A study of the handset antenna and human body interaction

Abstract

Abstruct-The antennal radiation pattern and other characteristics are significantly altered by the presence of the human body. This interaction as well as the resultant deposition of microwave power in the body (specific absorption rate-SAR) are of particular interest for cellular telephones and similar communication devices. This paper builds on and extends the previous analyses of parameters that influence the antenna-user interaction. Computer tomography (CT) and magnetic resonance imaging (MR1)-derived, high-resolution models of the human head are used. The numerical analysis is performed with the finite-difference time-domain (FDTD) method. The specific findings are: 1) a box model of a human head provides grossly distorted and unreliable results for the antenna radiation pattern; 2) a spherical model of the human head provides results that are relatively close to those obtained with a relatively simple, but more realistic, head model; 3) the SAR values obtained with spherical or simplified head models, that do not include the ear, are greater than those for a realistic head model that includes the ear; and 4) a hand holding the handset absorbs significant amount of antenna output power, which can be considerably decreased by modifying the geometiry of the handset metal box.

Effects of hand on EM absorption and antenna performances for internal handset PIFA

“…Additionally, presence of the user's hand leads to less conservative SAR values to the human head [16]. The human hand leads to reduce the SAR values to the head tissues, as it dispels a part of antenna radiated energy [17,18]. The effects of hand holding position on the EM interaction between mobile phone and human was investigated in [19].…”

Design Analysis of Ferrite Sheet Attachment for Sar Reduction in Human Head

“…Another approach is the use of a directional or reflecting antenna [13][14][15][16]. Such an antenna structure sacrifices the availability of signals received from all directions to the phone model.…”

“…Various studies on this subject exist [8][9][10][11][12][13][14][15][16][17][18][19][20], most of which mainly delve into the consequences of mobile-phone usage. Yet, devices and communication terminals operating in other frequency bands have also gained substantial interest in the last 15 years.…”

“…Although, in principle, the solution for general geometries does not require any additional effort with respect to the standard method, the technique requires the definition of the discretized space by assigning to each cell its own electromagnetic properties, which is not an easy process [12][13][14][15]. Specifically, the problems to be solved in SAR reduction need to correct representation of the cellular phone; anatomical representation of the head; alignment of the phone and the head and suitable design of ferrite sheet or other material.…”

Thin fim barium strontium titanate capacitors for tunable RF frond-end applications

“…The impedance of an antenna is sensitive to environmental changes and always becomes complex by, e.g., holding a cellular phone to the ear of the user [4,[168][169][170]. To eliminate the imaginary part of the load, to obtain the characteristic impedance of 50 Ω, the matching network should have an output impedance which equals the conjugate of the antenna impedance.…”