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1.
The attenuation coefficient of a rectangular dielectric line enclosed by a rectangular shield is obtained by the use of a rigorous mode-matching method to calculate the required mode field intensity. The cross section of the waveguide is overlaid by a grid, and numerical integration is used to determine the power flow, dielectric, and conductor losses and respective attenuation coefficients. To obtain experimental verification, a length of waveguide was made into a resonator, and measured and calculated Q factors were compared. The results for the E/sup y//sub 11/ mode show how the influence of the shield decreases with distance. This is relevant to the design of dielectric waveguide structures and in filter applications where dielectric resonators are used. 相似文献
2.
Cold tests and modeling of low-Q quasi-optical resonators 总被引:2,自引:0,他引:2
Measurements are reported on low-Q open resonators at 85 GHz with a large centered coupling hole in each mirror. This is the first study of open resonators with large diffraction losses and efficient input coupling at millimeter wavelengths. The input resonator for a quasi-optical gyroklystron is described with quality factor Q=2000 and 13% round-trip losses where approximately 65% of the incident power in the waveguide is coupled to the fundamental TEM00 mode. Two models have been developed to calculate the coupling from the rectangular waveguide through a circular aperture into the open resonator. Both models properly account for the increased diffraction loss of the resonator when coupling apertures are present. Measured results are in reasonably good agreement with values calculated using both scalar diffraction theory and an equivalent-circuit model 相似文献
3.
For a TM01δ mode dielectric rod resonator placed coaxially in a TM01 cutoff circular waveguide, characteristics such as the resonant frequency, its temperature coefficient, the unloaded Q , and the other resonances are discussed on the bases of accurate calculations using the mode-matching method. The results show that this resonator compares favorably with a conventional TE01δ mode dielectric resonator, particularly for realization of a high unloaded Q . Analytical results also verify that interresonator coupling between these two resonators can be expressed equivalently by a capacitively coupled LC resonant circuit. A four-stage Chebyshev filter having a ripple of 0.035 dB and an equiripple bandwidth of 27 MHz at a center frequency of 11.958 GHz was fabricated using these resonators. Its insertion loss is 0.5 dB, which corresponds to an unloaded Q of 17000, and no spurious response appears in the frequency range below 17 GHz 相似文献
4.
The impedance matrix for an arbitrary n -port ferrimagnetic resonator is derived by applying Poynting's theorem to a region of space surrounding the resonator. Simplifications to the impedance matrix for low-loss (Q >≈100) ferrite material make it possible to obtain an equivalent circuit model for the resonator, which can be used with most computer-based circuit simulation programs. The circuit model for the general-case polymodal ferrimagnetic resonator consists of a network of single-pole resonators, each of which has a possible non-frequency-dependent, nonreciprocal phase shift. The components of the circuit model are described in terms of the properties of the ferrite material, and the coupling strength of the microwave circuit to the magnetostatic modes of the ferrimagnet. The method is demonstrated in three simple examples, including a one- and two-port loop coupled filter, and a ferrimagnet in a waveguide 相似文献
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6.
The letter describes the analysis and design of a class of dielectric resonator filters in waveguide sections below cutoff. In these filters evanescent-mode coupling between the resonators can be realised by either an air-filled waveguide section or a dielectric slab-loaded waveguide section. Metallising the dielectric slab on both sides reduces the length of the coupling section and improves the stopband attenuation significantly. Filter characteristics can be predicted very accurately using a mode-matching technique to calculate the S-matrix of the filter component. This method accounts for the effect of finite metallisation thickness and higher-order modes. 相似文献
7.
本文分析了一种新型实用的微波滤波器结构:在矩形波导中插入圆柱形介质谐振器。文中将谐振器作为波导中的不均匀性,用模匹配法准确分析了其散射特性。理论结果不仅能计算谐振频率,而且还给出散射矩阵等网络参数。本文的理论分析与实验检测量结果吻合很好。通过理论与实验研究,本文对衬底的作用作出了新的解释。 相似文献
8.
In this paper, we use modified form of Bethe's small hole coupling theory to compute equivalent circuit parameters of an aperture coupled open resonator cavity. The open resonator cavity is composed of spherical mirrors of circular cross section. The cavity is coupled to a rectangular waveguide by means of a common hole in the mirror and the shorted end wall of the rectangular waveguide. Closed form expressions have been obtained for the equivalent circuit parameters. Experiments conducted in the W-band frequency range show good agreement with theory when an experimentally estimated correction to the transmission coefficient is applied for the thickness of the coupling holes 相似文献
9.
《Microwave Theory and Techniques》1986,34(9):972-976
A bandpass filter operating at 870 MHz was constructed using lambda/4-coaxial resonators. The resonators were made of metallized high- Q dielectric ceramic (Q>=10 000, epsilon/sub r/ = 37), and were directly coupled to each other through apertures which were formed on the outer side surface of the resonators. In order to couple the input and output resonators to the external circuit, a rectangular metal film was deposited on the open-circuit end. The resonant frequency of each resonator, coupling coefficients between adjacent resonators, and external Q's at both ends were adjusted before assembly. The resonators were then assembled in a housing with no further adjustment. The measured response was in excellent agreement with the theory. 相似文献
10.
Slot-fed higher order mode Fabry-Perot filters 总被引:1,自引:0,他引:1
Low-loss bandpass filters consisting of Fabry-Perot resonators excited by waveguide-fed slots coupling to higher-order resonator modes are demonstrated. For close reflector spacings, the waveguide couples efficiently through the slots to the TEM400 and TEM300 modes. The characteristics of both rectangular and circular waveguide feeds with various slot lengths and widths are presented. At X-band the filters have unloaded Q values which range from 1000 to 7000 with insertion losses less than 1 dB. The filters which have the rectangular waveguide feeds are mechanically tunable over a 20% bandwidth 相似文献
11.
Fiber-coupled short Fabry-Perot resonators 总被引:1,自引:0,他引:1
An air-gap Fabry-Perot resonator with plane mirrors between closely spaced fiber ends may yield low throughput because of the poor match between the modes of typical single-mode fibers and the resonant mode in the air-gap cavity. The throughput can be improved by confining the resonant mode by a hollow dielectric tube placed inside the resonator. Short fiber-coupled Fabry-Perot resonators with and without an inserted hollow dielectric waveguide and expressions for their transmission losses are derived. It is shown that the throughput of both types of resonator can be improved significantly by using fiber with large mode size to couple to the resonator. The special fiber is then spliced to a conventional single-mode fiber. It is concluded that the resonator with an inserted hollow dielectric waveguide offers increased throughput for resonators with high finesse 相似文献
12.
《Microwave Theory and Techniques》1969,17(7):354-359
The high permittivity dielectric resonator is a low loss microwave filter element whose size is substantiality less than metal waveguide cavities. Temperature stabilizing their resonant frequency increases the applicability of such elements. A temperature compensated 3-section band-rejection filter using dielectric resonators has been fabricated and tested. The measured electrical performance was comparable to metal waveguide filters and the frequency stability for temperature variations was comparable to brass waveguide cavity filters which are not temperature compensated. 相似文献
13.
This paper presents the first systematic evaluation and analysis of 60-GHz-band TE01δ-mode cylindrical dielectric resonators coupled to a microstrip line on a GaAs substrate. The loss components of the unloaded Q are analyzed using simple numerical techniques. The distance between the resonator center and the microstrip line which gives the maximum coupling coefficient is found to be approximately 3/5 of the resonator radius, whose ratio is almost constant for all practical cases. The temperature characteristics are also demonstrated and the origins of temperature dependences of the unloaded Q and the coupling coefficient are discussed. An equivalent circuit model for the dielectric resonator coupled to the microstrip line is presented, whose element parameters can express the dependences of the resonant frequency, the unloaded Q, and the coupling coefficient on the structural parameters and the temperature 相似文献
14.
《Microwave Theory and Techniques》1987,35(12):1161-1163
A bandstop filter realized by means of rectangular resonators coupled to the center dielectric strip of a nonradiative dielectric (NRD) waveguide is described.This filter has the advantage that it is simple to manufacture, making use of a center dielectric of standard cross section. The design procedure is similar to the conventional strip line design procedure, with the stubs replaced by "stubs" of dielectric, or resonators. The design equations for the stub coupling are derived the properties of the stubs are obtained through measurement. 相似文献
15.
This paper presents a rigorous approach for the calculation of resonant frequencies of a metallic cavity loaded by a dielectric resonator. Tangential fields at the air-dielectric interface are derived from dyadic Green's functions and boundary conditions are applied. Dyadic Green's identity and the boundary element method are used to solve the numerical problem. In order to validate the method, resonant frequencies are calculated for a cylindrical cavity loaded with a dielectric cylinder and compared with available results in the literature. Then resonance is studied for dielectric cylinder in a rectangular cavity. In the case of multiple dielectric resonators in the cavity, the coupling coefficient is computed with an original method based on the use of symmetries 相似文献
16.
The complicated loss behaviour of eigenmodes in unstable open resonators formed by finite convex cylindrical mirrors is explained in terms of a remarkably simple model that treats the resonator as a waveguide in the transverse direction. It is shown that selective coupling between two appropriately chosen waveguide modes suffices to establish the eigenmode loss characteristics. 相似文献
17.
A powder-filled rectangular groove in the surface of a plastic substrate has been demonstrated as a dielectric waveguide at 94 GHz. Propagation losses as low as 0.09 dB/cm were measured by direct transmission with nickel-aluminum titanate powder in a polypropylene substrate and with barium tetratitanate powder in a polytetrafluoroethylene (PTFE) substrate; values as low as 0.06 dB/cm were deduced from ring resonator measurements. Guide wavelengths measured for various combinations of guide dimensions, powders, and substrates agree within 10% with values predicted by the approximate theory of Marcatili for the E11y mode. Effective loss tangents for the powders at 94 GHz were calculated from waveguide attenuation measurements, using Marcatili's field solutions. Ring resonators fabricated by filling a groove in a polypropylene substrate with nickel-aluminum titanate powder exhibit Q's as high as 2400 at 94 GHz in an 8 cm diameter ring. Coupling to the resonators was achieved with adjacent straight powder core channel guides as directional couplers 相似文献
18.
Al Salameh M.S. Antar Y.M.M. Seguin G. 《Antennas and Propagation, IEEE Transactions on》2002,50(10):1415-1419
A novel coupling scheme to a rectangular dielectric resonator antenna is proposed and investigated. In particular, coupling to the resonator is achieved through a narrow slot at the end of a coplanar waveguide (CPW). The objectives of this design are to maximize the coupling, match the dielectric resonator to the CPW feed line, achieve resonance at the desired frequency, obtain linear polarization with low cross polarization components, and minimize back radiation without using a back conductor. An approximate and quick design approach is given followed by more accurate design and analysis using commercial software. The antenna was fabricated and tested. Measurements match well with simulation results. 相似文献
19.
The mode matching method is used to accurately model a generalized cylindrical dielectric resonator structure in a rectangular waveguide or cavity. The field distributions of different modes in cavities are given. The resonant frequencies of the cavities are calculated and compared to the measured data, showing very good agreement. The resonator structure can be a dielectric disk resonator, a ring resonator, a dielectric resonator with support, etc. This structure can be used in filter design as the basic element, providing very good mechanical stability. The slot coupling between cavities is also analyzed, showing some interesting results 相似文献
20.
理论分析了屏蔽腔中矩形介质的谐振频率,同时使用Ansoft HFSS对所设计的滤波器进行仿真分析。根据以往的双模结构,使用了利用切角进行双模耦合的新结构,对相邻腔体问的耦合采用耦合窗口和耦合杆相结合的方法。要求的滤波器参数指标为:中心频率f0=2140MHz,带宽BW=50MHz,插入损耗IL〈0.1dB,回波损耗RL〉22dB。仿真结果表明该结构可以更加有效地减小插入损耗,且体积比传统滤波器减小了很多,有利于器件小型化。 相似文献