Dual band dielectric resonator antenna for wireless application

The proposed technique combines a slot antenna and a dielectric resonator antenna (DRA) to effectively design a dual band dielectric resonant antenna without compromising miniaturization or its efficiency. It is observed that the resonance of the slot and that of the dielectric structure merged to achieve extremely wide bandwidth over which the antenna polarization and radiation pattern are preserved. Here the effect of slot size on the radiation performance of the DRA is studied. The antenna structure is simulated using two simulators (Ansoft HFSS and CST-Studio software). The simulated results are presented and compared with the measured results. This DRA has a gain of 6 dBi and 5.5 dBi at 6.1 and 8.3 GHz, respectively, 10 dB return impedance bandwidth of nearly 4% and 6% at two resonating frequencies and 98% efficiency has been achieved from the configuration. It is shown that the size of the slot can significantly affect the radiation properties of the DRA, and there are good agreements between simulation and measured results.

A new dual band dielectric resonator antenna (DRA) for WLAN band is presented. The DRA is excited by a vertical strip attached to the DRA, which is connected to a 50 Ω microstrip line on a defected ground plane. The deformed ground plane has a conducting strip under the DRA that cause the first resonance at 2.4 GHz. The second band is wide with 44% bandwidth between 5 to 8 GHz due to the dielectric resonator and the vertical strip excitation.

There are many commercial applications, such as mobile radio and wireless communications that use microstrip antennas. Microstrip antennas however have limitations in size, bandwidth, and efficiency. On the other hand, the dielectric resonator (DR) antenna is attractive due to its small-size, high radiation efficient, and ease of excitation.[1-3] Three dielectric properties of materials must be considered for DR antenna used: a high permittivity, a high quality factor, and a near zero temperature coefficient of resonant frequency. The size of the DR antenna decreases with increasing the permittivity of the dielectric resonator. The quality factor is representative of the antenna losses. Typically there are radiation, conduction, dielectric, and surface wave losses. Therefore the total quality factor is influenced by these losses. The DR antenna offers very high radiation efficiency due to its low dielectric loss and it has no metallic loss. A near zero temperature coefficient of resonant frequency are for high temperature stability. In traditionally, the DR with relatively small permittivity around 10 is chosen for DR antenna to enhance the radiation capability.[4-10] However, low profile DR antenna with relatively low resonant frequency can be achieved by using high permittivity. Recently, dual band antenna has been implemented for applications in WLAN (wireless local area network, 2.4–2.484 GHz), ISM (Industrial, Scientific, Medical) and Bluetooth at low band. Additionally, the dual band antenna can be applied at high band, such as HIPERLAN (high-performance radio local area network, 5.15–5.35 GHz) and Unlicensed National Information Infrastructure (UNNI) applied. In this paper, we present the design of a dual band hybrid antenna consists of a rectangular slot and a circular disk high permittivity dielectric resonator for operating at the ISM band and UNNI band. Details of the proposed antenna and experimental results are present. The characteristics of dual band hybrid antenna, such as return loss, input impedance, radiation pattern, and gain, have been measured and discussed.

Design of the wide dual-band rectangular souvenir dielectric resonator antenna (DRA) is discussed. The proposed wide dual-band rectangular DRA was excited by using a U-slot. The $TE_{111}{^{\mathrm {y}}}$ mode of the rectangular DRA and the slot resonator were employed to design the lower band, while the higher-order $TE_{113}{^{\mathrm {y}}}$ and $TE_{311}{^{\mathrm {y}}}$ modes were utilized to design the upper band. By merging two pairs of modes in each band, the impedance bandwidth of the lower and upper bands were enhanced simultaneously. New design formulas that determine the dimensions of the wide dual-band rectangular DRA were obtained. Design guideline was also given to facilitate the design. To demonstrate the usefulness of the formulas, a wide dual-band rectangular DRA fabricated using K-9 glass was designed for 2.4/5.2-GHz WLAN applications. To upgrade the antenna as the souvenir-DRA, the word “LOVE” was carved on the sidewall of the glass DRA by using the sandblasting machine, and it was found that the content and position of the word has little effect on the antenna performance. The impedance bandwidths of the proposed wide dual-band DRA can be achieved as ~25% for the lower band and ~13% for the upper band.

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.

A novel dual-band dielectric resonator antenna(DRA) with dual-polarization is presented in this paper. It consists of a dielectric resonator, a square ground and a well designed feeding network. This antenna makes use of HEM111 mode and HEM113 mode to realize dual-band characteristics. Dual polarization is realized by exciting two orthogonal ports, and the port isolation is better than 65dB over the band of interest. For each port, the −10 dB impedance bandwidth of the lower and upper bands are given by 1.83–1.99GHz and 2.58–2.63GHz respectively. It can also achieve a peak gain of 6.5dB at the upper hemisphere for both modes.

A new decoupling method is proposed in this article, which simultaneously realizes port and radiation pattern decoupling, namely, high isolation and undistorted radiation patterns, respectively. The proposed decoupling method shows its effectiveness in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 2$ </tex-math></inline-formula> dielectric resonator (DR) antennas (DRAs) even with zero spacing. Conformal strips are attached to the sidewall of the DRs and parallel to the E-plane of the DRAs. Coupled from the resonant DR, the conformal strips can generate an induced current, thus forming an induced field inside the DR. It can be noted that, inside the two DRs, the DR resonant field and the strip induced field are antiphase and in-phase, respectively. Tuning the conformal strips can change the amplitude ratio and phase difference between the resonant and induced fields, which can be used to cancel the fields inside the DR based on the superposition principle. When one DR is excited, the field inside the other DR can be very weak. The DRs can then work at their fundamental TE <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\delta 11}$ </tex-math></inline-formula> modes independently. Therefore, their radiation patterns are not distorted together with high port isolation. A new indicator, energy storage proportion (ESP), is proposed to evaluate the decoupling effect. It can be found that, when the ESP gets close to 1, the radiation patterns will be restored together with high isolation. To verify the idea, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 2$ </tex-math></inline-formula> DRAs are designed, fabricated, and measured. A reasonable agreement can be observed between the measured and simulated results for both H- and E-plane decoupled cases. All the measured overlapping impedance bandwidths are larger than 6%, the envelope correlation coefficients are lower than 0.059, and the isolations are higher than 20 dB. It should be highlighted that all the radiation patterns in this article have been restored, useful for practical applications using multiple-input multiple-output techniques.

A three-dimensional (3-D)-printed dual-fed dual-frequency dielectric antenna is investigated for vehicular communications. It combines a dielectric resonator (DR) antenna (DRA) and a dielectric lens antenna (DLA) for the low and high frequency bands, respectively. Both of the antenna parts share the same dielectric body that has three different effective dielectric constants. The DRA is excited by a vertical conducting adhesive strip on its sidewall, whereas the DLA is fed by a separate embedded slot-coupled cylindrical DRA. To verify the idea, a dual-frequency dielectric antenna operating at <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> - and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -bands is designed and fabricated with a 3-D printer. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> -parameters, radiation patterns, antenna gains, and antenna efficiencies of the two antenna parts are measured, and reasonable agreement between the measured and simulated results is found. The prototype has wide measured <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> - and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -band 10-dB impedance bandwidths of 40.2% and 19.5%, respectively. Also, its measured isolation between the two ports is desirably over 40 dB across the two bands. The measured peak antenna gains are given by 5.8 and 12.0 dBi in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> - and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -bands, which are suitable for short-distance vehicle-to-basestation and long-distance vehicle-to-satellite communications, respectively.

The goal of this study is to improve the bandwidth of a miniaturized antenna. The proposed technique combines a slot antenna and a dielectric resonator antenna (DRA) to effectively double the available bandwidth without compromising miniaturization or efficiency. With proper design it is observed that the resonance of the slot and that of the dielectric structure itself may be merged to achieve extremely wide bandwidth over which the antenna polarization and radiation pattern are preserved. In addition, using the DRA, a volumetric source, improves the radiation power factor of the radiating slot. A miniaturized antenna figure of merit (MAFM) is defined to simultaneously quantify aspects of miniaturized antenna performance including the degree of miniaturization, efficiency, and bandwidth. Figures for various common types of antennas are given and compared with that of the proposed structures. In order to determine the effects of varying design parameters on bandwidth and matching, sensitivity analysis is carried out using the finite-difference time-domain method. Numerous designs for miniaturized slot-fed dielectric resonator antennas are simulated and bandwidths exceeding 25% are achieved. Two 2.4 GHz antennas are built, characterized, and the results compared with theory.

High profile rectangular dielectric resonator antennas (RDRAs) with length to height ratio of two or less are not suitable for low profile applications because of low usable bandwidth and poor gain of the RDRAs. This paper presents an improvement in the useable bandwidth and gain of the RDRAs using an horn mounted on the RDRA. The horn is fabricated with plastic sheet and painted with silver epoxy. It is observed that the RDRA mounted with horn achieves almost 100 % greater gain than that of RDRA without horn at the resonating frequencies and that too with good return loss. It is also observed that the impedance bandwidth is increased slightly. The simulation results show that the gain achieved using RDRA mounted with horn is 13.53 and 12.85 dBi while the 10 dB return impedance bandwidth is 4.4 and 5.9 % at 5.7 and 8.1 GHz respectively.

The antennas for wireless communication devices have undergone a tremendous expansion from the external monoband resonant antenna to the internal non-resonant multi-band antenna. In this paper, a dual-band dielectric resonator antenna for high-speed applications is proposed. Due to the complex edge-shaped boundary between the dielectric and air in a rectangular dielectric resonator antenna, a complex closed form of expression is difficult to achieve. To address this problem a half-cut cylinder is placed over the rectangular dielectric to achieve excellent radiation characteristics. This proposed antenna provides a wide dual-band response with fractional impedance bandwidth of 21.92% and 19.09%while operating from7.32 GHz to 9.12 GHz and 10.71 GHz to 12.95 GHz. It provides an average gain of 3dBi with high gain stability in the entire operating frequency band. The radiation efficiency is found to be 96% due to low ohmic and dielectric losses. The cross-polarization is around 20 dB lesser than the co-polarization. Its gain and directivity can further be enhanced by implementing serial and parallel array structures. This design uses HFSS 14.0 commercial electromagnetic simulation tools.

To realize dual frequency service for WLAN applications, a mixed breed double band dielectric resonator antenna with parasitic opening encouraged by microstrip feed line is proposed. The recommended radio wire configuration contained circular dielectric resonator and U — space resonator. The U — space is composed on the ground plane of dielectric resonator antenna (DRA). By regulating design parameters, the circular dielectric resonator engage at upper band (5.6 GHz) and U — space slot engage at secondary band (2.4 GHz), the pair of resonators are diverging with two distinct radiation designs. In order to resolve the exploit of the recommended design, the practical parameters being return loss transmission capacity, voltage standing wave ratio and radiation designs are seen by the simulation of configuration with high frequency structure simulator (HFSS). The recommended antenna model is reasonable for WLAN applications.

A wideband low-profile connected rectangular ring dielectric resonator (DR) antenna (DRA) array is presented for millimeter-wave (mmWave) applications. It consists of four rectangular ring DRA elements. The DRA elements are excited by microstrip feedlines through four slots on the ground plane. A slot mode, the DRA <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm {TE}}^{\text {y}}_{1\delta 1}$ </tex-math></inline-formula> mode, and the perturbed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm {TE}}^{\text {y}}_{3\delta 1}$ </tex-math></inline-formula> mode are simultaneously excited, giving a wideband design. To avoid the alignment problem, the DRAs are connected to their adjacent elements through dielectric arms. It is found that the position of the dielectric arms has significant effects on the antenna performance. To demonstrate the idea, a prototype with a dielectric constant of 20.8 was designed, fabricated, and tested for licensed mmWave bands (24.25–29.5 GHz). A reasonable agreement between the measured and simulated results is observed. The measured 10 dB impedance bandwidth ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert \text{S}_{11}\vert \le - 10$ </tex-math></inline-formula> dB) is 31.6% (22.52–30.97 GHz), with a measured boresight realized gain being higher than 8 dBi from 22.5 to 30 GHz. The measured mutual couplings between the DRA elements of the array are lower than −20 dB in the operating frequency range. Furthermore, our prototype has a low profile of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.074~\lambda _{0}$ </tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the wavelength in air at the center frequency.

In this paper, a dual-band triangular dielectric resonator antenna (DRA) array is presented for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. Here, two triangular dielectric resonators are used as an array. The DRA array is excited by conformal strip connected to microstrip line which is an effective feed mechanism to obtain dual-band operation. Simulation process was done by using a CST microwave studio. The result shows that the proposed antenna achieves an impedance bandwidth from 3.35 to 3.70 GHz and 4.52 to 5.34 GHz covering 3.5 GHz WiMAX band and 5.2 GHz WLAN band. Parametric studies are carried out by varying the heights of the triangular shaped dielectric resonators and conformal strips. Simulated results show that DRA array has a better resonant frequency for DR height, h <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> = 11.5 mm and conformal strip height h <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> =10.4 mm. The average peak gain achieved is 7.02 dBi and 8.9 dBi at 3.5 GHz and 5.2 GHz respectively and directivity varies from 6.06 dBi to 9.26 dBi for overall frequency range. The proposed design can also be used for HIPERLAN (high-performance radio LAN) applications which operate at 5.15 GHz to 5.30 GHz. With these features, this design of triangular DRA array is suitable for dual-band wireless communication systems.

Dielectric resonator (DR) antenna (DRA) has been studied for decades, for its compact size, various radiation modes and radiation patterns, high efficiency, high design flexibility, and so on. As a fabrication‐friendly shape, cylindrical DRA is investigated in this chapter. To begin, the fundamentals of cylindrical DRA have been introduced first, including its mode nomenclature, resonant frequency calculation, field distribution, and various excitation methods. Especially, two kinds of planar feeding methods for exciting TM modes of a cylindrical DRA were developed recently and introduced. Researchers all over the world are exploring the diversity potential of DRA, including pattern diversity. However, it can be found that the resonant frequencies of the and modes cannot coincide, implying there are theoretical limitations for pattern‐diversity designs using fundamental modes. In this chapter, two pattern‐diversity designs are presented with the fundamental modes. The first wideband design uses a cylindrical DRA with a centrally loaded high‐permittivity material. This kind of material can lengthen the electrical length of the mode and therefore lower its resonant frequency. At the same time, the resonant frequency of the mode can be affected little. This design features an overlapping impedance bandwidth of 23.6%. For the latter compact design, a meanderline‐loaded ring slot is employed to excite the mode. By lengthening the current paths on the ground plane with the meander lines, the resonant frequency of the mode can be reduced, whereas that of the mode can be found to be unchanged. This compact design has a volume of and a profile of , where is the resonant wavelength in the dielectric. Both of the designs have low envelope correlation coefficients (ECCs), proving to be good diversity antennas.