Electromagnetic Near Fields of Rectangular Waveguide Antennas in Contact with Biological Objects Obtained by the FD-TD Method

Katsumi ABE; Shinya MIZOSHIRI; Toshifumi SUGIURA; Shizuo MIZUSHINA

Electromagnetic Near Fields of Rectangular Waveguide Antennas in Contact with Biological Objects Obtained by the FD-TD Method

Katsumi ABE, Shinya MIZOSHIRI, Toshifumi SUGIURA, Shizuo MIZUSHINA

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Multifrequency microwave radiometry for non-invasive measurement of temperature in biological objects has been investigated in our laboratory. An open-ended rectangular waveguide filled with a dielectric has been used as a contact-type antenna of a radiometer operating over a 1-4GHz range. In the radiometric measurement, the radiometer measures the thermal radiation emitted by the object via the antenna as the brightness temperature. The brightness temperature is related to the physical temperatures in the object through the radiometric weighting function. By virtue of the reciprocity of antenna, the weighting function can be derived from the field distribution induced in the object by the same antenna when it is operated in the active mode. In this paper, the FD-TD method is used to analyze the problem of coupling between the rectangular waveguide antenna and a biological object. The objects studied in this paper are a homogeneous and a four-layered lossy media. Working frequency is 1.2GHz, which is the center frequency of the lowest-frequency band of our radiometer. Numerical results are presented in the form of SAR patterns. It is found that the SAR patterns tend to spread out in the lateral directions in the bolus, skin and fat layers due to the diffraction which becomes stronger at lower frequencies. Results also suggest that the lateral spreading can be controlled to a certain extent by choosing the size elf antenna flange properly.

Publication: IEICE TRANSACTIONS on Communications Vol.E78-B No.6 pp.866-870

Publication Date: 1995/06/25

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Type of Manuscript: Special Section LETTER (Special Issue on Medical Applications of Electromagnetic Techniques)

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Katsumi ABE, Shinya MIZOSHIRI, Toshifumi SUGIURA, Shizuo MIZUSHINA, "Electromagnetic Near Fields of Rectangular Waveguide Antennas in Contact with Biological Objects Obtained by the FD-TD Method" in IEICE TRANSACTIONS on Communications, vol. E78-B, no. 6, pp. 866-870, June 1995, doi: .
Abstract: Multifrequency microwave radiometry for non-invasive measurement of temperature in biological objects has been investigated in our laboratory. An open-ended rectangular waveguide filled with a dielectric has been used as a contact-type antenna of a radiometer operating over a 1-4GHz range. In the radiometric measurement, the radiometer measures the thermal radiation emitted by the object via the antenna as the brightness temperature. The brightness temperature is related to the physical temperatures in the object through the radiometric weighting function. By virtue of the reciprocity of antenna, the weighting function can be derived from the field distribution induced in the object by the same antenna when it is operated in the active mode. In this paper, the FD-TD method is used to analyze the problem of coupling between the rectangular waveguide antenna and a biological object. The objects studied in this paper are a homogeneous and a four-layered lossy media. Working frequency is 1.2GHz, which is the center frequency of the lowest-frequency band of our radiometer. Numerical results are presented in the form of SAR patterns. It is found that the SAR patterns tend to spread out in the lateral directions in the bolus, skin and fat layers due to the diffraction which becomes stronger at lower frequencies. Results also suggest that the lateral spreading can be controlled to a certain extent by choosing the size elf antenna flange properly.
URL: https://global.ieice.org/en_transactions/communications/10.1587/e78-b_6_866/_p

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@ARTICLE{e78-b_6_866,
author={Katsumi ABE, Shinya MIZOSHIRI, Toshifumi SUGIURA, Shizuo MIZUSHINA, },
journal={IEICE TRANSACTIONS on Communications},
title={Electromagnetic Near Fields of Rectangular Waveguide Antennas in Contact with Biological Objects Obtained by the FD-TD Method},
year={1995},
volume={E78-B},
number={6},
pages={866-870},
abstract={Multifrequency microwave radiometry for non-invasive measurement of temperature in biological objects has been investigated in our laboratory. An open-ended rectangular waveguide filled with a dielectric has been used as a contact-type antenna of a radiometer operating over a 1-4GHz range. In the radiometric measurement, the radiometer measures the thermal radiation emitted by the object via the antenna as the brightness temperature. The brightness temperature is related to the physical temperatures in the object through the radiometric weighting function. By virtue of the reciprocity of antenna, the weighting function can be derived from the field distribution induced in the object by the same antenna when it is operated in the active mode. In this paper, the FD-TD method is used to analyze the problem of coupling between the rectangular waveguide antenna and a biological object. The objects studied in this paper are a homogeneous and a four-layered lossy media. Working frequency is 1.2GHz, which is the center frequency of the lowest-frequency band of our radiometer. Numerical results are presented in the form of SAR patterns. It is found that the SAR patterns tend to spread out in the lateral directions in the bolus, skin and fat layers due to the diffraction which becomes stronger at lower frequencies. Results also suggest that the lateral spreading can be controlled to a certain extent by choosing the size elf antenna flange properly.},
keywords={},
doi={},
ISSN={},
month={June},}

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TY - JOUR
TI - Electromagnetic Near Fields of Rectangular Waveguide Antennas in Contact with Biological Objects Obtained by the FD-TD Method
T2 - IEICE TRANSACTIONS on Communications
SP - 866
EP - 870
AU - Katsumi ABE
AU - Shinya MIZOSHIRI
AU - Toshifumi SUGIURA
AU - Shizuo MIZUSHINA
PY - 1995
DO -
JO - IEICE TRANSACTIONS on Communications
SN -
VL - E78-B
IS - 6
JA - IEICE TRANSACTIONS on Communications
Y1 - June 1995
AB - Multifrequency microwave radiometry for non-invasive measurement of temperature in biological objects has been investigated in our laboratory. An open-ended rectangular waveguide filled with a dielectric has been used as a contact-type antenna of a radiometer operating over a 1-4GHz range. In the radiometric measurement, the radiometer measures the thermal radiation emitted by the object via the antenna as the brightness temperature. The brightness temperature is related to the physical temperatures in the object through the radiometric weighting function. By virtue of the reciprocity of antenna, the weighting function can be derived from the field distribution induced in the object by the same antenna when it is operated in the active mode. In this paper, the FD-TD method is used to analyze the problem of coupling between the rectangular waveguide antenna and a biological object. The objects studied in this paper are a homogeneous and a four-layered lossy media. Working frequency is 1.2GHz, which is the center frequency of the lowest-frequency band of our radiometer. Numerical results are presented in the form of SAR patterns. It is found that the SAR patterns tend to spread out in the lateral directions in the bolus, skin and fat layers due to the diffraction which becomes stronger at lower frequencies. Results also suggest that the lateral spreading can be controlled to a certain extent by choosing the size elf antenna flange properly.
ER -