Showing papers on "Q factor published in 1981"

Precise Calculations and Measurements on the Complex Dielectric Constant of Lossy Materials Using TM/sub 010/ Cavity Perturbation Techniques

Abstract: An exact field theory solution for the cylindrical TM/sub 010/ cavity with a coaxial lossy dielectric cylinder is given. The error in the calculated field solutions is estimated to be less than 1 percent of the true values. Correction for the cavity holes used to introduce the sample is taken into account. The exact solution shows that the real part of the permittivity (epsilon') is a complex function of both the frequency shift and the change in the loaded Q-factor (Q/sub L/). On the other hand the imaginary part (epsilon") is nearly proportional to delta(1/Q/sub L/) and it has different slopes for varying frequencies. By means of active cavity techniques already reported, experimental measurements on epslion' and epsilon" taken at 2.2 GHz on a number of materials (water, teflon, n-proponal, methanol, etc.) agree with published data within 1 percent even when rising large samples.

Maximum Q-Factor of Microstrip Resonators

Abstract: The quality factors of microstrip half-wavelength resonators have been calculated as a function of substrate thickness for frequencies in the range 8-96 GHz, for different epsilon/sub r/. Conductor, dielectric, and radiation losses have been included. The optimum substrate thickness for the maximum Q-factor for 50-omega microstrip resonators has been derived as a function of frequency for different dielectric constants.

Analytical theory of an unloaded rectangular microstrip patch

Abstract: A graphical method for determining the size of a resonant rectangular microstrip patch for a specified frequency is given. Using an expression obtained from the reflection coefficient of a transverse electromagnetic (TEM) wave in a semi-infinite microstrip patch, the resonance condition of a given mode for a patch of finite size is derived in a manner analogous to that of a rectangular, waveguide cavity. Radiation is shown to be in the form of both surface waves and space waves and is dependent on the angles of incidence for waves impinging onto the edges of the patch. By varying the aspect ratio, it is also possible to modify the Q factor of a resonant path. Analytical expressions for the resonant frequency and the Q factor are then derived under the assumption of a very thin substrate slab, encountered frequently in the application. Design curves in the form of the "Argand diagram" are then presented for microstrip patches with fixed aspect ratios.

Mode coupled notched tuning fork type quartz crystal resonator

Abstract: A mode coupled tuning fork type quartz crystal resonator is mounted to a plug using support members of selected contour and dimensions to prevent acoustic energy loss from the plug and to avoid reduction in Q factor. A bend of 180 degrees in the support member and controlled length are factors in isolating fundamental and first overtone vibrations in flexure and fundamental torsional vibrations so as to reduce energy loss, maintain stable oscillation and improve the Q factor. A laterally extended base portion and/or tapered ends of the tuning fork arms enhance the beneficial results.

Millimeter wave measurement of both parts of the complex index of refraction using an untuned cavity resonator.

Abstract: It is demonstrated, both theoretically and experimentally, that simultaneous measurement of the real and imaginary parts of the complex index of refraction of small, strongly absorbing samples can be accomplished by placing the samples inside an oversized untuned resonator cavity. Nearly monochromatic radiation is fed into the cavity, and the change in cavity Q resulting from introduction of a sample is measured. Determination of n and k results from a series of such measurements on lamellar samples of different thickness. An analytic solution of the boundary value problem for a lamellar sample placed between two nonabsorbing windows is used to derive n and k from the measured changes in Q, and as a consequence the procedure is applicable to liquid as well as to solid samples. Although the measurements reported here were made at λ ≈ 4 mm, the technique offers similar advantages at submillimeter wavelengths.

Automatic measurement of Q factor and resonant frequency of microwave resonators

Abstract: The experimental system described is controlled by a desktop computer and a set of experimental data (transmitted power against frequency) is stored in it. By fitting the resonance curve to this experimental data, Q factor and resonant frequency are determined with an estimated accuracy of 0.1% and 1*10-7 respectively.

Finite Element Approach to Frequency-Temperature Characteristic Prediction of Rotated Quartz Crystal Plate Resonators

Abstract: The finite element technique is utilized for calculating the natural frequencies and frequency-temperature coefficients of thin anisotropic quartz crystal plates. The computer programs developed can accommodate a plate cut in any direction in the crystallographic coordinate. Examples of X-cut rectangular plates and DT-cut plano- convex plates are shown and numerical results are compared with mea- sured ones as well as with theoretical predictions if available. UARTZ crystal resonators present well-known problems but are still increasingly used as time-keeping devices not only for telephone and telecommunication systems but also for watches and microprocessors. A finite element method (FEM) has been applied to the calculation of the nat- ural frequencies and their associated modes in thin piezoelec- tric plates in plane motion together with their admittance characteristic at the electrical terminals (l). The temperature characteristic is another important factor of the resonator, particularly when it is utilized as a frequency control device. The prediction of the temperature dependence of the natural frequency and Q factor of a composite circular transducer (Langevin-type) has been demonstrated (2), in which the ad- hesive layers are assumed to be responsible for the temperature characteristic so that only their Young's modulus and loss factor are considered to be temperature-dependent and no geometrical expansion is taken into account. This paper is concerned with the prediction of the natural frequencies of thin quartz crystal plates and their temperature characteristics. The finite element technique is employed to calculate them, taking into effect the geometrical change of the plates due to thermal expansion and the temperature dependence of the elastic stiffness tensor. The plates are as- sumed to be thm and of plane-stress motion. No electro- mechanical coupling effect is included as it is small in quartz crystal. The computer program was developed to calculate the natural frequencies of various modes and their frequency- temperature coefficients (up to the third order) of a thin anisotropic plate cut in any direction of its crystallographic

Scattering of the TE/sub 01/ and TM/sub 01/ Modes on Transverse Discontinuities in a Rod Dielectric Waveguide-Application to the Dielectric Resonators

Abstract: Our purpose is to determine the resonance frequency together with the radiation quality factor of dielectric resonators. To do that, the reflection and the scattering properties of the TE/sub 01/ and TM/sub 01/ modes, incident on an abruptly ended dielectric rod, are analyzed. After the building of the complete mode spectrum on each side of the discontinuity, the continuity relations in the discontinuity plane associated with the orthogonality properties lead to a coupled integral equation system. That one is solved by means of an iterative procedure, providing all the characteristics of the discontinuity (reflection or coupling coefficients, radiation losses). Then, these solutions are used to determine the resonant frequency and the radiation quality factor of cylindrical resonators which are considered as waveguide lengths between two interacting discontinuities.

High-frequency measurements of multilayer ceramic capacitors

Abstract: A resonant coaxial transmission line, short circuited at one end and open circuited at the other, whose fundamental resonant frequency and Q factor are known, is perturbed with a test capacitor connected either in series at the shorted end of the line, or in shunt at the open end. Measuring the Q factor of the system with the delta f technique yields the effective series resistance, capacitance, and the Q factor of the test specimen. This method of measurement has the advantage that there are no adjustable elements to alter circuit conditions in an unprescribed way, the only variable is the frequency which can be measured with an uncertainty of less than 1 ppm, the loss of the line as a function of frequency is quite predictable, and the Q factor of the line can be made sufficiently high to support accurate measurements of low loss capacitors.

High Stability Coplanar Oscillators

Abstract: The feasibility is demonstrated of various kinds of coplanar oscillator stabilized by a high Q dielectric cavity; their performances are comparable with the ones obtained with microstrip circuits. An X-band coplanar oscillator is described with a frequency vs temperature stability lower than ±.2 ppm/°C over 100°C temperature range; a loaded quality factor QL?3500; pushing figure of about 8 ppm/V; and noise characteristics particularly appealing. The coplanar approach allows to reduce overall oscillator size, and place directly over the cavity a monolithic chip (including the active portion of the L.O.) avoiding unwanted L.O. couplings anywhere in the circuit.

Dielectric-resonator-tuned microwave solid state oscillator

Abstract: A microwave solid state oscillator of a compact size for generating an oscillation of a highly stabilized frequency, comprising a cavity resonator having a coupling window for coupling with an external circuit, a solid state oscillation device and a dielectric resonator of a large dielectric constant and a high Q factor, characterized in that the solid state oscillation device is installed in a recess which is formed on an inner side wall of the cavity resonator and having an opening sufficiently small compared with an internal size of the cavity resonator, and the dielectric resonator is disposed in the cavity resonator in a manner to face to and to be adjacent to the opening of the recess.

Tunable garnet laser with electrooptic Q switching

Abstract: A laser was constructed in which the active element was a Y3Al5O12:Nd3+ crystal placed in a dispersive resonator. This crystal emitted tunable radiation as a result of the 4F3/2→4I11/2 (λ = 1.064 μ) and 4F3/2→4I13/2 (λ = 1.318, 1.338, and 1.356 μ) transitions when the Q factor of the resonator was modulated by an electrooptic lithium niobate switch. The energy and time characteristics of the emitted lines were determined. When the pumping threshold was exceeded by a factor of 3, the energy of the output pulses at λ = 1.318 μ was comparable with the energy of the λ = 1.064 μ pulses. The duration of the pulses increased from 10 nsec (for the first transition) to 40–45 nsec (for the 4F3/2→4I13/2 transition).

Applications of a Twin Open Resonator System

Abstract: The advantages and application of a twin open-resonator system in measuring frequency and small frequency intervals are described. An improvement in the tuning sensitivity and in the ease of adjustment is achieved by the controlled insertion of a thin dielectric sheet which provides vernier tuning. Application of the system has provided measurements of the extinction scattering cross sections of simulated hail particles when dry and melting. The technique has been extended to measure mutual scattering between pairs of spheres.

Method of fabricating high-Q silicon varactor diodes

Abstract: A new processing technique has been developed for the fabrication of high-Q and high-voltage varactor diodes. The process utilises ion implantation and laser annealing for heavily-doped p++ and n++ layers and epitaxial growth for low impurity concentrations. The technique provides good yield and repeatability, and it has allowed fabrication of varactor diodes which have breakdown voltages of 120 V and a Q as high as 600 at −8 V bias and 50 MHz frequency.

Radiation suppressed high-Q-dielectric resonators for MIC applications

Abstract: A radiation suppressed high-Q dielectric resonator with a small and simple metal cap for MIC is described The measured Q0-factor over 10 000 is obtained at 25 GHz, which is comparable to a TE01 mode cylindrical waveguide resonator This resonator is useful for high frequency stability MIC oscillators

Ink jet array printer - has common drive circuit connecting resonator circuits of printing guns and arranged to equalise amplitude response

Abstract: The ink jet array printer comprises a row of printing guns including respective chambers, each provided with an orifice at one end. A resonant component is mounted to the chamber and devices are available for supplying ink under pressure to the chamber. Resonator circuits are connected in electrical parallel relationship for applying a high frequency voltage V to the parallel arrangement of the resonator circuits. The resistors (R1,R2..Rn) are placed in each of the parallel resonator circuits (R1,C1,L1,C'1,r2,C2,L2,C' ..RnCnLnC'n) in series with the resonator to effect reduction of the Q factor of the circuits. The resistors are indivudally chosen to have a value tending to equalise the amplitude response of the resonator circuits and consequently the break-up lengths of the ink jets.

Analysis of SAW Distributed Feedback Resonators

Abstract: The main characteristics and advantages of the surface acoustic wave (SAW) distributed feedback resonator are discussed. A coupled mode analysis provides physical insight and simple formulas for the resonant frequency, the quality factor, and the input imped- ance. Those results are verified by means of a transmission lie com- puter model and by a number of measurements in the frequency range 30-250 MHz. On YZ LiNbO3 substrates, quality factors of the order of 5000 are routinely obtained. ST quartz), the reflector can be made out of shallow grooves, one or two percent of a wavelength deep. The fingers of the coupling transducer can be located in between the grooves (Fig. l(b)) or can lie in the grooves of the reflector. Strongly piezoelectric substrates, such as YZ lithium niobate, allow for an easier approach: the resonating transducer in which the transducer fingers act as reflectors (by shorting out the piezo- electric field at the surface of the substrate). Although reso- nating transducers are mentioned in several papers (l) -(4), the modes of the resonant cavity are not discussed, and the reason for the resonant behavior is not fully explained. In this paper we present an analysis of the surface acoustic wave (SAW) resonance phenomenon encountered in the structure shown in Fig. 1. In the next section a simple approximate theory based on the coupling between the forward and back- ward propagating waves is proposed. This allows one to ob- tain a set of simple formulas that describe the essential char- acteristics of the resonant modes of a DFR. In the third section an equivalent circuit for the transducer exciting the DFR is derived starting from the modal fields calculated in Section 11. Finally, the results of this approximate theory are checked in two ways: first by comparison with the impedance characteristic of a DFR as calculated by a transmission line model for the structure and, secondly, by comparing with measurements made on DFRs. 11. COUPLED WAVE ANALYSIS OF THE DISTRIBUTED FEEDBACK RESONATOR In this section the resonant modes of the DFR are calculated by means of the coupled wave theory. This method has al- ready been successfully applied to the analysis of SAW grating structures (g) -( 101 and, although approximate, has the ad-

Automatic measurement of the complex permittivity at millimeter wavelengths

Abstract: A measuring system including an oversized cavity resonator operating in the TE01 mode for the determination of the complex permittivity e′- je″ of low-loss liquids at frequencies of about 36 GHz is described. While e′ is obtained by wavelength measurements in the filled and the empty resonator, e″ is determined from the variation of the Q factor of the filled resonator with the length of the dielectric sample. The Q factors of values of about 2·104 to 105 can be measured automatically by means of a desk calculator which controls the frequency and collects the digitized values of the detector output voltage. By means of the calculator, the Q factors of the resonator are determined by fitting analytical (Lorentzian) resonance curves to the measurement data. e″ and the Q factor for zero sample length are calculated according to Gottmann's methods.

New Very High Q Microwave Transistor Oscillators Using Dielectric Resonators

Abstract: Using the dielectric resonator as the matching as well as the frequency determining element, one port and two port Microwave Transistor oscillators having external quality factors much higher than the unloaded Q of the dielectric resonators, have been presented A self oscillating mixer has been proposed as the potential application of the two port FET oscillator presented

Passive CCD resonators [for high Q bandpass filters]

Abstract: The passive CCD resonator is a recursive CCD building block which is well suited for the realization of high Q bandpass filters. Its realization is compatible with the standard double-poly NMOS technology. Advantages of the new approach are an extremely low sensitivity of the center frequency which is determined by an external clock frequency, a relative bandwidth which does not depend on the center frequency but is controlled by a capacitance ratio, and signal frequencies at least up to some hundred kHz. The analysis, design considerations, and performance results are presented. A loaded Q factor of 30, a maximum stopband attenuation of 26 dB, and a negligible insertion loss in the passband are typical for a single CCD resonator. The maximum overall center frequency deviation /spl Delta/f/f due to fabrication tolerances is proportional to the transfer inefficiency of the CCD and has the value of about 2/spl times/10/SUP -4/.

A New Type of AT-Cut Quartz Resonator with Q-Factor and Frequency of the Unwanted Modes Controlled

Abstract: which the resonator is inserted, the other ones often limit its usefulness. It is well known that the unwanted resonances can produce loss of oscillation or erratic shifts of the output frequency in oscillator circuits, undesired change of the response curve of crystal fdters, etc. A method is described that permits a check of the Q-factor of the undesired vibrating modes in ATcut resonators and, withii certain limits, to vary their resonance frequencies with the aim of allocating them to regions where they are less likely to be damaging. This method, based on the deposition of multiple electrodes on the plate faces assures, during the setting-up phase, a high repeatability of characteristics in the device.

Rubidium atomic frequency standard

Abstract: PURPOSE:To improve the pumping radiation intensity and Q factor of the microwave of an atomic frequency standard by employing a rubidium lamp as a pumping radiation source constituting an atomic frequency standard as well as setting the lamp inside a cut-off waveguide. CONSTITUTION:At the opening of a cavity resonator 31 containing a cell 4, solar cell 8 and microwave antenna 7, a cut-off waveguide 32 is provided, inside which a pumping radiation source using a rubidium lamp 1 is set and oscillated by an exciting coil 2. Then, as usual, a series circuit comprising an amplifier having a phase synchronous detector, a low-frequency oscillator and a frequency synthesizer is connected between the solar cell 8 and the antenna 7, and a voltage-controlled crystal oscillator is provied between the amplifier and the synthesizer. Because the lamp 1 is set inside the waveguide 32 so as to be in one body with the resonator 31, the atomic frequency standard is made more compact, and the radiation intensity and Q factor are improved as well as the characteristics are stabilized.

Circuit to raise the effective quality of an oscillating circuit arrangement

Abstract: The quality or Q factor of a one-gate network consisting of an L-C circuit (C1, L) and an operational amplifier (4) is improved by a factor of 2 to 4 by the negative input resistance of the amplifier (4). In this way, the oscillating circuit can be made more useable for band pass filters at low frequencies, for which the aim is to achieve a low outlay on components and space. They are preferably used to filter out ambient sound signals, which are transmitted below the speech band, and would otherwise require relatively extensive coils for a high Q factor.

High-temperature measurements of Q-factor in rotated X-cut quartz resonators

Abstract: The Q-factors of piezoelectric resonators fabricated from natural and synthetic quartz with a 34 deg rotated X-cut orientation were measured at temperatures up to 325 C. The synthetic material, which was purified by electrolysis, retains a higher enough Q to be suitable for high temperature pressure-transducer applications, whereas the natural quartz is excessively lossy above 200 C for this application. The results are compared to results obtained previously at AT-cut resonators.