Resonator Antenna Research Articles

Port and Radiation Pattern Decoupling of Dielectric Resonator Antennas

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 Shaped-Beam Antenna for Wide-Angle Scanning Phased Array

A phased array usually suffers from severe gain drop when its beam steers in a wide range. In this article, an alleviating technique based on a gain-compensating approach is proposed. Isolated element pattern (IEP) and array factor are jointly considered. When calculating the array factor, mutual couplings between antennas in an array are also included. The IEP is optimized in such a way that the element gain is nearly inversely proportional to the peak gain of the array factor. As a result, the peak gain of the overall array beam can be kept almost the same in a wide scanning range. As an example, a cylindrical dielectric resonator antenna (DRA) array is investigated. In such a design, a dip is introduced to the top of the element pattern so that the top peak in the array factor envelope can be compensated. This idea is demonstrated by using an X-band cylindrical DRA, with its beam shaped by using a loading peripheral metal ring and two top dielectric slabs. This shaped-beam DRA element is used to construct a nine-element H-plane linear phased array. The element and array prototypes were fabricated and measured, and reasonable agreement between the measured and simulated results is observed. The measured 3-dB beamwidths of the DRA element are 172° and 149° in the E- and H-planes, respectively. It is found that the H-plane main beam of the DRA array can scan from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$- \mathrm{72}^{\circ }$ </tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$+ \mathrm{72}^{\circ }$ </tex-math></inline-formula> with a small gain fluctuation of less than 0.9 dB.

Design and Simulation of Miniaturization of Triangular Shape Dielectric Resonator Antenna Using AMC Surface for 5G Applications

A Dielectric Resonator Antenna (DRA) is a radio antenna. It is built up of ceramic material into blocks of various forms and is generally suitable at frequencies larger than 1 GHz (microwave frequencies and higher than microwave frequencies). Using this Dielectric Resonator Antenna, the operating frequency is achieved at 4.8GHz for 5G applications like IOT (Internet of Things), AI (Artificial Intelligence). Here, artificial magnetic conductor (AMC) surface is used to miniaturize a triangular shaped Dielectric Resonator Antenna (DRA). There are nine tiny copper patches forms the Artificial Magnetic Conductor (AMC) surface having gap of 1.5mm between the patches. AMC is installed on FR4 substrate which has dielectric constant as 4.4. On the AMC surface, a Dielectric Resonator (DR) of dielectric constant 2.2 is placed. The surface of the Artificial Magnetic Conductor is shorted with ground metal using tiny metallic vias. Antenna characteristics such as antenna gain, resonant frequency, and efficiency will not be affected due to the usage of Dielectric Resonator. As a result, the overall volume of DRA is significantly diminishing. There are three primary aspects in this design: (a) Impedance matching using a Parasitic Metallic Strip (b) Design miniaturisation with an AMC surface (c) Simple microstrip line Feeding. Overall volume of Dielectric Resonator Antenna size reduced by 85%. In addition, when compared to the original Dielectric Resonator Antenna without the surface of Artificial Magnetic Conductor, the ground surface is lowered by 15.5 percent.

Differentially Fed Dual-Polarized 2-D Multibeam Dielectric Resonator Antenna Array Based on Printed Ridge Gap Waveguide

In this article, a differentially fed dual-polarized dielectric resonator antenna (DRA) subarray excited by a substrate integrated waveguide (SIW) cavity is proposed. A #-shaped slot etched on the top wall of the SIW cavity is used to achieve the differential excitation due to the intrinsic field distribution of TE120 mode in the SIW. Based on the proposed antenna subarray, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times $ </tex-math></inline-formula> 2 dual-polarized 2-D multibeam DRA antenna array with simple structure is designed, fabricated, and measured, which can achieve high cross-polarization discrimination (XPD) in the direction of maximum radiation. To reduce substrate loss, the printed ridge gap waveguide (PRGW) technology is used to feed the SIW cavity. Two orthogonal PRGW Butler matrices are placed at different layers so as to realize 2-D beamforming scanning with dual-polarization. The SIW cavity is placed in the air gap of PRWG, which can increase the stability of the antenna structure. By cleverly combining the SIW cavity and PRGW structure, the proposed multibeam antenna array has the advantages of high XPD and high radiation efficiency. Measured results show that an impedance bandwidth of 10% (28.5–31.5 GHz) and a peak gain of 11.8 dBi are obtained. Also, the measured XPDs are 28.3 dB at the center frequency and larger than 19.2 dB over the band of operation. Besides, the measured radiation efficiency of 67% is achieved for both the polarizations at 30 GHz.

Substrate Integrated Waveguide - Dielectric Resonator Antenna for Future Wireless Communication

A substrate integrated waveguide (SIW) fed rectangular-shaped dielectric resonator antenna (DRA) is proposed for application in the D - Band frequency regime. The Dielectric Resonator (DR) is designed to operate in higher order modes. A rectangular-shaped narrow slot is used to excite the DR element, leading to multiple resonances. The resulting structure is a multi-resonant antenna operating at six frequencies at 123.64 GHz, 125.76 GHz, 127.4 GHz, 129.9 GHz, 134.9 GHz and 137.7 GHz frequencies. These are identified as TE10δ1, TE7δ5, TEδ31, TEδ25, TEδ31 and TEδ35 modes of operation of the resonator, respectively. These resonances are merged to achieve a −10 dB impedance bandwidth ranging between 122.58 GHz and 139.51 GHz, equivalent to 13.4% at a center frequency of 125.76 GHz. Moreover, the antenna possesses a stable radiation pattern in the broadband direction, across the entire frequency band of operation. Simulation results show that the antenna has a peak gain of 12.3 dBi, maximum directivity of 13.14 dBi and maximum efficiency of 84% at a frequency of 126 GHz. Simulated results show that the proposed design has potential and suitability for utilization in future wireless communications.

Varactor-Based Phase Shifters Operating in Differential Pairs for Beam-Steerable Antennas

A concept of varactor-based phase shifter operating in differential pair for beam-steerable antennas is presented in this article. The basic phase-tuning unit consists of a microstrip transmission line and several shorted-stub-terminated varactors loaded on its edge. A pair of these phase-tuning units working in differential mode can achieve a full 360° phase shift, which allows a low loss and simple structure. An accurate equivalent circuit model for this phase shifter is developed for fast calculation allowing the design and optimization of the structure with a genetic algorithm (GA). A pair of phase-tuning units, each including three stub-loaded varactors, is identified as a practical solution to produce a continuously tunable phase difference nearly covering 0°–360°, with two symmetrical 11°-wide blind zones and a maximum insertion loss of 2.04 dB. A 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times4$ </tex-math></inline-formula> beam-steerable dielectric resonator antenna (DRA) array is then designed, fabricated, and tested to demonstrate the practicality of the proposed phase shifter. The measured results illustrate that the array is able to continuously scan from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$- 45^\circ $ </tex-math></inline-formula> to 45°, with a tunable operating frequency band from 4.75 to 5.25 GHz. All these findings suggest that the proposed phase shifter concept is promising and practical to realize beam-scanning antennas.

Development of Rotaxanes as E-Field-Sensitive Superstructures in Plasmonic Nano-Antennas

We present the concept of electrostatic field-driven supramolecular translation within electrically connected plasmonic nano-antennas. The antenna serves as an anchoring point for the mechanically interlocked molecules, as an electrode for the electrostatic field, and as an amplifier of the antenna-enhanced fluorescence. The synthesis of a push–pull donor–π–acceptor chromophore with optical properties aligned to the antenna resonance is described and its immobilization on the surface is demonstrated. Photoluminescence experiments of the chromophore on a gold nano-antenna are shown, highlighting the molecule–antenna coupling and resulting emission intensity increase. The successful synthesis of an electrostatic field-sensitive [2]rotaxane in water is described and the tightrope walk between functionality and water solubility is illustrated by unsuccessful designs. In solution, an enhanced fluorescence quantum yield is observed for the chromophore comprising the mechanically interlocked [2]rotaxane in water and DMSO compared to the reference rod, ideal for future experiments in plasmonic nano-antennas.

Metamaterial Based Circularly Polarized Parasitic Element Driven DRA for Sub 6 GHz Wireless and 5G Communication Applications

Billions of wireless devices are directly communicating with each other and exchanging data worldwide. The 5G communication provides broad scope to this data exchange with low latency, high data rate, and efficient utilization of the EM spectrum. This paper articulates designing and developing a multiband Dielectric Resonator Antenna (DRA) with circular polarization for sub-6 GHz applications. The designed DRA of alumina occupies the dimension of radius ten and height of twenty mm on the FR4 substrate. The proposed DRA resonates at the quad-band with good impedance bandwidth covering the 5G band under the sub 6 GHz range. The designed antenna provides moderate gain and radiation efficiency of more than ninety-six percent. The prototype measured results show excellent matching with the simulation results of HFSS.

Isolation Enhancement of UWB MIMO rDRA for 5G Outdoor Applications

In this paper, a two-port Ultra-Wideband Multiple Inputs Multiple Outputs (UWB MIMO) rectangular Dielectric Resonator Antenna (rDRA) is proposed for 5G sub-6 GHz outdoor applications. An edged hole is inserted at the rDRA edge for isolation enhancement purposes. The effect of edged hole radius on isolation is investigated. Both UWB MIMO rDRA with and without edged holes are investigated for both parallel and orthogonal feed schemes (four scenarios). Isolation better than -22 dB is obtained for orthogonal orientation and edged hole rDRA. Surface current density distribution is used to explain that isolation enhancement. UWB bandwidth and high efficiency are obtained on the operating bands due to the usage of an aperture-coupled feed system and edged hole rDRA. The proposed antenna has two -6 dB operating frequency bands, the lower band (2.25 GHz – 2.52 GHz) and the higher band (3.6 GHz – 5.7 GHz). The Envelope Correlation Coefficient (ECC) and diversity gain DG are used to justify the MIMO antenna performance. Good agreement is obtained between measured and simulated results.

Hybrid lumped‐distributed loading design approach to wideband dual‐mode resonant monopole antennas

A dual-mode resonant monopole antenna using lumped and distributed loading is proposed. The third-order resonant mode within a monopole antenna is excited by a pair of stubs, so as wideband, dual-mode resonant characteristic can be attained. Two lumped inductors are loaded in a certain position of the paired stubs, so as the occupied space can be shrunk to yield compact antenna size. As is experimentally validated, the hybrid lumped-distributed loading scheme can effectively tune the third-order resonant mode downward, with the fundamental resonant mode rarely changed. Compared to the pure distributed, stub-loading scheme, the length of the perturbed stub can be reduced by 65%, while the impedance bandwidth is basically unchanged. The resultant dual-mode monopole antenna can operate in a wide frequency range from 3.66 to 5.80 GHz (i.e., fractional bandwidth of 45.2%) with an omnidirectional azimuth radiation pattern as evidently validated in experiment. The advanced design approach can maintain the intrinsic linear profile of resonant monopole antennas and exhibit low configuration complexity. It may be suitable for multi-mode resonant antennas development in space-limited portable terminals.

Ethylenediaminetetraacetic Acid (EDTA) Assisted Single Step Densification of Li2TiO3/PTFE Composites at Ultralow Sintering Temperature to Realize a High-Performance Ku-Band Antenna

In the last few decades, extensive research has been focused on the ever-increasing demand for energy-efficient materials and technologies in consumer electronics. The low-weight, low-cost, environmentally safe Li-based ceramics are widely investigated as potential materials for Li-ion batteries and low-temperature cofired ceramics (LTCC). In the present work, we combine high volume fractions of Li2TiO3 (LT) ceramic with incredibly versatile polytetrafluoroethylene (PTFE) to synthesize thermally stable, low-loss dielectrics at ultralow temperatures (<150 °C) in a single step without any additional transient liquid phase in a very short time, and the effect of different wt % of ethylenediaminetetraacetic acid (EDTA), which is a chelating agent, on the densification, microstructure, thermal, and broadband dielectric properties of these composites has been studied. X-ray photoelectron and FTIR spectroscopic analyses were used to explain the densification mechanism in these composites. The presence of the OH– ion on the surface of LT and manipulation of the ceramic-polymer interphase by EDTA are significant in the densification of LT-PTFE composites. A cylindrical prototype dielectric resonator antenna (CDRA) was designed, simulated, and fabricated with the 0.7LT-0.3PTFE-5EDTA composite having excellent thermal and dielectric properties, and antenna properties were experimentally verified. The return loss, input impedance, and radiation pattern of the CDRA were examined, and the experimental results match reasonably well with simulated results. This study shows that the 0.7LT-0.3PTFE-5EDTA composite is a potential candidate for the fabrication of an economical, low-loss, lightweight, easy-to-fabricate, wide bandwidth CDRA for telecommunication applications in the Ku-band. Further, it is possible to achieve enhanced bandwidth and gain, by varying the compositions of these composites.

An omnidirectional filtering dielectric resonator antenna based on metal patches

A novel filtering dielectric resonator (DR) antenna (DRA) is designed in this article. By using a single-layer planar feed structure, the TM01δ and TM011+δ modes of a cylindrical DR are excited. The proposed filtering DRA achieves a good omnidirectional radiation performance and a flat gain response. By loading a crossed patch with four shorting pins on the feed structure, the lower edge of the passband obtains a steep roll-off rate. By plating four metal patches on the side wall of the DR, a radiation null (RN) is successfully introduced at the upper sideband of the DRA. The suppression levels of the proposed filtering DRA in the lower and upper stopbands are above 18 dB. Therefore, the proposed filtering DRA achieves filtering function without additional circuits. For demonstration, a prototype DRA is fabricated and measured. The simulated and measured results are basically consistent.

A Wideband Single-fed circularly polarized dielectric resonator antenna with bandpass filtering response

ABSTRACT For integrated design of a filter and an antenna, a wideband circularly polarized (CP) dielectric resonator antenna (DRA) with filtering characteristics is proposed. A rectangular slot structure is etched on the ground to optimize the axial ratio (AR) bandwidth of the antenna singly fed by one port. Capacitive filtering branches are combined into the microstrip feeding line to effectively generate two radiation nulls outside the passband. To further enhance the suppression level in the high-frequency stopband, the stair-shaped DR is chamfered into a fish-shaped structure. A suppression level larger than 15 dB is found within the stopband. A prototype of the antenna is fabricated, and both of the simulated and measured results show a wide bandpass filtering performance over the operating frequency band. The antenna has an impedance bandwidth of 37.8%, an AR bandwidth of 25.1%, and a low profile of 0.078λ 0 (λ 0 is the free-space wavelength at 5.47 GHz), which can be a good candidate for 5 G and WLAN communication systems.

Cold sintering optimized LiF microwave dielectric ceramics for the development of dielectric resonator antennas at 5G millimeter-wave band

Cold sintering optimized LiF microwave dielectric ceramics for the development of dielectric resonator antennas at 5G millimeter-wave band

Light Emitting Si‐Based Mie Resonators: Toward a Huygens Source of Quantum Emitters

AbstractSilicon‐based micro‐ and nano‐structures for light management at near‐infrared and visible frequencies have been widely exploited for guided optics and metasurfaces. However, light emission with this material has been hampered by the indirect character of its bandgap. Here it is shown that, via ion beam implantation, light emitting G‐centers can be directly embedded within Si‐based Mie resonators previously obtained by solid state dewetting. Size‐ and position‐dependent, directional light emission at 120 K is demonstrated experimentally and confirmed by finite difference time domain simulations. It is estimated that, with an optimal coupling of the G‐centers emission with the resonant antennas, a collection efficiency of about 90% can be reached using a conventional objective lens. The integration of these telecom‐frequency emitters in resonant antennas is relevant for their efficient exploitation in quantum optics applications and more generally to Si‐based photonic metasurfaces.

A Wideband Circularly Polarized Dielectric Resonator Antenna Using Inverse f-Shaped Slot Excitation with Parasitic Metal Structure

In this paper, a single-fed wideband circularly polarized dielectric resonator antenna (DRA) is proposed. The antenna consists of a substrate, a cylindrical dielectric resonator, and four curved parasitic metal blocks that are rotated and placed around the dielectric resonator. The GND of the substrate is etched with an inverse f-shaped slot. The orthogonal working mode of the DRA is excited by the inverse f-shaped slot coupled to the microstrip, thereby obtaining circularly polarized radiation. The impedance bandwidth and axial ratio bandwidth of the antenna are improved by optimizing the structure of the inverse f-shaped slot and the shape and size of curved parasitic metal blocks, and finally, a circularly polarized dielectric resonator antenna with significant bandwidth advantages is obtained. The antenna is simulated, fabricated, and measured. The measured results show that the proposed circularly polarized DRA has an impedance bandwidth of 58.5% (2.61–4.77 GHz) and an axial bandwidth of 55.2% (2.75–4.85 GHz) and finally achieves an effective axial bandwidth of 53.7% (2.75–4.77 GHz), the peak gain of 6.84 dBi, and average efficiency of 90.78%, with excellent overall performance.

Design of a Wide-Beamwidth Pixelated Dielectric Resonator Antenna Using a Modified Stepped-Impedance Filter to Suppress Harmonics

This study designed a wide-beamwidth pixelated dielectric resonator antenna (DRA) combined with a low-pass filter (LPF) to suppress harmonics. The DRA was designed to create a wide-beam pattern with a pixelated structure. The pixelated DRA was optimized by a genetic-learning particle swarm optimization algorithm. To prevent significant higher-mode radiation and harmonics from occurring in the DRA, an LPF was included in its feeding line. The filter had a seventh-order Chebyshev design, and a hybrid step-impedance filter was proposed by modifying the step-impedance filter for use in narrow spaces behind the ground.

Multifunctional Low-Profile Fabry–Perot Resonator Antenna Integrated With Solar Cells

A novel multifunctional low-profile Fabry–Perot resonator (FPR) antenna integrated with solar cells (SCs) is proposed in this communication. It is mainly composed of a transparent partially reflective surface (PRS), a patch radiator, and an artificial magnetic conductor (AMC) made of SCs array. On the upper layer, the PRS is made of the transparent copper microgrid to perform the function of partial reflection as well as ensure that sufficient solar energy can be captured by the SCs. Here, the SCs array acting as AMC can reduce the profile of the FPR antenna, on the other hand, it can collect solar energy and convert it into direct current (dc) power to provide energy supply of the device. Through this design, the SCs and FPR antenna are well combined compatibly together. The proposed antenna is fabricated and verified, the measured results demonstrate that the proposed multifunctional FPR antenna has a realized gain of 11.5 dBi with high aperture efficiency of 58.3% and a good low-profile characteristic (approximately <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> /6). The measured output power of SCs can reach to 600 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{w}$ </tex-math></inline-formula> . The work proposed in this communication illustrates the multifunctional requirements of antenna with high radiation properties, low profile, and the capability of power harvesting, simultaneously. It may be a good scheme for self-powered occasions, such as outdoor and satellite communication devices.

A Wideband Leaky-Wave Lens Antenna With Annular Corrugations in the Ground Plane

We present a resonant leaky-wave lens antenna, fed by a circular waveguide with annular corrugations in the ground plane. The proposed leaky-wave feed reduces the impact of the spurious TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> leaky-wave mode in all planes over a wide bandwidth while reducing assembly complexity compared to previous methods. The proposed leaky-wave antenna has an aperture efficiency above 80%, a return loss below −15 dB, and a cross-polarization level below −20 dB over a bandwidth from 110–220 GHz (2:1). We have fabricated and measured a WR-5 band (140–220 GHz) antenna prototype with a lens diameter of 3 cm that achieves excellent agreement between measurement and simulation in terms of return loss, directivity, and gain.

Low-Profile Dual-Resonant Wideband Backfire Antenna for Vehicle-to-Everything Applications

A novel design approach to a low-profile dual- resonant wideband backfire antenna for Vehicle-to-Everything (V2X) applications is proposed. The antenna is composed of a semicircular principal radiator, a 152° sectorial reflector and a 112° sectorial director all installed above a metallic planar ground. At first, a 2.0-wavelength prototype magnetic dipole is introduced to lay down the flared angle, radius and the usable resonant TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1,1</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3,1</sub> modes of the principal radiator. In these ways, a wideband backfire radiation characteristic can be generated. Then, the multi-point equivalent source model is developed and used to predict the initial values of the sectorial reflector and director, e.g., the flared angles, radii, and the separations between the principal radiator and director/reflector. Prototype antennas are in final designed and fabricated to experimentally validate the dual-resonant wideband property on the 2 mm-thick air substrate, thereby exhibiting an impedance bandwidth of 27.6%. As also numerically and experimentally validated, the backfire gain can be further enhanced to 4.2 dBi. It is evidently validated that the proposed approach can be employed to effectively enhance the backfire radiation of low-profile, vehicular antennas.