A free-space method for measurement of complex permittivity of silicon wafers at microwave frequencies
07 Oct 2003-pp 119-123
TL;DR: In this paper, the free-space reflection and transmission coefficients of a silicon wafer sandwiched between two teflon plates which are quarter-wavelength at midband were measured in the frequency range of 11-12.5 GHz.
Abstract: A non-destructive, non-contact technique has been developed to characterize p-type and n-type silicon semiconductor wafers at microwave frequencies. The measurement system consists of a pair of spot-focusing horn lens antennas, mode transitions, coaxial cables and a vector network analyser (VNA). In this paper, the free-space reflection and transmission coefficients, S/sub 11/ and S/sub 21/, for a normally incident plane wave, are measured for a silicon wafer sandwiched between two teflon plates which are quarter-wavelength at midband. The actual reflection and transmission coefficient, S/sub 11/ and S/sub 21/, of the silicon wafers are calculated from the measured S/sub 11/ and S/sub 21/ of the teflon plate-silicon wafer-teflon plate assembly in which the complex permittivity and thickness of the teflon plates are known. From the complex permittivity, the resistivity and conductivity can be obtained. Results are reported in the frequency range of 11-12.5 GHz. The values of the dielectric constant obtained were close to published values for silicon wafers.
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TL;DR: In order to improve microwave absorption which would be used for in situ repair of asphalt pavement, Fe3O4 was enriched on the surface of steel slag particles through an activated carbon-reduction method.
Abstract: In order to improve microwave absorption which would be used for in situ repair of asphalt pavement, Fe3O4 was enriched on the surface of steel slag particles through an activated carbon-reduction method. The surface modified steel slags were then added into asphalt mixture to replace fine aggregates. The results showed that the microwave heating rate of modified steel slag was 84.3 °C/min. That was 34.1 and 65.1% higher than that of the control group of unmodified steel slag and fine basalt aggregate, respectively. Within the microwave frequency band of 2–4 GHz, the real part and imaginary part of the complex permittivity of the modified steel slag asphalt mixture (MSAM) increased by 6.4–12.5 and 4.7–13.7%, respectively, comparing those of the ordinary steel slag asphalt mixture (OSAM) and the ordinary basalt asphalt mixture (OBAM). Meanwhile, the real part and imaginary part of the complex permeability of the MSAM increased by 9.8–31.9% and over 6.2 times, respectively. Besides, the microwave heating rate of the MSAM increased by 44.2 and 82.1%, respectively, comparing those of the OSAM and the OBAM. Simulation indicated that after microwave heating for 15 min, the temperature within the OBAM ranged from 62.23 to 125.48 °C. Moreover, the temperature field distribution of numerical simulation was similar to that of the test results. Since microwave absorption was sharply enhanced in the asphalt pavement, it is expected to promote the microwave heating technology in the asphalt pavement.
20 citations
01 Jan 2013
TL;DR: In this article, a free space, non-destructive technique was used to measure the complex dielectric constant of natural rubber at microwave frequencies, and the results showed that er and tan δ increase with the filler content.
Abstract: In this paper, the measurement of complex dielectric constant of natural rubber at microwave frequencies is reported. A free space, non-destructive technique was used to measure the parameter for several rubber samples at X band. The samples were prepared using different amounts of carbon filler to alter the dielectric properties so that the relation between filler content and er can be investigated. Our studies show that er and tan δ increase with the filler content. In addition, er showed a decreasing trend, while tan δ increased with frequency.
15 citations
TL;DR: In this paper, a very thin layer of magnetic Fe3O4 films on coarse and fine aggregates, using chemical co-preci... was proposed to improve microwave heating efficiency of asphalt pavement.
Abstract: To improve microwave heating efficiency of asphalt pavement, a new technique was proposed by coating a very thin layer of magnetic Fe3O4 films on coarse and fine aggregates, using chemical co-preci...
11 citations
20 Jun 2010
TL;DR: In this paper, a free space method based on the gangway-reflection line (GRL) was applied to temperature-dependent complex permittivity for large-size heterogeneous asphalt mixture at the 2.45GHz microwave frequency.
Abstract: In order to assess the temperature-depended complex permittivity for asphalt mixture of microwave hot in-place recycling (HIPR), a free-space method based on the gangway-reflection-line (GRL) was applied to temperature-dependent complex permittivity for large-size heterogeneous asphalt mixture at the 2.45GHz microwave frequency. The academic model of the measurement method was employed, which was assumed that the microwave distribution was considered by the sum of the incident- and reflected-wave components. In addition, the test system was been set up. The GRL calibration method of measurement system and the time-domain-gating (TDG) technique improving the measurement accuracy were discussed. To measure the asphalt mixture dielectric properties in different temperature and fit the data by using the least square method, the data showed that the permittivity of asphalt mixture was nonlinear from 4 degree centigrade to 62 degree centigrade at the 2.45GHz. The complex permittivity of asphalt mixture decreased with the temperature increase, however it would decrease significantly less than 20 degree centigrade and decrease slowly in the late of heating temperature. Results produce certain influence for electromagnetic field and temperature field within asphalt mixture when microwave heats recycle asphalt mixture.
5 citations
Cites background from "A free-space method for measurement..."
...It is extremely important to research and test the dielectric properties of asphalt mixture for HIRP using microwave heating technology....
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01 Dec 2014
TL;DR: In this article, the effect of rubber properties on the antenna bandwidth, return loss and radiation patterns was investigated for 8 and 10 GHz inset feed patch antennas with different dimensions and the rubber samples were prepared using two different amounts of carbon at 20 and 25 % to alter the dielectric properties.
Abstract: This paper reports for the first time, the use of natural rubber as a substrate in the design of flexible antennas. Three inset feed patch antennas with different dimensions were simulated to resonate for 8 and 10 GHz. The rubber samples were prepared using two different amounts of carbon at 20 and 25 % to alter the dielectric properties. Investigations were done to understand the effects of natural rubber properties with the aim to facilitate efforts in flexible antenna design so that practical system requirements are met. The rest of this paper focuses on the effect of rubber properties on the antenna bandwidth, return loss and radiation patterns. From the results, it was observed that increasing the filler content and frequency would increase the antenna losses, but enhances the bandwidth, gain and directivity. This implies that the performance of rubber-based antennas can be controlled by the dielectric properties of rubber.
3 citations
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TL;DR: In this article, a free-space measurement system operating in the 8.2-40 GHz frequency range is used to measure the reflection and transmission coefficients, S/sub 11/ and S/ sub 21/, of planar samples.
Abstract: A free-space measurement system operating in the 8.2-40-GHz frequency range is used to measure the reflection and transmission coefficients, S/sub 11/ and S/sub 21/, of planar samples. The complex electric permittivity and the magnetic permeability are calculated from the measured values of S/sub 11/ and S/sub 21/. The measurement system consists of transmit and receive horn lens antennas, a network analyzer, mode transitions, and a computer. Diffraction effects at the edges of the sample are minimized by using spot-focusing lens antennas. Errors due to multiple reflections between antennas via the surface of the sample are corrected by using a free-space TRL (thru, reflect, line) calibration technique. For thin, flexible samples, the sample had to be sandwiched between two half-wavelength (at mid-band) quartz plates to eliminate sagging. Results are reported in the frequency range of 8.6-13.4 GHz for materials such as Teflon, sodium borosilicate glass, and microwave-absorbing materials. >
743 citations
Additional excerpts
...reflection [1-3] and transmission [ 4-6 ] techniques....
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TL;DR: In this article, the complex microwave conductivity of lightly-doped n and p-type silicon and genmanium was measured by observing the reflectivity of the circular T E01 mode at 48 GHz and were thus free of errors caused by the impedance of the waveguide.
Abstract: This paper presents measurements of the complex microwave conductivity of lightly‐doped n‐ and p‐type silicon and genmanium as functions of impurity concentration and of temperature between 77° and 300°K. The measurements were obtained by observing the reflectivity of the circular T E01 mode at 48 GHz and are thus free of errors caused by the impedance of the waveguide‐sample contact. Analysis utilized currently accepted scattering models including ionized impurity scattering, intravalley acoustic and optical mode scattering, and intervalley scattering. The results are used to investigate the temperature and doping dependence of the average relaxation time and the conductivity ``effective'' mass.
47 citations
TL;DR: In this paper, an attempt has been made to improve the reflection results from an analysis of the parameters of a circle diagram for reflection coefficient obtained on using a variable reactive termination after the semiconductor-filled waveguide section.
Abstract: Complex microwave conductivity of 9 /spl Omega/ /spl dot/ cm p-type silicon samples has been measured using conventional reflection and transmission bridges to examine their relative advantages and disadvantages. An attempt has been made to improve the reflection results from an analysis of the parameters of a circle diagram for reflection coefficient obtained on using a variable reactive termination after the semiconductor-filled waveguide section. In conformity with the calculated accuracy attainable from different types of measurement under the actual experimental condition, using commercial standards, the dielectric constant for the sample was found to be scattered over a region of /spl plusmn/0.4. It has been concluded that because of lack of accuracy in commercial standards for attenuation and phase shift, the potential accuracy of the conventional microwave methods falls too short of its mark to make any detinite conclusion about the effective mass of carriers in semiconductors at room temperatures.
17 citations
01 Jan 1970
17 citations
TL;DR: In this paper, a microwave electrodeless technique for measuring semiconductor conductivity using a circular or square semiconductor post mounted vertically in the center of a rectangular waveguide is presented.
Abstract: A theoretical analysis and experimental results are presented for a new microwave electrodeless technique for measuring semiconductor conductivity using a circular or square semiconductor post mounted vertically in the center of a rectangular waveguide. The validity of microwave studies of recombination effects in semiconductors using this geometry is also established by showing that there is a linear relationship between transmitted microwave power and excess carrier density for small values of excess carrier density.
10 citations
"A free-space method for measurement..." refers result in this paper
...results are shown in table I. The results show that ac and dc resistivity are within close proximity which have been reported by Holmes er al. [ 5 ] and Coue er al. [4]....
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...reflection [1-3] and transmission [ 4-6 ] techniques....
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