共查询到20条相似文献,搜索用时 15 毫秒
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含损耗介质和谐振子复合材料的电磁参数测定与反射系数计算 总被引:6,自引:1,他引:5
制备了一种含损耗介质和谐振子的环氧树脂基微波吸收复合材料,在8.2~12.4GHz频率范围内作了复合材料的电磁参数测试.结果表明:这种复合材料的磁损耗很小,主要损耗机制是介电损耗.由传输线等效电路模拟吸波复合材料,根据输入阻抗计算电磁波反射系数,给出了功率反射系数计算的BASIC程序.并把计算结果与扫频测试结果作了对比.对比结果表明:理论计算与实测的功率反射系数随频率的变化规律基本一致. 相似文献
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《IEEE transactions on instrumentation and measurement》1979,28(1):71-74
The attenuation rate of the electromagnetic energy in samples of fresh water has been measured at frequencies between 33 and 363 MHz. The technique employed the HP 8410A network analyzer and a broad-band transmission resonance cavity and provided reliable results which agree well with theory. The results suggest that it should be possible to develop a VHF radar system capable of sensing the depth of shallow fresh water for remote sensing applications. 相似文献
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Roberts GE 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1988,35(3):306-314
Although the four-frequency measurement process has been used successfully on coupled dual crystals from 9.4 MHz to 21.4 MHz, discrepancies between the crystal data and filter data at 45 MHz and 57.5 MHz suggested an error problem associated with the measurement system. To eliminate the errors, a twelve-term error model was chosen and the equations were derived for use with an automatic network analyzer. The details of the direct deviation of the four-frequency measurement process are given in which the two resonator frequencies and the synchronous peak separation frequency (SPSF) of a coupled dual crystal are calculated from the two frequencies of the zeros of the short-circuit driving point impedance, and the two frequencies of the zeros of the open-circuit driving point impedance. Determination of the four frequencies from the error-corrected S parameters is discussed, as well as the analysis of an external capacitor placed across the output circuit to obtain a more convenient distribution of the four frequencies. A comparison is made between data taken on the original fixture and data taken on an automatic network analyzer using error-corrected S parameters. 相似文献
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Free-space, broadband measurements of high-temperature, complexdielectric properties at microwave frequencies 总被引:1,自引:0,他引:1
Varadan V.V. Hollinger R.D. Ghodgaonkar D.K. Varadan V.K. 《IEEE transactions on instrumentation and measurement》1991,40(5):842-846
A free-space microwave measurement system that is used for the high-temperature measurement of dielectric constants and loss tangents of homogeneous materials and that is applicable to composite materials as well is discussed. The system is capable of operating in the 5.85-40-GHz frequency range and ambient to 850°C temperature range. A computer is used to control and coordinate furnace temperature, network analyzer functions, and data storage. Dielectric constants and loss tangents of the materials are calculated from the measured values of S21. The measurement system, including the high-temperature furnace and the calibration technique, is described. Dielectric constants and loss tangents are presented for fused quartz and boron nitride grade HP in the frequency range 13.0-17.4 GHz and the temperature range from ambient to 850°C 相似文献
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Hirvonen T.M. Vainikainen P. Lozowski A. Raisanen A.V. 《IEEE transactions on instrumentation and measurement》1996,45(4):780-786
A high-Q hemispherical open resonator is connected to an automatic network analyzer to enable precise and fast determination of the permittivity and loss tangent of low-loss dielectric materials at 100 GHz. Both scalar theory and vector theory with a frequency variation method are used to determine the dielectric properties of low-loss materials which are used in quasioptical components, for example in fusion reactor windows and tenses for millimeter-wave receivers. The uncertainty of the measurement is 0.02% to 0.04% for εr(ϵr⩾2) and 6-40×10-6 for tan δ(10-4⩽tan δ⩽10-3 ) 相似文献
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Munoz J. Rojo M. Parrefio A. Margineda J. 《IEEE transactions on instrumentation and measurement》1998,47(4):886-892
A free-wave method for determining the dielectric and magnetic properties of materials from reflection measurements made at normal incidence and transmission measurements made at normal and oblique incidence is proposed. The method combines frequency domain measurements and time domain (TD) analysis and uses polarization to avoid typical ambiguities in the results. Varying the incident angle and the polarization, measurements were made in the X-band. The technique was validated by comparing the results obtained with those from well-established waveguide techniques. A focusing assembly makes it possible to measure relatively small samples, thus avoiding diffraction problems. It also improves the ambiguity-solving procedure proposed for the technique. The measurement procedure is fully automated by using the HP8510 network analyzer controlled by an HP362 computer, which also processes the data. Results for low-loss dielectrics such as teflon, nylon, and polymethyl methacrylate (PMMA) and for microwave-absorbing materials are reported 相似文献
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Hwang C.S. Lin F.Y. Tseng P.K. 《IEEE transactions on instrumentation and measurement》1999,48(4):858-863
A real-time, Hall-probe automatic measurement system was developed at the Synchrotron Radiation Research Center (SRRC) for the magnetic field measurement of the “C”-type rectangular combined function bending magnet, multipole magnets, and the insertion device magnets. The sampling rate on the x-y-z table with dynamic moving speed of 15 cm/s can be up to 200 samples/s, and the precision is within ±0.01%. A PC is used as a system controller which connects instrument function cards with instruments via the PC bus and an IEEE-488 interface card. An inexpensive, stable within ±15 ppm current source is produced to supply a high-stability constant current for the Hall probe; a temperature controller maintains the Hall probe temperature within ±0.2°C. The system's software has been divided into different modules that can be connected into a network global data base. System testing has shown that the magnetic field measurement accuracy of this system is better than ±25 ppm in the static measurement 相似文献
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频谱分析仪检定的测量不确定度分析 总被引:1,自引:0,他引:1
在频谱分析仪检定过程中,对其测量结果进行不确定度分析是其中必不可少的一项工作。由于频谱分析仪检定项目多,考虑到频谱分析仪主要表征的是频率参量和幅度参量,所以选取频率读数测量和输入衰减器测量进行测量不确定度评定。并以检定HP8563E频谱分析仪为例,分析了影响其测量不确定度的几个因素,同时针对具体的数据进行了详细的分析,能够对从事频谱分析仪检定工作的计量人员提供帮助。 相似文献
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《IEEE transactions on instrumentation and measurement》1973,22(4):295-299
It has been recently recognized that an arbitrary six-port junction, four arms of which are terminated in power meters, can be calibrated to measure the circuit parameters, v, i, z, a, b, ?, etc., in addition to power. Because this scheme eliminates the need for frequency conversion, it provides a substantially simplified approach to the design of an automatic network analyzer. This paper outlines a calibration procedure for the six-port which is only slightly more complicated than that in use for existing automated measurement systems. 相似文献
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Yuen CM Tsang KF 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2005,52(5):834-836
A low cost, automatic tracking system for phase noise measurement has been implemented successfully. The tracking system is accomplished by applying a charge pump phase-locked loop as an external reference source to a digital spectrum analyzer. Measurement of a 2.5 GHz, free-running, voltage-controlled oscillator demonstrated the tracking accuracy, thus verifying the feasibility of the system. 相似文献
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基于GPIB总线的HP8563E型频谱分析仪检定系统 总被引:1,自引:0,他引:1
文中介绍了一种频谱分析仪的全自动检定系统,通过GPIB总线接口将所有测试仪器连成一体,使用LABVIEW和VC++开发系统的软件,通过PC机进行控制,实现了对HP8563E型频谱分析仪的全自动检定。 相似文献
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Blackham D.V. Pollard R.D. 《IEEE transactions on instrumentation and measurement》1997,46(5):1093-1099
An enhanced model for an open-ended coaxial probe used for making permittivity measurements is presented. A permittivity measurement system consisting of the coaxial probe and a network analyzer is described including details of the error correction and curve fitting techniques. Determination of the percent dissolved solids in fructose solutions from permittivity measurements is presented as example of the usefulness of the coaxial probe/network analyzer measurement system 相似文献