Dielectric Resonator Antenna Research Articles

Dielectric Behavior Characterization of RE/BaTiO3 Using Time Domain Spectroscopy: Application on High-Performance Dielectric Resonator Antennas

We are working to design dielectric resonator antennas based on binary composites made of epoxy resin (RE) and barium titanate (BaTiO3 or BT). The composite samples are prepared at room temperature and under atmospheric pressure. The dielectric properties of these composites were assessed using time domain spectroscopy (TDS). The antennas structure are designed, simulated, and optimized using electromagnetic software Ansys, HFSS. Two types of antennas are studied. The first type consists of a cylindrical dielectric resonator that gives three antenna models in terms of bandwidths, the antennas having a single frequency band, the antennas having dual-band, and the antenna covering three frequency bands, with peak gains varying between 3.68 and 8.15 dB achieved. The second type consists of dielectric resonators composed of two adjacent identical shapes each consisting of a rectangular joined with a cylindrical with the same height. The proposed antenna achieves ultra-wideband with a relative bandwidth of 97% covering the range of 6 to 17.32 GHz, and dual-band circularly polarized ( AR<3dB ), the range of the lower band is 9.62 to 10.14 GHz and the range of the upper band is 16.74 to 16.94 GHz. The focus of this research is on creating novel antennas for applications in wireless communications systems.

Wideband Millimeter-Wave Perforated Cylindrical Dielectric Resonator Antenna Configuration

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.

A wideband circularly polarized dielectric resonator antenna with flat gain response within the passband

In this letter, a wideband circularly polarized (CP) dielectric resonator antenna (DRA) with flat gain is proposed. The antenna consists of two layers of DRs (the lower part DR1, the upper part DR2), conformal microstrip on DR, and a dielectric substrate. Partitioning the DR into upper and lower sections with different dielectric constants is to equalize the gain within passband. Moreover, the conformal microstrips on both sides of the DR serve as feeders to excite the fundamental TEy111 and TEx111 modes, and high-order TEy113 and TEx113 modes of the DR. In addition, the 90° phase difference between the two resonant modes of each orthogonal pair is achieved by varying the corresponding conformal microstrip heights to improve circular polarization performance. For demonstration, a wideband CP DRA prototype was manufactured and measured. The measurements illustrate that the antenna achieves a wide impedance bandwidth of 38.5 % (3.48–5.14 GHz), an axial ratio (AR) bandwidth of 26.7 % (3.38–4.42 GHz) for left-hand circular polarization (LHCP), and a flat gain reaching 7.2 dBi in the passband.

The extended resonant modal theory and its applications

AbstractThe 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.

Mitigating mutual coupling effects on circular polarization for improved bandwidth in MIMO systems: A novel approach

An improved mutual coupling compensation in circularly polarized (CP) multi-input multi-output (MIMO) dielectric resonator antenna (DRA) is presented in this paper. Using trimming approach, the mutual coupling (MC) between closely spaced DRA units at 0.3λ has been significantly reduced while axial ratio performance has been maintained. Mutual coupling reduction is obtained by trimming the DRA to ensure low mutual coupling below −20dB. The exclusive features of the proposed MIMO DRA include wide impedance matching bandwidth (BW), triple band circular polarization, and suppressed MC between the radiating elements. The impedance bandwidth matches perfectly with a triple band's 3 dB axial ratio (AR). It is designed with characteristic mode analysis with good agreement of the measurement that has been obtained. Using the probe feed method, the DRA and patch strip are coupled together to allow bandwidth widening of the pro-posed DRA. An impedance bandwidth of 34% at a lower frequency to around 2% at a higher frequency was achieved in all resonance frequencies. Thus, we refer to our newly designed DRA as a proposed method for effectively reducing the mutual coupling between DRAs. Additionally, the 3 dB AR bandwidth matched at 3.3 GHz, 4.6 GHz, and 6.3 GHz with a percentage of 11.66%, 3.04%, and 2.22% obtained at the three different frequencies. Note that the proposed DRA exhibits low mutual coupling (below −20 dB) at the targeted frequencies, which is suitable for better signal reception for MIMO applications. By computing, the metrics envelop correlation coefficient, diversity gain, channel capacity loss, and total active reflection coefficient, the MIMO performance of the proposed antenna is verified. The experiments show a close result between simulated and computed validation of the proposed DRA.

A Compact Singly Fed Dielectric Resonator Antenna With Flat-Top Radiation Patterns

A Compact Singly Fed Dielectric Resonator Antenna With Flat-Top Radiation Patterns

High-Gain, Low-Coupling, Omnidirectional, and Dual-Polarized Dielectric Resonator Antenna Using High-Order Modes

High-Gain, Low-Coupling, Omnidirectional, and Dual-Polarized Dielectric Resonator Antenna Using High-Order Modes

Four-Element Biodegradable Substrate-Integrated MIMO DRA with Radiation Diversity

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.

Microwave dielectric properties of (Na0.5Bi0.5)MoO4–BaMoO4 composite ceramics with ultralow sintering temperature

AbstractThe 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 (varying from 25.4 to 16.6), quality factor values, and temperature coefficient of frequency (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 (, = 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.

The ultralow loss Li2Mg3Ti1−xAl4x/3O6 microwave dielectric ceramics and its design of dielectric resonator antenna

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.

Advanced Dielectric Resonator Antenna Technology for 5G and 6G Applications.

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.

High gain and high-efficiency compact resonator antennas based on spoof surface plasmon polaritons

Abstract 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.

Effective modeling of metasurface‐loaded circularly polarized dielectric resonator‐based MIMO antenna for sub‐6.0‐GHz band using machine learning algorithms

SummaryIn this article, a dual‐port dielectric resonator antenna (DRA) is modeled using machine learning (ML) algorithms, that is, deep neural network (DNN), random forest, and XGBoost. The unique properties of the proposed article are as follows: (i) Two different diversity techniques, that is, pattern (with the help of metallic wall) and polarization (mirror image of the aperture), improve the isolation value between the ports; (ii) ML algorithms are used to optimize and predict the reflection coefficient as well as mutual coupling of the proposed antenna. The accuracy of ML algorithms is verified by using the HFSS EM simulator and experimental validation. Error is less than 1%–2% between the value predicted from ML algorithms and HFSS/experimental results. The proposed design is working well in between 2.4 and 4.02 GHz with a 3‐dB axial ratio from 2.84 to 2.95 GHz. All these features make the radiator employable to the sub‐6.0‐GHz frequency band.

Dielectric Resonator Antennas for RF Energy-Harvesting/Wireless Power Transmission Applications: A state-of-the-art review

This article presents an overview of dielectric resonator (DR)-based sensing elements and their applications in RF energy-harvesting (RFEH) and wireless power transmission (WPT) systems. With increased wireless applications, the demand for electrical energy goes up, thereby enabling the development of various energy sources. RF energy is widely available and the most efficient energy source. Although DR antennas (DRAs) have been studied extensively in the last few decades, they have not been employed in RFEH and WPT applications. The intention of the proposed article is 1) to provide an overview of the DRA for RFEH and WPT applications; 2) to accommodate various performance enhancement approaches for the DRA; and 3) to highlight the research gap for developing a complete rectenna system that helps future researchers. We believe that this survey may help the DRA.

Dual‐mode dielectric resonator antenna design with stub‐loaded feeding slot

AbstractA dual‐mode dielectric resonator antenna based on a microstrip line‐slot coupling feed, operating in both the GMS‐900 and GMS‐1800 frequency bands, is presented. The antenna structure consists of a rectangular dielectric substrate and a cylindrical dielectric resonator, which is fed by a microstrip line‐slot coupling. The cylindrical resonant cavity and the dual‐stub coupling slot are designed so that the HEM111 and HEM311 modes are excited simultaneously, resulting in resonance at the two desired frequency points. The gain of the antenna is 3.74 and 7.63 dBi at 0.9 and 1.8 GHz respectively, and the efficiency of the antenna is greater than 70% in both operating bands.

Radiation Patterns of RF Wireless Devices Implanted in Small Animals: Unexpected Deformations Due to Body Resonance.

One challenge in designing RF wireless bioelectronic devices is the impact of the interaction between electromagnetic waves and host body tissues on far-field wireless performance. In this article, we investigate a peculiar phenomenon of implantable RF wireless devices within a small-scale host body related to the deformation of the directivity pattern. Radiation measurements of subcutaneously implanted antennas within rodent cadavers show that the direction of maximum radiation is not always identical with the direction to the closest body-air interface, as one would expect in larger-scale host bodies. For an implanted antenna in the back of a mouse, we observed the maximum directivity in the ventral direction with 4.6 dB greater gain compared to the nearest body-air interface direction. Analytic analysis within small-scale spherical body phantoms identifies two main factors for these results: the limited absorption losses due to the small body size relative to the operating wavelength and the high permittivity of the biological tissues of the host body. Due to these effects, the entire body acts as a dielectric resonator antenna, leading to deformations of the directivity pattern. These results are confirmed with the practical example of a wirelessly powered 2.4-GHz optogenetic implant, demonstrating the significance of the judicious placement of external antennas to take advantage of the deformation of the implanted antenna pattern. These findings emphasize the importance of carefully designing implantable RF wireless devices based on their placements and relative electrical dimensions in small-scale animal models.

A Review on Dielectric Resonator Antennas: Past and Present

A Review on Dielectric Resonator Antennas: Past and Present

Design of Self-Decoupled Circularly Polarized MIMO Dielectric Resonator Antenna Arrays Based on Polarization Orthogonality

Design of Self-Decoupled Circularly Polarized MIMO Dielectric Resonator Antenna Arrays Based on Polarization Orthogonality

Jeans Substrate Based Circularly Polarized Wearable Dielectric Resonator Antenna

Jeans Substrate Based Circularly Polarized Wearable Dielectric Resonator Antenna

Optimizing the geometry of a cylindrical dielectric resonator antenna (CDRA) in combination with the design of a microstrip patch antenna to improve antenna efficiency.

Optimizing the geometry of a cylindrical dielectric resonator antenna (CDRA) in combination with the design of a microstrip patch antenna to improve antenna efficiency.