Resonator Antenna Research Articles

A compact circularly polarized dielectric resonator antenna with MIMO characterizations for UWB applications.

Ultra-wideband (UWB) technology is extensively used in indoor navigation, medical applications, and Internet of Things devices due to its low power consumption and resilience against multipath fading and losses. This paper examines a multiple-input multiple-output (MIMO), circularly polarized (CP) dielectric resonator antenna for UWB systems. Compact form factor, high gain, wideband response, improved port isolation, and high data rates are the major design goals. This arrangement consists of two identical DRAs with self-decoupled orthogonal orientations eliminating the need for extra decoupling structures while achieving an impressive maximum isolation of 43 dB. The corner-edge feeding mechanism of the extended feedline generates two orthogonal E-fields, facilitating circular polarization. Additionally, a printed hook-shaped stub integrated with the ground plane enhances CP performance across the two operating bands without altering the DR structure. Fabrication and testing exhibit an impressive 133 impedance bandwidth (2.5-14 GHz) with high port isolation. For a 3 dB axial ratio reference, the single-element design exhibits axial ratio bandwidths (ARBW) of 1.2 GHz (3.6-4.8 GHz) and 0.8 GHz (9.3-10.1 GHz). Remarkably, the MIMO configuration achieves a single ARBW of 0.5 GHz (3.9-4.4 GHz). Detailed investigations of MIMO performance parameters, including diversity gain, envelope correlation coefficient, channel capacity loss, and total active reflection coefficient, underscore the design's efficacy, making it a good choice for UWB wireless applications.

Achieving high efficiency and bandwidth enhancement of DRA arrays: Synergic effects of LiMg4AlO6 microwave dielectric ceramic and 2D metamaterials

In this paper, LiMg4AlO6 ceramics with a sintering temperature of 1380 °C to 1460 °C are prepared, and the microwave dielectric properties of the ceramics and their potential application in dielectric resonator antenna (DRA) arrays are investigated. Analysis techniques such as XRD and Rietveld refinement reveal that the LiMg4AlO6 ceramics are rock salt structures and the space group is Fm-3 m (225). The ceramic obtained excellent microwave dielectric properties (εr = 10.17, Q×f = 172, 558 GHz, and τf = - 32.5 ppm/ °C) at 1440 °C. The εr of LiMg4AlO6 ceramics exhibits minimal variation across a wide temperature range (-100 °C to 400 °C) without phase transition. Furthermore, the 2D metamaterials (metasurfaces) are introduced in the DRA, which can significantly improve the radiation efficiency and bandwidth of the antenna. Measured results demonstrate that the antenna has a wide bandwidth ranging from 8.07 GHz to 8.57 GHz, with a maximum realized gain of 8.9 dBi and a peak radiation efficiency of 97%. The proposed ceramic antenna array combines the superior properties of 2D metamaterials and ceramic materials, which opens up a new avenue for ceramic antenna design and satellite communication applications.

Compact dual-band enhanced bandwidth 5G mm – wave MIMO dielectric resonator antenna utilizing metallic strips

A compact dual-band Multiple-Input Multiple-Output Dielectric Resonator Antenna with improved bandwidth for 5G mm-wave applications is presented. Two rectangular DRAs mounted on a substrate backed ground plane are excited by microstrip feed through aperture coupling. Notches cut out from center of the DRAs helps to achieve a dual-band response with improved bandwidth by exciting several modes. The isolation between the DRAs is achieved by appropriately positioning metallic strips on walls on of the DRAs. A dual-band response with enhanced bandwidth and mutual coupling reduction. The impedance bandwidth for the proposed design is between 26.5–30 GHz (12.4 %) and 34.2–40 GHz (15.6 %). The maximum isolation achieved in the lower band is 32 dB and above 45 dB in the upper band. The overall size of the design is 1.88λo x 0.94λo x 0.20λo. The design procedure is described, and the role of decoupling strips are explained. A prototype is fabricated and measured to validate the proposed design.

Design and Simulation of Circular Dielectric Resonator Antenna and Investigation of Structure, Microstructure, and Dielectric Properties of Mn‐Modified Sr2SnO4

Samples with compositions of Sr2Sn1−xMnxO4(SSM) with 0 ≤ x ≤ 0.10 are prepared by conventional ceramic route via heat treatment at 1350 °C. Phase and crystal structure analysis is studied using X‐ray diffraction and Rietveld refinement to confirm the crystallization of samples in the tetragonal structure under space group I4/mmm. The size‐strain plot method is employed to identify the role of Mn on crystallite size/microstrain/dislocation density. The scanning electron microscope and energy‐dispersive X‐ray spectroscopy analysis confirm a significant change in the grain size and compositional homogeneity of all samples with Mn‐doping. Dielectric properties of samples are explained in terms of interfacial and orientation polarization of dipoles . Modulus studies show the exclusion of electrode contribution from the electrical properties. The single‐segment circular dielectric resonator antenna is designed with the help of experimental dielectric parameters and showed two major resonant frequencies at 3.6 and 6.7 GHz. The reduction in the S11 parameter and −10 dB reflection coefficient bandwidth with Mn‐doping observed due to overlapping of the E‐field line suggests the application in patch array antenna for radar and satellite communication applications. This study also enables to explore Sr2SnO4‐based Ruddlesden Popper oxide for antenna and mm‐wave communication applications.

Synthesis and characterization of (Ba2Zn2Fe12O22)1−x(NiFe2O4)x ferrite composites for antenna applications

A series of (Ba2Zn2Fe12O22)1−x(NiFe2O4)x ferrites (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were successfully synthesized by one-pot coprecipitation route. XRD analysis reveals the formation of Ba2Zn2Fe12O22 and NiFe2O4 composite after sintering calcined precursor powder at 1200 °C/4 h. Densification behaviour was evaluated by Archimedes’ principle. Field emission scanning electron microscopy was used to study morphological characteristics. Room temperature magnetization behaviour was evaluated using a vibrating sample magnetometer. In composite, it was observed that the saturation magnetization (Ms) and coercivity (Hc) increased with increasing NiF content. With the increase of NiF in the composite, the permittivity (ε) decreased from 28.6 (for x = 0.2) to 13.6 (for x = 0.8) with the corresponding decrease in dielectric loss (tanδε) at 100 MHz. The permeability (μ) also decreased from 21.3 (x = 0.2) to 17.9 (x = 0.8) with the associated decrease of the magnetic losses (tanδμ) at 100 MHz. Miniaturization factor (n) of 19.2 and characteristic impedance of 1.1 were obtained for x = 0.4 composition at 100 MHz along with low dielectric loss factor (tan δε/ε) and magnetic loss factor (tan δµ/µ). The ferrite resonator antenna was fabricated using FR4 as substrate and ferrite pellet as magneto-dielectric resonator material. The antenna characteristics parameters reflection loss S (1,1) and voltage standing wave ratio (VSWR) were measured by vector network analyser (VNA).

High thermal stability of the microwave dielectric properties of ZnNb2O6 with CaTiO3 addition

This paper presents a study of the dielectric properties of ZnNb2O6 (ZNO) with added CaTiO3 (CTO) in the microwave (MW) region. An X-ray diffraction analysis is performed, and a reaction between ZNO and CTO is demonstrated that results in the formation of other crystalline phases. The dielectric properties in the MW region show no significant change in permittivity (ε'r), whereas the addition of CTO results in an increase in the dielectric loss (tan δ). The thermal stability is also measured, and the temperature coefficient of resonant frequency (τf) is varied from −88.95 to −8.16 ppm °C−1. Numerical simulations are carried out to evaluate these materials for use as a dielectric resonator antenna, and the results show a reflection coefficient (|S11|) of below −10 dB, a radiation efficiency above 96 %, a bandwidth ranging from 100 to 170 MHz, and a gain of above 4.50 dBi. The values obtained here show that these materials could be employed in electronic devices acting in the C- and S-bands.

Unveiling the Terahertz Nano-Fingerprint Spectrum of Single Artificial Metallic Resonator.

As artificially engineered subwavelength periodic structures, terahertz (THz) metasurface devices exhibit an equivalent dielectric constant and dispersion relation akin to those of natural materials with specific THz absorption peaks, describable using the Lorentz model. Traditional verification methods typically involve testing structural arrays using reflected and transmitted optical paths. However, directly detecting the dielectric constant of individual units has remained a significant challenge. In this study, we employed a THz time-domain spectrometer-based scattering-type scanning near-field optical microscope (THz-TDS s-SNOM) to investigate the near-field nanoscale spectrum and resonant mode distribution of a single-metal double-gap split-ring resonator (DSRR) and rectangular antenna. The findings reveal that they exhibit a dispersion relation similar to that of natural materials in specific polarization directions, indicating that units of THz metasurface can be analogous to those of molecular structures in materials. This microscopic analysis of the dispersion relation of artificial structures offers new insights into the working mechanisms of THz metasurfaces.

Dielectric resonator antenna with square slot dgs and amc support for gain enhancement

A miniatured Dielectric Resonator Antenna (DRA) designed on Defected ground structure (DGS) with backing of Artificial Magnetic Conductor (AMC) is presented in this work. The designed antenna showing wide bandwidth to cover WLAN, Wi-Fi and 5G communication applications under sub 6 GHz range and X-band for satellite communication device applications. Antenna occupying the dimension of 35 × 30 × 1.6 mm on Rogers RT-duroid 5880 substrate material, DRA on alumina material of permittivity 9.8 with dimension of 25 × 20 × 10 mm and the AMC surface of dimension 60 × 58 × 1.6 mm on FR4 substrate material. The constructed antenna resonating in the wide band from 3.4–11.5 GHz by holding overall bandwidth of 8.11GHz and an impedance bandwidth of 139%. The DRA placed over the antenna providing the axial ratio at two bands of 4.2–6 GHz and 9.2 to 11.4 GHz with axial bandwidth of 36% and 28% respectively. The placement of AMC structure beneath the antenna exhibiting an improvement in gain of 9% and an average gain attained in the operating band is around 7.2 dBi. The unique combination of monopole antenna with DRA and AMC providing excellent bandwidth, axial ratio and gain.

Detection of malignant breast tissue using SAR observation with microwave imaging and convolutional neural network

The research paper introduces a deep learning approach for distinguishing between benign and malignant breast tissues using Ultra Wide Band (UWB) microwave imaging. A multi-resonant monopole microstrip patch antenna was crafted and placed on a female breast phantom model containing a tumor. The phantom’s dielectric properties were adjusted to mimic those of benign and malignant tissues. The Specific Absorption Rate (SAR) was analyzed by rotating the antenna at various angles throughout the phantom’s trajectory. Images capturing the SAR distribution over the breast phantom at different antenna resonances were obtained. The popular Convolutional Neural Network (CNN) based AlexNet model was employed for autonomous feature learning from SAR images. To address the challenge of overfitting with a limited dataset, the study utilized image augmentation and transfer learning methods. The proposed model achieved an impressive 98.59% accuracy in classifying benign and malignant breast phantom images, surpassing the performance of three other CNN models—VggNet16, GoogleNet, and ResNet. Notably, this microwave imaging system based on SAR images detected tumors as small as 1 mm with an accuracy of 97.08% outperforming existing malignancy screening techniques.

Broadband magnetoelectric antenna driven by multiple high-overtone bulk acoustic wave modes

High-overtone bulk acoustic waves driven magnetoelectric (ME) antennas operate in the acoustic resonant frequency range, exhibiting continuous narrowband electromagnetic radiation. ME antennas based on cooperative excitation of multiple high-overtone bulk acoustic waves are expected to achieve broadband performance and are worthy of in-depth exploration. High-overtone bulk acoustic resonator (HBAR) antennas with polished and rough acoustic reflection interfaces were fabricated and tested to investigate the influence mechanisms of acoustic modes in the HBAR on the radiation bandwidth, as well as the relationship between antenna impedance and radiation response. Far-field radiation characteristics indicate that the antenna with rough acoustic reflection interfaces featuring more high-overtone bulk acoustic wave modes suppress radiation dips of up to 5 dB at anti-resonant frequencies without sacrificing radiation gain. The radiation gain of the antenna was calculated using the gain-comparison method to be −35 dBi, with a −3 dB bandwidth of 120 MHz and a fractional bandwidth of up to 11.4%. Finally, a comparison of the radiation characteristics of the HBAR piezoelectric antenna without the magnetic film demonstrates that the broadband radiation of the HBAR ME antenna originates from dynamic magnetic flux driven by high-overtone bulk acoustic waves.

A birdcage resonant antenna for helicon wave generation in TORPEX.

A birdcage resonant helicon antenna is designed, mounted, and tested in the toroidal device TORPEX. The birdcage resonant antenna is an alternative to the usual Boswell or half-helical antenna designs commonly used for ∼10 cm diameter helicon sources in low temperature plasma devices. The main advantage of the birdcage antenna lies in its resonant nature, which makes it easily operational even at large scales, an appealing feature for the TORPEX device whose poloidal cross section is 40cm in diameter. With this antenna, helicon waves are shown to be launched and sustained throughout the whole torus of TORPEX. The helicon waves can be launched at low power on a pre-existing magnetron-generated plasma with little effect on the density profiles. The birdcage antenna can also be used alone to produce plasma, which removes the constraint of a narrow range of applied magnetic fields required by the magnetron, opening the way to a new range of studies on TORPEX with the external magnetic field as a control parameter.

Dual-frequency dielectric resonant antenna based on low sintering temperature Li5Mg4NbTiO11-LiF microwave dielectric ceramics

Li5Mg4NbTiO11-x wt% LiF microwave dielectric ceramics were successfully developed using the solid state way. The phase structure, microstructure, Raman vibration, and microwave dielectric properties of LiF doped Li5Mg4NbTiO11 ceramics were studied. The researches show that LiF doping can effectively decrease the sintering temperature of Li5Mg4NbTiO11 ceramic. At x = 6, the ceramic sintered at 860 °C show the best performance (εr = 15.56, Q × f = 89,713 GHz, and τf = −40.48 ppm/°C) and is chemically compatible with Ag electrodes. In addition, a dual-frequency dielectric resonant antenna based on 6 wt% LiF-doped ceramics was designed, which has high gain (2.94 and 6.90 dBi) and efficiency (75.5 and 95.6 %) around the resonant frequency (2.4 and 6 GHz). The comprehensive results show that this material is not only a promising LTCC material, but also a viable candidate material for 5/6G applications.

Microwave dielectric properties of Li2Mg2Ga2Ti3O12 ceramics with spinel-type

Novel spinel-type Li2Mg2Ga2Ti3O12 ceramics were prepared by the solid-state method. Rietveld refinement revealed that the Li2Mg2Ga2Ti3O12 ceramics possess a cubic spinel structure with the Fd3‾m(227) space group. Raman spectrum analysis indicated that the Q × f and FWHM of ceramics exhibit an inverse relationship. According to the P-V-L theory, the Ti-O bond has the highest percentage of contribution to both of bond ionicity and lattice energy, indicating a significant impact on εr and Q × f, respectively. The Li2Mg2Ga2Ti3O12 ceramics showed the best microwave dielectric properties (εr = 15.72, Q × f = 69,633 GHz, and τf = −20 ppm/°C), sintering at an optimum temperature of 1200 °C. Additionally, a dielectric resonance antenna, on the basis of Li2Mg2Ga2Ti3O12 ceramics was designed and simulated.

A multiple resonant microstrip patch heart shape antenna for satellite and Wi-Fi communication

A multiple resonant microstrip patch heart shape antenna for satellite and Wi-Fi communication

Novel Slot-MIMO Antenna Approach for Improved Connectivity in Sub-6 GHz Applications

This paper presents a proposed Slot-MIMO antenna with two identical ports, each port is fed through 50-Ohm microstrip line to operate within the sub-6 GHz (3.5-4.5 GHz) for fifth-generation (5G) cellular phone applications. The proposed MIMO antenna has been designed on FR-4 dielectric substrate (ɛ = 4.4, δ = 0.025, and h = 1.6 mm). The ground has two basic slots, one square slot radiator, and one irregular square slot radiator filled with a Diamond conductor shape. In addition, the ground has a DGS structure (8-slots) beside the two basic slots. The ground DGS is used to adjust the resonance frequency as well as to reduce the mutual coupling between the ports. The simulated result indicated that the proposed MIMO antenna has a gain of about 2.5 dBi and an impedance bandwidth of 614 MHz at the -10-dB (3.751-4.365 GHz). However, an impedance bandwidth of 1180 MHz at -6-dB (3.32-4.5 GHz) is achieved. The mutual coupling is less than -24 dB overall the bandwidth, and the efficiency is more than 80% at the antenna resonance frequency (4.15 GHz). This antenna has been implemented and measured, and the results have been agreed with the simulated ones. In addition, the proposed Slot-MIMO antenna can be used as a MIMO antenna-cell with the smartphone. Many MIMO cells can be etched on the smartphone motherboard to improve connectivity with high isolation.

Study on the preparation and magnetodielectric properties of ferrite composite Co2Z/LFO-LZT for broadband antenna application

Magnetic materials are anticipated to address the bandwidth and size limitations of dielectric resonant antennas (DRAs) to fulfill the application demands of 5G base station antennas. The present study focuses on the development of a novel Co2Z/LFO-LZT magnetic composite with exceptional microwave dielectric-magnetic properties through a hybrid ceramic process. The proposed ceramic achieves uniform dispersion of spinel magnetic nanocrystals at the grain boundary of Co2Z, resulting in the formation of a particular micro-concrete structure that significantly enhances ceramic densification and reduces magnetic-dielectric loss. The electromagnetic parameters of the ceramic optimized and used for antenna design are εr = 11; μr = 2; tanδε = 0.001; tanδμ = 0.08 at 5 GHz. A high-performance Magnetodielectric Resonant Antenna (MDRA) was designed, which exhibits a low profile of 11.4% λ0 at 5 GHz, and broadband performance covering 19.0% and 11.8% bandwidth at 5 and 8 GHz.

Enhancement of gain and bandwidth of cylindrical dielectric resonator antenna excited by cavity-backed slot

Dielectric resonator antennas have been demonstrated to be an efficient radiator, especially with the possibility of fabricating it at low cost based on 3-D printing technologies. However, they have two main limitations which are: their relatively small gain (about 5dBi) and narrow bandwidth. To enhance the gain of DRA, higher-order mode excitation can be utilized; however, typically this has a limit of a few dB increments besides its negative effects on the bandwidth. This study employs a cavity-backed slot to provide an appropriate feeding method for a cylindrical dielectric resonator antenna (CDRA). This design effectively facilitates the excitation of higher-order modes, resulting in a significant gain of up to 15 dBi, which is essential for many wireless systems that are unable to support larger aperture sizes through the standard use of arrays. Additionally, two modes are excited to keep a relatively broadband of about 15 %. The proposed design consists of a cylindrical dielectric placed on top of a cavity-backed slot that is excited by a coaxial probe soldered to the top patch of the cavity. With this feeding, a good matching is achieved for different dielectric resonator heights, hence, the gain can be adjusted easily without the need of reoptimizing the antenna or the feed structures. The design process is explained in addition to performing a sensitivity analysis of fabrication tolerances which confirms that the 3-D printer provides enough accuracy with a negligible effect on the antenna’s performance. Then a prototype with a medium length is fabricated and measured to provide high realized gain and impedance bandwidth of 11 dBi and 14.5 %, respectively. The measured data demonstrate the good performance of the antenna with great matching compared to the simulated ones. Furthermore, the antenna presents a good performance in terms of sidelobes and polarization. This proposed design outperforms other DRA designs based on higher-order modes.

A Wideband Millimeter-Wave Dual-Beam Dielectric Resonator Antenna with Substrate Integration Capability.

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°.

Circularly Polarized Modified Minkowski Metasurface-Based Hybrid Dielectric Resonator Antenna for 5G n79 Wireless Applications

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.

Bilateral rectangular shape dielectric resonator antenna coupled with offset microstrip lines for wideband circular polarization

SummaryIn 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.