Showing papers on "Dielectric resonator antenna published in 2012"

Resonator optimizations for wireless energy transfer

Abstract: Described herein are improved configurations for resonator for wireless power transfer that includes a magnetic material having at least one hollow section, and at least one electrical conductor wrapped around the magnetic material. The cavity of the magnetic material may be used for lossy elements such as circuit boards or electronics with reduced perturbations on the properties of the resonator compared to if the lossy elements were outside of the magnetic material next to the resonator.

Dielectric resonator array antenna

Abstract: Disclosed herein is a dielectric resonator array antenna including one or more series-feed type array elements installed to be arranged in parallel in a multilayer substrate, wherein first high frequency signals having the same or different phases or time delays are adjusted to be applied to the respective series-feed type array elements and respective radiated 1D array beams are individually used or combined to adjust beamforming of 2D array beams. Also, since the series-feed type array element is configured by connecting a plurality of dielectric resonator antennas in series, it can be easily and simply fed in series through coupling generated by the intervals between the feeding lines of the pertinent feeding unit of the plurality of dielectric resonator antennas connected in series. In addition, the broadband characteristics can be obtained by using the plurality of dielectric resonator antennas, whereby the overall antenna performance can be enhanced.

Higher Order Mode Excitation for High-Gain Broadside Radiation From Cylindrical Dielectric Resonator Antennas

Abstract: A resonant mode (HEM12δ), other than those ( HEM11δ and TM01δ) conventionally excited and used in a cylindrical dielectric resonator antenna (CDRA) has been examined with a view for using it as another radiating mode with broadside radiation patterns. Excitation of the mode, being the most challenging aspect, has been discussed and resolved by employing an innovative technique. The proposed concept has been successfully verified and experimentally demonstrated for the first time. More than 8-dBi peak gain with excellent broadside radiation has been obtained from a prototype shaped from a commercially available low-loss dielectric material with relative permittivity 10.

Omnidirectional Cylindrical Dielectric Resonator Antenna With Dual Polarization

Abstract: This letter proposes an annular cylindrical dielectric resonator antenna (DRA) with two-port diversity realizing simultaneously omnidirectional horizontally and vertically polarized radiation patterns with low cross coupling. The horizontally and vertically polarized radiation patterns are achieved by exciting the orthogonal TE01δ and TM01δ modes in a single cylindrical dielectric resonator (DR). Due to the high Q-factor of the TE01δ mode, an air gap and multiple feeding lines are introduced to increase the impedance bandwidth. The proposed antenna provides an impedance bandwidth of 19.1% in the vertically polarized mode and an overlapping bandwidth of 7.4% in the horizontally polarized mode, with the overlapping band ranging from 3.78 to 4.07 GHz. Antenna diversity and multiple-input-multiple-output (MIMO) performance are examined in terms of envelope correlation coefficient and mean effective gain.

Wideband Stacked Rectangular Dielectric Resonator Antenna at 5.2 GHz

Abstract: This paper presents a design of stacked rectangular dielectric resonator antenna (RDRA) with wide bandwidth, in the range of 13.56 % is described. The antenna exploits two low-Q modes with overlapping bandwidths to achieve a wide continuous bandwidth. This is achieved using low-permittivity DRA volume placed on high permittivity DRA volume. The antenna consists of dielectric constant of 10 and 32, stacked vertically to obtain improved bandwidth as compared to the conventional RDRA. A 50 Ω microstrip line is used in the proposed antenna as a feeding mechanism. Physical parameters of stacked RDRA have been optimized by extensive simulations using Ansoft HFSS. The parameters of antenna are 17x7x4.56 mm 3 with grounded substrate size: 80x50 mm 2 . The prototype is fabricated. Measured and simulated results are both in good agreement. The prototype antenna designed to operate in band from 5.0 to 5.7 GHz with measured gain at 5.2 GHz resonant frequency. The proposed antenna is suitable for wireless local area networks (WLAN) applications in 5 GHz frequency band (in the frequency range 5.15-5.35 GHz and 5.5-5.7 GHz). This stacked RDRA exceeds the bandwidth requirements for IEEE 802.11a WLAN applications within a required VSWR. Parametric studies of the stacked DRA are presented.

Omnidirectional Linearly and Circularly Polarized Rectangular Dielectric Resonator Antennas

Abstract: The rectangular dielectric resonator antenna (DRA) centrally fed by a probe is investigated. Its operating mode is analogous to the TM011 mode of a cylindrical DRA. The DRA radiates like an electric monopole, generating omnidirectional linearly polarized (LP) fields. Based on this LP design, a novel omnidirectional circularly polarized (CP) DRA is studied for the first time. Slots are introduced to the sidewalls of the DRA, exciting a degenerate mode for the generation of CP fields. To demonstrate the idea, an omnidirectional CP DRA was designed for WLAN (2.4-2.48 GHz) applications. The reflection coefficient, axial ratio (AR), radiation pattern, and antenna gain are studied, and reasonable agreement between the measured and simulated results is observed.

Design of a MIMO Dielectric Resonator Antenna for LTE Femtocell Base Stations

Abstract: A novel multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) for long term evolution (LTE) femtocell base stations is described. The proposed antenna is able to transmit and receive information independently using TE and HE modes in the LTE bands 12 (698-716 MHz, 728-746 MHz) and 17 (704-716 MHz, 734-746 MHz). A systematic design method based on perturbation theory is proposed to induce mode degeneration for MIMO operation. Through perturbing the boundary of the DRA, the amount of energy stored by a specific mode is changed as well as the resonant frequency of that mode. Hence, by introducing an adequate boundary perturbation, the TE and HE modes of the DRA will resonate at the same frequency and share a common impedance bandwidth. The simulated mutual coupling between the modes was as low as - 40 dB . It was estimated that in a rich scattering environment with an Signal-to-Noise Ratio (SNR) of 20 dB per receiver branch, the proposed MIMO DRA was able to achieve a channel capacity of 11.1 b/s/Hz (as compared to theoretical maximum 2 × 2 capacity of 13.4 b/s/Hz). Our experimental measurements successfully demonstrated the design methodology proposed in this work.

Transcutaneous power transmission utilizing non-planar resonators

Abstract: A system for omni-orientational wireless energy transfer is described. A transmitter unit has a transmitter resonator with a coil that is configured to be coupled to a power supply to wirelessly transmit power to a receiver unit. A receiver unit has a receiver resonator with a coil coupled to a device load. At least one of the resonators is a non-planar resonator that spans a non-degenerate two-dimensional surface having at least one concave portion.

Wideband Omnidirectional Circularly Polarized Dielectric Resonator Antenna With Parasitic Strips

Abstract: A wideband omnidirectional circularly polarized (CP) rectangular dielectric resonator antenna (DRA) is investigated in this communication. An inclined slot, loaded by a parasitic conducting strip, is fabricated on each sidewall of the DRA. The parasitic strips can excite a CP mode, which combines with the CP DRA mode to provide a wideband axial-ratio (AR) bandwidth of more than 25%. To fully utilize the increased AR bandwidth, the impedance bandwidth is also broadened by introducing a hollow cylinder at the center of the DRA. The hollow region is also used to accommodate a coaxial probe that excites the antenna. The reflection coefficient, AR, radiation pattern, antenna gain, and efficiency of the antenna are studied, and reasonable agreement between the measured and simulated results is observed. A parametric study was also carried out to characterize the proposed wideband CP omnidirectional antenna.

Design of a wideband rasorber with a polarisation-sensitive transparent window

Abstract: The present thesis considers two different subjects in the research area of electromagnetics. The first part is concerned with antenna design and the second with radar absorbers and rasorber.In the first part, a novel excitation technique for cylindrical dielectric resonator antennas is introduced to produce circular polarization. The exciter is a tape helix that is wound around the dielectric resonator and is fed by a coaxial probe. The helix excites the HE11σ modes in phase quadrature in the cylindrical dielectric resonator antenna. The height of the helix is determined using the Hansen-Woodyard condition for an end-fire array based on the phase velocity of the surface wave traveling along the dielectric resonator side wall. This phase velocity is estimated from the phase velocity in an infinitely long dielectric rod with the same permittivity and radius as the dielectric resonator antenna. The helical exciter is required to operate in the helix axial mode. The height of the helix is usually taller than the height of the dielectric resonator core. Using this type of excitation, a 3 dB axial-ratio bandwidth of 6.4% was achieved for a sample design with dielectric constant er ~ 11. The achieved 3 dB axial-ratio bandwidth is greater than that typical of other reported single feed cylindrical dielectric resonator antennas. A prototype of the sample design is fabricated and measured and a good agreement between simulation and measurement is observed. Furthermore, two approaches for the enhancement of the 3 dB axial ratio bandwidth are proposed: removing the central portion of the cylindrical dielectric resonator and using stacked cylinders. The advantages and limitations of each approach are discussed. Another perspective on the proposed design is to consider the antenna as a helix with a dielectric resonator core. In this perspective, the effects of the dielectric core on the helix antenna are discussed.The second part of the thesis is concerned with the design of thin wideband electromagnetic planar absorber for X- and KKu-band which also has a polarization sensitive transparent window at frequencies lower than L-band. The design is based on a two layer capacitive circuit absorber with the backmetal layer replaced with a polarization sensitive frequency selective surface. The structure is studied for normally incident waves with two orthogonal linear polarizations. The structure is optimized to have high transparency at low frequencies for one of the polarizations and at the same time good absorption efficiency for both polarizations at the high-frequency band. For one of the polarizations a -1.9 dB transmission with a transmission loss of less than 10% at 1 GHz as well as a 2.25:1 (75%) bandwidth of -20 dB reflection reduction are achieved. For the other polarization we obtained more than 3:1 (100%) bandwidth of -19 dB absorption. Compared with our earlier design based on a Jaumann absorber, we succeed in significantly reducing the transmission loss at the transparent window. Furthermore, the module of absorption quality is extensively improved. The improvements are based on using periodic arrangements of resistive patches in the structure design. The investigation of the structure for oblique angles of incidence and non-ideal materials is also accomplished.

High frequency pcb coils

Abstract: Described herein designs for high frequency printed circuit board (PCB) resonator coils. The resonator coils are printed or etched on a thin substrate. The number of loops of the resonator coil, the width of each trace, the spacing between the traces, and the like are adjusted to increase the quality factor Q of the resonator coils.

Energy harvesting from a standing wave thermoacoustic-piezoelectric resonator

Abstract: In this paper, a one-dimensional thermoacoustic-piezoelectric (TAP) resonator is developed to convert thermal energy, such as solar or waste heat energy, directly into electrical energy. The thermal energy is utilized to generate a steep temperature gradient along a porous stack which is optimally sized and placed near one end of the resonator. At a specific threshold of the temperature gradient, self-sustained acoustic waves are generated inside the resonator. The resulting pressure fluctuations excite a piezoelectric diaphragm, placed at the opposite end of the resonator, which converts the acoustic energy directly into electrical energy without the need for any moving components. The theoretical performance characteristics of this class of thermoacoustic-piezoelectric resonators are predicted using the Design Environment for Low-amplitude ThermoacousticEnergy Conversion Software. These characteristics are validated experimentally on a small prototype of the system. Particular emphasis is placed on monitoring the temperature field using infrared camera, the flow field using particle image velocimetry, the acoustic field using an array of microphones, and the energy conversion efficiency. Comparisons between the theoretical predictions and the experimental results are also presented. The developed theoretical and experimental techniques can be invaluable tools in the design of TAP resonators for harvesting thermal energy in areas far from the power grid such as nomadic communities and desert regions for light, agricultural, air conditioning, and communication applications.

Compact Asymmetrical T-Shaped Dielectric Resonator Antenna for Broadband Applications

Abstract: A compact dielectric resonator antenna (DRA) for broadband applications is proposed. By applying an optimized asymmetrical T-shaped dielectric resonator (DR) and an inverted-trapezoidal patch as a feeding mechanism, an impedance bandwidth of about 75.1%, covering the frequency range from 3.81 to 8.39 GHz, is obtained. The volume of the proposed DRA without ground plane is 0.555 λd3 (λd is the dielectric wavelength at the central operating frequency). Taking a comprehensive consideration of the bandwidth and the size, the proposed DRA can provide maximum bandwidth per unit volume in related conformal patch excited wideband DRA designs. Design details of the proposed antenna and the results of both simulation and experiment are presented and discussed.

Compact UWB Band-Notched Antenna Design Using Interdigital Capacitance Loading Loop Resonator

Abstract: In this letter, a new compact ultrawideband (UWB) antenna with band-notched characteristic is proposed for UWB communication applications By using a C-shaped ground, the overall dimension of the proposed antenna is dramatically decreased to 24 × 28 × 1 mm3 To avoid potential interferences, interdigital capacitance loading loop resonator (IDCLLR) is utilized to reject certain bands within the passband of the antenna Due to its high capacitance, the resonator has a smaller size and forms a narrower notched band than many other structures, thus the present design effectively saves many more useful frequencies Good agreement is achieved between the simulation and measurement, which shows that the proposed antenna has an operation frequency band from 3 to 13 GHz with good rejection to the wireless local area network bands (WLANs) (52- and 58-GHz bands)

Hybrid Monopole-DRAs Using Hemispherical/ Conical-Shaped Dielectric Ring Resonators: Improved Ultrawideband Designs

Abstract: Two geometries of dielectric ring resonator (DRR) have been investigated as new variants for designing ultrawideband hybrid monopole-DRAs (dielectric resonator antennas) with improved features. They are simply hemispherical and conical in shape and have been implemented individually. Hybrid monopole-DRA is actually a combined configuration using a grounded monopole surrounded by a small DRR touching the same ground plane. Compared to an earlier version using cylindrical DRR of same dielectric material, the proposed ones promise for about 25% larger impedance bandwidth maintaining identical gain and radiation properties. As much as 126% impedance bandwidth with consistent monopole type radiation and 2-4 dBi peak gain has been demonstrated using a set of prototypes shaped from dielectric rod with er = 10. Physical insight in to the ultrawideband operation along with a comprehensive design guideline is presented.

Two-Segments Compact Dielectric Resonator Antenna for UWB Application

Abstract: A new compact two-segments dielectric resonator antenna (TSDR) for ultrawideband (UWB) application is presented and studied. The design consists of a thin monopole printed antenna loaded with two dielectric resonators with different dielectric constant. By applying a combination of U-shaped feedline and modified TSDR, proper radiation characteristics are achieved. The proposed antenna provides an ultrawide impedance bandwidth, high radiation efficiency, and compact antenna with an overall size of 18 × 36 × 11 mm . From the measurement results, it is found that the realized dielectric resonator antenna with good radiation characteristics provides an ultrawide bandwidth of about 110%, covering a range from 3.14 to 10.9 GHz, which covers UWB application.

Compact high isolation quad-band bandpass filter using quad-mode resonator

Abstract: A compact quad-band bandpass filter utilising the proposed quad-mode resonator is presented. The proposed resonator, which has four tunable symmetrical resonant poles, can be treated as a two-side open-circuit stepped-impedance resonator with short-circuit stubs in its low-impedance sections. With the multi-paths propagation mode configuration of the two resonators, transmission zeros among each passband are generated to improve passband selectivity and achieve high isolation. As an example, a quad-band bandpass filter centring at 1.9/2.8/4.3/5.2GHz is designed, fabricated and measured. The measurement results agree well with the full-wave EM simulated responses.

Segmented Hemispherical DRA: New Geometry Characterized and Investigated in Multi-Element Composite Forms for Wideband Antenna Applications

Abstract: Hemispherical dielectric resonator antenna (HDRA) is reinvestigated by splitting it into four uniform quarters, which indeed generates a new DRA shape, proposed to call as “quarter-Hemispherical DRA” (q-HDRA). An innovative idea, gathered by the authors through their previous investigations, has been employed to investigate four-element q-HDRA resonating with dominant and first higher modes over a large impedance bandwidth (S11 <; -10dB) and producing improved monopole-like radiation pattern. The improvement has been described in terms of uniformity and symmetry in the radiation patterns obtained consistently over the entire operating bandwidth. No degradation or compromise in impedance bandwidth is observed. For this purpose, the new DRA unit (q-HDRA) has been characterized using simulated and measured data. Prototypes of single and multi-element q-HDRA have been measured and compared with some earlier versions. Unlike earlier one, consistently symmetric monopole-like radiation from a four element q-HDRA has been demonstrated.

Wideband Microstrip Bandpass Filter Based on Quadruple Mode Ring Resonator

Abstract: A novel wideband microstrip band-pass filter is presented in this letter based on a quadruple-mode ring resonator, which is developed by introducing a stepped-impedance one-wavelength ring resonator (SORR) into a stepped-impedance half-wavelength resonator (SHR). In order to suppress the harmonic responses of the filter for a wide stop-band, two band-stop sections with asymmetrical -type structure are introduced. A prototype filter having 49.3% of 1 dB and 57.9% of 3 dB fractional bandwidth is fabricated with advantages of high selectivity and high out-of-band rejection. In the pass-band, the return loss is larger than 18.8 dB and at the centre frequency insertion loss is 0.6 dB. The experiments are in good agreement with the simulations.

Rapid antenna design optimization using shape-preserving response prediction

Abstract: An approach to rapid optimization of antennas using the shape-preserving response-prediction (SPRP) technique and coarsediscretization electromagnetic (EM) simulations (as a low-fidelity model) is presented. SPRP allows us to estimate the response of the high-fidelity EM antenna model, e.g., its reflection coefficient versus frequency, using the properly selected set of so-called characteristic points of the low-fidelity model response. The low-fidelity model, corrected by means of SPRP, is subsequently used to predict the optimal design. The design process is cost efficient because most operations are performed on the low-fidelity model. Performance of our technique is demonstrated using a dielectric resonator antenna and two planar wideband antenna examples. In all cases, the optimal design is obtained at a cost corresponding to a few high-fidelity simulations of the antenna under design.

Pseudo-Traveling-Wave Resonator With Magnetically Tunable Phase Gradient of Fields and Its Applications to Beam-Steering Antennas

Abstract: A pseudo-traveling-wave resonator with magnetically tunable phase gradient of field distribution is investigated, and a new type of beam-steering antenna based on the resonator is experimentally demonstrated for the first time. It is a short-ended transmission-line resonator and is composed of a nonreciprocal phase-shift composite right/left-handed transmission line using a polycrystalline yttrium-iron-garnet rod. The resonator operates as zeroth-order resonator if there is no dc magnetic field, and the radiation beam directs to broadside. By increasing an externally applied dc magnetic field normal to the substrate, the effective dc magnetization in the ferrite increases under the unsaturated regime. The phase gradient of the field distribution along the resonator is then continuously increased. As a result, the radiation beam direction changes obliquely with respect to broadside. Continuous backfire-to-endfire beam steering with more than 40° was achieved with almost constant gain of 5 dBi. In addition, numerical simulation results show considerably high radiation efficiency of 85%-95%, and the measured beam angle and gain were found almost constant within the relative bandwidth of 2%.

Compact Wideband Multimode Dielectric Resonator Antennas Fed With Parallel Standing Strips

Abstract: As the number of resonances increases, it becomes difficult to improve and maintain the performance of dielectric resonator antennas (DRAs), over the expanded impedance bandwidth. To remove unwanted modes, adjust the frequency distance between individual modes, reduce antenna size and cross polarization, and preserve radiation patterns in a wideband configuration, a dielectric resonator antenna fed with parallel standing strips is proposed in this paper. The use of parallel standing strips provides several degrees of freedom in the design procedure to enhance the DRA characteristics. To validate the effectiveness of this approach, two DRAs with parallel standing strips were fabricated using different procedures. The antennas were tested and characterized. The measured results are in good agreement with simulation ones. A 46% size reduction was achieved for the multimode DRA. The impedance bandwidth of the proposed DRA of simple rectangular shape was over 60% with a measured gain ranging from 5.5 to 9.5 dBi. Broadside radiation patterns with fairly low cross polarizations can be maintained over the impedance bandwidth. The simulated radiation efficiency is more than 96% within the frequency band.

Electronically Frequency-Reconfigurable Rectangular Dielectric Resonator Antennas

Abstract: The full implementation of a slot-fed frequency-reconfigurable rectangular dielectric resonator antenna (DRA) is described. It uses two conducting walls, on opposite vertical faces of the DRA, which are switched via conducting tabs to be in contact or not with the groundplane. Theoretical and experimental performance results for such DRAs, using either PIN or varactor diode switches, are described, where prototypes were designed to operate between 3-8 GHz. The PIN diode-loaded and varactor-loaded DRAs achieved a tuning range of 91% and 55%, respectively, with other performance metrics detailed in the communication.

Multi-mode filter

Abstract: A dielectric resonator body for a multi-mode cavity filter, the resonator including a piece of dielectric material, with at least one substantially flat face for mounting on a substrate layer, the piece of dielectric material having a shape such that it can support at least a first resonant mode and at least one substantially degenerate resonant mode; wherein the shape of the piece of dielectric material is such that the first resonant mode and the at least one substantially degenerate resonant mode are capable of being simultaneously independently excited, and wherein the piece of dielectric material is at least partially covered with a layer of conductive material. The piece of first dielectric material may include at least one region having a different dielectric constant to the first dielectric material, whereby the presence of the region of different dielectric constant alters the frequency separation of the resonant mode and the spurious response.

A 27 MHz temperature compensated MEMS oscillator with sub-ppm instability

Abstract: This paper reports on the design, implementation and characterization of a low phase-noise 27 MHz MEMS oscillator with sub-ppm temperature instability based on a high-Q composite bulk acoustic wave (BAW) resonator. An array of silicon dioxide (SiO 2 ) pillars has been uniformly embedded in the body of a piezoelectrically transduced silicon resonator to compensate its negative temperature coefficient of frequency (TCF). Using this technique, an overall frequency drift of 83 ppm is achieved for the resonator over the temperature range of −20°C to 100°C while resonator Q remains greater than 7,500 in atmospheric pressure. An electronically compensated oscillator using this resonator exhibits sub-ppm temperature instability with a consistent phase noise (PN) behavior over the entire temperature range and a value of −101dBc/Hz at 1 kHz offset-frequency. Long-term stability measurement has been carried out for both temperature-compensated resonator and oscillator in an environmental chamber to study their stability over time.

Optical Bistability in a Silicon Waveguide Distributed Bragg Reflector Fabry–Pérot Resonator

Abstract: We demonstrate optical bistability in a silicon waveguide Fabry-Perot resonator formed by a pair of distributed Bragg reflectors. In the bistable regime, the output power of the resonator ceases to be uniquely determined by the input power because multiple powers within the cavity satisfy the resonance condition. Pulsating behavior is observed within the resonator output, and is attributed to noise within the experimental setup driving the resonator between the multiple allowed output powers.

Compact dual-band bandpass filter with controllable bandwidths using stub-loaded multiple-mode resonator

Abstract: A compact microstrip-line dual-band bandpass filter using a stub-loaded multiple-mode resonator is presented. This multiple-mode resonator is formed by loading three stubs (one short-circuited and two open-circuited stubs) in shunt to a simple uniform impedance resonator in the centre and two symmetrical locations, respectively. By properly adjusting the lengths of the three stubs, the first two resonant modes of this multiple-mode resonator can be allocated within the first passband, whereas the third and fourth resonant modes can be allocated within the second passband of the dual-band filter. This results in the formulation of a novel dual-band filter with compact-size and high isolation between passbands by incorporating this multiple-mode resonator with source-load coupling. Two coupling paths are used to control the bandwidth of each passband independently. To illustrate the concept, two dual-band filters of different frequency ratios are designed, fabricated and measured. Simulated and measured results are found to be in good agreement with each other, showing that a rejection level of 15 dB up to more than four times the first passband frequency can be obtained.

Effect of single complimentary split ring resonator structure on microstrip patch antenna design

Abstract: This paper had been comparing the performance of the normal patch antenna with single complimentary SRR patch antenna. Four different shapes of single complimentary split ring resonator structure had been incorporated into the microstrip patch antenna - square, circular, triangular, and rhombic. This simulation works had been done in CST Microwave Studio simulation software. The operating frequency of this antenna is 2.40 GHz for Wireless Local Area Network (WLAN) application. The parameters that considered in these works are return loss, resonant frequency, input impedance, gain, radiation pattern and bandwidth. The focusing parameter is to achieve the best gain performance that obtained from the single complimentary split ring resonator patch antenna. The addition of square SRR onto patch antenna will improve the gain from 6.334 dB to 6.508 dB.