91 GHz was successfully designed and fabricated using a Mg 1.8 Ni 0.2 Al 4 Si 5 O 18 substrate. The antenna exhibited excellent performance with a gain of 5.83 dBi and an efficiency of 76 %, showing promise to be employed in 5 G/6G millimeter-wave communication technology. [ABSTRACT FROM AUTHOR]