A Method to Calculate the Net Power Delivered into a TEM Cell Using a Directional Coupler in a Probe Calibration Application

In a probe calibration facility employing the TEM cell as the field generator, a method to calculate the net power delivered into the TEM cell is presented through monitoring the coupling power of the directional coupler. The new formula requires the effective reflection coefficient of the dual coupler and takes into consideration the directivity of the coupler, the mismatch between the coupler and the TEM cell, the mismatch between the power sensor and the coupling port of the coupler. The formula can provide sufficient accuracy in calibration purpose application using a TEM cell with a coupler combined with power sensors to monitor the net power.

Simulation for Microwave Nondestructive Detection of Thickness and Delamination in Layered-Dielectric in Metallic Substrate

Microwaves penetrate inside of low loss dielectric materials and they are sensitive to the presence of internal interfaces and non-uniformities. This allows microwave nondestructive inspection techniques to be utilized for inspecting dielectric in metallic substrate. This article simulated Microwave inspecting thickness and delamination in layered-dielectric in metallic substrate, using open-ended rectangular waveguide probe. Effective reflection coefficient of microwave is used in the detection and evaluation to thickness or delimination in the media. This paper optimized the detection frequency and standoff, which provide a reference for the experimental study.

Microwave Imaging for the Integrity Assessment of IC Packages

Since IC packages have been made thinner and smaller, the delamination and crack, which may be induced in the soldering process, have become important factors affecting the reliability of the package. The ability to penetrate deeply inside dielectric materials, and to reflect completely at the metal surface makes microwave inspection very suitable to detect such delamination. The authors have recently developed a new microwave imaging technique that uses an open-ended coaxial line sensor to detect the delamination in IC packages. The image was created by measuring the phase of the effective reflection coefficient at the aperture of the coaxial line sensor. For better evaluation of the shape and the size of the delamination, a method to further increase the spatial resolution of microwave imaging was studied in the present paper. The resolution affected by the dimensions of the sensor, the frequency of operation, and the standoff distance between the sensor and the sample was investigated by experiment. The experimental results indicate that microwave imaging is a promising technique for the integrity assessment of IC packages.

RADIATION BOUNDARY CONDITIONS FOR VERTICALLY HETEROGENEOUS ACOUSTIC MEDIA

Several radiation boundary conditions for inhomogeneous acoustic media are investigated. Previous investigators have developed various approximate radiation conditions and have studied their accuracy by calculating an effective reflection coefficient for plane waves incident on such radiating boundaries. In this paper, it is shown that effective reflection coefficients can be calculated for a class of parabolic approximations to the Helmholtz equation. These results are valid for vertically heterogeneous media. Comparison of these radiation conditions is given through numerical examples.

Radio Echo Sounding of Horizontal Layers in Ice

Radio echo-sounding surveys of Antarctica and Greenland have revealed extensive layering within the ice. Formulae for the effective reflection coefficient, when viewed by a pulsed radar, are derived for isolated or multiple randomly spaced layers. In the latter case the variation in dielectric constant with depth is described by a vertical autocorrelation function and a standard deviation. Some measurements of the reflection coefficient of layers, and the dielectric absorption of ice are given. The significance of the fading of layer echoes and the possible causes of variations in the dielectric constant are considered and some further investigations are suggested. It is concluded that the echo strengths found in the Antarctic may be explained by multiple layering, and that the necessary fractional change in the dielectric constant may be as small as 10−4. It is suggested that this change in dielectric constant may be due to differences in orientation of anisotropic ice crystals.

Radio Echo Sounding of Horizontal Layers in Ice

Radio echo-sounding surveys of Antarctica and Greenland have revealed extensive layering within the ice. Formulae for the effective reflection coefficient, when viewed by a pulsed radar, are derived for isolated or multiple randomly spaced layers. In the latter case the variation in dielectric constant with depth is described by a vertical autocorrelation function and a standard deviation. Some measurements of the reflection coefficient of layers, and the dielectric absorption of ice are given. The significance of the fading of layer echoes and the possible causes of variations in the dielectric constant are considered and some further investigations are suggested.It is concluded that the echo strengths found in the Antarctic may be explained by multiple layering, and that the necessary fractional change in the dielectric constant may be as small as 10−4. It is suggested that this change in dielectric constant may be due to differences in orientation of anisotropic ice crystals.