Showing papers by "Dominique Cros published in 2000"
TL;DR: In this article, a sapphire-rutile resonator was designed with mode frequency-temperature turning points between 50-80 K, with Q-factors of order 10/sup 7.
Abstract: The highest short-term frequency-stable microwave resonator oscillators utilize liquid-helium-cooled sapphire dielectric resonators. The temperature coefficient of frequency of such resonators is very small due to residual paramagnetic impurities canceling the temperature coefficient of permittivity (TCP). At high temperatures, which are accessible in space or with liquid nitrogen, the effect is too weak, and if extra impurities are added, the loss introduced is too great. An alternative technique involves using two low-toss dielectric materials with TCP of opposite sign. Following this approach, a sapphire-rutile resonator was designed with mode frequency-temperature turning points between 50-80 K, with Q-factors of order 10/sup 7/. Previous designs used thin disks of rutile fixed to the ends of the sapphire cylinder. Due to the high permittivity of rutile, such resonators have a high density of spurious modes. By placing rings at the end faces instead of disks, the majority of the spurious modes are raised above the operation frequency and the requirement for thin disks is removed. Finite-element analysis has been applied and compares well with experiment. The application to the design of high stability "fly-wheel"oscillators for atomic frequency standards is discussed.
30 citations
TL;DR: In this article, a composite sapphire-rutile frequency-temperature compensated resonator was designed for WGE/sub 9,0,0/ mode at 13.1 GHz with a Q-factor of 30 million.
Abstract: Experimental results for the novel design of a composite sapphire-rutile frequency-temperature compensated resonator are presented. The frequency-temperature dependence was annulled when a specific balance of electric energy in the rutile and sapphire was reached at 56 K in a WGE/sub 9,0,0/ mode at 13.1 GHz with a Q-factor of 30 million.
17 citations
TL;DR: In this paper, a very low loss silicon micromachined coplanar technology was presented, where the design of the structures was achieved through three dimensional finite element method electromagnetic simulations.
Abstract: We present in this article a very low loss silicon micromachined coplanar technology. The design of the structures was achieved through three dimensional finite element method electromagnetic simulations. A silicon micromachined cavity resonating at 95 GHz with a quality factor greater than 9000 was realized.
13 citations
11 Jun 2000
TL;DR: In this article, the authors presented a general method to synthesize a four-pole transversal filter composed of the banking of two two-pole filters with whispering gallery modes.
Abstract: This paper presents a general method to synthesize a four-pole transversal filter composed of the banking of two two-pole filters. This method is here applied to the case of a transversal filter realized with quarter cut resonators acting on whispering gallery modes. Experimental realization at 20 GHz is presented to demonstrate the efficiency of our method.
12 citations
TL;DR: In this article, an SiO2 whispering gallery mode resonator has been implemented in order to test its ability to realize high Q microwave cavities, and the observed resonance frequencies of the quasi-TE (WGH) and quasi-TM (WGE) modes are compared with numerical computations obtained using the finite element method.
Abstract: An SiO2 whispering gallery mode resonator has been implemented in order to test its ability to realise high Q microwave cavities. The authors present preliminary experimental results at room temperature and at 77 K. The observed resonance frequencies of the quasi-TE (WGH) and quasi-TM (WGE) modes are compared with numerical computations obtained using the finite element method.
6 citations
07 Jun 2000
TL;DR: Some novel new resonator designs based on the distributed Bragg reflector are presented, showing that a Q-factor of 70,000 and 65,000 can be achieved with and without the condition of zero frequency-temperature coefficients, respectively.
Abstract: Distributed Bragg reflector resonators (DBRR) have been initially suggested in order to improve the quality factor of sapphire loaded cavity (SLC) resonators. They were constructed from thin plates of sapphire designed to confine most of the energy of the resonant mode in free space. Q-factors larger than the dielectric loss limit of sapphire have been obtained using this method. However, these devices are necessarily larger than the whispering gallery (WG) resonators, as they require multiple layers to achieve sufficient confinement. Moreover, they are very sensitive to alignment and a special tool must be manufactured to properly construct the resonator. Finite element analysis of the structure has also revealed a large spurious mode density. Over 50 modes in a 1 GHz range at X-band were discovered. In this paper we introduce the concept of a compact solid microwave DBRR with reduced frequency temperature dependence and a Q-factor close to that of a pure sapphire resonator.
6 citations
01 Oct 2000
TL;DR: A negative resistance circuit is introduced in a passive bandpass filter to compensate its losses and realise a high-Q selective structure and the synthesis of an adjustable active inductance close to an ideal element over the 3.8-4.2 GHz band is presented.
Abstract: In this paper, we present a method to synthesise microwave active bandpass and bandstop filters using negative resistance circuits and/or active inductance circuits realised in MMIC technology. We show measurements of a negative resistance circuit which is after associated with passive lumped elements to realise an active bandstop filter, tuneable in frequency. We also present the synthesis of an adjustable active inductance close to an ideal element over the 3.8-4.2 GHz band. This element is introduced in a passive bandpass filter to compensate its losses and realise a high-Q selective structure.
6 citations
01 Oct 2000
TL;DR: In this paper, the design and fabrication of a new type of millimeter-wave micromachined band pass filters, using silicon waveguides, is described, along with two examples of two and four pole filters at 42 GHz.
Abstract: This paper describes the design and the fabrication of a new type of millimeter-wave micromachined band pass filters, using silicon waveguides. The main interest of these components is their ability to be integrated along with other MMICs using flip chip bonding techniques. The micromachining fabrication technique allows to maintain very good fabrication tolerances, while the resulting filters are very compact. The design methodology is presented along with two examples of two and four pole filters at 42 GHz.
4 citations
01 Oct 2000
TL;DR: In this article, a theoretical study of dielectric temperature compensated resonators is presented, where the authors define rules of design to predict the temperature of inversion, and use finite element method software, which permits the design of the inversion point at any temperature.
Abstract: This work presents a theoretical study of dielectric temperature compensated resonators. It has been shown that use of two dielectric materials with opposite temperature coefficient of permittivity allow the realisation of a resonator with a zero temperature coefficient of frequency. By using sapphire and rutile materials, which have low loss tangents, some resonators with very high unloaded Q-factors have been already realised. To continue this work it is necessary to define rules of design to predict the temperature of inversion. This has been achieved by using finite element method software, which permit the design of the inversion point at any temperature
2 citations