Cylindrical Dielectric Resonator Research Articles

Compact back‐to‐back DRA‐based four‐port MIMO antenna system with bi‐directional diversity

This Letter presents a dielectric resonator (DR)-based multiple-input-multiple-output (MIMO) antenna with bi-directional pattern diversity. The back-to-back arrangement of cylindrical DR antennas DRAs (cDRAs) is one of the unique features of the proposed design. The cDRAs are placed on an FR4 substrate with a common ground plane. Each cDRA element is excited by two ports to establish a four-port MIMO antenna system. At ports 1 and 2, the top cDRA is excited via co-planar waveguide (CPW) fed conformal strip lines. In case of ports 3 and 4, the bottom cDRA is excited by microstrip line fed conformal strip lines. Isolation between all ports is improved (better than 18 dB) by generating orthogonal modes in the cDRAs and use of opposite excitations. Measured results confirm that the proposed four-port MIMO antenna system is useful for the frequency ranges between 5.4 and 6.0 GHz for WLAN applications.

Investigation on Mutual Coupling of Aperture Coupled Cylindrical Dielectric Resonator Antenna (DRA)

In this research, study on mutual coupling of aperture coupled cylindrical DRA and its influence on return loss, radiation pattern including the directivity, gain and bandwidth was computed and illustrated. The DRA was excited by a micro strip line with aperture coupled slots where the slot locations were calculated using the characteristic of standing wave ratio over a short ended micro strips. Small dielectric resonator antenna was designed using high permittivity dielectric material with permittivity the substrate of 3.38. The diameter of the dielectric resonator is 12mm with the height of 4.2mm. The element spacing that been investigated for the effect of mutual coupling was at 0.5λ, 0.75λ and 1λ with maximum of four DRA been used. The final result shows the effect of mutual coupling is decreased with three DRA element with the gain measured at 5.948GHz frequency is about 8.619dB with high directivity measured at 11.4dBi. This shows that the proposed DRA with three 1λ spacing DRA elements exhibits an enhancement of the gain and directivity in comparison with a single pellet DRA. Hence, by increasing the level of isolation between the two identical DRAs to 1λ it actually helps electromagnetic interaction to attract and further increase the directivity and effective area.

A Novel Compact Cylindrical Dielectric Resonator Antenna for Wireless Sensor Network Application

In this article, a compact stacked cylindrical dielectric resonator antenna loaded with a patch is proposed for the wireless sensor network (WSN). Stacking of two dielectric material techniques is used to enhance the bandwidth of the antenna, and the metallic patch is used as a reflector for improving the gain and enforce compactness. The dielectric resonator antenna (DRA) is excited by the central coaxial probe feed with TM21 mode being observed at 6.7GHz resonant frequency. The proposed antenna is fabricated, and a close agreement is found between simulated and measured results. The proposed structure offers wide impedance bandwidth of 7.5GHz from 5.7 to 13.2GHz. A peak gain of 6.8 dBi is measured over the desired frequency band. The proposed DRA finds scenarios in WSNs and sensor node application.

Four port MIMO integrated antenna system with DRA for cognitive radio platforms

An integrated four-port multi input multi output (MIMO) system with Cylindrical Dielectric Resonator Antenna (CDRA) for Cognitive Radio (CR) application is investigated. In this study the proposed design performs dual state operation i.e ultrawideband (UWB) and narrowband (NB) functionality with modified feeding mechanism, where the feeding line of UWB antenna is made orthogonal to NB CDRA. In UWB state the proposed integrated antenna consisting of two port circular radiators, excited by micro-strip transmission line. In NB state two CDRAs are integrated on the UWB radiators where the current density is effectively low. The DRAs are excited by aperture coupled orthogonal T feed micro-strip transmission line to perform the triband operation at targeted bands. The proposed integrated MIMO system occupies a compact total area of 0.18λ02(λ0 is the highest operating wavelength) with isolation less than −15 dB among all ports. The design approach is verified by fabricating the antenna prototype and the performances are experimentally evaluated in terms of S parameter, radiation pattern and gain. Moreover, the MIMO performance metrics in terms of Envelope correlation coefficient (ECC), diversity gain (DG) and mean effective gain (MEG) are also evaluated for satisfactory diversity performance.

Triple‐port, two‐mode based two element cylindrical dielectric resonator antenna for MIMO applications

AbstractIn this letter, a triple‐port multiple‐input–multiple‐output (MIMO) cylindrical dielectric resonator based antenna (cDRA) supporting 2 simultaneous operating modes is presented. The cDRAs are excited by 3 ports supporting MIMO operation. Mode‐1 is an array mode achieved by exciting the 2 element cDRA array via a simple combiner at port‐1. Ports‐ 2 and −3 support individual element excitation via coaxial probes for mode‐2 yielding individual element MIMO operation. The isolation between ports‐1, 2, and 3 is improved by generating orthogonal modes in the cDRA via proper excitation. The isolation between ports‐2 and 3 is improved by etching 2 C‐shaped defected ground structure slits. For all the cases, the isolation between the ports exceeds 20 dB over the operating band. The presented dual‐mode 3‐port MIMO antenna covers the bands between 5.15 and 6.0 GHz.

Triple‐band hybrid antenna with integral isolation mechanism for MIMO applications

AbstractThis research article explains the designing of triband multiple input multiple output (MIMO) hybrid radiator for diversified wireless applications. It comprises of two symmetrically placed hybrid radiators. These hybrid radiators are placed on a FR4 substrate with protruded ground plane to provide maximum isolation and improved diversity performance. Hybrid radiator consists of two C‐shaped printed lines and cylindrical dielectric resonator (CDR). A dual C‐shaped printed line behaves as a magnetic dipole and produces two different radiating modes in CDRA, that is, HE11δ and TE01δ mode. For confirming the simulated results, the prototype has been constructed and examined. Good agreement has been establish between simulated and experimental results. The proposed radiator is working over three frequency bands, that is, 1.86–2.60, 3.3–3.64, and 4.42–6.75 GHz. Different MIMO diversity performance parameters (ECC, DG, MEG, and CCL) are also examined and found to be in acceptable limit.

An Investigation of Massive Gain in Hybrid Configurable Cylindrical Dielectric Resonator Antenna

In this article a high gain of two layer cylindrical dielectric resonator antenna fed through coaxial probe is projected and developed and conjointly offer complete implementation of superstrate dielectric resonator antenna on patch. The hybrid structure is operated under controlled electric field and magnetic field. The design is loaded with superstrate. The results on reflection coefficient S11, Gain of assorted stages of antenna design are simulated victimisation high frequency structured simulator and conferred. High permittivity material is used as a fluid inside the cylindrical resonator. The resonant frequency of the antenna can be modified by ever-changing the dielectric constant of fluid. It has been investigated that use of superstrate increases antenna gain from by varied biasing voltage reconfigurability are often obtained. The measured gain found to be 11dBi. Reconfigurability is the key parameter during this work a completely unique cylindrical stacked dielectric resonator antenna of high gain with band is presented for Wi-Fi, Wi-max and WLAN communications. The concept becomes compatible with patch antennas for high Gain applications.

Optical-antenna: Great attraction for communication community

The Dielectric Resonator Antenna (DRA) has mainly focus on good quality communication with low profile Antenna. Cylindrical Dielectric Resonator optical Antenna (CDROA) is compact in structure, light in weight conformable to surface planar some natural carbon atom form hollow cylinder without side diameter of only one nano meter. The Resonator Antenna is well suited for microwave devices integration and feeding Technique and, especially with the microwave integrated circuit technology. This unique type antenna has unique applications for direct broadcast Technique as well as satellite system on satellite communication at global positioning system (GPS) and high frequency navigation system and good accuracy and a large variety of radar systems demand for good quality Antenna for the best performance of antenna system.

Dual polarized triple‐band dielectric resonator based hybrid MIMO antenna for WLAN/WiMAX applications

AbstractIn this article, a dual polarized triple‐band dielectric resonator based hybrid multiple‐input multiple‐output (MIMO) antenna is presented. The proposed MIMO antenna is designed with the help of two cylindrical dielectric resonators along with two symmetrical modified Y‐shaped microstrip printed lines. Two metallic strips and a slot on the ground plane are used to enhance the isolation. A prototype of the proposed design is fabricated and tested to validate the simulation outcomes. The measured outcomes confirmed that the proposed antenna can be utilized in three different frequency bands such as 2.21–3.13, 3.40–3.92, and 5.30–6.10 GHz with fractional bandwidth of 34.45%, 14.2%, and 14%, respectively. The modified Y‐shaped printed line is used to obtain circular polarization in the upper frequency band with fractional axial ratio (AR) bandwidth of 4.18%. Besides, MIMO performance has also been examined in terms of diversity parameters like envelope correlation coefficient (ECC), mean effective gain (MEG), diversity gain (DG), and channel capacity loss (CCL).

Dielectric resonator antenna array for X‐band and microwave imaging applications

AbstractIn this article, simulation and experimental studies of compact dielectric resonant antenna array have been performed for microwave imaging systems and X‐band applications. A novel feed structure has been proposed to excite the four cylindrical dielectric resonators. The proposed antenna array shows dual band characteristics i.e., 4.15–7.2 GHz and 9.35–17.2 GHz with the bandwidth of 3.05 GHz and 7.85 GHz respectively. The proposed antenna has been fabricated and tested. Measurement results have been extracted and found in good agreement with simulated results. The proposed antenna array affords appropriate gain, high radiation efficiency, wide bandwidth, small size, and stable radiation patterns over the entire bands which are essential performance characteristics to be utilized for C band, X band, and Ku band applications.

Design and analysis of tri‐band dual‐port dielectric resonator based hybrid antenna for WLAN/WiMAX applications

This paper presents a tri-band dual-port dielectric resonator based hybrid antenna for different wireless applications. The proposed antenna includes two symmetrically placed hybrid radiators. Some of the attractive characteristics of proposed radiator are as follows: (i) circular ring together with T-shaped printed line generates dual hybrid radiating modes in cylindrical dielectric resonator antenna (CDRA) (HEM 11δ and HEM 12δ modes); (ii) hybrid radiator module (grouping of circular ring and CDRA) is utilised to create tri-band characteristics; (iii) metallic strip together with slitted ground surface is adopted to provide good isolation (| S 12 | <;-25 dB) between two radiators in all three operating frequency bands. In order to authenticate the proposed radiator, the archetype has been realised and tested practically. Good settlement has been found between software generated and experimental outcomes. The proposed multiple-input multiple-output (MIMO) based hybrid radiator operates over three frequency bands, i.e. 1.5-2.55, 3.21-4.0 and 4.59-5.98 GHz with the fractional bandwidth 51.21, 21.91 and 26.30%, respectively. Various diversity parameters are also investigated, which approve that the proposed hybrid radiator is an appropriate candidate for MIMO applications.

Omnidirectional Dielectric Resonator Antenna With a Planar Feed for Circular Polarization Diversity Design

The cylindrical dielectric resonator (DR) antenna (DRA) is excited in its omnidirectional TM $_{01\delta }$ mode by a planar shorted microstrip cross. With this nonintrusive feed, the DRA can be fabricated without the need of drilling a hole in the DR as required in the probe feed method. This DRA is applied to the first omnidirectional circularly polarized (CP) diversity DRA. To generate omnidirectional CP fields, the TM $_{01\delta }$ and TE $_{011+\delta }$ modes are excited simultaneously. The TE $_{011+\delta }$ mode is excited by four microstrip arcs. They provide a pair of equivalent magnetic dipoles that generate fields that are orthogonal to those of the TM $_{01\delta }$ mode. Omnidirectional CP fields can be obtained when the (orthogonal) fields of the TM $_{01\delta }$ and TE $_{011+\delta }$ modes are equal in amplitude but in phase quadrature. In our two-port CP diversity design, phase differences of +90° and −90° are obtained in ports 1 and 2 to generate right- and left-hand CP fields, respectively. Prototypes at ~2.4 GHz were designed, fabricated, and measured for WLAN applications. The S-parameters, radiation patterns, antenna gains, and efficiencies are studied. For the diversity design, the axial ratio, envelope correlation coefficient, and mean effective gain are also obtained. The measured and simulation results are in reasonable agreement.

Excitation of Higher Order Modes of Cylindrical Dielectric Resonator Antenna using Dual-slot feed

Excitation of the higher order modes (HOM) of a cylindrical dielectric resonator antenna(DRA) of high relative permittivity, using dual feed scheme is investigated. The feed scheme uses a pair of narrow slots and is chosen on the basis of the field distribution of the desired DRA modes. Numerical studies using ANSYS HFSS show that the dual-feed excited a combination of two HOMs, which are identified as HEM21δ and TM01δ. The mixed-up nature is further verified through studying the radiation pattern of the DRA which shows azimuthal asymmetry and low gain. It is suggested that if one of the HOM is suppressed, better antenna performance can be achieved.

Dielectric resonator‐based two‐element MIMO antenna system with dual band characteristics

In this research article, a dielectric resonator-based multiple input multiple output (MIMO) antenna system is presented with dual band characteristics. The proposed MIMO antenna includes two symmetrical hybrid radiators. Each hybrid radiator consists of a modified annular ring printed line along with a cylindrical dielectric resonator antenna (CDRA). A modified annular ring printed line acts as a magnetic dipole and creates two different radiating modes (HEM11δ and TE01δ) in the dielectric resonator. The approach of the hybrid antenna (combination of the modified annular ring printed line and CDRA) is taken into account for achieving dual band characteristics. Orthogonally placed antenna elements and a narrow slit in the ground plane are used to improve isolation (|S12| < −20 dB) in the entire operating frequency range. The antenna prototype is fabricated and measured for validating the simulated results. The proposed MIMO radiator is operating over two frequency bands, i.e. 1.75–2.4 and 3.5–5.5 GHz. Different MIMO diversity performance parameters (envelope correlation coefficient, diversity gain, mean effective gain, total active reflection coefficient, and channel capacity loss) are also inspected and found within acceptable limits.

A broadband high-transmission gradient phase discontinuity metasurface

Metasurfaces have attracted significant attention due to the control of the electromagnetic waves that they enable. In this paper, we demonstrate a high-transmission gradient phase discontinuity metasurface composed of metallic rods and cylindrical dielectric resonators operating at a broadband microwave frequency from 8 GHz to 9.8 GHz, with a fractional bandwidth of 20.2%. The proposed gradient phase discontinuity metasurface can achieve complete 2π transmission phase coverage with π/4 phase intervals by varying the geometric parameters of the dielectric resonators and metallic rods. It is shown that the proposed metasurface can refract a normally incident plane wave to an angle of 30°. The broadband metasurface is flexible, and the refracted angle can be adjusted easily by varying the lattice constant. Besides the broadband anomalous refraction, we also demonstrate the metasurface can produce an interesting vortex and wave-focusing in the wide frequency range from 8 GHz to 9.8 GHz. Finally, we demonstrate that the present metasurface can tailor interference wavefronts to plane wavefronts.

Dual-band multiple-input multiple-output antenna based on half split cylindrical dielectric resonator

In this article, a dual-band half split cylindrical dielectric resonator antenna is proposed for multiple-input multiple-output (MIMO) applications. The dual-band operation is achieved by simultaneously exciting and modes in an aperture coupled fed half split cylindrical dielectric resonator. The topology of four element MIMO antenna is such that it provides both spatial and polarization diversities. Over both the operating bands, the measured port-to-port isolation is better than 20 dB. The proposed antenna exhibits broadside radiation with cross polarization level below dB in both xz- and yz-plane. The peak gain of antenna is 4.88 and 5.32 dBi at lower and upper operating frequency, respectively. The MIMO performance of the proposed antenna is found to be good with ECC0.06. Moreover, the channel capacity of the proposed MIMO is near to uncorrelated case for uniform propagation scenario. The proposed antenna could be suitable for LTE 22/LTE 42 and WLAN applications.

Dielectric resonator based circularly polarized MIMO antenna with polarization diversity

AbstractIn this article, a dual sense dual port circularly polarized cylindrical dielectric resonator antenna (CDRA) is discussed for multiple input multiple output (MIMO) applications. Three exclusive features of the proposed radiator are (i) modified circule‐shaped aperture generates circular polarization for both the ports; (ii) proposed structure can generate left‐hand circular polarization (LHCP) and right‐hand circular polarization (RHCP) that depends on feed port selection; (iii) by introducing the concept of polarization diversity (LHCP/RHCP) and defected ground structure (DGS) between the two radiator, isolation is improved. A prototype of proposed radiator is fabricated and experimentally tested to authenticate the simulated results. The fractional impedance bandwidth for port 1 and port 2 is 15.1% and 14.9%, respectively. Within the targeted operating band, the isolation is better than −25 dB between the ports. Different diversity performance parameters are also calculated and they are also lie within their optimum limit. The proposed MIMO antenna is suitable for WLAN (5.5/5.8 GHz) applications.

Differential‐fed printed monopole antenna loaded with half cylindrical DR for UWB handheld device application

AbstractLoaded with dielectric resonator (DR), a differential‐fed printed monopole antenna is proposed and investigated. Consisting of a half sector cylindrical DR and a two‐layer dielectric substrate, the antenna has a pair of differential‐fed monopoles acting as radiator as well as feeding network for the DR. When the DR is loaded, the differential reflection coefficient bandwidth is improved from 52.95% to 115.4%. Moreover, different from the traditional antenna, cross polarization of the antenna can radiate in co‐polarization null radiation pattern regions in E‐plane. So, cross polarization and co‐polarization can together radiate omnidirectional patterns in E‐plane, which indicates that the antenna can be used as handheld device to receive signals efficiently.

Magnetodynamic Study of Spin Resonances in Cylindrical and Spherical YIG Samples

Rigorous magnetodynamic (MD) study presented in this paper reveals what seems to be the real nature of ferromagnetic resonances occurring in gyromagnetic samples situated in larger resonant cavities. Experiments were performed with cylindrical and spherical YIG samples inserted into either cylindrical dielectric resonator or typical rectangular cavity. It is shown that the dominant mode present in the YIG sample, which was identified as the $\text {HE}_{111}^{+}$ mode, satisfies the magnetic plasmon resonance condition defined by the effective permeability ${\mu }_{r}\approx {-1}$ for cylindrical samples or ${\mu }_{r}\approx {-2}$ for spherical samples. Experiments confirmed the existence of surface resonances, identified as magnetic plasmons, and volume resonances. Comparison between the MD model, the quasi-magnetostatic model, and the perturbation theory was performed and limitations of the approximate approaches are shown.

High-quality trapped modes in all-dielectric metamaterials.

A planar all-dielectric metamaterial made of a double-periodic lattice whose unit cell consists of a single subwavelength dielectric particle having the form of a disk possessing a penetrating hole is considered. The resonant states in the transmitted spectra of the metamaterial are identified considering modes inherent to the individual cylindrical dielectric resonator. A correlation between the asymmetry in the particle's geometry, which arises from the off-centered displacement of the hole and the formation of the Mie-type and trapped modes, is established. The advantages of using a coaxial-sector notch instead of a round hole for the trapped mode excitation are explained.