Showing papers on "Dielectric resonator antenna published in 2019"
TL;DR: In this paper, a multiple-input-multiple-output (MIMO) dielectric resonator antenna with enhanced isolation is proposed for future 5G millimeter (mm)-wave applications.
Abstract: A multiple-input–multiple-output dielectric resonator antenna with enhanced isolation is proposed in this letter for the future 5G millimeter (mm)-wave applications. Two rectangular dielectric resonators (DRs) are mounted on a substrate excited by rectangular microstrip-fed slots underneath DRs. Each DR has a metal strip printed on its upper surface moving the strongest part of the coupling field away from the exciting slot to improve the isolation between two antenna elements. The proposed antenna obtains a simulated impedance bandwidth ( S 11 ≤ –10 dB) from 27.25 to 28.59 GHz, which covers the 28 GHz band (27.5–28.35 GHz) allocated by the Federal Communications Commission for the 5G applications. A maximum improvement of 12 dB on the isolation over 27.5–28.35 GHz is achieved. The mechanism of the isolation improvement and the design procedure are given in this letter. A prototype is manufactured and measured as a validation of the proposed decoupling method.
197 citations
TL;DR: In this article, a simple decoupling method of using metallic vias to improve the isolation of millimeter-wave multiple-input-multiple-output (MIMO) dielectric resonator antenna (DRA) elements is investigated.
Abstract: A simple decoupling method of using metallic vias to improve the isolation of millimeter-wave multiple-input-multiple-output (MIMO) dielectric resonator antenna (DRA) elements is investigated. The vias are vertically added to the DRA elements, at appropriate positions. By means of the interaction with the electromagnetic fields, the vias can potentially affect the filed distributions and further reduce the coupled fields effectively. The isolation between the MIMO DRA elements can, therefore, be enhanced substantially. As the vias are placed inside the DRA elements, no extra footprint is needed, making the entire antenna system very simple and compact. Two typical examples, including an H-plane and an E-plane, coupled $1\times2$ MIMO DRA arrays, have been designed, fabricated, and measured to demonstrate the feasibility and universality of this method. The results show that by using the vias appropriately, the isolation of the H-plane coupled MIMO DRA array can be enhanced from ~15.2 to 34.2 dB, while that of the E-plane array can be improved from ~13.1 to 43 dB at 26 GHz.
87 citations
TL;DR: In this article, a compact quasi-isotropic dielectric resonator antenna (DRA) with filtering response is investigated in a communication. But the authors only evaluated the performance of the DRA at 2.4 GHz.
Abstract: A compact quasi-isotropic dielectric resonator (DR) antenna (DRA) with filtering response is first investigated in this communication. The cylindrical DRA is fed by a microstrip-coupled slot, exciting in its ${\text {HEM}}_{11 \delta }$ mode which radiates like a magnetic dipole. A small ground plane is used for this DRA and it radiates like an electric dipole. The combination of the two orthogonal dipoles leads to a quasi-isotropic radiation pattern, with gain deviation as low as 5.8 dB in the 360° full space. To integrate the filtering function, the microstrip feed-line and the ground plane are turned upside down, and further two stubs with different lengths are used together to excite the DR. Due to the different loading effects of the feeding stubs, two resonances of the DR ${\text {HEM}}_{11 \delta }$ mode are excited in the passband, effectively enhancing the bandwidth of DRA ( $\varepsilon _{r} = 20$ ) to 7%. Furthermore, two controllable radiation nulls are generated by the DR loaded microstrip feed-line, bringing about high frequency selectivity at the edges of the passband and a quasi-elliptic bandpass response. For demonstration, a prototype operating at 2.4 GHz was fabricated and tested; reasonable agreement is obtained between the simulated and measured results.
72 citations
TL;DR: In this article, a glass dielectric resonator antenna (DRA) incorporating a liquid-metal polarizer capable of polarization reconfiguration is introduced, which operates at 2.4 GHz with a wide effective bandwidth (overlapped impedance bandwidths of the three states) of 18.0% and a high radiation efficiency of more than 80%.
Abstract: In this communication, we introduce a glass dielectric resonator antenna (DRA) incorporating a liquid-metal polarizer capable of polarization reconfiguration. The polarizer is formed by a type of liquid-metal alloy composed of gallium, indium, and tin. The antenna is capable of generating three different polarizations: a −45° polarization (STATE 1), a +45° polarization (STATE 2), and a $y$ -axis polarization (STATE 3). The glass DRA is designed to operate at 2.4 GHz with a wide effective bandwidth (overlapped impedance bandwidths of the three states) of 18.0% and a high radiation efficiency of more than 80%. The experimental results agree well with the theoretical analyses.
63 citations
TL;DR: The measured results demonstrated that the proposed singly fed DRA with EBG on the ground plate is suitable for implementing wideband circular polarized MIMO antennas in a compact size.
Abstract: We present a wideband circularly polarized (CP) multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) with enhanced diversity. In the DRA element, two diagonal edges of the DR were truncated at 45° to obtain a wider axial ratio larger than 0.65 GHz. The DRA element was excited by a cross-ring slot with specific slot-arm ratio through microstrip-line (MSTL) implemented at the backside of the FR4 substrate to generate CP fields. Small triangular stands at the edge of the DR were employed to hold it in place to avoid any degradation from the uncontrollable bonding agent used for attaching DR onto the FR4 substrate. The DRA achieved an impedance bandwidth better than 0.8 GHz with an antenna gain of 4.83 dBi. Using the DRA with the MSTL feed, two-element CP-DRA array was implemented with electromagnetic band-gap (EBG) structure etched onto the ground plane of the MSTL. The proposed architecture achieves isolation better than 26 dB over the desired frequency band without any performance degradation while maintaining its compact size in the array. Various diversity analysis was carried out on the implemented circularly polarized MIMO DRA. The measured results demonstrated that the proposed singly fed DRA with EBG on the ground plate is suitable for implementing wideband circular polarized MIMO antennas in a compact size.
56 citations
TL;DR: In this paper, a 3-dimensional printed wideband multi-ring dielectric resonator antenna (DRA) is investigated for the first time, which consists of four concentric rings with decreasing effective Dielectric constants in the radial direction.
Abstract: A three-dimensional (3-D)-printed wideband multi-ring dielectric resonator antenna (DRA) is investigated for the first time. It consists of four concentric dielectric rings with decreasing effective dielectric constants in the radial direction. To facilitate the 3-D-printed design, a basic unit cubic cell that can be easily adjusted to provide different effective dielectric constants is used. An axial coaxial probe is used to excite the DRA in three transverse magnetic (TM) modes (TM01δ, TM02δ, and TM03δ), which are merged to provide a wide impedance bandwidth. For demonstration, a prototype operating in C -band is designed and fabricated using a 3-D printer. Its reflection coefficient, radiation pattern, antenna gain, and antenna efficiency are measured, and reasonable agreement between the measured and simulated results is observed. The prototype has a wide measured 10-dB impedance bandwidth of 60.2% (4.3–8.0 GHz) with a low profile of 0.18 λ 0, where λ 0 is the wavelength in air at the center frequency (6.15 GHz). The prototype has an average measured antenna efficiency of 89%, with the peak efficiency given by 95%.
54 citations
TL;DR: A novel wideband circularly polarized multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) has been proposed for worldwide interoperability for microwave access (WiMAX) applications and the mutual coupling between closely placed DRA units at $0.5\lambda has been significantly reduced by using a new hybrid technique.
Abstract: In this paper, a novel wideband circularly polarized multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) has been proposed for worldwide interoperability for microwave access (WiMAX) applications. The mutual coupling (MC) between closely placed DRA units at 0.5λ has been significantly reduced by using a new hybrid technique. The exclusive features of the proposed MIMO antenna include wide impedance matching bandwidth (BW), broadband circular polarization (CP), and suppressed MC between the radiating elements. The first step of hybrid technique is the employment of parasitic patch at an optimized distance beside the conformal metal strip of the two identical rectangular DRAs in order to generate CP wave along with a wide impedance matching BW over the same frequency range. In the final step, the MC is suppressed significantly along with the broadband CP by placing the DRAs diagonally at an optimized position. The proposed MIMO antenna is the hybrid of the parasitic patch and the diagonal position of radiating elements. The CP BW offered by the proposed antenna is ~20.82% (3.58-4.40 GHz) in conjunction with an impedance-matching BW of ~38.51% (3.50-4.95 GHz). Moreover, MC less than -28 dB is achieved over the entire band and -26 dB at 3.89 GHz (minimum of the AR) through the hybrid technique. The prototype of the proposed antenna geometry is fabricated and measured. A good agreement has been attained between the simulated and measured results.
47 citations
TL;DR: In this paper, a dual-band circularly polarised (CP) response along with the miniaturisation of a singly fed rectangular dielectric resonator (DR) antenna is obtained by applying the metallic strips on the sidewalls of the DR.
Abstract: A technique is proposed to obtain the dual-band circularly polarised (CP) response along with the miniaturisation of a singly fed rectangular dielectric resonator (DR) antenna. The miniaturised response is obtained by applying the metallic strips on the sidewalls of the DR. The specific format of the applied metallic strips excites the orthogonal degenerate modes. Thus, a dual-band CP response is obtained along with the miniaturisation of antenna. The proposed antenna is designed to obtain the small frequency ratio. The frequency ratio can also be tuned by changing the surface area of the applied metallic strips.
41 citations
TL;DR: In this paper, a stacked DRA with high-permittivity dielectric strips layered on low-perceptivity substrate is adopted for bandwidth and gain benefits for satellite applications.
Abstract: A circularly polarized (CP) dielectric resonator antenna (DRA) with wide bandwidth and low axial ratio (AR) values is presented in this communication. The antenna consists of a stacked DRA, and it is fed by a substrate integrated waveguide coupling slot from the bottom. The stacked DRA structure, with high-permittivity dielectric strips layered on low-permittivity substrate, is adopted for bandwidth and gain benefits. Here, a pair of dielectric strips rather than a single one is placed above the coupling slot with 45° inclination for generating good CP radiation, and it is elaborately designed to provide three closely coupled CP modes, constituting a wide operating bandwidth. To facilitate the application in antenna array, a cavity-backed antenna design along with a $2 \times 2$ subarray are further presented. To verify the design, a subarray prototype is developed and tested at Ku-band for satellite applications, showing an impedance bandwidth of 25.1%, a wide 1 dB AR bandwidth of 15.6%, and a peak gain of 15.1 dBi.
41 citations
TL;DR: Comparisons show that PSADEA possesses significant advantages in efficiency compared to a state-of-the-art surrogate model-assisted EA for antenna optimisation, the standard parallel differential evolution algorithm, and parallel particle swarm optimisation.
Abstract: Computational efficiency is a major challenge for evolutionary algorithm (EA)-based antenna optimisation methods due to the computationally expensive electromagnetic simulations. Surrogate model-assisted EAs considerably improve the optimisation efficiency, but most of them are sequential methods, which cannot benefit from parallel simulation of multiple candidate designs for further speed improvement. To address this problem, a new method, called parallel surrogate model-assisted hybrid differential evolution for antenna optimisation (PSADEA), is proposed. The performance of PSADEA is demonstrated by a dielectric resonator antenna, a Yagi-Uda antenna, and three mathematical benchmark problems. Experimental results show high operational performance in a few hours using a normal desktop 4-core workstation. Comparisons show that PSADEA possesses significant advantages in efficiency compared to a state-of-the-art surrogate model-assisted EA for antenna optimisation, the standard parallel differential evolution algorithm, and parallel particle swarm optimisation. In addition, PSADEA also shows stronger optimisation ability compared to the above reference methods for challenging design cases.
40 citations
TL;DR: In this paper, 3D printed zirconia using nano-particle jetting was characterized in terms of chemistry, density, crystallography, sintering shrinkage and dielectric properties as a foundation for developing high performance radio frequency (RF) components.
Abstract: Additive manufacturing of ceramics has been actively investigated with the objective of fabricating complex structures that compete in terms of material performance with traditionally manufactured ceramics but with the benefit of increased geometric freedom. More specifically, zirconia provides high fracture toughness and thermal stability. In addition, its dielectric permittivity may be the highest among materials available for 3D printing, and may enable the next generation of complex electromagnetic structures. NanoParticle Jetting™ is a new material jetting process for selectively depositing nanoparticles and is capable of printing zirconia. Dense, fine-featured parts can be manufactured with layer thicknesses as small as 10 μm and jetting resolution of 20 μm after a final sintering step. For this study, 3D printed zirconia using NanoParticle Jetting™ was characterized in terms of chemistry, density, crystallography, sintering shrinkage and dielectric properties as a foundation for developing high performance radio frequency (RF) components. The experimental results indicate a yttria-stabilized ZrO2 structure exhibiting a bulk relative permittivity of 23 and a loss tangent of 0.0013 at microwave frequencies. A simple zirconia dielectric resonator antenna is measured, confirming the measured dielectric properties and illustrating a practical application of this material.
TL;DR: In this article, a water dielectric resonator antenna with reconfiguration and broadband characteristics is presented, where pure water is injected into various cavities of the Plexiglass holder.
Abstract: A water dielectric resonator antenna with reconfiguration and broadband characteristics is presented. By injecting pure water into various cavities of the Plexiglass holder, the antenna can be switched among left-hand circular polarization, right-hand circular polarization, and linear polarization in almost the same operating frequency range. With the high relative permittivity, water acts as a dielectric resonator as well as an interface similar to electric wall to form a broad axial-ratio bandwidth. Thus, a broad usable bandwidth is measured to be over 22%, and the measured radiation efficiency and realized gain centralize in 60%–70% and 3–4 dBi, respectively.
TL;DR: In this article, a pattern reconfigurable high gain spherical dielectric resonator antenna (DRA) operating on higher order mode was proposed, which can reconfigure its radiation pattern by using a feeding structure, which is consist of two microstrip patches and the reconfigured switch network.
Abstract: This letter proposes a pattern reconfigurable high gain spherical dielectric resonator antenna (DRA) operating on higher order mode. Two microstrip patches were used to excite $\text{TE}_{301}$ mode in the different direction. A reconfigurable switch network was designed and it has three switching modes for selecting each patch alone or selecting them simultaneously. The proposed antenna can reconfigure its radiation pattern by using a feeding structure, which is consist of two microstrip patches and the reconfigurable switch network. A prototype antenna operating on $\text{TE}_{301}$ mode at 5.8 GHz was fabricated by ceramic material. By experiment, we validated the new concept of pattern reconfigurable spherical DRA.
TL;DR: In this paper, a kind of circular polarized (CP) stacked dielectric resonator (DR) antenna with wide bandwidth and high gain is presented in this communication, where a two-layer DR with improved performance in bandwidth and gain is used as the basic resonator.
Abstract: A kind of circular polarized (CP) stacked dielectric resonator (DR) antenna with wide bandwidth and high gain is presented in this communication. For this design, a two-layer DR with improved performance in bandwidth and gain is used as the basic resonator. By further applying it into a stacked design, two similar modes with adjacent resonant frequencies can be merged together, providing a wide axial ratio bandwidth of more than 20%. The single-feed CP operation is achieved by adopting a coupling cross-slot, which is beneficial for fine-tuning and array forming, as compared to multifeed structures. Two design examples working at different frequency bands and for different senses of CP have been presented to demonstrate the effectiveness of the design concept.
TL;DR: In this article, a partial reflector surface structure was proposed to improve the isolation and correlation coefficient values between cylindrical dielectric resonator antennas (cDRAs) for multiband multiple-input-multiple-output (MIMO) applications.
Abstract: This letter presents a novel partial reflector surface structure to improve the isolation and correlation coefficient values between cylindrical dielectric resonator antennas (cDRAs) for multiband multiple-input–multiple-output (MIMO) applications. To achieve multiband characteristics, three different groups of cDRA are proposed to cover 5.2, 5.5, and 5.8 GHz bands, respectively. Each group has two cDRAs. Thus, three groups (i.e, six cDRA) are placed at the top of the substrate and each cDRA is excited using a coplanar waveguide-fed conformal strip-line. To achieve improved isolation, three different phase gradient frequency selective surfaces (FSSs) are designed, which operate at 5.2, 5.5, and 5.8 GHz bands, respectively. This phase-gradient FSS is utilized as a superstrate above each group of the DR elements. As a result, two different far-field patterns are achieved from each group of antenna elements, which deliver improved isolation as well as low field correlation. This exclusive technique offers more than 12 dB of enhancement in the isolation values and more than 70% improvement in the envelope correlation coefficient values, thus guaranteeing improved MIMO performance.
TL;DR: In this article, a four-port multi-input-multi-output (MIMO) dielectric resonator (DR) antenna with pattern diversity is proposed. But the antenna is not suitable for MIMO applications.
Abstract: A new compact four-port multi-input-multi-output (MIMO) dielectric resonator (DR) antenna is proposed with pattern diversity. The antenna contains four DR elements, the epsilon-shaped and cylindrical. These four DR elements are placed together such that they resonate at the same frequency. The specific geometry of the DR elements allows to place them at separation which is much smaller than operating wavelength. Hence, the combination of the four DR elements acts as a single DR. This helps in maintaining the compactness of the antenna structure. The antenna operates with the hybrid of modes HEM
11δ
and TM
01δ
excited in epsilon-shaped and cylindrical DR elements, respectively. The excitation of these orthogonal modes helps in obtaining the pattern diversity allowing the antenna for multi-directional coverage. The antenna provides 15.73% overlapping 10 dB impedance bandwidth with the variation of gain within ranges 4-6 and 6-6.5 dBi at port 1/2 and port 3/4, respectively. In addition, the antenna provides the high radiation efficiency >93% at port 1/2 and 97% at port 3/4. Other parameters required for MIMO applications such as envelope correlation coefficient and diversity gain are within the acceptable limits.
TL;DR: In this article, a dual-mode wideband circularly polarized (CP) DRA is implemented by using a stair-shaped microstrip feed line, a pair of L-shaped slots in the ground plane, and a rectangular DR.
Abstract: An examination of a new kind of rectangular dielectric resonator antenna (DRA) demonstrates that it delivers better gain and radiation efficiency for operating in the Worldwide Interoperability for Microwave Access (Wi-MAX) (3.3-3.7 GHz) band. The new dual-mode wideband circularly polarized (CP) DRA is implemented by using a stair-shaped microstrip feed line, a pair of L-shaped slots in the ground plane, and a rectangular DR.
TL;DR: In this article, a differentially coplanar-fed filtering dielectric resonator antenna (DRA) is proposed for millimeter-wave applications, which can be manufactured with a single-layer laminate using standard printed circuit board technology.
Abstract: In this letter, a differentially coplanar-fed filtering dielectric resonator antenna (DRA) is proposed for millimeter-wave applications. To realize a low-profile design, a novel coplanar feeding method is presented by incorporating a dielectric resonator and its feeding structure in the same layer, which minimizes the assembly errors. The DRA is shaped by hollowing out the substrate and can be manufactured with a single-layer laminate using standard printed circuit board technology. The DRA operates at TE111 mode that is excited differentially by a pair of microstrip lines with metallic vias. The filtering function is obtained by etching two pairs of slots with different lengths in the ground plane, resulting in two radiation nulls at both upper and lower band edges. For demonstration, a prototype is designed, fabricated, and measured. Good agreement can be observed between simulated and measured results.
TL;DR: In this article, the authors proposed a new type of compact dual-frequency antenna, which is realized by using a single rectangular dielectric block with a groove along its center, which integrates a microwave DRA with a millimeter-wave Fabry-Perot resonator antenna (FPRA).
Abstract: This communication investigates a new type of compact dual-frequency antenna, which is realized by using a single rectangular dielectric block with a groove along its center. It integrates a microwave dielectric resonator antenna (DRA) with a millimeter-wave Fabry–Perot resonator antenna (FPRA). The DRA is fabricated out of a dielectric block, excited by a vertical conducting strip on its side wall. The FPRA is realized by sticking the adhesive copper tape on the surfaces of the groove, forming a pair of parallel plates and the ground plane. The FPRA is excited by a sleeve-integrated L-probe, which suppresses the cross-polar fields and widens the bandwidth of the FPRA. To validate the idea, a dual-frequency antenna, covering both the 2.4 and 24 GHz ISM bands, was designed and measured. The DRA operates in its TEx111 mode, whereas the FPRA operates in its fundamental mode. Next, a wideband dual-frequency antenna was designed to further cover the 4G and future 5G frequency bands. Both of the TEx111 and TEx113 modes of the DRA are excited, broadening the bandwidth in the microwave band. Also, the FPRA mode and two L-probe modes are simultaneously excited to increase the bandwidth in the millimeter-waveband. The S-parameters, radiation patterns, antenna gains, and antenna efficiencies of the dual-frequency antennas are studied in detail. Reasonable agreement between the measured and simulated results is observed.
TL;DR: It is conceived that the proposed MIMO antenna designed using hybrid techniques for Long Term Evolution (LTE) applications can be a good candidate for LTE applications due to the validated excellent throughput performance.
Abstract: In this paper, a triple band Multiple-Input Multiple-Output (MIMO) Rectangular Dielectric Resonator Antenna (RDRA) designed using hybrid techniques for Long Term Evolution (LTE) applications is investigated and presented. The proposed MIMO antenna can transmit and receive data independently by covering LTE Band 8 at 0.9 GHz, LTE Band 3 at 1.8 GHz, and LTE Band 40 at 2.3 GHz. Hybrid technique is adopted in this design by combining a meander line antenna with an RDRA to realize multiband operation. Meander line antenna has been proposed over the long vertical microstrip feeding line at 0.9 GHz, to employ a size reduction in the antenna, while two modes of RDRA are applied in this design: $TE_{1\delta 1}^{y}$ mode at 1.8 GHz and $TE_{2\delta 1}^{y}$ mode at 2.3 GHz. The proposed MIMO antenna has been fabricated and experimentally tested. The measured impedance bandwidths ( $S_{11}$ <-10 dB) for the three stated bands are 4.40%, 11.36%, and 2.54% at Port 1, respectively and 5.47%, 10.54%, and 3.43% at Port 2, respectively. Measured isolations of −15.3 dB, −17.8 dB, and −47.0 dB are obtained at each described frequency, respectively. The performance of the proposed MIMO antenna is further validated using over-the-air LTE downlink throughput test. Throughputs of 93.16 Mbps, 93.01 Mbps, and 87.30 Mbps have been achieved for 0.9 GHz, 1.8 GHz, and 2.3 GHz, respectively, using 64 Quadrature Amplitude Modulation (QAM). In this regard, it is conceived that the proposed MIMO antenna can be a good candidate for LTE applications due to the validated excellent throughput performance.
TL;DR: In this article, a novel technique is proposed to enhance the gain of a rectangular dielectric resonator antenna over a wideband range of frequencies, which has a relative bandwidth of 27.5% in the 60 GHz band (16 GHz of absolute bandwidth).
Abstract: A novel technique is proposed to enhance the gain of a rectangular dielectric resonator antenna over a wideband range of frequencies. The proposed antenna structure has a relative bandwidth of 27.5% in the 60 GHz band (16 GHz of absolute bandwidth), and a peak realized gain of 12.6 dBi. The simulated antenna radiation efficiency goes up to 96%. A printed electromagnetic bandgap technology has been used to feed the antenna and eliminate any parasitic radiation from the feedline.
TL;DR: A robust performance has been offered by the antenna against human body lossy effects and the measured results agree very well with the simulated results.
Abstract: A unique circularly polarized (CP) compact wearable dielectric resonator antenna (DRA) has been proposed for off-body communication in wireless body area network (WBAN) applications. The design is singly fed and a new H-shaped conformal metal strip has been used to excite the DRA. A circular polarization over a bandwidth of ~9.6% (7.47-8.25 GHz) in conjunction with an impedance matching bandwidth of ~20.7% (6.95-8.68 GHz) has been offered by the antenna. A prototype has been fabricated and measured. The antenna has been tested both in free space and on-body environment. A robust performance has been offered by the antenna against human body lossy effects. The measured results agree very well with the simulated results.
TL;DR: In this article, the authors investigated the microwave dielectric properties through the Hakki-Coleman method of BiVO4 ceramic matrix, obtained by the solid-state reaction method, using 8, 16, 24 and 32% of CaTiO3.
Abstract: This paper investigated the microwave dielectric properties through the Hakki-Coleman method of BiVO4 ceramic matrix, obtained by the solid-state reaction method, using 8, 16, 24 and 32 wt% of CaTiO3. The X-ray diffraction (XRD) was used for the structural characterisation of the crystalline phases present in ceramic before the sinterisation process. The thermal-stability in microwave range was measured in all dielectric samples, and the temperature coefficient of resonant frequency (τf) was found varying from −244.03 ppm °C−1 to −2.7 ppm °C−1. The CaTiO3 addition reduced the value of the dielectric permittivity (e’) close to 25% of the BiVO4 values, keeping the dielectric loss (tan δ) around 10−3. The experimental and numerical simulated values of the dielectric resonator antenna (DRA) results show the agreement of the input impedance, return loss, bandwidth and radiation patterns. Moreover, all antennae features realised gain above 5dBi. In antenna results, the CaTiO3 addition increased the bandwidth, compared to BiVO4 DRA, that presented bandwidth around 34 MHz.
TL;DR: In this article, a wideband artificial grid dielectric resonator antenna (GDRA) array for mm-wave applications is presented, which consists of a GDRA layer and a substrate-integrated waveguide feeding layer.
Abstract: Wideband artificial grid dielectric resonator antenna (GDRA) arrays at 32 GHz for mm-wave applications are presented. The antenna array comprised a GDRA layer and a substrate-integrated waveguide feeding layer. The GDRA array layer is built by embedding small rectangular metal grid structures in low-permittivity dielectric polymethyl methacrylate (PMMA) using deep X-ray lithography (DXRL) and electroforming. The rectangular metallic inclusions significantly increase the effective permittivity of the base material up to 17 by creating high electric flux density regions inside. Low-loss substrate-integrated waveguide (SIW) feeding with longitudinal slots is utilized to excite the GDRA array layer. A $200~\mu \text{m}$ -thin perforated layer of PMMA is applied between the rectangular grid structures and the SIW feedlines to avoid shorting the metal inclusions to the excitation slots while improving broadband energy coupling to the GDRA layer. The size of the single GDRA array element is only 2.7 mm $\times2.7$ mm $\times0.5$ mm ( $0.29\lambda _{\mathrm {o}}\times 0.29\lambda _{\mathrm {o}}\times 0.05\lambda _{\mathrm {o}}$ ). Four-element ( $1 \times 4$ ) and eight-element ( $1 \times 8$ ) GDRA arrays have been fabricated and measured. A measured impedance bandwidth of 6 GHz with a broadside peak gain of 12 dBi and 76% measured radiation efficiency is obtained at 32 GHz for the $1 \times 8$ GDRA array.
TL;DR: This paper postulates a novel omnidirectional low-profile ultra-wideband (UWB) antenna with features of both low- profile dielectric resonator (DR) and thin planar monopole antenna, where the laminated equilateral triangular DR and the rectangular metal patch monopole are stacked up.
Abstract: This paper postulates a novel omnidirectional low-profile ultra-wideband (UWB) antenna, which is structured by discrete embedded dielectric resonator antenna with features of both low-profile dielectric resonator (DR) and thin planar monopole antenna, where the laminated equilateral triangular DR and the rectangular metal patch monopole are stacked up. This new design can lower the profile of the antenna. Furthermore, the symmetric DR and the monopole structure are able to make the surface currents in some operating modes opposite in phase, together with the characteristics of the coplanar waveguide (CPW) feed structure and the DR, the cross-polarization is reduced effectively. The mode analysis has been done to show how the antenna achieves the UWB. The CPW which can integrate with integrated circuits easily is used to provide the excitation source. The antenna provides consistent omnidirectivity, consistent gain, low cross-polarization, and high-radiation efficiency within the entire operation band. A prototype (dimensions are 17.6 mm $\times33.6$ mm and 1.524 mm thickness) is fabricated and measured. The measurements are well correlated with the simulations.
TL;DR: In this paper, various fractal geometries have been introduced for antenna applications, and the main objective of fractal applications is to reduce the size of the antenna for wideband characteristics, while maintaining other design parameters at an acceptable level.
Abstract: Until the 1980s, shielded dielectric resonators (DRs) were used as high-quality factor energy storage devices for filter and oscillator applications [1]. Later, they gained status as effective radiators due to the efforts of Long, McAllister, and Chen [2]. Since then, enormous DR antenna (DRA) designs have been explored and different feeding techniques introduced to achieve optimum antenna characteristics like high gain and low quality factor (Q-factor), etc. Compared to microstrip antennas, DRAs offer attractive features such as low loss, high efficiency, and wide impedance bandwidth (BW). Low-profile design and BW enhancement are two important aspects of effective antenna synthesis. Various BW enhancement techniques-like the compact slot DRA [3], aperture feeding, perturbation, cavity-backed disk, ring-shaped DRA, and the stacking of two or more dielectric layers [4]-can be applied on DRAs for this purpose. The stacked DRA, dual-segment, hybrid DRA, and slots in ground-plane approaches were also well suited to improve the impedance BW of DRA [5]-[10]. Various multilayer cylindrical DRA (MCDRA) structures have been proposed and investigated for BW enhancement like the stacked cylinder approach [11], [12], slotted coaxial layered structure [13], etc. More recently, various fractal geometries have been introduced for antenna applications. The main objective of fractal applications is to reduce the size of the antenna for wideband characteristics, while maintaining other design parameters at an acceptable level. Several antenna configurations based on fractal geometries have been previously examined [14].
TL;DR: The proposed DRA implemented in a low-cost integrated-passive-device technology is flip-chip packaged onto the CMOS antenna array chip through low-loss gold bumps and is the one with the highest order operation mode at THz frequencies reported thus far.
Abstract: A single dielectric resonator antenna (DRA) capable of enhancing the antenna gain of each element of a $2\times 2$ terahertz (THz) antenna array realized in a 0.18- $\mu \text{m}$ CMOS technology is proposed in this paper. The DRA implemented in a low-cost integrated-passive-device technology is flip-chip packaged onto the CMOS antenna array chip through low-loss gold bumps. By designing the DRA to work at the higher order mode of TE $_{3,\delta,9}$ , only a single DRA, instead of conventionally needing four DRAs, is required to simultaneously improve the antenna gain of each element of the $2\times 2$ antenna array. This not only simplifies the assembly process, but it can also reduce the assembly cost. Moreover, the DRA can provide great antenna gain enhancement because of being made of high-resistivity silicon material and higher order mode operation. The simulated antenna gain of each on-chip patch antenna of the $2\times 2$ CMOS antenna array can be increased from 0.1 to 8.6 dBi at 339 GHz as the DRA is added. To characterize the proposed DRA, four identical power detectors (PDs) are designed and integrated with each element of the $2\times 2$ THz antenna array. By measuring the voltage responsivity of each PD output, the characteristics of each antenna of the antenna array with the proposed DRA, including the gain enhancement level and radiation pattern, can be acquired. The measurement results match well with the simulated ones, verifying the proposed DRA operation principle. The four PDs with the proposed DRA are also successfully employed to demonstrate a THz imaging system at 340 GHz. To the best of our knowledge, the proposed DRA is the one with the highest order operation mode at THz frequencies reported thus far.