TY - JOUR
T1 - Human Operator Coupling Effects on Radiation Characteristics of a Portable Communication Dipole Antenna
AU - Chuang, H. R.
N1 - Funding Information:
Recently, Portable co”unication systems (including two-way portable radios and portable cellular phones) have been extensively utilized by the general public. In these present and future portable communication systems, the carrier frequencies are all very high, and reach microwave frequency bands. For example, the current cellular phone systems are using an 800-900 MHz band. At such a high frequency, since the operator is very near the vicinity of the radiating antenna of the portable handset, the electromagnetic (EM) coupling between the antenna and the nearby body will significantly affect the antenna characteristics. These antenna characteristics include the antenna input impedance which vanes from face to torso positions, the antenna current distribution, the antenna radiation pattern, and the antenna radiation efficiency which is reduced due to the radiated power absorbed by the body. Hence, in order to design a high-performance portable antenna, the EM coupling between the antenna and the operator body must be fully counted and analyzed in antenna design optimization. Moreover, the level of EM energy deposition from the radiating antenna into the nearby operator body (especially the head) have become a public concern as a potential health hazard. Hence, it is also necessary to analyze the RF dosimetry problem. Extensive research results have been reported on the energy deposition in a human body model exposed to the dipole antenna fields [ I]-[3]. However, the detailed EM coupling effects between portable communication dipole antennas and a realistically shaped full-body model at the portable communication band (800-900 MHz) have been unavailable. To date, the effects of the EM coupling Manuscript received February 11, 1993; revised October 14, 1993. This work was supported by the National Science Council of the Republic of China under Grant NSC 81 -0404-E006-006. The author is with the Department of Electrical Engineering, National Cheng Kung University, Tainan, Taiwan, Republic of China. IEEE Log Number 9400504.
PY - 1994/4
Y1 - 1994/4
N2 - EM coupling effects of a human operator on antenna radiation characteristics, such as the antenna input impedance, radiation patterns, the radiation power (into free space), the power absorbed by the body, the radiation efficiency, etc., of a portable communication dipole antenna were investigated in detail. A realistically shaped 3-D man model and a proximate linear dipole antenna were used to model this problem. Coupled integral equations (CIE) and the method of moments (MoM) were employed to numerically solve this antenna-body coupling problem. Numerical examples are presented for the antenna located in front of the head (distance ranging from 5 to 1 cm) or adjacent to the abdomen (0.6 cm distance) at 840 MHz. It is found that, when coupled with the operator body, the antenna input impedance will have significant deviation from those in free space and different positions. Due to the operator body absorption effect, the maximum attenuation of the H-plane antenna gain may reach about 15 dB for the antenna at the head position and 25 dB for the abdomen position, toward the direction of the body side. Also, the antenna radiation efficiency is reduced to the range from 0.72 to 0.29 for the head position and 0.15 for the abdomen position, respectively. Moreover, the cross-polarization field is significant, especially in the E plane of [formula ommited]. This is important for the antenna RF design and communication link budget consideration of portable radio systems.
AB - EM coupling effects of a human operator on antenna radiation characteristics, such as the antenna input impedance, radiation patterns, the radiation power (into free space), the power absorbed by the body, the radiation efficiency, etc., of a portable communication dipole antenna were investigated in detail. A realistically shaped 3-D man model and a proximate linear dipole antenna were used to model this problem. Coupled integral equations (CIE) and the method of moments (MoM) were employed to numerically solve this antenna-body coupling problem. Numerical examples are presented for the antenna located in front of the head (distance ranging from 5 to 1 cm) or adjacent to the abdomen (0.6 cm distance) at 840 MHz. It is found that, when coupled with the operator body, the antenna input impedance will have significant deviation from those in free space and different positions. Due to the operator body absorption effect, the maximum attenuation of the H-plane antenna gain may reach about 15 dB for the antenna at the head position and 25 dB for the abdomen position, toward the direction of the body side. Also, the antenna radiation efficiency is reduced to the range from 0.72 to 0.29 for the head position and 0.15 for the abdomen position, respectively. Moreover, the cross-polarization field is significant, especially in the E plane of [formula ommited]. This is important for the antenna RF design and communication link budget consideration of portable radio systems.
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U2 - 10.1109/8.286229
DO - 10.1109/8.286229
M3 - Article
AN - SCOPUS:0028406393
VL - 42
SP - 556
EP - 560
JO - IEEE Transactions on Antennas and Propagation
JF - IEEE Transactions on Antennas and Propagation
SN - 0018-926X
IS - 4
ER -