Elliptical Dielectric Resonator Research Articles

Reconfigurability analysis of an all‐dielectric thermal microfluidic‐based metasurface

AbstractMetasurface tuning is performed using different ways for a wide range of applications. This study presents the design of a thermally‐tuned all‐dielectric reconfigurable metasurface. A microfluidic channel, filled with different concentrations of tellurium–selenium (Te‐Se) alloy, is added on the top of the elliptical dielectric resonator (EDR) unit cell of the considered metasurface. The electrical properties of used semiconductor alloy are varied in the range of 400 to 700°C (steps size of 100°C). The impact of thermal tuning on the reflection and transmission characteristics of the designed metasurface is analyzed in the frequency range of 20–30 GHz using COMSOL Multiphysics. Obtained results demonstrated that the realized metasurface exhibits reconfigurable behavior in terms of variations in the reflection and transmission characteristics with a change in either temperature or concentrations of selenium and tellurium. The wider bands with high reflection and low transmission frequency bands are obtained with lower concentrations of selenium and tellurium for all operating temperatures.

Reconfigurable GNR based elliptical dielectric resonator antenna for THz band applications

This article presents a novel approach to investigating a reconfigurable Dielectric Resonator antenna using Graphene Nano Ribbon (GNR) in the terahertz band. Two Elliptical shape DRAs are merged to realize High gain and radiation efficiency. The Roger-6010 is utilized to construct an Elliptical shape Dielectric Resonator (EDRA), and GNR structures are constructed on top of it to achieve reconfigurability. The radiation performance of projected EDRA is investigated in terms of 10 dB Impedance bandwidth, reflection coefficient, surface current, directivity, radiation efficiency, and gain in the frequency range from 0.55-to-0.75-THz. The proposed EDRA design has an impedance bandwidth of 15.64 %, a peak gain of 11.9dBi, peak directivity of 13.1dBi, and radiation efficiency of 97.3 %. Moreover, the reconfigurability nature is investigated by the chemical potential of the surface conductivity of graphene and then GNR-based EDRA radiation parameters. The projected EDRA is suitable for various applications in the THz band.

Thumb positioning analysis of new elliptical‐shaped microwave sensors for non‐invasive glucose monitoring

Diabetes is a chronic disease where millions of sufferers invasively prick their skin over the course of a day to take blood samples. Non-invasive glucose monitoring would bring relief to diabetics because it offers reduced skin damage. Microwave sensors are becoming a good choice for non-invasive glucose monitoring. This Letter presents two designs based on microwave sensors. The sensors have elliptical shapes and consist of a patch reflector and dielectric resonator (DR) that resemble a human thumb. A four-layer thumb model is presented, with a focus on the permittivity of the blood layer. The thumb was moved to various positions on the two microwave sensors to observe the effect it had on the frequency shift with various blood permittivity values. Observations showed that the elliptical DR sensor was less sensitive to errors and thumb positioning when taking glucose measurements than the elliptical patch sensor. The elliptical DR had an error of 55 MHz from the centre frequency, whereas that of the elliptical patch was 140 MHz. The effects of thumbs with various blood permittivity values were explored and explained.

Chiral All-Dielectric Metasurface Based on Elliptic Resonators with Circular Dichroism Behavior

We present the design of a new microwave all-dielectric chiral metasurface with circular dichroism behavior based on elliptic dielectric resonators (EDRs). During the design procedure, we have first optimized numerically the effects of the main design parameters such as the resonator’s size and orientation, as well as the size of the slot within them, on the metasurface transmission over the frequency band 10–20 GHz. Measurements on the final metasurface prototype have shown a large circular dichroism (Δ=0.61 and Δ=0.5) over two bands (17.55–17.61 GHz and 17.91–18.05 GHz) with ellipticities close to 45° which means that the developed device can be used as a circular polarization filter and circular polarizer at microwave frequencies.

An X-band dielectric resonator antenna using a single elliptical shaped dielectric resonator

This paper presents design evolution of a single elliptical dielectric resonator antenna to achieve wide measured impedance band-width extending from 8.26 GHz to 12.15 GHz. Design evolved from a right circular cylindrical DRA by varying the dimension along the semi-minor axis and thereby resulting in an elliptical DRA that supports near similar field distribution over the X-band. This similar field variation is achieved by tuning the eccentricity of the elliptical geometry, the feed position as well as height of the DRA. A fabricated prototype is developed and measured results agree well with that obtained from simulation. Apart from wide impedance bandwidth, the observed pattern bandwidth is also similar.

Transmission Control of Electromagnetic Waves by Using Quarter-Wave Plate and Half-Wave Plate All-Dielectric Metasurfaces Based on Elliptic Dielectric Resonators

We present the design of all-dielectric Quarter-Wave Plate (QWP) and Half-Wave Plate (HWP) metasurfaces based on elliptic dielectric resonators (EDRs) for the transmission control of electromagnetic waves over the frequency band 20–30 GHz. First, an extensive numerical analysis was realized by studying the effect of the resonators geometry (thickness and ellipticity) on the transmission of both x- and y-polarized waves. Then, based on the numerical analysis, we have realized and characterized experimentally both QWP and HWP all-dielectric metasurfaces.

Hybrid mode splitting in elliptical dielectric resonator

In this paper, the concept of hybrid mode splitting in an elliptical dielectric resonator (EDR) for realising dual-band bandpass filter is introduced. It is observed that hybrid mode splitting occurs in an EDR loaded asymmetrically along z-axis in a rectangular cavity. However, modes are getting coupled to single mode in case of symmetrically placed EDR. So, this concept is used to realise a dual-band bandpass filter with different bandwidths. The proposed filter is designed at centre frequencies of 13.97/14.66 GHz with bandwidth of 100/430 MHz, respectively. These types of filter are specially used for high-frequency space applications. Experimental studies have been done for cylindrical dielectric resonator (DR) to validate the proposed concept.

Circular Polarized Dielectric Resonator Antenna for Portable RFID Reader Using a Single Feed

A new design of circular polarized elliptical dielectric resonator antenna (DRA) with single feed for handheld radio frequency identification (RFID) reader is presented. The elliptical dielectric resonator antenna with an aspect ratio of 1.5 is used. This design has achieved 66.7 MHz impedance bandwidth (for S11 < –10 dB) by using material with dielectric constant material (εr = 12) in conjunction with coaxial probe feed in free space. The DRA models are simulated using two different numerical techniques, the finite element method and the finite integral technique. The numerical results of the two different computational methods approache are investigated and compared. The results are in good agreement within the desired frequency band, 5.65 GHz – 5.95 GHz. A model for a handheld RFID reader device including the elliptical DRA in the presence of human hand models is, also, investigated. The return loss is <10 dB over the frequency range of 5.49– 6.967 GHz resulting in frequency bandwidth of 1.47 GHz. A high front to back ratio and gain of 5.726dBi are obtained.

Study on Sequential Feeding Networks for Subarrays of Circularly Polarized Elliptical Dielectric Resonator Antenna

Circularly polarized (CP) dielectric resonator antenna (DRA) subarrays have been numerically studied and experimentally verified. Elliptical CP DRA is used as the antenna element, which is excited by either a narrow slot or a probe. The elements are arranged in a 2 by 2 subarray configuration and are excited sequentially. In order to optimize the CP bandwidth, wideband feeding networks have been designed. Three different types of feeding network are studied; they are parallel feeding network, series feeding network and hybrid ring feeding network. For the CP DRA subarray with hybrid ring feeding network, the impedance matching bandwidth (S11<-10 dB) and 3-dB AR bandwidth achieved are 44% and 26% respectively

Single‐feed elliptical dielectric resonator antennas for circularly polarized applications

AbstractA single‐feed elliptical shape dielectric resonator antenna (DRA) is designed for circular polarization application. The antenna is simple in structure and could be excited by either a probe or a narrow aperture. This antenna excites two degenerate orthogonal modes with 90° phase difference. From experimental studies, the single probe feed DRA achieves 5.2% 3‐dB axial ratio (AR) bandwidth and 17.3% impedance matching bandwidth (S11 &lt; −10 dB), and the single aperture feed DRA achieves 4.2% AR bandwidth and 26.5% impedance matching bandwidth. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48:2340–2345, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21937

RESONANCE FREQUENCIES AND FAR FIELD PATTERNS OF ELLIPTICAL DIELECTRIC RESONATOR ANTENNA: ANALYTICAL APPROACH

In this paper the classical boundary value approach employing the separation of variable technique is used to analyze the properties of elliptic dielectric resonator antennas. In this approach, the fields inside the resonator are expanded in terms of Mathieu and modified Mathieu functions. Numerical results are given for resonant frequencies of different modes as well for fields distribution inside the resonator. Series Green's functions are used to calculate the fields inside the cavity and also far field patterns for a given feed. Using the Green's function method provides more accurate results compared to a pure cavity model technique. The analysis and design are verified through numerical simulations. A parametric study has been performed to show effects of the elliptical dielectric resonator antennas (EDRAs) parameters on far field patterns.

Broadband elliptical dielectric resonator antenna

A broadband low-loss elliptical dielectric resonator antenna (DRA) excited by using the microstrip-line technique is proposed. The effect of geometrical modifications of the microstrip feed line on the gain, bandwidth, and radiation performances of the antenna has also been investigated. The proposed antenna offers enhanced radiation characteristics compared to conventional microstrip-patch antennas. © Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 65–67, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21262