Showing papers on "Dielectric resonator antenna published in 1992"

Theoretical and experimental resonant frequencies of rectangular dielectric resonators

Abstract: In the paper the theoretical and experimental resonant frequencies of isolated and shielded rectangular dielectric resonators are reported. The dielectric waveguide model has been used for the analysis. Lowest-order modes of the resonator have been identified. The effect of shielding on the resonant frequencies of different modes has been studied. Experimental schemes that have been tried to excite various modes of the resonator are reported. Results of theory are compared with those of experiment.

Integrated tunable resonators for use in oscillators and filters

Abstract: An integrated tunable resonator (100) includes a common semiconductor carrier (110). Formed on the common semiconductor carrier (110) is an integrated voltage variable capacitor (104). A bulk acoustic wave resonator is formed on the common semiconductor carrier (110) and coupled to the voltage variable capacitor (104). In one aspect of the present invention, a thin film resonator (106) is coupled to the voltage variable capacitor (104) both of which are formed on a common semiconductor substrate (110). The combination of these three elements provide for a tunable integrated resonator (100). In another aspect of the present invention, a surface acoustic wave resonator (522), formed on a common semiconductor carrier (514), is coupled to a voltage variable capacitor (520) in order to provide a tunable resonator (500).

Microwave needle dielectric sensors

Abstract: Method and apparatus for in vivo or in vitro sensing of complex dielectric properties of lossy dielectric materials, particularly biological tissue. Configured as a needle-like dielectric sensor, a coaxial cable (1) having a circumferential gap (12) in the shield (2) is wrapped with an electrically thin dielectric substrate (18). The cable center conductor (6) extends immediately past gap (12) and is shorted to cable shield (2). A thin conductive dipole resonator (16) is positioned on substrate (18) and over feed gap (12) to achieve inductive coupling between the cable center conductor (6) and the dipole resonator (16) through gap (12). Superstrate (22), which could be a dielectric catheter, covers the entire sensor assembly (10). By measurement of the resonator resonant frequency and the input impedance matching factor at the resonant frequency, the real and imaginary dielectric components (e', e") of the test material into which the sensor is inserted are determined.

Microwave reflection resonator sensors

Abstract: A highly sensitive, direct-contact, in situ sensor for nondestructively measuring or monitoring the complex dielectric and conductive properties of solids, liquids, or gasses at microwave frequencies. A metal microstrip dipole resonator (11) is etched on the surface of a dielectric substrate (12) which is bonded to a copper ground plane (14). The dipole resonator is electromagnetically driven by mutual inductive coupling to a short nonresonant feed slot (13) formed in the ground plane (14). The slot (13) is driven by a coaxial feed line (7) or a microstrip feed line (16) extending from a swept microwave frequency source (2) which excites the incident wave (17). Alternatively, the metal resonator is omitted and the length of the slot (15) is increased so that it becomes the resonator. In use, the sensor is placed in close physical contact with the test material (9) having complex dielectric constant e* (=e'-je") or conductivity σ. As the frequency of the microwave source (2) is swept, a sharp dip in the reflected wave (18) occurs at the resonant frequency, provided that the coaxial feed line (7) or microstrip feed line (16) is nearly critically coupled to the sensor input. Measurement of the resonant frequency and input coupling factor determines small changes in e', e" and σ with great resolution. To diminish the electromagnetic coupling between the resonator (11) and the test material (9), and to protect the resonator (11) from damage and wear, a superstrate (26) may be added.

Low-loss dielectric resonant devices having lattice structures with elongated resonant defects

Abstract: A dielectric resonator comprising a resonant defect structure diposed in a lattice structure formed of a plurality of multi-dimensional periodically arranged dielectric elements confines electromagnetic energy within a frequency band in the photonic band gap. The frequency band of the confined electromagnetic energy is tunable. The unique structure of the dielectric resonator leads to reduced power dissipation losses when used in microwave and millimeter wave components. Accordingly, the dielectric resonator may be used to produce high quality resonant cavities, filters and power generators.

Adjustable resonator arrangement

Abstract: An adjustable resonator arrangement comprises a main resonator (T1) and a secondary resonator (T2) reactively coupled thereto. The secondary resonator includes a switching element (S), e.g. a varactor, having at least two states. When the switching element is in a first state the secondary resonator behaves as a half-wave resonator having a resonant frequency f o substantially different to the resonant frequency f of the main resonator. Consequently the secondary resonator has no appreciable affect on the resonant frequency of the main resonator. However, when the switching element is in a second state, the secondary resonator behaves as a quarter-wave resonator having a resonant frequency 2*f o which is closer to the inherent frequency f of the main resonator and sufficiently close to cause a shift Δf in the effective frequency of the main resonator. Suitably the main resonator is realized as a dielectric resonator and the secondary resonator is realized as a strip line resonator in the form of a conductive strip provided on a side face of the dielectric block from which the main resonator is formed.

Dielectric filter having coupling electrodes for connecting resonator electrodes, and method of adjusting frequency characteristic of the filter

Abstract: A tri-plate type dielectric filter having a dielectric substrate, a plurality of resonator electrodes embedded in the substrate, and coupling electrodes formed within the dielectric substrate for capacitively connecting the resonator electrodes to provide capacitors between adjacent resonator electrodes. The resonator electrodes may take the form of parallel elongate strips each providing a stripline type λ/4 or λ/2 TEM mode resonance circuit. One end of each strip is exposed at an outer surface of the substrate. This end of each strip is trimmed to adjust the resonance frequency of the resonance circuit.

Temperature compensated dielectric filter

Abstract: A temperature compensated filter comprises a block (1) of dielectric material having at least one transmission line resonator (3) formed herein. All surfaces except one side surface of the block are substantially coated with an electrically conductive layer (11). For achieving temperature compensation, a capacitor (6) coupled to the conductive layer (11) through a strip line (7) is attached, in a heat conductive way, to the uncoated side surface of the dielectric block. The capacitor (6) tunes the main resonator and the temperature dependence of its frequency is opposite that of the dielectric body so that it compensates the temperature dependence of the frequency of the main resonator.

Cooled, ultrahigh Q, sapphire dielectric resonators for low-noise, microwave signal generation

Abstract: Ultra-high Q, X-band resonators, used in a frequency discriminator for stabilization of a low-noise signal generator, can provide a means of obtaining significant reduction in phase noise levels. Resonator unloaded Qs on the order of 500 K can be obtained in sapphire dielectric resonator (DR) operating on a low-order (i.e. TE/sub 01/) mode at 77 K and employing high-temperature superconducting (HTS) films installed in the DR enclosure covers. Rigorous analysis for the determination of resonator frequency, modes, and unloaded Q have been carried out using mode matching techniques. Trade-off studies have been performed to select resonator dimensions for the optimum mode yielding highest unloaded Q and widest spurious mode separation. Field distributions within the resonator have been computed to enable practical excitation of the required mode. The results of both analysis and prototype device evaluation experiments are compared for resonators fabricated using enclosures consisting of conventional, metal sidewalls and covers employing HTS films as a function of cover conductivity. >

Miniature dual mode planar filters

Abstract: A dual mode microstrip resonator (1) usable in the design of microwave communication filters. The substantially square resonator (1) provides paths for a pair of orthogonal signals which are coupled together using a perturbation located in at least one corner of the resonator (1). The perturbation can be introduced by notching (3) the resonator (1) or by adding a metallic or dielectric a stub (83) to the resonator (1).

Microwave interstitial hyperthermia probe

Abstract: Method and apparatus for in vivo or in vitro selective deposition of microwave power patterns in lossy dielectric materials, particularly biological tissue. Configured as a needle-like probe, a miniature coaxial cable (1) having a circumferential gap (12) in the shield (2) is wrapped with an electrically thin dielectric substrate (18). The cable center conductor (6) extends immediately past gap (12) and is shorted to cable shield (2). A thin conductive dipole resonator (21) is positioned on substrate (18) and over gap (12) to achieve inductive coupling between the cable center conductor (6) and the dipole resonator (21) through gap (12). The ends of the dipole resonator (21) are capacitively (22) loaded so as to make the current on resonator (37) more uniform and to greatly reduce and stabilize the resonant frequency to be essentially insensitive to the dielectric properties of the surrounding material. A thin metal strip (27) is positioned on first superstrate (23) over and parallel to resonator (21), to diminish the hot spot near feed gap (12) and to make coupling to the surrounding lossy material (7) along the length of resonator (21) more uniform. Second superstrate (33), which could be a dielectric catheter, covers the entire probe assembly (30).

Thin film resonating device

Abstract: A thin film resonator (TFR) antenna is disclosed which is characterized by substantially lower effective dielectric constant for the layer of dielectric material deposited between the ground metal layer and the top metal layer (transducer) of the TFR antenna. The dielectric constant is substantially lowered by forming an array of dielectric posts in the dielectric layer. The posts support the top metal layer of the TFR antenna. The interstices between the posts are occupied by air in the preferred embodiment. The lower effective dielectric value results in reduced ohmic losses which in turn leads to enhanced gain in the TFR antenna system.

Method and apparatus for attenuating acoustic vibrations in a medium

Abstract: Apparatus is provided for attenuating acoustic vibrations in a medium comprising a tunable acoustic resonator (3) with an open end (5) for interfacing with the medium, at least one transducer (11) to provide a resonator signal indicative of a dynamic parameter of the medium within the resonator (3), and a resonator controller (8) operable in response to the resonator signal to tune the resonator (3) to a selected frequency of the acoustic vibrations.

Sapphire dielectric resonator transducers

Abstract: A recently developed sapphire dielectric resonator transducer has high Q factor at room temperature and can allow the construction of transducers with very high electromechanical coupling and very low losses at 4.2 K. In this paper the authors present the theory and experimental tests of a sapphire dielectric resonator transducer. They explain the shape of the tuning curves and describe a new configuration which can have even more sensitivity. The performance of a room temperature prototype transducer which has a noise floor of 10-14 mHz-1/2 is described. Accelerometers with sensitivity of 10-13 g could be constructed using this device.

Flat-plate antenna with strip line resonator having capacitance for impedance matching the feeder

Abstract: A flat-plane antenna for mobile communications, used in automobiles, etc. including a table form antenna element made up of a conductive flat-plate section and a plurality of leg sections which connect to the flat-plate section to a ground plate, a strip line resonator provided beneath the table form antenna with a space in between, and a capacitor electrode provided on the strip line resonator directly under the center of the table form antenna element. A feeding line is connected to the strip line resonator.

Ladder-type electric filter device

Abstract: A ladder-type electric filter device in which a casing is partitioned into two compartments, one for containing strip-shaped series piezoelectric resonator elements which are operated at a longitudinal oscillation mode and the other for containing square shaped parallel piezoelectric resonator elements which are operated at a peripheral oscillation mode, each of the series and parallel resonator elements is layered along the height of the casing. Alternatively, an input, output and grounding terminal plates for electrically connecting rectangular piezoelectric resonator elements operated at a longitudinal oscillation mode are integrally formed with a casing for containing the rectangular piezoelectric resonator elements.

Analysis and realization of L-band dielectric resonator microwave filters

Abstract: High power L-band dielectric resonator microwave filters, used in satellite systems because of their good temperature and vibration characteristics, low weight, and size, are discussed. The electromagnetic and electrical parameters of different microwave dielectric resonator structures are computed by means of the two-dimensional and three-dimensional finite element method, which are applied both for free and forced oscillation systems. The design and response evaluation of an elliptic filter using rectangular dielectric resonators excited in their TM/sub 110/ mode are presented. >

Low-cost, low-noise, temperature-stable, tunable dielectric resonator oscillator

Abstract: A dielectric resonator oscillator having a resonant structure connected to an amplifier the output of which is fed back to the input of the resonant structure. The resonant structure includes a metal cavity in which a dielectric disk is centrally mounted by a low-loss dielectric post. A pair of microstrip transmission lines extend into the cavity to provide energy outputs and inputs. Dielectric and conductive tuning screws are mounted on the cavity walls. Electrical tuning is provided via a varactor diode whose bias is adjustable. The diode may be connected in series or parallel with the microstrip transmission line.

Phase plate or spiral phase wheel driven linear frequency chirped laser

Abstract: Frequency modulated radar transmitters with a repetitive linear increase in frequency with time, referred to as "frequency chirps", are required for many radar applications. The present invention provides a simple way of obtaining such a chirped frequency modulation for a laser radar transmitter or the like. The principle is to translate an optical wedge in the direction of its wedge gradient at constant velocity across the optical path of a laser resonator. The resulting increase or decrease in the effective optical length of the resonator causes frequency chips. In a first embodiment of the present invention, a rotating phase plate on the face of a rotating wheel with the added phase varying linearly with angular position around the wheel is placed within a laser's resonator cavity to tune the optical pathlength of the cavity and thereby the longitudinal mode of the resonator to produce the chirp. This embodiment can be used in either a reflective or a transmissive mode. In a second embodiment of the present invention, the outer peripheral rim of a spiral wheel having a spirally increasing or decreasing radius is used, whereby the rim functions as a mirror, is disposed within the laser resonator. Rotating the wheel changes the optical pathlength of the resonator and causes the longitudinal modes of the resonator to tune so as to generate the required chirp sequence. Lastly, various systems are proposed for eliminating various types of errors in the system as well as for generating both up-chirps and down-chirps sequentially and/or simultaneously.

Microwave resonator of compound oxide superconductor material having a tuning element with a superconductive tip

Abstract: A microwave resonator includes a superconducting signal conductor formed on a first dielectric substrate, and a superconducting ground conductor formed on a second dielectric substrate. The first dielectric substrate is stacked on the superconducting ground conductor of the second dielectric substrate. A rod is adjustably provided to be able to penetrate into an electromagnetic field created by a microwave propagation through the superconducting signal conductor, so that the resonating frequency ƒ0 of the microwave resonator can be easily adjusted by controlling the position of a tip end of the rod.

Mechanism for adjusting resonance frequency of dielectric resonator

Abstract: A mechanism for adjusting the resonance frequency of a dielectric resonator having TE 01 δ mode as its operation mode under the presence of the electromagnetic field including: a hole extending along the axis of the dielectric resonator; a tuning bar, made of a dielectric material of a low loss, having a male screw formed on the peripheral surface thereof; and a female screw, to engage the male screw, formed on the wall of the hole. The tuning bar is reciprocated in the hole with the tuning bar engaging the hole so as to adjust the resonance frequency.

TE101 triple mode dielectric resonator apparatus

Abstract: A dielectric resonator apparatus is provided with a dielectric resonator which has a generally spherical dielectric placed within a shield case having a rectangular cavity, and uses each resonance of a x mode, a y mode and a z mode of TE 101 , where an electric field is caused respectively around a x axis, a y axis and a z axis of a rectangular coordinate system predetermined in the dielectric, and an external coupling means for coupling the above described resonator to an external circuit, whereby the dielectric resonator apparatus, which has no-load Q larger than in the conventional embodiment, can be made smaller in size, and also, can realize three resonators with one apparatus.

Mounting assembly for dielectric resonator device

Abstract: A dielectric resonator device includes an enclosure having a bottom wall, a pedestal made of quartz seated inside the enclosure on the bottom wall, a dielectric resonator element seated on the pedestal, a bracket made of quartz for holding the dielectric resonator down on the pedestal and a clamping disc and screws for securing the bracket to the bottom wall.

Dielectric material for antennas

Abstract: This invention relates to the fabrication of dielectric material suitable for dielectric antennas such as Luneburg-type lens antennas and to an according antenna system. It is an object of the present invention to produce dielectric material with a low weight and the possibility of adjusting a dielectric constant quite easily. According to the invention dielectric pieces, which collectively form the dielectric material, have a hollow shape. By the variation of the thickness, the effective dielectric constant can be varied. The antenna system according to the invention includes a virtuel lens antenna with extended reflecting means. The material produced according to this invention can preferably be used for the production of Luneburg-type lenses.

Half-wave folded cross-coupled filter

Abstract: A folded high frequency resonant cavity filter 30 includes a filter housing 32 that contains a half-wave resonator rod 36, 64 and a plurality of evanescent mode resonator rods 34, 34'. The half-wave resonator rod 36, 64 and plurality of evanescent mode resonator rods 34, 34' are mounted to the filter housing 32 such that they all lie along a single plane. The filter housing 32 has an inner wall 42 that physically isolates two groups of evanescent mode resonator rods 34, 34' from each other. An aperture 40 is is formed in the inner housing wall 42 between two physically opposing evanescent mode resonator rods 34' to allow a capacitive cross-coupling to occur between the two evanescent mode resonator rods 34'. The capacitive cross-coupling is fine tuned by a tuning rod 44 that is positioned through the inner wall 42 and within the aperture 40. The half-wave resonator rod 36, 64 can be either a shunt half-wave resonator rod 36 or a series half-wave resonator rod 64, whereby the shunt half-wave resonator rod 36 is fine tuned by a tuning disc 46 and the series half-wave resonator rod 64 is fine tuned by a pair of tuning rods 68. Input and output ports 48 are supplied with coupling loops 49 to allow input and output coupling, respectively, with the filter 30.

Sensor having optical passive ring resonator using sagnac effect

Abstract: A sensor which makes use of a non-reciprocal optical effect, such as the Sagnac effect has a passive ring resonator defining a closed light path. Light from a broadband light source is coupled to the passive ring resonator by 2×2 couplers in a first direction of propagation and a second direction of propagation opposite thereto. The 2×2 couplers also couple light out of the passive ring resonator. A 3×3 optical coupler is provided, by which light having circulated in said ring resonator in the first direction of propagation is superimposed to light having circulated in the ring resonator in the second direction of propagation to provide interference. The detector is exposed to this interfering light.

Gain enhancement of dielectric resonator loaded waveguide antennas with dielectric overlays

Abstract: The gain characteristics of a dielectric resonator loaded coaxial probe fed circular waveguide antenna (DRLWA) with overlaying parasitic discs have been investigated experimentally. Results indicate that, when properly spaced, the overlays can enhance the gain by more than 6 dB.

Multi-slab solid state laser system

Abstract: The laser system features a plurality of thin solid-state gain channels mounted radially about a common axis. These gain channels may be excited by multiple flashlamps or by extended arrays of light-emitting-diodes. The gain channels are also mounted in a parallel configuration within a single optical resonator and thereby share a common cavity mode. The resonator may be a stable resonator, a conventional unstable resonator, or a toric resonator. Each resonator configuration may be externally phase-locked via external reference oscillator injection or by self-injection via an internally generated master oscillator. When incorporating a very large number of gain channels, the concept provides an efficient and inexpensive means for constructing extremely high powered, optically-pumped, lasers in very small physical packages. The technique, which is applicable to a wide variety of laser gain media, either solid or liquid, permits high average power operation to be achieved without serious beam quality degradation. Typical solid state gain media include Nd:YAG, Nd:Glass, GSGG, GGG and Alexandrite.

Planar dielectric resonator stabilized HEMT oscillator integrated with CPW/aperture coupled patch antenna

Abstract: A novel design of an active antenna with a dielectric resonator stabilized HEMT (high electron mobility transistor) oscillator (DRO) and an aperture-coupled patch antenna is reported. The circuit is fabricated using a coplanar waveguide (CPW) with the oscillator and the antenna on opposite sides of the substrate. The active antenna was demonstrated at 7.6 GHz; however, the design can be scaled to higher frequencies. Excellent oscillator characteristics and radiation patterns have been obtained. >

Split-ring resonator bandpass filter with adjustable zero

Abstract: A bandpass filter, having an input port and an output port, comprises a first microstrip split-ring resonator coupled to input port, and a second microstrip split-ring resonator coupled to the first microstrip split-ring resonator, and coupled to the output port. A lumped or distributed capacitance is disposed between the first microstrip split-ring resonator and the second microstrip split-ring resonator.