Resonator Antenna Research Articles

A novel single‐feed filtering dielectric resonator antenna using slotline‐loaded coupling structure

AbstractThis paper proposes a novel single‐feed filtering dielectric resonator antenna (FDRA) using fusion design method and the microstrip‐slot coupled feeding structure. Two pairs of slotlines are elaborately designed and perpendicularly loaded on the coupling slot to provide two radiation nulls at the edges of the passband. Therefore, a compact DRA with a quasi‐elliptic function bandpass response is constructed without extra filter circuits. Furthermore, two radiation nulls can be individually controlled through changing the length of the corresponding slotlines. For proving the effectiveness of the design, a prototype FDRA operation at 3.45 GHz is fabricated and measured. The measured results show that the peak realized gain is 5.84 dBi and the ‐10dB impedance bandwidth is 10.29% (3.29 ‐ 3.65 GHz). The proposed FDRA not only has good performance, but also has simple design.

Analysis Method of Bending Effect on Transmission Characteristics of Ultra-Low-Profile Rectangular Microstrip Antenna.

With the advent of wearable communication devices, microstrip antennas have developed multiple applications due to their ultra-low-profile properties. Therefore, it is essential to analyze the problem of frequency shift and impedance mismatch when the antenna is bent. For the case of a rectangular patch antenna E-plane bent on the cylindrical surface, (1) this paper introduces the effective dielectric constant into the cavity model, which can accurately predict the resonance frequency of the antenna, and (2) according to the equivalent circuit model of the antenna resonance mode, the lumped element parameters are calculated based on the above effective dielectric constant, so that impedance characteristics and the S-parameter matching the port can be quickly constructed. From the perspective of circuit frequency characteristics, it explains the change in the transmission performance of the curved antenna. The experimental results show that the maximum difference between the experimental and theoretical calculation frequencies is less than 1%. These results verify the validity and applicability of the theory in the analysis of ultra-low-profile patch antennas and wearable electronic communication devices. It provides a theoretical basis for the fast impedance matching of patch antennas under different working conditions.

Broadband high gain cavity resonator antenna using planar electromagnetic bandgap (EBG) superstrate

AbstractThis paper presents a broadband miniaturized Fabry–Perot cavity resonator antenna (CRA) made of novel electromagnetic bandgap (EBG) superstrate as partially reflecting surface (PRS) and reactive impedance surface (RIS) backed rectangular patch antenna. To the best of the authors' knowledge, the proposed EBG exhibits the highest stopband bandwidth (BW) with a bandgap existing between 7.37 and 12.4 GHz (50.9%). Frequency-selective property of the EBG is utilized under plane wave incidence to demonstrate it as PRS superstrate in CRA antenna. The cavity is excited with a rectangular microstrip antenna which is made of two dielectric substrates with an additional RIS layer sandwiched between them. The RIS provides wideband impedance matching of the primary feed antenna. A 7 × 7 array of the EBG superstrate is loaded over the patch antenna having an overall lateral dimension of only 45 × 45 mm2 or 1.62 λ0 × 1.62 λ0 where λ0 is the free space wavelength at the center frequency of 10.8 GHz. The proposed Fabry–Perot CRA (FP-CRA) achieves gain enhancement of 6.59 dB as compared with the reference antenna and has a 10 dB return loss BW of 23.79% from 10.07 to 12.79 GHz. A prototype of the FP-CRA is fabricated and experimentally tested with single and dual layers of EBG superstrate. Measured results show BWs of 21.5 and 24.8% for the two cases with peak realized gain of 12.05 and 14.3 dBi, respectively. Later a four-element antenna array with corporate feeding is designed as the primary feed of the CRA. The simulation result shows a flat gain of >13 dBi with gain variation <1.2 dB over the impedance BW of 13.2%.

Tunable terahertz dual-band circularly polarized dielectric resonator antenna

A tunable terahertz (THz) dual-band circularly polarized (CP) dielectric resonator (DR) antenna (DRA) is numerically analysed and implemented. Initially, an aperture coupled dual-band rectangular DRA is designed. This operates with the fundamental mode in the lower band and third order mode in the upper band and provides the linearly polarized response. The diagonal corners of the rectangular DR are truncated for obtaining the orthogonal degenerate components of the operating modes and thus the CP response is achieved. The tunability is achieved in the frequency response by applying a monolayer graphene material coating at the radiating surface of the chamfered DR. The antenna offers 10 dB impedance bandwidth of 18.41% (3.21−3.86 THz) and 4.7% (4.77−5.0 THz) along with 3 dB axial ratio bandwidth of 3.48% (3.38−3.5 THz) and 1.39% (4.98−5.05 THz). Furthermore, the proposed tunable dual-band THz CPDRA provides the gain of more than 6 dBic along with the radiation efficiency of more than 95% in each operating band.

High selective parallel‐scheme filtering antenna synthesized by transversal coupling matrix

A novel synthesis method based on transversal coupling matrix for the parallel-scheme filtering antenna with high out-of-band selectivity is proposed. The filtering antenna consists of three resonant radiation elements that are connected to a common feed point. By adopting the parallel scheme, the design of a third-order filtering antenna can be decomposed into three first-order sub filtering antennas. Each resonant antenna element can be separately designed and little adjustment is needed after combining these elements. Given a specification with up to two radiation nulls, the corresponding parameters of the three elements can be synthesized using the coupling matrix theory based on transversal topology. A practical filtering antenna centered at 5.74 GHz with the bandwidth of 410 MHz (7.2%) and two radiation nulls at 5.43 GHz and 6.13 GHz is fabricated. The measurements show the gain of 7.5 dBi and out-of-band suppression more than 30 dB at both passband sides can be achieved within the total size of 1.208λ0 × 1.725λ0 × 0.024λ0, where λ0 is the free space wavelength of the center frequency.

Dual-Band and Dual Polarized Inverted Pentagonal Shaped Hybrid Cylindrical Dielectric Resonator Antenna for Wireless Applications

Dual-Band and Dual Polarized Inverted Pentagonal Shaped Hybrid Cylindrical Dielectric Resonator Antenna for Wireless Applications

High Gain and Wideband Fabry-Perot Resonator Antenna Based on a Compact Single PRS Layer

In this paper, a wideband and high gain Fabry Perot Resonator Antenna (FPRA) is proposed. It is based on a synthesized compact single partially reflective surface (PRS) layer acting as a superstrate to a slot-coupled feed antenna, which acts as a radiating source element for the proposed design. The PRS is based on a 2-D printed unit cell, where the lower part is a simple circular ring Frequency Selective Surface (FSS), incorporated with a synthesized FSS unit cell, using an automated system through a VBA based interface established between CST Microwave studio and Matlab, and optimized using a binary genetic algorithm. This new FSS layer acts as the upper part of the proposed PRS layer and provided a positive phase gradient. It almost perfectly resembles that of the optimum PRS over the desired frequency range, with a relatively high reflection magnitude, which makes it a promising superstrate candidate for wideband and high gain FP resonator antennas. The fabricated prototype achieved an important performance in terms of impedance bandwidth with 42%, ranging from 11.32 to 17.35 GHz. In addition, the 3-dB gain bandwidth is 36 % from 11.68 to 16.78 GHz, with a maximum peak gain of 14.72 dB achieved at 16 GHz. Consistent and almost invariant radiation patterns are achieved over the Ku-band frequency band of interest. The experimental and simulated results are in good agreement, justifying the feasibility of the proposed design as a high gain and wideband FP resonator antenna.

High-Gain Single-Feed Overmoded Cavity Antenna With Closely Spaced Phased Patch Surface

High-gain single-feed antennas are desired for current and future wireless systems. Slot-based highly overmoded cavity antennas are one solution, but the fact that they can only radiate broadside beams limits their applications. An innovative phase-control technique is developed for slot-based resonant cavity antennas that utilizes a planar array of closely-spaced, appropriately-sized metallic patches integrated into the very near field of their slot arrays. It facilitates the design and realization of the phase distribution over their radiating aperture that is required for them to generate single and/or multiple tilted beams pointed at specified directions. A TE(10)(11)(0)-mode slot-based cavity antenna is selected as the pathfinder system. A TE110-mode single-slot cavity antenna that is equivalent to the half-wavelength subsection of that cavity is introduced initially to monitor the phase radiated from each slot. The phase control surface is then carefully engineered to facilitate tilted output beams from the base design. The approach is validated with two subsequent tilted-beam systems. The first system achieves a single beam tilted to 30° with respect to the broadside direction. The second system is extended to produce two independently-directed titled beams pointing at –10° and 20°, respectively. All of the measured results agree well with their simulated values.

Design of Microstrip Patch Antenna for 5G Applications

Millimeter-wave wireless technology (mmWave) has become a part of human life for fast and secure data transmission. This document introduces a 37GHz resonant frequency square microstrip patch antenna for mm Wave wireless communication. The antenna was designed and tested on a Rogers RT5880 board with a relative permittivity of 2.2 and a loss factor of 0.0009. Uses electromagnetic simulation software High Frequency Structure Simulator. The result of this paper shows minimal return loss -0.0812 dB, gain -1.205 dB, and impedance bandwidth 16.22% at 37 GHz resonant frequency. The voltage standing wave ratio (VSWR), radiation pattern has also presented for the proposed antenna which can be strong candidate for 5G mmWave cellular communication.

Gain Enhancement of Dielectric Resonator Antenna Using Electromagnetic Bandgap Structure

High gain antennas are highly desirable for long-range wireless communication systems. In this paper, a compact, low profile, and high gain dielectric resonator antenna is proposed, fabricated, experimentally tested, and verified. The proposed antenna system has a cylindrical dielectric resonator antenna with a height of 9 mm and a radius of 6.35 mm as a radiating element. The proposed dielectric resonator antenna is sourced with a slot while the slot is excited with a rectangular microstrip transmission line. The microstrip transmission line is designed for a 50 Ω impedance to provide maximum power to the slot. As a result, the proposed antenna operates at 5.15 GHz with a 10-dB absolute bandwidth of 430 MHz (4.98 – 5.41 GHz). It is important to mention that the gain of the dielectric resonator antenna is enhanced by the introduction of an electromagnetic bandgap (EBG) structure. In fact, EBG units are placed below the antenna, which enhances the realized peak gain from 5.32 dBi to 8.36 dBi at 5.15 GHz. More specifically, a gain enhancement of 3.04 dB is observed with the introduction of the EBG array. This antenna has several good features such as high gain, compact size, large bandwidth, and lower losses which make it a suitable choice for long-range wireless communication systems.

Mutual Coupling Reduction in Closely Spaced MIMO Dielectric Resonator Antenna in H-Plane Using Closed Metallic Loop

In this study, the mutual coupling in multiple-input-multiple-output (MIMO) dielectric resonator antenna (DRA) is reduced by employing closed metallic loops. The loops are wrapped around the adjacent edges of the dielectric resonators (DR) where magnetic coupling is significant. The proposed method employs only the conductive metallic strips for mutual coupling reduction and this makes the entire design very simple and compact. The impedance bandwidth varies from 4.73 to 5.1 GHz, covering the Sub–6 GHz 5G band. The realized MIMO DRA has an isolation of 28 dB at the resonant frequency with a measured peak gain at each port of 3.5 dBi and a peak radiation efficiency of 93%. The obtained measured results yield a low correlation coefficient (<0.05) mostly at the entire band that contribute to diversity gain (> 9.8 dB) to increase the capacity of communication system, is reported in this paper. The proposed antenna was fabricated and the closed loop strip is wrapped around using in house facility. Furthermore, some issues related to the fabrications tolerance have been investigated to justify the difference between some simulated and measured results.

Ultra-Wideband Annular Ring Fed Rectangular Dielectric Resonator Antenna for Millimeter Wave 5G Applications

In this article an ultra-wideband rectangular Dielectric Resonator Antenna is designed for millimeter wave 5G frequency band applications. Indoor 5G communications require antenna system with wide bandwidth and high efficiency to enhance the throughput in the channel. To fulfill such requirements a Dielectric Resonator Antenna (DRA) is designed here which has achieved an ultra-wide bandwidth of 20.15% (22.32–27.56 GHz) which is 5.24 GHz of bandwidth centered at 26 GHz as resonating frequency. This covers the complete band 30 (24.3–27.5 GHz) of 5G spectrum. 26 and 28 GHz are considered as most popular frequencies in millimeter wave 5G communications. The aperture fed DRA designed here has also achieved an efficiency of 96 percentage with maximum radiation in the broadside direction (Phi = 0, Theta = 0). The measured gain of the DRA is 6.3 dB. The DRA designed here has dimensions of 0.25 λ0×0.22 λ0×0.12 λ0. under the characteristic's mode. The DRA is placed over a substrate with dimensions 0.5 λ0×0.5 λ0×0.02 λ0. A cross slot aperture has been made on the ground plane which is placed above to the substrate. Here a full ground plane is used to resonate the antenna and is of similar dimension to the substrate. A microstrip line with two concentric rings makes an annular feed structure is used to excite the DRA and is placed below the substrate. The DRA is excited here in characteristics mode TE1Y1 and is the only mode of excitation. The DRA is linearly polarized, and the characteristic mode of excitation is maintained with 50 Ohm input impedance of the antenna. The DRA also gives here a good difference between the co-pol and cross pol approximately 15 to 20 dB. This antenna is more suitable for 5G indoor applications in millimeter wave frequency band centered at 26 GHz.

Ultra-Wideband Hybrid Magneto-Electric Dielectric-Resonator Dipole Antenna Fed by a Printed RGW for Millimeter-Wave Applications

Future communication standards have an increasing interest in Millimeter Wave (mm-wave) bands, where wide bandwidth and secured communication can be assured. This trend in communication standards stimulates the research community to provide novel antenna configurations in the mm-wave bands. This article proposes a novel design and analysis of hybrid magneto-electric dielectric-resonator dipole antenna that features an electrically small size with ultra-wideband operation and consistent radiation characteristics in the mm-wave band. The proposed antenna is designed based on the combination of multi-resonances produced by a Magneto-Electric (ME) dipole and stacked Dielectric Resonator Antennas (DRAs). In addition, the proposed antenna is implemented using state-of-the-art Printed Circuit Board (PCB) technology, namely, Printed Ridge Gap Waveguide (PRGW) for low loss and cost-efficiency. The combination between the ME-dipole and stacked DRA is adopted to ensure symmetric radiation characteristics in both E- and H-planes over ultra-wideband operation with a deep matching level. Both DRA and ME-dipole elements are designed and studied separately, where a systematic design procedure is presented to obtain initial design parameters. Proper integration between the radiating elements introduced an electrically small size antenna ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.64\,\,\lambda \times 0.48\lambda $ </tex-math></inline-formula> ) covers the full Ka-band (26-40 GHz) with a matching level beyond −20 dB and gain stability of 8± 1 dB. The antenna prototype is fabricated, where a good agreement is shown between both simulated and measured results.

ULTRA-WIDEBAND DIELECTRIC RESONATOR ANTENNAS: UNDERSTANDING OF MODAL ANALYSIS AND ITS RECENT ADVANCES

This paper presents a brief review of the development of Dielectric Resonator Antennas (DRAs) targeting Ultra-wideband(UWB) bandwidth range by exciting higher resonant modes or a combination of multiple resonant modes. Different schemes that have been tried to excite various modes of the resonator are reported. The expressions for the resonant frequency, fundamental and higher mode configurations of different geometries are stated. The information assists in the selection of the different antenna geometries for the UWB frequency range by generating different order modes for modern communication systems

Plasma and electrical characteristics depending on an antenna position in an inductively coupled plasma with a passive resonant antenna

We investigated the plasma and electrical characteristics depending on the antenna position in an inductively coupled plasma with a passive resonant antenna. When the powered antenna and passive resonant antenna are installed near the top plate and in the middle of the cylindrical reactor (setup A), respectively, the ion density at the resonance is about 2.4 times to 9 times higher than that at non-resonance. This is explained by the reduction in power loss in the powered antenna (including the matching circuits) and the increase in power absorbed by the plasma discharge. However, when the powered antenna and passive resonant antenna are interchanged (setup B), the ion density at the resonance is not significantly different from that at the non-resonance. When RF power is changed from 50 to 200 W, the ion density at the resonance of setup B is 1.6 times to 5.4 times higher than at the non-resonance of setup A. To analyse this difference, the profile of the z-axis ion density is measured and the electric and magnetic field simulations are investigated. The results are discussed along with the electron kinetics effect and the coupling loss between the antenna and the metal plate.

Compact and Low-Profile Linear-/Circular-Polarization Dielectric Resonator Antennas With Extended Bandwidths

The dielectric resonator antenna (DRA) with wide bandwidth, compact size and low profile is considered as an attractive candidate for 5G wireless communications. However, most of the reported DRAs either have bulky volumes or have limited bandwidths. In this paper, a kind of compact and low-profile DRA with extended bandwidth is proposed. By observing the E-field distribution differences between the two target modes and modifying the dielectric characteristics (such as material and dimension) of the designated region where the E-field is very weak for fundamental TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">111</sub> mode but quite strong for high-order TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">131</sub> mode, the frequency of TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">131</sub> mode can be significantly affected and shifted down to merge with that of TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">111</sub> mode which is less affected. As a result, extended operating bandwidth can be obtained. This technique also benefits from not having to enlarge the planar size of the high permittivity DR, therefore making the antenna compact enough for 5G beam-scanning and low profile applications. For demonstration, linear- and circular- polarization antenna prototypes were designed and measured. The LP antenna has a −10 dB impedance bandwidth of 17.3% and a peak gain of 7.1 dBi while the CP antenna achieves a 3-dB axial ratio (AR) bandwidth of 12% and a peak gain of 6.6 dBic. Both the antennas have compact volumes of no larger than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.35{\lambda } _{0} \times 0.35{\lambda } _{0} \times 0.11{\lambda } _{0}$ </tex-math></inline-formula> . Based on the LP and CP antenna elements, two <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times5$ </tex-math></inline-formula> antenna arrays with the capability of beam scanning are designed and simulated. Wide scanning angles of ±45° and ±40° can be obtained for the LP and CP arrays, respectively.

Critical Analysis of the Recent Trends and Advancements in Dielectric Resonator Antennas

Critical Analysis of the Recent Trends and Advancements in Dielectric Resonator Antennas

A Machine Learning Generative Method for Automating Antenna Design and Optimization

To facilitate the antenna design with the aid of computer, one of the practices in consumer electronic industry is to model and optimize antenna performances with a simplified antenna geometric scheme. The ease of handling multi-dimensional optimization problems and the less dependence on the engineers' knowledge and experience are the key to achieve the popularity of simulation-driven antenna design and optimization for the industry. In this paper, we introduce a flexible geometric scheme with the concept of mesh network that can form any arbitrary shape by connecting different nodes. For such problems with high dimensional parameters, we propose a machine learning based generative method to assist the searching of optimal solutions. It consists of discriminators and generators. The discriminators are used to predict the performance of geometric models, and the generators to create new candidates that will pass the discriminators. Moreover, an evolutionary criterion approach is proposed for further improving the efficiency of our method. Finally, not only optimal solutions can be found, but also the well trained generators can be used to automate future antenna design and optimization. For a dual resonance antenna design, our proposed method is better than the other mature algorithms.

Fundamental Limits on Substructure Dielectric Resonator Antennas

We show theoretically that the characteristic modes of dielectric resonator antennas (DRAs) must be capacitive in the low frequency limit and that as a consequence of this constraint and the Poincaré Separation Theorem, the modes of any DRA consisting of partial elements of an encompassing super-structure with the same spatial material properties cannot resonate at a lower frequency than the encompassing structure. Thus, design techniques relying on complex sub-structures to miniaturize the antenna, including topology optimization and meandered windings, cannot apply to DRAs. Due to the capacitive nature of the DRA modes, it is also shown that the Q factor of any DRA sub-structure will be bounded from below by that of the super-structure at frequencies below the first self-resonance of the super-structure. We demonstrate these bounding relations with numerical examples.

Synthesizing Radiation Properties of Dual-band Dual-mode High Gain Dielectric Resonator Antenna for Wireless Applications

Synthesizing Radiation Properties of Dual-band Dual-mode High Gain Dielectric Resonator Antenna for Wireless Applications