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In this paper, the high-quality factor mullite microwave dielectric ceramic is employed to introduce in dielectric resonator antenna (DRA). The microwave dielectric properties of ɛr ∼ 5.8, Q × f ∼ 31 240 at 9.66 GHz, and loss tangent tanδ = 1/Q ∼ 2.7 × 10−4 can be obtained by the solid-state reaction method in mullite microwave dielectric ceramic sintered at 1700 °C. On this basis, the resonant modes of the proposed broadband high-gain rectangular DRA are analyzed by using a dielectric waveguide theoretical model and the antenna performance is evaluated by a commercial CST Microwave Studio 2021® software. It has been found that the proposed rectangular DRA can provide a broad bandwidth of 35.9%, a maximum gain of 10 dBi at 3.61 GHz, and a radiation efficiency of 90% in the range of 3.13–4.42 GHz. For demonstration, adequate consistency between the simulation results and the measurement results was achieved. The proposed DRA has great application potential and value in 5G communication scenarios requiring wideband and high-gain antenna. [ABSTRACT FROM AUTHOR]

Summary: This article explains the design and implementation of a multiple input multiple output (two‐port) antenna, based on dielectric resonators. The antenna design not only demonstrates high isolation between its ports but also showcases robust diversity performance. The initial step introduces an asymmetrical ground plane radiating stub microstrip feed for circular polarization generation in a single‐port cylindrical dielectric resonator antenna (CDRA). This approach utilizes an asymmetrical ground plane and incorporates three radiating stubs connected to a microstrip feed line to generate HEM11δ modes in a cylindrical DRA. The proposed dual‐port CDRA offers high impedance bandwidth of 29.73% (2.95–3.98 GHz) and the axial ratio falls below 3 dB specifically from 3.01–3.35 GHz. The antenna demonstrates left‐handed circularly polarized fields with an average gain of 4.95 dBi and a radiation efficiency of 90.56%. All of these characteristics make the developed radiator appropriate for WiMAX (3.3–3.5 GHz) applications. [ABSTRACT FROM AUTHOR]

Summary: In this paper, a decoupling mechanism is discussed for different mode excitations in the cylindrical dielectric resonator antenna (cDRA) by utilizing absorbing surface wall. In the cDRA, the fundamental radiating mode is HE11δ. Another higher order mode for radiation purpose in cDRA is HE12δ. Both HE11δ and HE12δ create broadside radiation. To analyze multiple‐input multiple‐output (MIMO) performance, two different dual‐port DRAs are proposed. Each antenna structure consists of two DRA with dual similar ports supporting the same mode. Therefore, two different antenna structures are proposed for two different modes. For each antenna, two 2 × 3 absorber array walls are designed, and they are placed in between the DRA to reduce the mutual coupling. When the absorber array walls are placed in between the antenna elements, they blocked the free‐space electromagnetic (EM) field interaction in between the DRA. Due to the reduction of free‐space radiation interaction, the mutual coupling between the ports is improved tremendously. For both HE11δ and HE12δ modes, the mutual coupling is reduced by more than 10 dB. To analyze efficacy of the proposed method, the antenna structure featuring the HE11δ mode is fabricated and experimentally tested. [ABSTRACT FROM AUTHOR]

Summary: Developing wireless communication systems depends on reconfigurable microwave filters (MF) and dielectric resonator antenna (DRA) because the functionality of the various filters and antennas available for a wireless communication system is limited, and reconfigurable DRA and MF are utilized to overcome these limitations. The throughput of a multiantenna system can be achieved with reconfigurable DRA and filter. Various switching strategies and classifications of reconfigurable DRA and MF are presented. The electrical reconfiguration technique is most suitable for developing a reconfigurable DRA and filter among all the switching techniques. In this approach, reconfigurability may be accomplished by utilizing a PIN diode, a varactor diode, and a radio‐frequency microelectromechanical switch (RF‐MEMS). These switches are more reliable, highly efficient, and easily integrated with the microwave circuit. Reconfigurable DRA with machine learning is demonstrated. The application of reconfigurable DRA and filters in cognitive radio (CR) is also demonstrated. Also, the review article focused on the performance parameters, design, and challenges of reconfigurable antenna and MF. [ABSTRACT FROM AUTHOR]

The current paper reports on the crystal structure, microwave dielectric properties as well as the antenna parameters of (1-x)MgTiO 3 - xSrTiO 3 (abbreviated as (1-x)MT-xST) for x = 0.025, 0.05, 0.075, 0.1 ceramic based dielectric resonator antennas (DRAs). The (1-x) MT - xST samples have been prepared with the help of a solid-state reaction route. The SrTiO 3 was introduced to MgTiO 3 as a τ f compensator for developing a tunable τ f material. Rietveld refinement results of X-ray diffraction data suggest that all the samples exhibit a combination of two crystallographic phases i.e., rhombohedral (R-3) + cubic (Pm-3m). The SEM micrographs show clear and well-defined grains for (1-x)MT - xST (for x = 0.025–0.1) ceramics. The modes of vibration of the crystal structures of the materials have been identified by the Raman spectroscopy method. The bond strength, bond valency, bond energy, and tolerance factor have been determined for (1-x)MT - xST (for x = 0.025–0.1) materials. The microwave dielectric performances of ceramics have been analyzed over a frequency band of 1–10 GHz. It has been found that the dielectric constant is almost constant along the microwave frequency range. The behavioral change of tuned temperature coefficient of resonant frequency (τ f) along with quality factor have been reported. Besides, DRAs have been formed using all ceramic compositions, and simulations were performed to determine the various antenna properties, such as efficiency, input impedance, radiation properties, gain, and reflection coefficient. This study supports the use of microwave dielectric ceramics in antenna fields and highlights the enormous potential of (1-x)MT - xST for (x = 0.05) materials in communication systems. [ABSTRACT FROM AUTHOR]

This review offers an extensive examination of the evolving landscape of Long Range (LoRa) Microstrip Patch Antennas (MPAs), highlighting their crucial role in optimizing LoRa systems within the Internet of Things (IoT). As the demand for energy-efficient standards like LoRa grows with the expanding IoT market, this research becomes increasingly relevant. This comprehensive review, the first of its kind, serves as a foundational resource for researchers seeking to optimize LoRa systems within the IoT. The study has categorized these LoRa MPAs – including monopole, Planar Inverted F Antenna (PIFA), dipole, yagi-uda, and array – into single band, dual-band, multiband, and wearable antennas, thus providing substantial viewpoints on their diverse design architectures and performance characteristics. Through systematic tabulation, the review facilitates a thorough comparison of antenna advancements. Notably, the review addresses inherent challenges in LoRa MPAs, emphasizing critical aspects that necessitate attention, including the need for miniaturization and integration, advancements in substrate materials and fabrication techniques, and the imperative for reconfigurable and adaptive antennas. Various approaches to enhance antenna performance are explored, including the metamaterial incorporation, slot-based enhancements, Electromagnetic Band Gap (EBG), dielectric resonator antennas (DRAs), substrate material considerations, and corrugation techniques. Looking ahead, the paper explores the future trends and subtle considerations that are poised to shape the trajectory of LoRa MPAs. To the best of our knowledge, this paper represents the first comprehensive review on the multifaceted topic of LoRa MPAs, serving as a foundational resource for researchers in the field. [ABSTRACT FROM AUTHOR]

Summary: In this article, a dual port Multiple Input Multiple Output (MIMO) cylindrical Dielectric Resonator (DR)‐based frequency tunable antenna with a machine learning (ML) approach for a 5G New Radio (NR) application is presented. According to the author's best knowledge, it is the first time‐frequency tunable MIMO hybrid DR with ML is reported. A dual port MIMO DRA is placed in the orthogonal configuration with the connected ground to obtain higher isolation S12<−19dB in the entire frequency range. The proposed dual port antenna provides a total spectrum (TS) and tuning range (TR) of 98.99% and 80.93%, respectively. The different MIMO parameters, Envelope Correlation Coefficient (ECC), Total Active Reflection Coefficient (TARC), and Diversity Gain (DG) are investigated and found within the acceptable limits. The optimization of the proposed dual port tunable antenna is done through the various ML algorithms, including Artificial Neural Network (ANN), K‐Nearest Neighbor (KNN), Decision Tree (DT), Random Forest (RF), and Extreme Gradient Boosting (XGB). The KNN ML algorithm provides more than 98% accuracy for predicting the S‐parameters in all configurations. Hence, the proposed antenna is suitable for 5G NR applications. [ABSTRACT FROM AUTHOR]

This study investigates the dielectric properties of ceramic waste derived from roof tiles and bricks commonly used in civil construction. The materials were analyzed by grinding them into a fine powder, followed by producing of cylindrical samples through uniaxial pressing on a steel matrix. The samples were sintered at temperatures of 1000 °C, 1050 °C, and 1100 °C to analyze the effect of temperature on the electrical characteristics of the ceramics. XRD and SEM analyses were performed to evaluate microstructural parameters and coalescence behavior. The dielectric characterization aimed to obtain the real relative electrical permittivity with average values of 2.85, 3.56, and 3.65, correlated with apparent porosity levels of 30.74 %, 20.54 %, and 9.11 %, and the loss tangent of 7.5 × 10−5, 3.9 × 10−5, and 12 × 10−5, respectively. The loss tangent values are lower than those obtained in commercial dielectrics from 1 to 6 GHz frequency range. The dielectric characteristics of samples manufactured from ceramic waste from bricks and tiles can serve as sustainable alternatives to produce dielectric resonator antennas (DRA), applicable to fifth-generation wireless communication devices in the sub-6GHz band. [ABSTRACT FROM AUTHOR]

A Rectangular Dielectric Resonator Antenna (RDRA) design for mmWave-frequency-band MIMO metrics is proposed, with a compact, low-complexity, high-gain structure that is easy to fabricate and offers reduced inter–port isolation. The RDRA operates in the mmWave spectrum, featuring a compact size of 1.307 λ 0 × 1.307 λ 0 , an impedance bandwidth of 6%, and a resonant frequency of 28 GHz, with a peak gain of 7 dBi. A four element MIMO system iteration was developed while maintaining the performance of the single element antenna. Additionally, a simple, low-complexity slot-etching technique was applied to achieve an average inter-port element isolation of 14 dB. The design also achieved a novel four-beam petal-splitting radiation pattern. The MIMO metrics, with an envelope correlation coefficient (ECC) of <0.5 and a diversity gain (DG) < 10, were successfully met. The simulated and measured results are in good agreement. [ABSTRACT FROM AUTHOR]

This paper presents a circularly polarized hybrid cylindrical dielectric resonator antenna (HCDRA) over a modified Minkowski unit-cell-based metasurface for 5G n79 band (4.4–5 GHz) and IEEE 802.11n WLAN (5 GHz) applications. The location of the perturbed probe feed mechanism and the asymmetric nature of the metasurface are the factors that influence the circularly polarized (CP) radiation within the DR element. The magnitude of E-field distribution and parametric study of the antenna to obtain the optimized feed location are the pieces of evidence of CP radiation. The return loss (RL) and axial ratio (AR) bandwidths produced by the proposed antenna are 1.837 GHz and 750 MHz with a peak gain of 7.04 dBic. The gain obtained is more than 5 dBic across the offered bandwidth of the proposed antenna. The proposed antenna is fabricated and tested in an anechoic chamber for measured results, and these results closely match with the simulation results. [ABSTRACT FROM AUTHOR]

Summary In this work, an offset microstrip line coupled bilateral rectangular‐shaped dielectric resonator antenna (RDRA) is designed for broadband circular polarization (CP), which is fabricated and experimentally verified. The vertical microstrip is added in an offset position to generate orthogonal modes and the fundamental modes TEx111 and TEy111. The generation of orthogonal modes designates the antenna structure as a CP antenna with orthogonal modes. Moreover, the location of the microstrip feed arrangement is used to control the polarization state in the proposed work. In the proposed design, the simulated and hand‐measured input impedance bandwidth(|S11| ≤ −10 dB) obtained is 32.6% (3.53–4.9 GHz) and 33.2% (3.56–4.98 GHz), respectively, whereas the simulated and measured axial ratio (AR ≤ 3 dB) shows 16.1% (3.71–4.36 GHz) and 17.03% (3.7–4.39 GHz) of axial ratio bandwidth, respectively. This design shows a consistent radiation pattern and good average gain, with acceptable agreement between simulation and hand‐measured results. The simulated result shows 94% radiation efficiency in the working frequency range. [ABSTRACT FROM AUTHOR]

This study presents experimental investigations and numerical simulations of the microwave (MW) dielectric and evaluation of the electrical properties in the radiofrequency region (RF). The ceramic matrix Li2LaNbTiO7 (LLNT) is obtained through the solid‐state reaction method. The synthesis of LLNT is confirmed using the X‐ray diffraction technique. In the complex impedance spectroscopy study, permittivity (ε′r) and loss tangent (tanδ) values are analyzed at room temperature. The study of the conductivity spectrum at different temperatures demonstrates that the conduction process is thermally activated, presenting a value of 0.65 eV for the activation energy. Numerical simulations are employed to evaluate the behavior of the LLNT matrix as dielectric resonator antennas (DRA), whereas this ceramics demonstrated a reflection coefficient of less than −10 dB at the resonant frequency, achieving a gain of 3.71 dBi, a bandwidth of 144 MHz and a radiation efficiency greater than 97%. The results indicate that the LLNT matrix would be a promising candidate for RF and MW operating devices. [ABSTRACT FROM AUTHOR]

This investigation introduces a MIMO antenna using cylindrical shaped dielectric resonators and discusses both the design and implementation approaches. The proposed antenna design employs a CSRR structure and L-shaped metallic reflectors to improve isolation across many frequency bands. The typology operates at five different frequency ranges: 2.48, 3.92, 5.36, 7.4, and 8.56 GHz. It provides isolation levels of 39, 52.5, 33.8, 42.9, and 37.2 dB, respectively. The semi-circular tapered feed enables for circular polarization between 5.3 and 5.75 GHz. The simulated results indicate that the specified antenna is appropriate for usage in five frequency ranges: 2.1–2.6, 2.7–4.4, 4.9–5.8, 6.9–7.8, and 8.1–9.1 GHz. In a multiple-input multiple-output configuration, antenna performance is evaluated using a variety of diversity indicators, including the envelope correlation coefficient, mean effective gain, diversity gain, channel capacity loss, and total active reflection coefficient. Both simulations and measurements reveal that the proposed antenna can handle Wi-Fi 6, Wi-Max, and W-LAN services, including X-band. [ABSTRACT FROM AUTHOR]

The frequency diverse array (FDA) is a very interesting technique in wireless communications. Many research papers are introduced in this field. A lot of them is concerned with linear point sources array. In this paper, a design of a time-modulated planar frequency diverse array architecture is proposed for tracking single or multi-target for the first time. The time-modulation array (TMA) and FDA are combined for detecting single and multi-target. The effectiveness of this combined scheme is demonstrated through simulation results that compared with a point source case to show its superior performance. Authors introduce planar FDA array instead of linear FDA array and realize the planar array using cylindrical dielectric resonator antenna array (CDRA). A planar array consists of 8 × 8 CDRA is used to enable the detection of single target/multi-target. The operating frequency of the antenna is set at 10 GHz, aligning with its applications in the FDA radar. The radiation characteristics of the CDRA antenna element are introduced. High maximum gain of 6 dBi is achieved with a remarkably high efficiency. A set of representative results is reported and analyzed to assess the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

In this paper, a Substrate-Integrated Waveguide (SIW)–based Cylindrical Dielectric Resonator Antenna (CDRA) is designed for 6G THz applications. This antenna provides a Quad-band response at 2.14 THz, 3.41 THz, 5.61 THz, and 9.02 THz respectively. The unique feature of the proposed SIW-CDRA is its ability to exhibit Circular Polarization (CP) behavior across three frequency bands. Graphene material is added onto the top of the proposed CDRA to achieve tunability in the antenna's resonant frequency. CP tuning is also achieved by varying the graphene potential of the antenna. Furthermore, this proposed antenna shows both Right Hand Circular Polarization (RHCP) and Left Hand Circular Polarization (LHCP) behavior at different resonant frequencies. The antenna exhibits a maximum gain of 6.97 dB and a maximum radiation efficiency of 84.53%. Notably, the antenna showcases a 3 dB Axial Ratio (AR) bandwidth of 11.05% (1.968–2.195 THz), 4.58% (5.483–5.734 THz), and 5.22% (8.843–9.313 THz) is achieved. Moreover, the CDRA generates two higher-order modes, specifically HEM11δ at 5.61 THz and HEM12δ at 9.02 THz. Additionally, the antenna exhibits a unique feature of converting multiband response to wideband response by changing the length of the aperture slots. All these results show that the proposed multiband SIW with CDRA is unique and suitable for THz applications. [ABSTRACT FROM AUTHOR]

Dielectric resonator antennas (DRAs) use dielectric material as a resonator to accomplish high radiation efficiency and avoid severe conductor loss. The dielectric material that behaves as a resonator is plagued by a number of limitations, including strong cross-polarised (XP) radiation and difficulties integrating with any development platform. Yet, it also offers a lot of benefits, including compact size, lightweight, affordable price, and diversity in form, including cylindrical, rectangular, conical, and ring. A discussion of DRAs, covering DRA propagation modes, geometries, feeding mechanisms, and different bandwidth augmentation approaches, is presented. A stacked arrangement with two or more DRs has achieved the widest impedance bandwidth (BW). The perforated topology is a straightforward alternative for increasing the DRA's bandwidth while maintaining a small, discrete size. [ABSTRACT FROM AUTHOR]

A wideband dual-beam dielectric resonator antenna (DRA) with substrate integration capability was proposed for millimeter-wave (mm-wave) applications. The four rows of air vias along the x-direction and two extended rectangular patches could shift the undesirable radiation mode upward and move the conical-beam radiation mode downward, respectively. Thus, the TE211 mode and the TE411 mode of the patch-loaded perforated rectangular substrate integrated dielectric resonator (SIDR) supporting the dual-beam radiation can be retained in the operating band, and their radiation can be improved by the air vias along the y-direction. The T-shaped line coupled dual-slot structure could excite the above two modes, and a dual-slot mode supporting dual-beam radiation could also work. Then, a wideband DRA with a stable dual-beam radiation angle can be achieved, and its impedance matching can be improved by two air slots on two sides. Compared with the state-of-the-art dual-beam antennas, the proposed antenna shows a wider bandwidth, a higher radiation efficiency, and the substrate integration capability of DRA, making it more suitable for mm-wave applications. For demonstration, a 1 × 4 array was designed with the 10 dB impedance matching bandwidth of 41.2% and the directions of the dual beams between ±30° and ±35°. [ABSTRACT FROM AUTHOR]

This research examines the performance of two Z-shaped dielectric resonator antenna designs that employ silicon substrate material and operate at a frequency of 10 terahertz. CST software was used to simulate and create a two-Z shape DRA. Results of enhanced gain are analyzed and compared with earlier research. The suggested Two Z shape DRA has a gain of 7.31 dB and a return loss of -15.9 dB.The two Z-shaped dielectric resonator antennas have an impedance bandwidth of 66.66%.The VSWR of two Z-shaped dielectric resonator antennas is around 2 dB, which is acceptable. This proposed approach may be suitable for a wide range of communication applications, including wireless and terahertz applications. [ABSTRACT FROM AUTHOR]

A high-tuning range frequency reconfigurable dual-band compact cylindrical Dielectric Resonator Antenna (DRA) for 5 G Sub 6 GHz applications is presented in the proposed work. The work presented here provides compactness, frequency reconfigurability (FR), and dual-band. FR is obtained through two PIN diode switches, which operate in ON-ON, ON-OFF, OFF-ON, and OFF-OFF configurations and offer a maximum wide tuning range and a total spectrum of 44.44% and 71.49%, respectively. In the cylindrical DRA, the ${\rm{HE}}{{\rm{M}}_{11{\rm{\delta }}}}$HEM11δ and ${\rm{HE}}{{\rm{M}}_{12{\rm{\delta }}}}$HEM12δ modes create dual-band, while the hybrid structure and higher order mode excitation yield compactness. [ABSTRACT FROM AUTHOR]

Summary In this article, a two‐port multiple‐input multiple‐output (MIMO) hybrid rectangular dielectric resonator antenna (DRA) with machine learning (ML) approach for the n261 5G New Radio (NR) application is presented. The proposed antenna is designed on an RT/duroid 5880 (Ɛr = 2.2) substrate activated by 50 Ω, L‐shaped microstrip slot feeds beneath both DRAs. The isolation is more than 19 dB, and the gain is 10 dBi in the operating frequency range. The proposed antenna is optimized through knowledge‐based neural networks (KBNN), artificial neural networks (ANNs), and ML. The optimal design parameters of the proposed antenna are accomplished using the ML optimization approach, which includes ridge regression, ANNs, and KBNN. KBNN ML techniques provide 96.88% accuracy and correctly predict the S‐parameters of the proposed antenna. The MIMO diversity parameters like envelope correlation coefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), and channel capacity loss (CCL) are calculated and found within the limits. Hence, the proposed antenna is used for 5G NR mm‐wave application. [ABSTRACT FROM AUTHOR]

A substrate-integrated cylindrical cavity (SICC) fed polarization flexible cylindrical dielectric resonator antenna (CDRA) is presented in this literature. To excite the CDRA, a unique and simple feeding approach based on substrate-integrated waveguide (SIW) technology is demonstrated. This SICC is fed by two 50Ω microstrip lines, oriented orthogonally to each other. The SICC with a cross slot on its top metalized surface and the TM110 mode excites inside it act together to couple energy efficiently to the CDRA. Applying different phase combinations signals at the two input ports of the SICC, the CDRA can radiate in four different orientations linear polarization (LP) (along φ = 0°, 45°, −45°, and 90° ), left-handed circular polarization (LHCP), and right-handed circular polarization (RHCP). A conventional cylindrical dielectric resonator having relative permittivity ϵd = 10 is preferred. Its diameter, height, and cross-slot dimensions are optimized to operate the CDRA over Ku-band with 12% impedance bandwidth, 2-dB axial ratio (AR) bandwidth of 11%, and 3-dB gain bandwidth of 12%. In this operating band, CDRA resonates at three different higher-order modes (HEM32δ, HEM113, and HEM12δ+2) with 8 ± 1.6 dBi/dBic gain for all the polarization states. The measurements of this antenna are conducted using two external phase shifters and one power divider. [ABSTRACT FROM AUTHOR]

This study explored the synthesis and sintering of potassium sodium niobate (KNN) nanoparticles, emphasizing morphology, crystal structure, and sintering methods. The as-synthesized KNN nanoparticles exhibited a spherical morphology below 200 nm. Solid state sintering (SSS) and laser-induced shockwave sintering (LISWS) were compared, with LISWS producing denser microstructures and improved grain growth. Raman spectroscopy and x-ray diffraction confirmed KNN perovskite structure, with LISWS demonstrating higher purity. High-resolution x-ray photoelectron spectroscopy spectra indicated increased binding energies in LISWS, reflecting enhanced density and crystallinity. Dielectric and loss tangent analyses showed temperature-dependent behavior, with LISWS-3 exhibiting superior properties. Antenna performance assessments revealed LISWS-3's improved directivity and reduced sidelobe radiation compared to SSS, attributed to its denser microstructure. Overall, LISWS proved advantageous for enhancing KNN ceramics, particularly in antenna applications. [ABSTRACT FROM AUTHOR]

A wideband circularly polarized (CP) stacked rectangular dielectric resonator antenna (RDRA) is proposed in this article. The 3 dB axial ratio (AR) and 10 dB impedance bandwidth overlap of more than 66% is obtained. For increased bandwidth, the antenna comprises two dielectric resonators separated by an air gap. The upper dielectric layer is rotated at ∠45∘ $\angle 4{5}^{\circ }$ relative to the lower layer to obtain orthogonal modes for CP Both layers have dielectric constant εr=9.8 ${\varepsilon }_{r}=9.8$. The rotation aids excitation of orthogonal modes TEδ11x∕TE1δ1y,TEδ31x∕TE3δ1y $T{E}_{\delta 11}^{x}\unicode{x02215}T{E}_{1\delta 1}^{y},T{E}_{\delta 31}^{x}\unicode{x02215}T{E}_{3\delta 1}^{y}$, and TEδ21x∕TE1δ2y $T{E}_{\delta 21}^{x}\unicode{x02215}T{E}_{1\delta 2}^{y}$ in RDRA. The higher‐order modes generate left‐hand circular polarization at frequencies 6.75, 7.8, and 10.7 GHz, respectively. The upper layer consists of three holes giving a 10 dB impedance bandwidth of 66.7% from 6.52 to 11.02 GHz. The CP gain of 8.7, 6.8, and 6.4 dBi for 6.75, 7.8, and 10.7 GHz, respectively, is measured. The conformal orthogonal feeds enable a 72% $ \% $ 3 dB AR bandwidth across the entire frequency band. The radiation efficiency is observed above 89% $ \% $ in the entire band (6.5–11 GHz). This work demonstrates a 66.7% $ \% $ overlap of 10 dB impedance and 3 dB AR bandwidth along with high gain in a single design which is suitable for 5G applications in C‐band as well as other X‐band applications. [ABSTRACT FROM AUTHOR]

The rapidly ever‐growing wireless communication demands development of low loss, ultralow sintering temperature dielectric ceramics with excellent microwave properties. In this work, fabrication and properties of novel microwave dielectric composite ceramics (1 − x)(Na0.5Bi0.5)MoO4–xBaMoO4 (x = 0.3–0.6), in short as ((1 − x)NBM–xBM), synthesized via solid‐state reaction method with an ultralow sintering temperature is reported. X‐ray diffraction analysis confirms the coexistence of both (Na0.5Bi0.5)MoO4 and BaMoO4 scheelite phases. Scanning electron microscopy analysis demonstrated dense microstructures of ceramics sintered at 650°C and 700°C. The dielectric properties of (1 − x)NBM–xBM (x = 0.3–0.6) ceramic are significantly tailored by incorporation of BaMoO4. With the increase in x from 0.3 to 0.6, the (1 − x)(Na0.5Bi0.5)MoO4–xBaMoO4 displays noticeable change in microwave permittivity εr${\varepsilon }_r$ (varying from 25.4 to 16.6), quality factor (Q×f)$(Q \times f)$ values, and temperature coefficient of frequency (τf)$({\tau }_f)$ (range tunable from +37.6 ppm/°C to −14.2 ppm/°C). The microwave dielectric ceramic, 0.5(Na0.5Bi0.5)MoO4–0.5BaMoO4, has optimum dielectric properties (εr=19.02${\varepsilon }_{\mathrm{r}} = 19.02$, Q×f$Q \times f$ = 15 164 GHz, τf = −0.2 ppm/°C) at sintering temperature of 650°C. The dielectric resonator antenna designed using (1 − x)(Na0.5Bi0.5)MoO4–xBaMoO4 ceramics demonstrated excellent radiation performance at resonance frequency of 5.905 GHz, gain of ∼5.8 dBi and 140 MHz bandwidth, which validates its microwave applications utilization within the field of ultralow temperature cofired ceramics technology. [ABSTRACT FROM AUTHOR]

In this paper, a slotted frustum-shaped $ 4\times 4 $ 4 × 4 multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) is designed and developed for portable 5G Wi-Fi ( $ 5.15{-}5.85\, {\rm GHz} $ 5.15 − 5.85 GHz ) applications. The DRA is excited by $ HEM_{11\delta } $ HE M 11 δ and $ HEM_{21\delta } $ HE M 21 δ modes. A slotted right-angle frustum-shaped (SRFS) structure of alumina material as a dielectric resonator (DR) is positioned on the ground plane of the FR4 substrate to design a DRA. Based on the designed DRA, a compact ( $ 2.57\, \lambda _g\times 2.57 \,\lambda _g $ 2.57 λ g × 2.57 λ g , where $ \lambda _g $ λ g is guided wavelength and calculated at a lower cut-off frequency, $ 5.0\, {\rm GHz} $ 5.0 GHz , for $ \epsilon _f $ ϵ f of $ 4.4 $ 4.4) $ 4\times 4 $ 4 × 4 MIMO antenna with high isolation of greater than $ 27.13\, {\rm dB} $ 27.13 dB (from $ 5.0 $ 5.0 to $ 6.1\, {\rm GHz} $ 6.1 GHz ) and $ 24.3\, {\rm dB} $ 24.3 dB (from $ 6.1 $ 6.1 to $ 6.25\, {\rm GHz} $ 6.25 GHz ) is proposed. The developed MIMO antenna's measured working frequency ranges from $ 5.0 $ 5.0 to $ 6.25\, {\rm GHz} $ 6.25 GHz , with an impedance bandwidth, $ BW_i $ B W i of $ 22.22\% $ 22.22 % , peak gain, $ G_P $ G P of $ 5.85\, {\rm dBi} $ 5.85 dBi and an average peak gain, $ G_{av} $ G av of $ 5.25\, {\rm dBi} $ 5.25 dBi . The calculated MIMO antenna's diversity performance parameters, channel capacity loss $ (C_{CL}^{ij}) $ (C CL ij) , diversity gain $ (D_G^{ij}) $ (D G ij) , envelop correlation coefficient $ (E_{CC}^{ij}) $ (E CC ij) , mean effective gain $ (M_{EG}^i) $ (M EG i) , total active reflection coefficient $ (T_{ARC}) $ (T ARC) , and channel capacity $ (C_C) $ (C C) are obtained as $ { \lt }0.17\, {\rm bits}/{\rm sec}/{\rm Hz} $ < 0.17 bits / sec / Hz , $ { \gt }9.99 \, {\rm dB} $ > 9.99 dB , $ { \lt }0.0301 $ < 0.0301 , $ { \lt }-6.06\, {\rm dB} $ < − 6.06 dB , $ { \lt }-12.5\, {\rm dB} $ < − 12.5 dB , and $ { \lt }21.6\, {\rm bits}/{\rm sec}/{\rm Hz} $ < 21.6 bits / sec / Hz , respectively. The agreement between the simulation and measurement results is found to be remarkably consistent. [ABSTRACT FROM AUTHOR]

Machine to Machine communication or Internet of things are emerging fields of communication. To support such technologies advanced electronics like wearable devices are popular field of research. The proposed Button shaped wearable Cylindrical Dielectric Resonator Antenna (CDRA) is specially designed to support IoT applications at 2.4 GHz band. The planer section of the DR antenna is developed over FR4 substrate and Dielectric resonator consists of Alumina material. An Aperture coupled feed is used to excite the antenna. There are two holes arranged on the structure such that it can be easily placed over any upper outfit like jacket or coat. To investigate the performance of the proposed wearable DRA over the body and to identify the best portion of the body where the antenna can be worn, the simulation has been done on three different phantoms of different age groups and gender on CST voxel phantom models. To analyse the performance four important parameters reflection coefficient, gain, radiation pattern, and bandwidth are selected. It is discovered that the button-shaped wearable CDRA well satisfies the performance requirements for IoT applications at 2.4 GHz band. Finally, the proposed antenna is developed and its performance has been measured. The measured output and the simulated results have been found to be in good agreement. [ABSTRACT FROM AUTHOR]

Over the last 30 years, various dielectric resonator antennas (DRAs) have been developed for application in portable wireless communications and millimeter wave systems. However, current methods to feed the antennas suffer from radiation leakage and high losses. In this paper, we propose using a topological photonic crystal (TPC) as an effective feeding method, which can effectively suppress the reflecting loss at the feeder/DRA interface. As a demonstration, we numerically design a DRA with a TPC feeder, operating in a high-order resonant mode at 1.5 THz. Simulation results show that the antenna has a return loss as low as 44 dB, an impedance bandwidth of 3.9%, a maximum gain of 7.4 dBi, and 3dB angular widths of 58 degrees. Over 99% radiation efficiency can be achieved at the operating THz band. The proposed all-dielectric antenna can be suitably used for integrated photonic chips, biomedical applications, and 6G. [ABSTRACT FROM AUTHOR]

Abstract The authors extend the resonant modal theory (RMT) developed previously for a metal object to an arbitrary source region consisting of metals, dielectrics, or a combination of both. The influences of dielectrics on the fields are replaced by equivalent volume sources through the use of the compensation theorem in electromagnetic theory. The resonant frequencies can be determined by finding the roots of the determinant of the matrix resulted from the discretisation of the real homogeneous volume–surface integral equation derived from the requirement that the difference of stored field energies in the source region vanishes. As applications of the extended RMT, three examples have been investigated. The first example is a dielectric resonator antenna and is designed by exciting the first resonant mode of the composite structure in which the dielectric cylinder is combined with a conformal metallic strip. The second example is a dual‐band dielectric‐coated metallic wire antenna. The third example studies the resonant modes of a rectangular patch antenna.

Abstract The design of three‐dimensional (3D)‐printed heterogeneous ceramics exhibiting isotropic and anisotropic dielectric permittivities at microwave frequencies is studied for dielectric resonator antenna (DRA) applications. The heterogeneous ceramics are engineered by using periodic structures made up of subwavelength unit cells filled with zirconia ceramic and air. Ceramic stereolithography (CSLA) allows the 3D printing of a one‐piece ceramic block mixing isotropic and anisotropic dielectric regions. In order to demonstrate the possibility of exploiting such 3D‐printed ceramics, a singly fed dual‐band circularly polarised DRA is presented. To achieve circular polarisation at both bands, the relative permittivity of the dielectric resonator is locally controlled by introducing anisotropic dielectric regions. The 3D‐printed DRA is finally measured, and its results agree well with the simulations.

This paper introduces an innovative and cost-effective approach for developing a millimeter-wave (mmWave) frequency-reconfigurable dielectric resonator antenna (DRA), which has not been reported before. The antenna integrates two rectangular DRA elements, where each DRA is centrally fed via a slot. A strategically positioned PIN diode is employed to exert control over performance by modulating the ON–OFF states of the diode, thereby simplifying the design process and reducing losses. In the OFF state, the first DRA, RDRA-I, exclusively supports the TE311 resonance mode at 24.3 GHz, offering a 2.66% impedance bandwidth and achieving a maximum broadside gain of 9.2 dBi. Conversely, in the ON state, RDRA-I and RDRA-II concurrently operate in the TE513 resonance mode at 29.3 GHz, providing a 2.7% impedance bandwidth and yielding a high gain of up to 11.8 dBi. Experimental results substantiate that the proposed antenna presents an attractive solution for applications necessitating frequency-reconfigurable and high-performance mmWave antennas in 5G and Beyond 5G (B5G) communication systems. [ABSTRACT FROM AUTHOR]

The authors extend the resonant modal theory (RMT) developed previously for a metal object to an arbitrary source region consisting of metals, dielectrics, or a combination of both. The influences of dielectrics on the fields are replaced by equivalent volume sources through the use of the compensation theorem in electromagnetic theory. The resonant frequencies can be determined by finding the roots of the determinant of the matrix resulted from the discretisation of the real homogeneous volume–surface integral equation derived from the requirement that the difference of stored field energies in the source region vanishes. As applications of the extended RMT, three examples have been investigated. The first example is a dielectric resonator antenna and is designed by exciting the first resonant mode of the composite structure in which the dielectric cylinder is combined with a conformal metallic strip. The second example is a dual‐band dielectric‐coated metallic wire antenna. The third example studies the resonant modes of a rectangular patch antenna. [ABSTRACT FROM AUTHOR]

A novel dual band tunable terahertz (THz) circularly polarized dielectric resonator antenna (CPDRA) is designed and numerically studied. Hybrid Silicon-Graphene materials are employed as radiator with cross-slot shaped aperture coupled feed, enabling tunable linearly and circularly polarized radiation. Silicon is a good material as dielectric resonator with its operation in the THz regime due to lack of absorption, cheaper to grow and machine. Cross shaped slots of appropriate dimensions are engraved in the centre of the ground plane to split the fundamental mode of the rectangular DR into two near degenerate orthogonal modes having quadrature phase difference. As a result, circular polarization is obtained in the upper passband. Introducing cross slot also helped to improve the impedance matching and dual band operation is achieved with linearly polarized response in lower band and circularly polarized response in the upper band. By adjusting the chemical potential of graphene, frequency tunability in the both the operating bands is obtained, without changing the physical geometry of the antenna. The proposed antenna operates with 10 dB impedance bandwidth of 4.24 \% (2.31–2.41 THz) and 12.1 \% (3.11–3.51 THz) and 3 dB axial ratio bandwidth of 3.54 \% (3.33–3.45 THz). The antenna parameters are calculated and gain of 6.11 dBi and 5.8 dBiC in lower and upper band, respectively and radiation efficiency of 96.5 \% in both operating bands is obtained. This hybrid radiator-based THz CPDRA shows great potential in the development of tunable THz devices and could pave a path for new researchers. [ABSTRACT FROM AUTHOR]

This communication discusses and examines a dual port filtering hybrid (Silicon-graphene) based antenna. The main appearances of the designed THz radiator are: (i) a modified circular patch created HEM 11 δ x and HEM 11 δ y inside silicon ceramic, which in turn created a circularly polarized wave from 2.59 to 2.89 THz (axial ratio ≤3 dB); (b) a defected ground structure (DGS) along with patch creates band pass filtering features (5.0 dBi within the operating band and −15 dBi outside the operating band) within the operating band; and (c) coating of graphene material over the ceramic adds the re-configurability feature in proposed radiator. The designed radiator works effectively in between 2.49 and 3.29 THz (|S11|≤ −10 dB) with more than 25 dB isolation (due to orthogonal orientation). Due to the aforementioned features, the designed radiator is employable for different wireless THz applications. [ABSTRACT FROM AUTHOR]

The application of ceramic for a circularly polarized (CP) filtering antenna is studied in this paper. The dielectric resonator (DR) of sintered aluminum oxide (Al 2 O 3) ceramic has a dielectric constant of 9.5 and low dielectric loss of 0.003, and excellent mechanical properties. The dielectric resonator antenna (DRA) consists of two parts, the upper part is a DR, and the lower part uses a feeding network containing two hairpin bandpass filters. The measured | S 11 | of the DRA is 48.0 % and the axial ratio (AR) bandwidth is 33.5 %. Meanwhile, the peak gain of the DRA is 6.13 dBi, and the suppression level across the stopband exceeds 15.2 dB. The DRA uses the hairpin bandpass filters to improve the filtering characteristics of the antenna and uses the corner-cutting processing of the DR to improve the AR, which can be implemented to reduce the cost of fifth-generation (5 G) communication. [ABSTRACT FROM AUTHOR]

We proposed a high gain high-efficiency compact metallic resonator antenna operating at even-mode meander line spoof surface plasmon polaritons (MLSSPPs). The high radiation efficiency is caused by the bulk of fields crowded in lossless air near the antenna rather than in lossy dielectric as in conventional dielectric resonator antennas (DRAs). The proposed antenna also exhibits compact size because of its high effective refractive index. A reliable equivalent circuit model is proposed for the design of the resonator antenna with basic mode of half wavelength resonant mode. As an example, a meander-line SSPP antenna is designed, fabricated and measured. Both the simulated and measured results show the advantages of high efficiency and compact volume. In addition, the antenna achieves higher gain and wider relative bandwidth per wavelength cube volume compared with its counterparts. This method provides a good alternative for designing DRAs. [ABSTRACT FROM AUTHOR]

This paper presents the design of a two-port dual-band dual-circularly-polarized dielectric resonator antenna (DRA). The proposed DRA is formed by stacking two dielectric resonators (DRs) of different shapes, including a hexagonal DR on top and a cross-shaped DR on the bottom. It is designed to resonate at two near-degenerate orthogonal modes of TE111 and TE113, and an aperture-coupled feeding through a cross-like slot is used to achieve dual-band impedance matching simultaneously for right- and left-handed circular polarizations. Tests were conducted on a prototype working in C-band to verify the design concept. The experiment results demonstrate that the proposed DRA has exceptional performance with measured −10 dB reflection bandwidths of 24.4% and 17.4%, 3 dB axial ratio bandwidths of 21.2% and 16.3%, and maximum gains of 5.64 and 8.13 dBic for the lower and upper bands, respectively. Moreover, the measured channel isolation is more than 15.8 dB. The results obtained from the experiments show good agreement with the simulation, and hence, it can be concluded that the proposed DRA is a promising solution that can be used for various wireless communication applications. [ABSTRACT FROM AUTHOR]

In this Paper, a low-profile circularly polarized (CP) chamfered rectangular dielectric resonator antenna (RDRA) is designed and investigated for radio frequency energy harvesting (RFEH) applications. The proposed modified RDRA comprises of dielectric resonator (DR) made up of Alumina material (εr = 9.9) mounted on the PEC ground plane. Dual unequal triangular-shaped vertical slits are engraved on the rectangular DR for generating the orthogonal modes with CP characteristics. The optimized antenna offers an impedance bandwidth (IBW) of 51.4% (2.25–3.81 GHz) and axial ratio bandwidth (ARBW) of 14.8% (3.25–3.77 GHz), respectively. The peak realized gain and maximum radiation efficiency are 7.18 dBi and 97.8% in desired frequency bands. Due to the wide impedance and AR bandwidths with realized gain and radiation efficiency, the optimized antenna is suitable for integration with a rectifier circuit for RF energy harvesting applications. A rectifier circuit with a single shunt diode topology is also designed for rectification purposes. The rectifier achieved 67.16% RF-DC power conversion efficiency (PCE) at 3.5 GHz and 5dBm input power. At 0dBm input power, the rectifier achieved 60.26% PCE. The effective input power range, during which the PCE maintains above 50%, is calculated to be 15.2 dBm from −3.5 to 11.7 dBm. [ABSTRACT FROM AUTHOR]

This paper presents a novel Multiple Input Multiple Output (MIMO) circularly polarized stacked Cylindrical Dielectric Resonant Antenna design integrated with graphene and polarization switching, propelling significant advancements in THz wireless communication. The proposed antenna achieved a wideband Impedance bandwidth of 3.12 THz, complemented by an overlapping Axial Ratio (AR) bandwidth (ARBW) of 2.01 THz, respectively. The antenna incorporates a new Defected Ground Structure to generate a wideband frequency response. The integration of graphene on top of the DRAs further enhances the antenna's performance, significantly boosting gain and radiation efficiency. A standout feature of this antenna is its seamless switching capability between Left-Hand Circular Polarization and Right-Hand Circular Polarization, making it highly adaptable for diverse communication scenarios. Additionally, the resonant frequency of the antenna can be precisely tuned by varying the graphene chemical potential (µc), offering enhanced flexibility. The paper also investigates a 2 × 2 MIMO configuration with excellent performance parameters, showcasing its suitability for THz wireless communication. Furthermore, the proposed antenna exhibits very high isolation between the ports by varying µc. The key features of the antenna include wideband frequency response and AR response, polarization switching, tuning of resonant frequency, high gain, and high efficiency. These advantages mark a significant milestone in THz wireless communication, setting new benchmarks for efficiency, adaptability, and overall performance in this rapidly evolving field. [ABSTRACT FROM AUTHOR]

A new tri-band rectangular DRA is simulated and tested for wireless communication applications like ISM, Wi-Max, and WLAN. The dielectric resonator antenna structure is excited by a 50Ω transmission line. The rectangular DRA with concentric square rings is designed to acquire the operation of triple-bands. The investigated antenna parametric study has been accomplished on HFSS tool. The implemented design exhibits triple-band characteristics at 2.16-2.57 GHz, 3.35-4.45 GHz, and 5.35-5.95 GHz, with a fractional bandwidth of 17.3%, 28.1%, and 10.6%, respectively. The implemented concentric square rings are imposed on FR4-substrate material to emphasize the antenna parameters and to minimize the size. The designed antenna has a compact size, good radiation properties, and optimal operational bandwidth. To validate the antenna, it is fabricated, and the results match well with the simulated ones. The antenna is well suitable for wireless communication applications. The fabricated rectangular DRA is measured by using MS2037C Anritsu-Combinational Analyzer. [ABSTRACT FROM AUTHOR]

This paper presents a novel wideband circularly polarized millimeter-wave (mmWave) hemispherical dielectric resonator antenna (HDRA). Two distinct configurations of alumina dielectric resonator antennas (DRAs) are investigated, each featuring a different coating: the first configuration incorporates a polyimide layer, while the second involves a perforated alumina. Both configurations demonstrate promising characteristics, including impedance and axial ratio (AR) bandwidths of 58% and 17.7%, respectively, alongside a maximum gain of 10 dBic at 28 GHz. Leveraging additive manufacturing technology, the HDRA with the perforated coating layer is fabricated, simplifying assembly and eliminating potential air gaps between layers, thereby enhancing the overall performance. This innovative approach yields a circularly polarized (CP) HDRA suitable for Beyond 5G (B5G) communication systems. Agreement between measurements and simulations validates the efficacy of the proposed design, affirming its potential in practical applications. [ABSTRACT FROM AUTHOR]

This paper presents a high gain diagonally-probe-fed multi-layered dielectric resonator antenna (DPF-ML-DRA) designed for 77 GHz automotive radar applications. A comparison with the conventional probe-fed ML-DRA demonstrates that the proposed DPF-ML-DRA achieves higher antenna gain by 1 dB. The sub-array utilizing the proposed DPF-ML-DRA is tailored to meet specific radar system requirements, including a broad impedance bandwidth (> 5 GHz), high antenna gain (> 12 dBi), and wide half-power beamwidth (> ± 60°). Simulated results validate that the sub-array performance meets the aforementioned antenna requirements. To attain high azimuthal and elevational angular detecting resolution, 3 sub-arrays with 12 DF-ML-DRA for the Tx channel and 4 sub-arrays with 10 DF-ML-DRA for the Rx channel were designed and simulated. The fabricated radar system underwent field testing, demonstrating a maximum range of up to 160 m and a field of view of 120° for 100 m. Remarkably, the proposed DPF-ML-DRA exhibits equivalent radar performance while featuring a smaller form-factor compared to commercially available state-of-the-art automotive radar systems. Consequently, the proposed DPF-ML-DRA proves to be well-suited for 77 GHz automotive radar applications. [ABSTRACT FROM AUTHOR]

The design of three‐dimensional (3D)‐printed heterogeneous ceramics exhibiting isotropic and anisotropic dielectric permittivities at microwave frequencies is studied for dielectric resonator antenna (DRA) applications. The heterogeneous ceramics are engineered by using periodic structures made up of subwavelength unit cells filled with zirconia ceramic and air. Ceramic stereolithography (CSLA) allows the 3D printing of a one‐piece ceramic block mixing isotropic and anisotropic dielectric regions. In order to demonstrate the possibility of exploiting such 3D‐printed ceramics, a singly fed dual‐band circularly polarised DRA is presented. To achieve circular polarisation at both bands, the relative permittivity of the dielectric resonator is locally controlled by introducing anisotropic dielectric regions. The 3D‐printed DRA is finally measured, and its results agree well with the simulations. [ABSTRACT FROM AUTHOR]

Abstract A dual‐band liquid cylindrical dielectric resonator antenna with pattern diversity at two different frequency bands is proposed using the lower order and higher order modes of the HEM and TM modes namely HEM11δ, HEM12δ+1, HEM31δ+1, HEM13δ, TM01δ, and TM02δ. The proposed antenna is designed to cover the GPS L2 band and the lower Wi‐Fi band at 1.227 and 2.4 GHz frequencies, respectively. The HEM modes which constitute the primary radiating modes achieved around 20.84% and 19.35% impedance bandwidth at lower and higher bands, respectively. In the later stage, beam‐steering is performed, whereby the realised broadside HEM modes at both lower and higher bands were passively steered with simple physical re‐orientation of the antenna structure. For this, the liquid's natural fluidic property of adhering to gravity is taken as an advantage which makes the proposed antenna adaptively steer its radiation pattern always towards the sky, irrespective of the tilt angle of the antenna. This concept of passively steering two modes at two different frequency bands without the use of any mechanical, electrical, or other associated components is presented for the first time.

Summary: In this communication, a dielectric resonator based dual‐port radiator is designed. Loading of meta‐surface over the dual‐port antenna creates two important features that make it unique to the proposed design: (i) conversion of the linear polarized plane waves into circularly polarized plane wave (ii) improve the isolation between the antenna port by more than 30 dB. Experimental measurement confirms that proposed design is working in the frequency range 5.14–5.55 GHz, and a 3‐dB axial ratio is produced from 5.36 to 5.45 GHz. Stable radiation pattern and good value of diversity performance are also achieved in the proposed radiator. All of these characteristics make the developed radiator appropriate for WLAN (5.4 GHz) applications. [ABSTRACT FROM AUTHOR]

We review dielectric resonator antenna (DRA) designs. This review examines recent advancements across several categories, specifically focusing on their applicability in array configurations for millimeter-wave (mmW) bands, particularly in the context of 5G and beyond 5G applications. Notably, the off-chip DRA designs, including in-substrate and compact DRAs, have gained prominence in recent years. This surge in popularity can be attributed to the rapid development of cost-effective multilayer laminate manufacturing techniques, such as printed circuit boards (PCBs) and low-temperature co-fired ceramic (LTCC). Furthermore, there is a growing demand for DRAs with beam-steering, dual-band functions, and on-chip alignment availability, as they offer versatile alternatives to traditional lossy printed antennas. DRAs exhibit distinct advantages of lower conductive losses and greater flexibility in shapes and materials. We discuss and compare the performances of different DRA designs, considering their material usage, manufacturing feasibility, overall performance, and applications. By exploring the pros and cons of these diverse DRA designs, this review provides valuable insights for researchers in the field. [ABSTRACT FROM AUTHOR]

This article presents a four-element directional multiple input multiple output (MIMO) rectangular dielectric resonator antenna (RDRA) equipped with strategically placed copper reflector plates to enhance port isolation. This design aims to achieve an extended coverage range without compromising the coverage area. The proposed MIMO antenna is 3D printed using biodegradable polylactic acid to ensure mechanical robustness and then integrated with the substrate to prevent mis-mounting issues. The proposed design exhibits good MIMO characteristics, registering a 3-GHz bandwidth (4-7 GHz) for |S11|≤-10 dB and a minimum radiation gain of 7 dBi for all four RDRAs. The antenna demonstrates a rotation of radiation patterns for different ports, thus enabling beam formation in specific directions. With a beam width of 71.2˚, the antenna covers all directions without any fade zones. The proposed 3D printed antenna offers simplicity, strong MIMO properties, and practicality for wireless communication systems, making it suitable for industrial, scientific, and medical band applications. [ABSTRACT FROM AUTHOR]

This article delves into the capabilities of 3D-printed millimeter-wave (mmWave) layered cylindrical dielectric resonator antennas (CDRAs). The proposed design yielded promising results, boasting a remarkable 53% impedance bandwidth spanning the frequency spectrum from 18 to 34 GHz. Furthermore, the axial ratio (AR) bandwidth achieved an impressive 17%, coupled with a maximum gain of 13.3 dBic. These notable results underscore the efficacy of the proposed design, positioning it as a viable solution for applications in Beyond 5G (B5G). A novel assembly technique was also investigated, employing additive manufacturing to seamlessly merge two layers with distinct dielectric constants into a singular layer. This innovative approach systematically eliminates the potential for air gaps between layers, enhancing the antenna's overall performance. This approach exhibited potential, particularly in the performance of a millimeter-wave circularly polarized (CP) cylindrical DRA featuring a perforated coating layer. The synergy between measurements and simulations demonstrates a remarkable alignment, providing robust validation of the effectiveness of the proposed design. [ABSTRACT FROM AUTHOR]

The Li2Mg3Ti1−xAl4x/3O6 (0 ≤ x ≤ 0.1) ceramics are synthesized using the solid phase method, showing excellent microwave dielectric properties with εr = 14.05, Q × f = 144 500 GHz, and τf = −43 ppm/°C at x = 0.04. Rietveld refinements, based on the XRD data, reveal that the Li2Mg3Ti1−xAl4x/3O6 ceramics crystallize in the rock salt structure with Fm-3m space group. The relationship between the crystal structure and intrinsic microwave dielectric properties is studied in detail. The variation in the dielectric constant is related to ionic polarization and relative density. The quality factor (Q × f) demonstrates a strong correlation with lattice energy, relative density, and concentration of Ti3+. The variation of τf is influenced by the bond thermal expansion coefficient and bond valence. The dielectric resonant antenna, manufactured from Li2Mg3Ti0.96Al0.0533O6-0.09TiO2 ceramic with near-zero τf, shows a bandwidth of 230 MHz at 7.40 GHz and a high radiant efficiency, which indicates that high-quality factor Li2Mg3Ti0.96Al0.0533O6 ceramic has significant potential in relevant fields such as 5G and smart driving. [ABSTRACT FROM AUTHOR]

The research describes a novel method for boosting gain in quantum CDRAs that involves replacing the silicon dioxide substrate with a Teflon substrate. The enhanced gain results are analyses and compared to earlier research findings. CST software was used to create and simulate a quantum CDRA. The antenna structure includes cylindrical dielectric resonators with a greater antenna gain at a frequency of 504 THz. The quantum CDRA has an impedance bandwidth of 9.41 percent. The reported quantum CDRA has a gain of 6.3 dB and a return loss of − 27.5 dB. Terahertz applications are feasible with the suggested quantum CDRA. [ABSTRACT FROM AUTHOR]