Rectangular Dielectric Resonator Antenna Research Articles

Circularly polarized rectangular dielectric resonator antenna fed with unequal parallel microstrip lines for Wi‐MAX applications

ABSTRACTIn this article, a circularly polarized rectangular dielectric resonator antenna (RDRA) is proposed for Wi‐MAX applications. Unequal parallel Microstrip lines are used as feed circuit. In the proposed structure fundamental mode similar to TE111 polarized in two orthogonal directions to generate orthogonal modes are generated. The proposed structure shows measured input impedance bandwidth (S11 < −10 dB) and axial ratio (AR < 3 dB) of 23.8% (at center frequency 3.31 GHz) and 9.2% (at center frequency 3.46 GHz), respectively. It exhibits excellent radiation pattern and average gain of 5.5 dB in working frequency range. The proposed design is suitable for Wi‐MAX applications (3.3–3.7 GHz). Radiation efficiency over 95% (3.3–3.6 GHz) is achieved in the proposed structure. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:1182–1188, 2017

Wideband circularly polarized dielectric resonator antenna coupled with meandered-line inductor for ISM/WLAN applications

A new meandered-line inductor fed wideband circularly polarized rectangular dielectric resonator antenna (DRA) with partial ground plane has been developed in this work. Meandered-line inductor feed and partial ground plane are used for generation of orthogonal modes, hence circular polarization (CP) in DRA. By controlling the length of meandered-line inductor, three different CP DRA have been designed for different wireless applications such as Wi-MAX and WLAN/ISM 2400 band. Distribution of electric field inside rectangular DRA shows that all three antenna having TE11δ mode. Finally, a lower frequency band application at 2.4 GHz (ISM) called here as Proposed Antenna, has been considered for fabrication. This designed antenna shows measured −10 dB input impedance bandwidth of 20.67% and 3-dB axial ratio bandwidth of 27.95% in broadside direction. All these three CP antennas (Antenna-1 to Proposed Antenna) are showing stable gain and right hand circular polarization in broadside direction.

Design of Planar Dielectric Resonator Antenna Array at 28 GHz

<p>This article presents a planar array of rectangular Dielectric Resonator Antenna operating for 28 GHz applications. The proposed antenna is formed through two stages of designs which are a single element and planar array. It is made up from a ceramic material with a dielectric constant of 10 and mounted on RT/Duroid 5880 with a relative permittivity of 2.2 and a thickness of 0.254 mm. A prospective study using three different configurations of three by three planar array is done in order to obtain the best performance in terms of bandwidth, gain, and cost reduction. Besides that, this study is also conducted for a beam steering capability of each configuration. Finally, the best configuration is proposed for 5G application.</p>

Design and development of wideband RDRA FED with parallel conducting strips chamfered at edges separated by partial matching slab

ABSTRACTIn this article, a compact wideband rectangular dielectric antenna fed using parallel standing strips chamfered at the edges with partial dielectric matching slab is proposed for upper C‐band and X‐band applications. Inclusion of the external conducting strip helps in reducing the size of the DRA, facilitates greater ease of fabrication, and helps in shifting the resonant frequency without varying the size of the DRA. Also chamfering the edges of the conducting strips eradicates the discontinuities in the reactance and thus enhances the bandwidth by 10–12%. Two DRAs with dimensions 4.8 mm × 9.6 mm × 10.6 mm were fabricated. The designed antenna has the broad bandwidth ranging from 6.5 to 13.1 GHz. The proposed antenna has the return loss of −45 dB at 7.0 GHz and the impedance bandwidth up to 75% is achieved. The low value of VSWR suggests that the antenna is broadly lossless. Moreover, a comparison with the DRA fed without the partial conducting strip shows that the size of the DRA is reduced considerably around 25%. A parametric study of the variation with external partial conducting strip and internal conducting strip is also carried out. The measured results and the simulated results of the proposed RDRA (Rectangular Dielectric Resonator Antenna) match considerably well with each other. The proposed antenna has an omni‐directional broadband pattern having the gain of 6.0 dBi. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:695–698, 2017

Throughput Measurement of a Dual-Band MIMO Rectangular Dielectric Resonator Antenna for LTE Applications.

An L-shaped dual-band multiple-input multiple-output (MIMO) rectangular dielectric resonator antenna (RDRA) for long term evolution (LTE) applications is proposed. The presented antenna can transmit and receive information independently using fundamental TE111 and higher order TE121 modes of the DRA. TE111 degenerate mode covers LTE band 2 (1.85–1.99 GHz), 3 (1.71–1.88 GHz), and 9 (1.7499–1.7849 GHz) at fr = 1.8 GHz whereas TE121 covers LTE band 7 (2.5–2.69 GHz) at fr = 2.6 GHz, respectively. An efficient design method has been used to reduce mutual coupling between ports by changing the effective permittivity values of DRA by introducing a cylindrical air-gap at an optimal position in the dielectric resonator. This air-gap along with matching strips at the corners of the dielectric resonator keeps the isolation at a value more than 17 dB at both the bands. The diversity performance has also been evaluated by calculating the envelope correlation coefficient, diversity gain, and mean effective gain of the proposed design. MIMO performance has been evaluated by measuring the throughput of the proposed MIMO antenna. Experimental results successfully validate the presented design methodology in this work.

Simple procedure to evaluate singularity free expressions for radiation patterns of an antenna with rectilinear symmetry

An efficient, simple technique is demonstrated here to find a singularity free analytic solution for the far-field radiation patterns of an antenna with rectilinear symmetry. Closed form singularity free expressions are given for the rectangular slot antenna, rectangular microstrip antenna, rectangular dielectric resonator antenna, equilateral triangular microstrip antenna (ETMA) and TMAs. Theoretical results are verified with measured data as found in the published literature. It is found that one can easily avoid singularities and complex mathematical calculations for the far-field radiation patterns by applying this novel technique. This procedure is also applied here to evaluate certain types of complex integrals which are essential to evaluate conductor loss and stored energy within a cavity, waveguide and antenna. Typical results are shown for ETMA where 18 numbers of integrals are replaced by a single integration. Theoretical results are verified by numerical integration using the inbuilt function of MATLAB®. Therefore, it is concluded that this novel technique can efficiently be utilized (i) to give singularity free expressions for the far-field radiation patterns (ii) to reduce unnecessary, time consuming mathematical processing (iii) to provide a much more efficient analysis than these offered by the commercial numerical simulator.

An Investigation of Resonant Modes in Rectangular Dielectric Resonator Antenna Using Transcendental Equation

This article presents an analysis of resonant modes in a rectangular dielectric resonator antenna and investigates the generation of higher order modes. Mathematical analysis of resonant frequency and transcendental equation using MATLAB has been performed. A prototype model for rectangular DRA has been developed. Resonant frequency of higher modes based on delta (ź) variation (where delta = 0.1---0.9) on Eigen vector has been investigated. The paper demonstrates that the design of a compact size dielectric resonator antenna (DRA) covering wide range of frequency with multiple modes is possible by selecting the value of p less than 1 (p < 1), where p is number of half-wave variations in the z-direction of TEmnp modes. An orthogonal feed has been used to cancel out the undesired modes. Simulations and experimental measurements were carried out to verify the proposed idea. Theoretical, simulated, and experimental results of resonant frequency and gain of the antenna have been compared and are found to be in agreement with each other. The results presented should have useful potential applications in wireless communication systems and satellite applications.

Theoretical and Experimental Investigations on Rectangular Dielectric Resonator Antenna Array for Radar and Satellite Application

ABSTRACTIn this article, the theoretical, simulation, and experimental study of high gain dual segment 4-element linear broadside rectangular dielectric resonator antenna array shaping the -field components with copper sheet on one side, has been carried out. Copper strip connected to microstripline is introduced to excite the proposed dielectric resonator antenna array to achieve the coupling for dielectric resonator material with lower dielectric constant (≤10). Proposed antenna array with copper strip excitation has been successfully fabricated and tested. The voltage standing wave ratio, gain, and radiation characteristics of the proposed array have been explored using Ansoft HFSS 15.0 simulation software. Antenna array is also investigated using the finite-difference time-domain numerical technique. Good agreement between the simulated, calculated, and measured results is obtained. High gain and appreciable bandwidth together with low cross polarization is always defiance for researchers. The gain of the proposed array has been raised by a factor of 6.05, compared with the gain of a single dielectric resonator antenna. The proposed antenna provides a high gain of 10.50 dBi with a medium bandwidth of 512 MHz (3.44–3.95 GHz) and low cross-polarization, which is definitely better than previous reported literatures. The proposed structure is a good substitute to patch antennas in array applications as it offers high gain, medium bandwidth, and nice impedance matching. However, one disadvantage compared to microstrip arrays is the added fabrication complexity involved in having to place and bond the individual elements. In the future, for mass production applications, this process could be automated using robotic pick-and-place machines.

Dual‐band MIMO dielectric resonator antenna for WiMAX/WLAN applications

In this study, a novel dual-band multiple-input multiple-output (MIMO) rectangular dielectric resonator antenna (DRA) for Worldwide interoperability for microwave access (WiMAX) (3.4–3.7) GHz and wireless local area network (WLAN) (5.15–5.35) GHz applications is proposed and investigated. The design operates at fundamental TEδ11 x, TE1δ1 y and higher order TEδ21 x, TE2δ1 y modes, excited through two coaxial probes, symmetrically placed adjacent to the DRA. A compact design is achieved by stacking a high permittivity material. The obtained impedance bandwidth at 3.6 GHz is 9.97% and at 5.2 GHz is 8.88%. Measured antenna gain through both ports at 3.6 GHz is 5.7 dBi and at 5.2 GHz is 6.61 dBi, respectively. Isolation achieved at 3.6 GHz is −13 dB and at 5.2 GHz is −16 dB, respectively. Co- and cross-polarisation, radiation efficiency, diversity gain, envelope correlation and mean effective gain of the proposed design are measured. Results show that the proposed design is suitable for use in MIMO WiMAX/WLAN applications.

High Gain Rectangular Dielectric Resonator Antenna Using Uniaxial Material at Fundamental Mode

The use of uniaxial anisotropic materials in rectangular dielectric resonator antennas (DRAs) increases the radiation from their side walls compared to their top walls due to the fundamental radiating mode, which leads to the improvement of boresight directivity. The different boundary conditions on the walls of DRA are also investigated. The main phenomenon of gain enhancement is also theoretically explained. The proposed method is validated by comparing the simulation results for the cases of isotropic DRAs and anisotropic DRAs (ADRAs). The measured results for an aperture-coupled uniaxial ADRA show an impedance bandwidth of 20.65% between 3.17 and 3.9 GHz and a peak broadside gain of 8.4 dB.

Differentially Fed Wideband Rectangular DRA with High Gain using Short Horn

A differentially fed rectangular dielectric resonator antenna (DRA) is presented. The DRA is excited by a microstrip gap between two identical transmission lines carrying a differential signal. It is shown that this new method can be adopted to excite the fundamental TE1δ1 mode in a rectangular DRA. Furthermore, by adding a stub to each transmission line, an additional nonradiating resonance is obtained that results in bandwidth enhancement. A conventional hybrid (rat-race) coupler is used for a single-end operation. A common ground plane is shared between the DRA (placed in + z -plane) and the hybrid coupler (placed in –z -plane) to preserve the footprint of the antenna. For | S 11| ≤ –10 dB, a wide impedance bandwidth of 30% is measured from 2.27 to 3.07 GHz. Additionally, a surface-mounted short horn (SMSH) is incorporated to enhance the boresight gain throughout the band. In measurements, an optimum boresight gain of 12.2 dBi with an improvement of 5.8 dB is obtained at 2.6 GHz using the proposed DRA with SMSH.

Gain Improvement of Rectangular Dielectric Resonator Antenna by Engraving Grooves on Its Side Walls

A new technique for increasing the boresight gain of a rectangular dielectric resonator antenna (DRA) operating at its fundamental radiating $TE_{111}^y$ mode is introduced. The idea is to increase the radiations from the side walls of the DRA compared to that of its top wall by engraving grooves on the side walls. A model based on the array theory is developed to explain the high-gain nature of the antenna. The measured results demonstrate that the proposed antenna achieves an impedance bandwidth of 21% over a band of 3.24–4 GHz, with a maximum gain of 9.6 dB. This is significantly higher with respect to available data in the literature.

Circularly Polarized Dielectric Resonator Antenna Arrays with Fractal Cross-Slot-Coupled DRA Elements

In the design of circularly polarized (CP) dielectric resonator antenna (DRA) arrays, the regular-shaped DRAs with simple feeding configurations are mostly used as array elements to make the design procedure more efficient. However, such array element DRA usually achieves only about 6% axial ratio (AR) bandwidth. In this paper, a CP DRA element coupled by a fractal cross-slot which can radiate efficiently and excite the rectangular DRA simultaneously is considered. By adjusting the dimensions of the fractal cross-slot properly, the resonances of the fractal cross-slot and the dielectric resonator can be merged to obtain a wider AR bandwidth. Based on the proposed fractal cross-slot-coupled CP DRA element, two different CP DRA arrays are designed: a wideband CP DRA array and a low-sidelobe-level (SLL) CP DRA array. The designed DRA arrays are fabricated and measured, and structures and performances of the arrays are presented and discussed.

Compact wideband circularly polarised dielectric resonator antenna

A new geometry of compact wideband/dual-band circularly polarised dielectric resonator antenna (DRA) is presented. First, a wideband DRA is realised by a rectangular dielectric resonator excited by a vertical coaxial probe feed which is supported by a small substrate. Circular polarisation is achieved by utilising a configuration of the DRA feed that excites orthogonal modes inside the DRA. A 3 dB axial-ratio bandwidth of about 20.8% (9.05-11.14 GHz) is achieved. Second, extension to dual-band circularly polarised operation is then realised by additionally removing a corner of the rectangular DRA at 45° and adding a floating parasitic strip. The experimental results demonstrate an impedance bandwidth of about 59.8% (6.57-12.18 GHz) and the dual 3 dB axial-ratio bandwidths of about 10.6% (8.31-9.24 GHz) and 13.5% (10.18-11.66 GHz). The measured peak gain varies from 4.47 to 4.86 dBiC in the lower band and 4.33 to 4.91 dBiC in the upper band.

Dual‐band mimo rectangular dielectric resonator antenna with high port isolation for LTE applications

ABSTRACTA novel dual‐band dual‐polarized rectangular dielectric resonator antennas (DRA) for long term evolution (LTE) is described and fabricated. It covers LTE band 11 (1.43–1.50) GHz at low frequency and LTE band 7 (2.50–2.69) GHz at high frequency. The isolation between two antenna ports is more than 23 dB and 32 dB at 1.45 GHz and 2.6 GHz respectively. A u‐shaped and a rectangular ground planes have been used above and below the substrate to achieve high isolation. DRA is excited through a coaxial probe and a rectangular slot. The proposed antenna can transmit and receive information independently using fundamental and higher order modes of DRA. Scalable behavior and frequency ratio has also been investigated in this work Results of Co and Cross‐polarization, envelop correlation coefficient and diversity shows that the proposed design is suitable for MIMO LTE applications. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:44–49, 2017

Compact uniaxial anisotropic dielectric resonator antenna operating at higher order radiating mode

A compact, wideband and high gain anisotropic rectangular dielectric resonator antenna is reported. This antenna consists of a multilayer dielectric structure which emulates uniaxial anisotropy and a relatively tall feed probe that acts both as a perfect electric conductor symmetry plane and the excitation of the higher order radiating mode. The multilayer structure and the tall feed probe are responsible for producing wide impedance bandwidth and size reduction, respectively. Measured results indicate that more than 50% size reduction is achieved without complicating the dielectric resonator antennas structure. Moreover, a wide impedance bandwidth of 19.4% along with a maximum gain of 8.1 dB is measured.

A Compact Filtering Dielectric Resonator Antenna With Wide Bandwidth and High Gain

A rectangular filtering dielectric resonator antenna (FDRA) with low profile, wide bandwidth, and high gain is first investigated in this communication. It is fed by a microstrip-coupled slot from bottom, with open stub of the microstrip feedline elaborately designed to provide two radiation nulls at band edges for a filtering function. A separation is introduced in the slot to provide a good suppression level in lower stopband, while two parasitic strips are parallelly added to the microstrip feedline to offer good suppression in the upper stopband, and consequently, a compact FDRA with a quasi-elliptic bandpass response is obtained without involving specific filtering circuits. Based on the design, a modified DRA fed by a pair of separated slots is proposed to further enhance the gain by $\sim 4$ dB. A prototype operating at 5 GHz has been fabricated and measured for demonstration. The reflection coefficient, the radiation pattern, and the antenna gain are studied, and reasonable agreement between the measured and simulated results is observed. The prototype has a 10-dB impedance bandwidth of 20.3%, an average gain of 9.05 dBi within passband, and an out-of-band suppression level of more than 25 dB within a wide stopband.

Wideband circularly polarized rectangular DRA fed with dual pair of right-angled microstrip line

In this article, design and development of wideband circularly polarized CP rectangular dielectric resonator antenna RDRA is presented. To generate wideband CP in proposed antenna, different feeding mechanism have been studied. Three antenna configurations based on different feeding have been discussed using single and dual pair of microstrip lines aligned perpendicular to each other to generate orthogonal modes resulting in circular polarization. It has been claimed here that excitation of RHCP/LHCP field and its direction of radiation could be controlled using height of microstrip feed lines. Finally antenna configuration-3 is fabricated and measured which shows 36.8% of input impedance bandwidth 3.48-5.05 GHz and axial ratio bandwidth of 14.46% 3.67-4.24 GHz in broadside direction at i¾?=0i¾?, i¾?=0i¾?. The final proposed structure exhibits consistent far-field characteristics with average LHCP gain of 6.4 dB and almost stable radiation efficiency in entire operational frequency range. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:713-723, 2016.

Investigation of dual-band omnidirectional rectangular dielectric resonator antenna

A dual-band omnidirectional rectangular dielectric resonator antenna (DRA) is presented in this paper. Higher order and modes of a rectangular DRA with square cross section are used to realize dual-band omnidirectional operation. Working principle of using modes for omnidirectional pattern is explained based on dielectric waveguide model (DWM) method. Frequency ratio of the two bands for different dimensions and permittivities is studied. A prototype antenna for 3.5-GHz WiMAX and 5.8-GHz WLAN bands was designed, fabricated, and measured. Proposed design concept is verified by the simulated and measured results.

Direct microstrip line-fed dielectric resonator antenna array

In this paper, a 1×4 rectangular dielectric resonator antenna array is designed using direct microstrip lines at the center frequency of 6.7 GHz for obtaining higher directive gain. A prototype has been fabricated with Arlon AD270 substrate and experimental measurements have been carried out. The array offers an impedance bandwidth of 9.6% and a maximum gain of 11.8 dBi at the operating frequency. A close agreement between simulated and measured results has been obtained.