Design of a 900/1800 MHz dual-band loop antenna mounted on a handset considering the human hand and head effects

This paper presents FDTD design analysis of a dual-band loop wire antenna for a 900/1800 MHz mobile handset with consideration of the human hand and head effects. The loop wire antenna, with a small gap of a 1 FDTD-cell size (2.5 mm) is mounted on a metallic box covered by a plastic coating. The human head is modeled as a multilayered superquadric ellipsoid. This model can cover the cases of a sphere, ellipsoid, square cube, or rectangular cube, which facilitate the modeling of the head-shape and tissue properties. The superquadric ellipsoidal head model (with ears) comprises 9 different tissues of skin, cartilage, fat, muscle, bone, blood, nerve, brain, and eye-lens. Considering the proximity between the handset held by hand and the ear of a head, a y-oriented loop wire antenna is positioned at a distance of 1.25 cm. FDTD computation and experimental measurement of the antenna VSWR (mounted on a metallic box with a plastic coating) in free space and held by a hand close to a head is performed. The radiation characteristics of the loop antenna affected by the head and the SAR (specific absorption rate) distribution are important for antenna design and RF exposure studies.