Showing papers on "Dielectric resonator antenna published in 2005"

Compact slot and dielectric resonator antenna with dual-resonance, broadband characteristics

Abstract: The goal of this study is to improve the bandwidth of a miniaturized antenna. The proposed technique combines a slot antenna and a dielectric resonator antenna (DRA) to effectively double the available bandwidth without compromising miniaturization or efficiency. With proper design it is observed that the resonance of the slot and that of the dielectric structure itself may be merged to achieve extremely wide bandwidth over which the antenna polarization and radiation pattern are preserved. In addition, using the DRA, a volumetric source, improves the radiation power factor of the radiating slot. A miniaturized antenna figure of merit (MAFM) is defined to simultaneously quantify aspects of miniaturized antenna performance including the degree of miniaturization, efficiency, and bandwidth. Figures for various common types of antennas are given and compared with that of the proposed structures. In order to determine the effects of varying design parameters on bandwidth and matching, sensitivity analysis is carried out using the finite-difference time-domain method. Numerous designs for miniaturized slot-fed dielectric resonator antennas are simulated and bandwidths exceeding 25% are achieved. Two 2.4 GHz antennas are built, characterized, and the results compared with theory.

Stacked multi-resonator antenna

Abstract: An antenna structure comprising a ground plane, a feed line and at least one resonator element that is embedded in a dielectric substrate and which is meandering in shape such that it includes at least two adjacent resonator segments. As a result, the resonator element resonates in two separate frequency bands. A second resonator element is preferably provided, the second resonator element being dimensioned to resonate in a frequency band located on one side of a third operating frequency band, the feed line and ground plane being arranged to cause a resonance in a frequency band located on the other side of the third operating frequency band. During use, the combined effect of the resonance of the second resonator element and of the feed line and ground plane is to cause the antenna structure to resonate in the third operating frequency band.

A planar resonator antenna based on a woodpile EBG material

Abstract: A resonator antenna made from a complex artificial surface and a metallic ground plane is described. The complex surface is realized using a woodpile electromagnetic bandgap (EBG) material, which is shown to have a frequency dependent reflection plane location. A highly directive radiation pattern is created due to the angle-dependent attenuation of the resonator antenna coupling to free space. The antenna has the advantages of low height, low loss, and low sidelobes. It is shown that the directivity can be varied over a fixed range by changing the aperture size of the device, with the maximum directivity determined by both the feed element and EBG material properties. The complete bandgap for the woodpile EBG material is confirmed from a band diagram, and its properties as a complex surface are investigated through transmission calculation and measurement. The design of the antenna is described, and two means of exciting the resonator, a microstrip patch and a double slot, are investigated. Theoretical results for these two antennas are calculated the using finite-difference time-domain and are shown to be in good agreement with measured results.

Strip-fed rectangular dielectric resonator antennas with/without a parasitic patch

Abstract: A rectangular dielectric resonator antenna (DRA) was studied theoretically and experimentally. The rectangular DRA is excited by a strip, which is compatible with a coaxial probe. Both linearly polarized (LP) and circularly polarized (CP) fields of the antenna are considered. In previous studies of the LP rectangular DRA, only the fundamental TE/sub 111/ mode has received much attention. In this paper, it is found that the fundamental TE/sub 111/ mode, together with the higher-order TE/sub 113/ mode, can be used to design a wide-band LP DRA. The bandwidth of the dual-mode DRA can be over 40% for a conventional rectangular DRA with a simple feed. For the CP mode, a parasitic patch is attached on a side wall of the DRA to excite a degenerate mode. In both the LP and CP cases, the finite-difference time-domain (FDTD) method is used to analyze the problems. The results agree reasonably with measurements.

Ultra wideband monopole/dielectric resonator antenna

Abstract: A hybrid antenna is presented, consisting of an annular dielectric resonator antenna combined with a quarter-wave monopole to simultaneously act as a radiator and a loading element, producing an ultra wideband response. A prototype antenna is designed and a 3:1 bandwidth is demonstrated.

High-gain 1D EBG resonator antenna

Abstract: Theoretical and experimental results are presented for a high-gain electromagnetic bandgap (EBG) resonator antenna. This antenna uses a 1D EBG material made from low-dielectric-constant substrates, which results in a low-profile geometry. The operating frequency of the antenna is accurately predicted using dielectric multilayer theory. Theoretical results calculated using the FDTD method for the gain, directivity, return loss, efficiency, and radiation patterns are shown to be in good agreement with the measured performance of a test antenna. We also describe the behavior of the antenna as a function of frequency over the operating bandwidth, and examine the dependence of directivity on aperture size. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 107–114, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21095

A hybrid-resonator antenna: experimental results

Abstract: Experimental results are presented for a hybrid-resonator antenna, consisting of a microstrip patch resonator coupled to a dielectric resonator. They demonstrate a 10 dB return-loss bandwidth of 5.14-6.51 GHz (23.5%) and a radiation pattern similar to that of a conventional microstrip patch or dielectric-resonator antenna. The peak cross-polarization level in the upper hemisphere is at least 18 dB below the peak co-polarization level.

Coupled baw resonator based duplexers

Abstract: A duplexer comprising a transmit resonator device and a receive resonator device for filtering transmit and receive signals. The resonator device has a first BAW resonator for generating an acoustic wave signal from an input electric signal, a first acoustic delay for delaying the acoustic wave signal, and an intermediate BAW resonator for receiving the delayed acoustic wave signal at one end and converting the delayed acoustic wave signal to an electric signal. Through electrical coupling, the electric signal also appears at another end of the intermediate BAW resonator for generating a further acoustic wave signal at the other end. The resonator further comprises a second delay for delaying the further acoustic wave signal, and a second BAW resonator for producing an output electric signal from the delayed further acoustic wave signal. The duplexer can be used in a transceiver in a mobile phone.

Zeroeth-order resonator

Abstract: A high frequency resonator circuit and method of fabrication is described which has a resonant frequency independent of physical resonator dimensions. The resonator operates in a zeroeth-order mode on a composite right/left-handed (CRLH) transmission line (TL). The LH wave properties of the CRLH-TL contributing anti-parallel phase and group velocities. In one variation, the unit cells are formed from microstrip techniques, preferably creating alternating interdigitated capacitors and stub inductors. The resonant wavelength of the resonator is dependent on the electrical characteristics of the unit cells and not the physical size of the resonator in relation to the desired resonant wavelength. The resonator is created with at least 1.5 unit cells and the Q of the resonator is substantially independent of the number of unit cells utilized. The resonator circuit is particularly well suited for reducing resonator size, and allows resonators of various wavelengths to be fabricated within a fixed board area.

Broadband L-shaped dielectric resonator antenna

Abstract: In this letter, a broadband inverted L-shaped dielectric resonator antenna (DRA) is proposed. The DRA with the two equiangular-triangle across sections is built on a ground plane and excited by a coaxial probe to provide broadside radiation patterns. The simulated and measured results verify that the proposed antenna offers a bandwidth of 38% (from 1.71 to 2.51 GHz) and stable broadside radiation patterns. The proposed antenna is suitable for multiband wireless communication applications as digital communication systems (DCS; 1710-1880 MHz), personal communication systems (PCS; 1850-1990 MHz), universal mobile telecommunication systems (UMTS; 1920-2170 MHz), and wireless local area networks (WLANs; 2.4-2.485 GHz).

Isolated planar mesogyroscope

Abstract: An inertial sensor includes a mesoscaled disc resonator comprised of micro-machined substantially thermally non-conductive wafer with low coefficient of thermal expansion for sensing substantially in-plane vibration, a rigid support coupled to the resonator at a central mounting point of the resonator, at least one excitation electrode within an interior of the resonator to excite internal in-plane vibration of the resonator, and at least one sensing electrode within the interior of the resonator for sensing the internal in-plane vibration of the resonator. The inertial sensor is fabricated by etching a baseplate, bonding the substantially thermally non-conductive wafer to the etched baseplate, through-etching the wafer using deep reactive ion etching to form the resonator, depositing a thin conductive film on the through-etched wafer. The substantially thermally non-conductive wafer may comprise a silicon dioxide glass wafer, which is a silica glass wafer or a borosilicate glass wafer, or a silicon-germanium wafer.

Experimental study of broadband embedded dielectric resonator antennas excited by a narrow slot

Abstract: A narrow slot coupled to a microstrip line excites a dielectric resonator antenna (DRA) consisting of a small dielectric disc embedded in a larger disc is built and tested. Two different configurations of DRAs are tested with two different slots providing eight different possibilities. One configuration provides a bandwidth over 50%. These antennas have broadside radiation patterns because of the symmetry presence of the slot with the DRA. Sample of radiation patterns are provided.

Theory and implementation of dielectric resonator antenna excited by a waveguide slot

Abstract: Excitation of dielectric resonator antennas (DRAs) by waveguide slots is proposed as an alternative to traditionally used excitation mechanisms in order to enhance the frequency bandwidth of slotted waveguide radiators and to control the power coupled to the DRA. The analysis is based on the numerical solution of coupled integral equations discretized using the method of moments (MoM). The dielectric resonator (DR) is modeled as a body-of-revolution based on the integral equation formulation for the equivalent electric and magnetic surface current densities. The analysis of an infinite or a semi-infinite waveguide containing longitudinal or transverse narrow slots uses the appropriate dyadic Green's function resulting in closed-form analytical expressions of the MoM matrix. The scattering parameters for a slotted waveguide loaded with a dielectric resonator antenna disk are calculated and compared with finite-difference time-domain results. Bandwidth enhancement is achieved by the proper selection for the antenna parameters.

System and method for stabilizing light sources in resonator gyro

Abstract: Methods and apparatus are provided for stabilizing laser light sources of a resonator gyro. A resonator gyro comprises a first light source configured to produce a first input light, a second light source configured to produce a second input light, a resonator coupled to the first and second light sources, a resonance detection circuit coupled to the resonator, and a controller coupled to the resonance detection circuit and the first and second light sources. The resonance detection circuit detects a resonance frequency for each of the counter-propagating directions of the resonator. The controller tunes the first input light to a clockwise resonance frequency, and tunes the second input light to a counter-clockwise resonance frequency. A difference between the resonance frequencies is proportional to a rotational rate of the resonator gyro.

The slot-coupled hemispherical dielectric resonator antenna with a parasitic patch: applications to the circularly polarized antenna and wide-band antenna

Abstract: The aperture-coupled hemispherical dielectric resonator antenna (DRA) with a parasitic patch is studied rigorously. Using the Green's function approach, integral equations for the unknown patch and slot currents are formulated and solved using the method of moments. The theory is utilized to design a circularly polarized (CP) DRA and a wide-band linearly polarized (LP) DRA. In the former, the CP frequency and axial ratio (AR) can easily be controlled by the patch location and patch size, respectively, with the impedance matched by varying the slot length and microstrip stub length. It is important that the AR will not be affected when the input impedance is tuned, and the CP design is therefore greatly facilitated. For the wide-band LP antenna, a maximum bandwidth of 22% can be obtained, which is much wider than the previous bandwidth of 7.5% with no parasitic patches. Finally, the frequency-tuning characteristics of the proposed antenna are discussed. Since the parasitic patch can be applied to any DRAs, the method will find applications in practical DRA designs.

Single-port multi-resonator acoustic resonator device

Abstract: A single port multi-resonator acoustic resonator device ( 200, 300, 400, 490 ) possesses an input impedance that exhibits precisely designed electrical resonances. The device contains at least three parts: a transducer/resonator ( 201, 301, 401. 491 ) used both to interface to an external electrical circuit and to transform electrical energy into mechanical (i.e. acoustic) vibrations (and vice versa), and also function as a resonator; a mechanical (i.e. acoustic) resonator ( 203, 303, 460, 480 ) and an acoustic coupler ( 202, 302, 404, 494 ) that controls the acoustic interaction between the transducer/resonator and the mechanical resonator.

Wide-band stacked double annular-ring dielectric resonator antenna at the end-fire mode operation

Abstract: A novel wide-band stacked double annular-ring dielectric resonator antenna (DRA) is numerically investigated in this paper. At either layer, a larger annular-ring dielectric resonator is placed concentrically outside a smaller annular-ring one to form a stacked double annular-ring DRA. The antenna is operating at the end-fire mode. The effects of antenna parameters such as dielectric constant, probe length and air-gaps thickness are investigated. Compared to the obtained 18% bandwidth of the stacked annular-ring DRA, the proposed stacked double annular-ring DRA can offer an impedance bandwidth of /spl sim/42% for the return loss below -10 dB. The radiation patterns are stable in the passband.

Optical microfiber loop resonator

Abstract: We demonstrate a microloop resonator created from the subwavelength-diameter microfiber in free space. The resonator was tuned to exhibit Q-factor 15000 and to the critical coupling regime with the magnitude of transmission oscillations 34 dB

Bandwidth enhancement and frequency tuning of the dielectric resonator antenna using a parasitic slot in the ground plane

Abstract: The slot-fed hemispherical dielectric resonator antenna (DRA) with a parasitic rectangular slot in the ground plane is studied in this paper. It is found that the length and position of the parasitic slot can be used to widen the DRA bandwidth or to tune the DRA frequency. The exact DRA Green's function is used in the formulation, and the unknown slot currents are solved using the method of moments. Measurements were carried out to verify the calculations, and good agreement between theory and experiment is obtained.

Broadband Cylindrical Dielectric Resonator Antenna Excited by Modified Microstrip Line

Abstract: The impedance bandwidth of a high permittivity cylindrical dielectric resonator antenna excited by a microstrip line was significantly improved by modifying the feed geometry. The 10 dB return loss bandwidth is enhanced from 12 to 26% without much affecting the gain and other radiation properties of the antenna. Good agreement has been observed between the predicted and measured results.

Piezoelectric resonator element, piezoelectric, resonator, and piezoelectric oscillator

Abstract: Exemplary embodiments provide a piezoelectric resonator element, to reduce the reaching of an attenuating vibration of a main vibration to a marginal edge of the piezoelectric resonator element, as well as to stabilize an oscillating-frequency without worsening the CI value, nor inducing another vibration mode. The piezoelectric resonator element having a thickness shear vibration as a main vibration, a first groove and a second groove formed so as to surround the center part of a main surface, and the thickness at the first groove and the second groove structured to be between 70% to 96%, inclusive, of the thickness of the center part of the resonator element.

Near-field scanning microwave microscope using dielectric resonator

Abstract: Provided is a near-field microscope using a dielectric resonator, which makes it possible to minimize influences by external environments, and to enhance its sensitivity, resolution and function by adjusting the distance between a sample and an apex of a probe. The near-field microscope includes a wave source, a dielectric resonator, a probe, a distance adjusting unit, and a detector. The wave source generates a wave, and a frequency of the wave is adjustable by the wave source. The dielectric resonator propagates the wave from the wave source, and a resonance frequency, impedance, a Q factor and an electromagnetic wave mode of the wave is freely adjustable. The probe scans the wave output from the dielectric resonator on a sample. The distance adjusting unit measures a distance between the probe and the sample and maintains the distance to a predetermined value. The detector detects a wave that propagates through the probe, interacts with the sample and then propagates through the probe and the dielectric resonator.

Compact self-tuned electrical resonator for buried object locator applications

Abstract: A self-tuning resonator for use in a transmitter apparatus for inducing alternating currents in a buried conductor. The resonator is dynamically tuned at frequencies below 500 kHz by exploiting the inherent voltage-variability of net capacitance in multilayer ceramic capacitors. The transmitter apparatus provides improved efficiency and induced output power suitable for use in a man-portable locator system, providing a very high magnetic field output from a physically small battery-powered resonator at frequencies under 500 kHz. The resonator exhibits a very low equivalent series resistance (ESR) and is adaptively retuned to a predetermined resonant frequency responsive to any changes in resonance arising from phenomena such as component heating, thereby supporting very high tank circuit currents from battery-powered source to produce very high magnetic flux output.

Excitation of dielectric resonator antennas by a waveguide probe: modeling technique and wide-band design

Abstract: Analysis of a dielectric resonator antenna (DRA) fed by a waveguide probe is presented. The probe is excited by the dominant mode of a waveguide and extends into the DRA through an aperture in the waveguide wall. The DRA has, in general, an arbitrary shape and resides on an infinite ground plane, which coincides with the exterior of the waveguide broad wall. A simple and efficient analysis procedure is implemented where the problem is divided into two parts. In the upper part, the input impedance of the DRA excited by a coaxial probe is obtained with respect to the feeding position on the ground plane independent of the waveguide part. Then the input impedance is transformed to the waveguide part as a concentrated load at the end of the probe connected to the waveguide wall. The effect of the wall thickness is taken into account by modeling the section of the probe passing through the waveguide wall as a coaxial cable transmission line supporting the transverse electromagnetic mode. Thus the DRA input impedance is transferred from the ground plane reference to the waveguide inner wall reference. Results obtained using the method of moments are compared with those obtained using the finite-difference time-domain method and exhibit very good agreement. The procedure is used to achieve a bandwidth of 50% for a stacked DRA excited by a waveguide probe.

On improving impedance matching of a cpw fed low permittivity dielectric resonator antenna

Abstract: In this paper, a new coplanar waveguide (CPW) feed structure is proposed to improve impedance matchingof low- permittivity dielectric resonator antennas (LPDRAs). The structure is studied experimentally for a two element-rectangular LPDRA array. In the proposed structure, a horizontal strip is centrally connected at the center strip of the CPW and symmetrically added to a coplanar rectangular coupled slot. The dielectric radiators are fed by the CPW through the slot. Based on the above design concept, several antenna prototypes have been successfully designed, fabricated and tested. The measured results show that the proposed antenna exhibits unique and attractive features in terms of impedance matching, gain and the realization of an array.

Integral resonator gyroscope

Abstract: The present invention discloses an inertial sensor having an integral resonator. A typical sensor comprises a planar mechanical resonator for sensing motion of the inertial sensor and a case for housing the resonator. The resonator and a wall of the case are defined through an etching process. A typical method of producing the resonator includes etching a baseplate, bonding a wafer to the etched baseplate, through etching the wafer to form a planar mechanical resonator and the wall of the case and bonding an end cap wafer to the wall to complete the case.

Broadband dielectric resonator antennas excited by L-shaped probe

Abstract: Dielectric resonator antennas (DRA) designed for broadband applications and excited by L-shape probe are analyzed numerically. The L-probe is housed under a free space groove between the DRA and the ground plane. A 32% matching bandwidth is achieved with broadside radiation patterns. The new structure is mechanically better than other wideband DRA antennas.

Frequency-tunable designs of the linearly and circularly polarized dielectric resonator antennas using a parasitic slot

Abstract: A method for tuning the operation frequency of a dielectric resonator antenna (DRA) in the design stage is proposed. The method employs a parasitic annular slot, which can be applied to both the linearly-polarized (LP) and circularly-polarized (CP) DRAs. To demonstrate the former, an annular-slot-excited hemispherical DRA is used. By changing the radius of the parasitic slot, the operating frequency of the antenna can be adjusted while maintaining good impedance match and stable radiation patterns. For the CP case, a CP DRA excited by a shorted annular slot is used for the demonstration of this idea. It is found that good impedance matches and axial ratios can be obtained across the tunable frequency range. The radiation patterns are, again, stable across the frequency range. The problems are formulated using the Green's function approach, with the unknown slot currents solved using the method of moments. Measurements were carried out to verify the theory, and reasonable agreement between them is obtained.

Investigations on Two-Segment Dielectric Resonator Antennas

Abstract: Two segmented dielectric-resonator antennas have been investigated. A weighted average model is used to predict the resonant frequency. A simple method is then introduced to optimize the lower segment of the antenna. Finally, a fast and efficient design algorithm is presented. Three examples are used to implement the methods and the algorithm in three different frequency bands. Impedance bandwidths of up to 30% are achieved with the optimum design. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 533–537, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20871