Showing papers on "Dielectric resonator antenna published in 1993"

Theory and experiment of a coaxial probe fed hemispherical dielectric resonator antenna

Abstract: A hemispherical dielectric resonator antenna fed by a coaxial probe is studied both theoretically and experimentally. The Green's function for the evaluation of the input impedance is derived rigorously and expressed in a form convenient for numerical computations. The method of moments is used to obtain the probe current from which the input impedance of the DR antenna is calculated. Both delta gap and magnetic frill source models are considered. Moreover, the results using a reduced kernel as well as the exact kernel are presented. Both entire basis (EB) and piecewise sinusoidal (PWS) expansion modes are used and the results are compared. The effects of the probe length, feed position, and dielectric constant on the input impedance are discussed. Finally, the theoretical radiation patterns for the first three resonant modes (TE/sub 111/, TM/sub 101/, and TE/sub 221/) of the DR antenna are presented. >

Electric-monopole antenna using a dielectric ring resonator

Abstract: A dielectric ring resonator antenna structure which radiates like an electric monopole is reported. The use of high er resonator material leads to small antenna height. Experiments show that the proposed antenna configuration is potentially useful for constructing small and compact ‘electric-monopole’ antennas.

A numerical study of a dielectric disk antenna above grounded dielectric substrate

Abstract: An antenna made of a dielectric disk with a high permittivity mounted on top of a grounded dielectric substrate of low permittivity is analyzed. A numerical procedure based on surface integral equations, derived from the equivalence principle, is used to compute the natural resonant frequencies for the HEM/sub 11/ mode from which the radiation Q factor of the antenna is obtained. Then the radiation pattern of the antenna, operating at the resonant frequency evaluated previously, is computed with an electric dipole excitation located within the dielectric substrate under the dielectric disk. The effect of various parameters on the radiation characteristics of the antenna is studied, and presented in the form of diagrams. The low values of the radiation Q, combined with the high values of the dielectric Q and conductor Q, indicate that this antenna promises to be more efficient then the microstrip antenna. >

Analysis of a hemispherical dielectric resonator antenna with an airgap

Abstract: A probe-fed hemispherical dielectric resonator antenna with an airgap of hemispherical shape between the dielectric and the ground plane is investigated theoretically by using a Green's function formulation. Input impedance of the efficiently radiating mode of TE/sub 111/ is calculated and analyzed. It is found that, with the presence of the airgap, the antenna bandwidth, obtained from the 3-dB impedance bandwidth, can be considerably enhanced. This study provides a new design for bandwidth enhancement of the dielectric resonator antenna. >

A half-split cylindrical dielectric resonator antenna using slot-coupling

Abstract: A half-split cylindrical dielectric resonator placed on a metallic plane and excited in its magnetic dipole mode is a potentially useful antenna element. The use of a microstrip line-slot feed scheme for exciting this antenna is reported. Experimental results show that the antenna displays the anticipated radiation pattern and it has a high operating frequency bandwidth (about 10%). The overall antenna configuration can be easily integrated with MICs. >

Micro-machined resonator oscillator

Abstract: A micro-miniature resonator-oscillator is disclosed. Due to the miniaturization of the resonator-oscillator, oscillation frequencies of one MHz and higher are utilized. A thickness-mode quartz resonator housed in a micro-machined silicon package and operated as a "telemetered sensor beacon" that is, a digital, self-powered, remote, parameter measuring-transmitter in the FM-band. The resonator design uses trapped energy principles and temperature dependence methodology through crystal orientation control, with operation in the 20-100 MHz range. High volume batch-processing manufacturing is utilized, with package and resonator assembly at the wafer level. Unique design features include squeeze-film damping for robust vibration and shock performance, capacitive coupling through micro-machined diaphragms allowing resonator excitation at the package exterior, circuit integration and extremely small (0.1 in. square) dimensioning. A family of micro-miniature sensor beacons is also disclosed with widespread applications as bio-medical sensors, vehicle status monitors and high-volume animal identification and health sensors. The sensor family allows measurement of temperatures, chemicals, acceleration and pressure. A microphone and clock realization is also available.

Radio frequency coaxial cavity resonator as an ignition source and associated method

Abstract: An apparatus for providing an ignition source for internal combustion engines comprises a radio frequency oscillator, an amplifier and a coaxial cavity resonator The coaxial cavity resonator is adaptable for communication with a combustion chamber of the internal combustion engine An associated method is also provided

Input impedance of aperture coupled hemispherical dielectric resonator antenna

Abstract: A hemispherical dielectric resonator (DR) antenna fed by a microstripline through an aperture on the ground plane is investigated both theoretically and experimentally. The broadside TE111 mode input impedance of the antenna configuration is evaluated, and reasonable agreement between theory and experiment is obtained. The effects of the slot length and the slot width on the input impedance are studied and discussed.

Dielectric resonator antenna with wide bandwidth

Abstract: The invention relates to a dielectric resonator antenna system which exhibits an unusually wide bandwidth. This is achieved by chosing a patch antenna/dielectric resonator combination with shape and dimensions such that resonance modes over a continuous range wavelengths can be established therein. The bandwidth and transmission properties of the device are further improved by including a dielectric coupling element (between the dielectric resonator and air) whose antireflection characteristics are optimized for a wavelength which is slightly different from the maximum wavelength of the patch antenna.

Hybrid antenna including a dielectric lens and planar feed

Abstract: A hybrid antenna including a dielectric lens-antenna in the shape of an extended hemispherical dielectric lens than is operated in the diffraction limited regime. The dielectric lens-antenna is fed by a planar-structure antenna. The planar antenna is mounted on the flat side of the dielectric lens-antenna, using it as a substrate. An optimum extension distance is found experimentally and numerically for which excellent beam patterns and simultaneously high aperture efficiencies can be achieved. The hybrid antenna is diffraction limited, space efficient in an array due to its high aperture efficiency, and is easily mass produced, thus being well suited for focal place receiver arrays.

Dielectrically loaded cavity resonator

Abstract: A method of producing a microwave resonator comprising a cavity (50) defined, at least in part, by a generally cylindrical wall (64) having an electrically conductive inner surface and containing a generally cylindrical piece of low loss dielectric material (22), characterised by forming a generally cylindrical piece of low loss dielectric material of predetermined size and placing same in a cavity to produce a microwave resonator which operates in a particular mode at a specific frequency at a particular temperature Microwave radiation corresponding to a further operating mode is then passed into the cavity and then the frequency corresponding to the further operating mode is searched for and measured A further generally cylindrical piece of dielectric material is produced by scaling from the first piece of dielectric material according to the ratio between the first and second frequencies Then, the diameter and/or height of the cavity is varied to compensate for manufacturing inaccuracies in the crystal so as to obtain an output frequency close to the desired output frequency

Input impedance of a hemispherical dielectric resonator antenna excited by a coaxial probe

Abstract: A more rigorous model of the probe-fed hemispherical antenna than that of K W Leung et al (1991) is considered This model accounts for all possible azimuthal modes that can be excited by this structure The input impedance is computed for a dielectric sphere antenna of radius a=254cm, /spl epsi//sub r1/=89, and loss tangent 00038 >

Gas slab laser with folded resonator structure

Abstract: A resonator design is disclosed particularly suited for an RF excited (20), carbon dioxide, slab waveguide laser (10). The laser (10) includes a pair of elongated electrodes (12, 14, 120) spaced apart in a manner to define a slab discharge region (16) having a narrow waveguide axis between the electrodes (12, 14, 120) and a wide axis extending parallel to the electrode surfaces. The resonator is a hybrid design and is a stable, waveguide in the narrow axis, and a negative branch unstable resonator in the wide axis. A pair of mirrors (30, 32, 34, 36) are provided at each end of the electrodes (12, 14, 120) to create a folded beam path in the wide axis. The folded configuration increases the effective length of the resonator which substantially increases the power stability of the laser (10). The multiple mirror resonator can also be used to increase the width of the discharge region (16) while minimizing spherical aberrations. Each leg of the path has the alignment characteristics of a negative branch unstable resonator so that the alignment of the overall resonator is highly stable.

Method of manufacture of high dielectric antenna structure

Abstract: The present invention discloses a method for manufacturing a high dielectric antenna structure. In one embodiment, one or more high dielectric film layers are applied to a dielectric base layer by silk-screening to yield a dielectric structure having a dielectric constant greater than that of the dielectric base layer. After firing, a patch antenna element having a predetermined configuration is disposed on the top surface of the dielectric structure by silk-screening a conductive paste thereupon and firing. A ground plane is disposed on the bottom surface of the dielectric structure by silk-screening a conductive paste thereupon and firing. A pre-drilled dielectric base layer may be employed with registered holes defined in the various silk-screened layers to provide access for an RF feed means, or alternatively, a feed hole can be bored through the antenna structure to permit interconnection between an RF feed means and the patch antenna element. For multiple-frequency applications, additional stacked dielectric structures and patch antenna elements can be manufactured according to the disclosed method, with the uppermost patch antenna element being interconnected with the RF feed means.

Oscillator circuit for use with high loss quartz resonator sensors

Abstract: The disclosure is directed to a Lever oscillator for use in high resistance resonator applications, especially for use with quartz resonator sensors. The oscillator is designed to operate over a wide dynamic range of resonator resistance due to damping of the resonator in mediums such as liquids. An oscillator design is presented that allows both frequency and loss (R m ) of the resonator to be determined over a wide dynamic range of resonator loss. The Lever oscillator uses negative feedback in a differential amplifier configuration to actively and variably divide (or leverage) the resonator impedance such that the oscillator can maintain the phase and gain of the loop over a wide range of resonator resistance.

Gaussian-beam open resonator with highly reflective circular coupling regions

Abstract: A high-Q open resonator with quasi-optical coupling regions is described. The resonator consists of a pair of spherical mirrors, on each of which a highly reflective, partially transparent circular region is fabricated with a diameter larger than several wavelengths. The signal is coupled in and out as a Gaussian beam by means of these regions. Both very weak coupling and very efficient mode conversion are simultaneously achieved. This results in a Q-factor over 2*10/sup 5/ and a high signal-to-noise ratio at 105.9 GHz. The Q-factor of the open resonator can be varied by rotating the output mirror to change the angle between the directions of the conducting stripes on the two mirrors. >

Resonator for CO2 slab waveguide laser

Abstract: A CO 2 slab waveguide laser (10) is disclosed including a pair of spaced apart electrodes (36,38) having opposed light reflecting surfaces. The electrodes are dimensioned in a manner to guide light in a plane perpendicular to the reflecting surfaces. Light parallel to the reflecting surfaces is not constrained other than by the resonator mirrors (30,32). The resonator structure includes a negative branch unstable resonator in the nonwaveguide dimension. A stable resonator is used in the waveguide dimension but the mirror spacing from the end of the guide is based in part on the configuration of the unstable resonator. A unique support structure is disclosed for maintaining the electrodes in a spaced apart orientation without confining the discharge. Further refinements are disclosed for cooling the laser and for accommodating thermal expansion of the parts. An improved adjustable mirror assembly (26, 28) is provided which allows the tilt angle of the mirror to be varied from outside of the housing. The subject laser is capable of generating high energy short duration pulses which can be used to treat tissue with reduced trauma.

Broadband cavity-like array antenna element and a conformal array subsystem comprising such elements

Abstract: The invention concerns a broadband antenna element for array antennas using microstrip technology. In accordance with the invention, an etched patch 2 on a dielectric substrate 1 is disposed at the bottom of a cavity 7 defined by conductive walls 8, cylindrical walls, for example, or walls of more complicated geometry. Depending on the embodiment, the conductive walls 8 can extend through the dielectric substrate 1 to form an electric contact with the ground plane 6 or a second resonator comprising a second etched patch 12 on a second thin dielectric substrate 11 may be placed in front of the cavity 7. The invention also applies to antenna subarrays constructed from a plurality of these antenna elements and to array antennas constructed from a plurality of these subarrays.

RF filters and multiplexers with resonator decouplers

Abstract: An RF filter having a housing defining a cavity with plural elongated resonators and plural resonator decouplers adjacent each of plural pairs of the resonators in the housing. The decouplers are grounded adjacent each of their ends only to the housing to provide an enhanced resonator decoupling effect. The filter may instead comprise a dielectric block with resonator holes and resonator decoupler holes each appropriately metalized with the decoupler holes being grounded at each end at external metalized block surfaces.

Optical force transducer based on a Fabry-Perot resonator, with a sweeping Fabry-Perot resonator as an element of the transducing part

Abstract: The invention concerns a transducer for measurement of force The transducer comprises a body part (15), a sensing element (4,27,37) springedly mounted on the body part (15), the actuated sensing element acting as a force-receiving element whose deflection relative to the body part (15) can be employed for computing the force applied onto the sensing element (27,37), and an optical detection assembly (1,6,8) for determining the deflection of the sensing element (27,37) According to the invention the body part (15) and the sensing element (27,37) form a short, optical, Fabry-Perot-type resonator (21,23) operated in the reflection mode, and the optical detection assembly (1,6,8) comprises a wide-spectrum light source (1), an intensity detector (8) for detecting the light intensity received from the sensing resonator (21,23), optical conductors (3) for routing a ray of light from the light source (1) to said resonator (21,23) and back therefrom to the detector (8), and placed along the optical path between the light source (1) and the detector (8), a sweeping Fabry-Perot resonator (6,41,49,51) having an optical length which is cyclically controllable over the optical length of the sensing resonator (4), whereby the detector provides indication of an intensity minimum or maximum, and phase detection elements for detecting the phase angle at the minimum or maximum in the intensity signal from the sweeping resonator (41,49,51) for the purpose of determining the optical length of the sensing resonator (4) which is proportional to the force (F,F') applied onto the sensing element (27)

Bandwidth enhancement of dielectric resonator antennas

Abstract: An experimental investigation of bandwidth enhancement of dielectric resonator antennas (DRAs) using parasitic elements is reported. Substantial bandwidth enhancement for the HE/sub 11/spl delta// mode of the stacked geometry and for the HE/sub 13/spl delta// mode of the coplanar collinear geometry has been demonstrated. Excellent radiation patterns for the HE/sub 11/spl delta// mode were also recorded. Because of excellent return loss and radiation characteristics, the DRA should be excited in HE/sub 11/ mode when used as radiating elements in an array. >

Silica-based finesse-variable ring resonator

Abstract: A finesse-variable ring resonator with a free spectral range of 2.5 GHz is demonstrated using silica-based optical waveguides. The finesse is controlled with a coupling-ratio-variable coupler, which is composed of a symmetrical Mach-Zehnder interferometer and thermooptic phase shifters. The finesse of the resonator is changed continuously from 6 to 27. >

Radial polarization laser resonator

Abstract: A laser resonator is provided for producing a radially polarized laser beam. The laser resonator includes an active laser medium disposed between a highly reflective end mirror and an opposing partial transmission mirror which define a laser resonator cavity therebetween for producing oscillating optical radiation. A conical Brewster window is further located within the laser resonator cavity and has an optically transparent medium oriented in accordance with the polarizing (i.e., Brewster) angle. As the optical radiation oscillates within the resonator cavity, the conical Brewster window causes the radiation transmitted therethrough to have a radial polarization. Accordingly, the laser resonator produces a laser output which has a radially polarized electric field associated therewith.

Stripline filter device having a coupling dielectric layer between two stripline resonators

Abstract: A stripline filter device including two or more dielectric substrate assemblies each having a pair of superimposed dielectric substrates between which at least one resonator conductor is disposed, wherein the dielectric substrate assemblies are stacked with an intermediate dielectric layer being sandwiched between the adjacent substrate assemblies so as to couple the resonator conductors in a direction perpendicular to the plane of each substrate, and by suitably setting the material and/or the thickness of each intermediate dielectric layer the coupling quantity between the resonators can be adjusted to obtain a desired frequency bandwidth.

An integrated rectangular dielectric resonator antenna

Abstract: The use of a rectangular dielectric resonator as an antenna element is reported. The resonator is excited in its lowest order magnetic dipole mode using a microstrip line-slot combination. Measured results on the proposed antenna configuration show that the antenna has a bandwidth of about 10% and that its far field pattern is similar to that of a magnetic dipole. The overall antenna configuration is small in size, and can be easily integrated with MIC's (microwave integrated circuits). The proposed configuration should be useful in applications such as active antenna arrays where the active circuitry can be fabricated on the same substrate. >

Evanescent-field interrogator for atomic frequency standards

Abstract: A novel atomic frequency standard includes an absorption cell containing a first volume of atoms for varying an intensity of light energy passing therethrough; at least one dielectric resonator for generating an evanescent electromagnetic field that effects hyperfine energy level transitions of the first volume of atoms; a waveguide for housing the absorption cell and one or more dielectric resonator(s); a photo detector mounted near an end of the waveguide for receiving light energy; and an electromagnetic energy injector for electromagnetically exciting the dielectric resonator(s). Preferably, a filter cell is positioned adjacent to a dielectric resonator between the absorption cell and the light source. Tuning of the resonant frequency of the dielectric resonator(s) can be accomplished by adjusting the distance between the filter cell and the adjacent dielectric resonator, and can also be accomplished by positioning a dielectric tuning disk adjacent a dielectric resonator, and adjusting the distance between the dielectric resonator and the dielectric tuning disk.

Fluid monitor system and method using a resonator

Abstract: A non-invasive, fluid monitor engages an open resonator with a segment of fluid line. The fluid line is disposed such that it and the fluid within become a part of the dielectric loading on the resonator. The open resonator is a part of an oscillator circuit that changes frequency of oscillation in response to the dielectric loading on the resonator. A frequency discriminator monitors the frequency of the oscillator to detect an air bubble in the fluid line. In the case where the resonator comprises a microstrip line, the microstrip line is disposed in parallel to the segment of the fluid line and the length of the microstrip line is selected to be equal to or greater than the maximum length of air bubble permitted thus providing a volumetric air-in-line sensor. The output of the frequency discriminator is compared to a threshold to determine a frequency shift large enough to indicate the presence of an air bubble.

Analysis of the dynamic response of a ring resonator to a time-varying input signal.

Abstract: An analysis of the time-dependent response of an all-fiber ring resonator is given in which the ring is illuminated by a phase-modulated input beam. The resonator is operated as a high-resolution scanning spectrometer and has a demonstrated optical resolution of 20 kHz for a single-frequency cw source. Unusual effects are observed when the ring is used to measure the spectrum of an optical signal subject to frequency or phase modulation.

Interdigital bandpass filter

Abstract: An interdigital bandpass filter is provided which presents improved performance and is easy to manufacture. The filter is provided with a resonator plate which includes a plurality of resonator elements formed integrally with the resonator plate. For defining a space for accommodating these resonator elements, spacer plates are formed with respective openings. The filter is assembled by stacking the spacer and resonator plates and case plates and securing them to each other. Input/output conductors are coupled to the resonator elements through coaxial line coupling portions which are provided in such a manner that they extend in directions intersecting with the plane of the resonator plate toward the accommodating space.

Impedance matrix of an antenna array in a quasi-optical resonator

Abstract: The power from numerous millimeter-wave solid-state sources can be efficiently combined using quasi-optical techniques. One technique is to place an array of active radiating sources within a quasi-optical resonator. The driving point impedance of each antenna is strongly affected by the presence of all other active antennas as well as by the mode structure and Q of the resonator. The impedance matrix for an array of antennas radiating into a plano-concave open resonator is determined here through use of the Lorentz integral. The resulting expressions include the effect of diffraction loss and are valid for arbitrary reflector spacing, source frequency, array location and geometry. The result can be used for impedance matching of each active source to its antenna, facilitating design of an efficient power combining system. Simulations using the impedance matrix in conjunction with an antenna impedance model are compared with two-port measurements. >