Effects of Shell and Body Tissue Simulating Liquid (BTSL) Thickness on Capsule Antenna Performance M.S. Zulkefli 1 , F. Malek 1 , M.F. Jamlos 1 , S.H. Idris 1 , S.H. Ronald 1 , M.H. Mat 1 , K.M. Juni 2 and M.I.M Saleh 2 1 School of Electrical System Engineering Universiti Malaysia Perlis (UniMAP) Blok A, Tingkat Satu, Taman Seberang Jaya Fasa 3, Kuala Perlis 02000, Perlis, MALAYSIA 2 Electrical Engineering Department Politeknik Tuanku Syed Sirajuddin 02600 Arau, Perlis, MALAYSIA muhammadsolihin@gmail.com, mfareq@unimap.edu.my, faizaljamlos@unimap.edu.my, syedidris@unimap.edu.my, hr.suzanna@gmail.com, hafizuddin.mat@gmail.com, khairudi@jke.ptss.edu.my, iskandar@jke.ptss.edu.my Abstract— In this paper, the study of shell and body tissue simulating liquid (BTSL) thickness and its effects on capsule antenna performance at 2.45 GHz were presented. Two simulation setups which consists two different sets of shell and BTSL position near the capsule antenna were used in the simulation process. The reflection coefficient, directivity, gain and efficiency performance in those simulation setups were determined and compared. The influence of human tissue thickness on the antenna behavior must be considered. Keywords-component: capsule antenna; body tissue simulating liquid; shell; bio-telemetry; I. INTRODUCTION The miniaturized antenna can be used as great communication tools which embedded into the human or pet body. The vital information (such as temperature, blood pressure, cardiac beat, etc.) can be transmitted from implantable devices to the external equipment by use of a wireless communication link. The idea of creating small antenna that can be implanted into the human body or for the use of other application is no longer an act of science fiction. Rather, it is now a reality that is prevalent in many applications. Whether they are used for diagnostic purposes or for health treatments, military, commercial and personal, the study of antennas is the focus of many researchers. A dual spiral antenna for wideband capsule endoscope system is introduced by Sang Heun Lee, Kihun Chang, and Young Joong Yoon. This dual resonance structure is composed of two different spiral elements and single feed wire connects these elements. When a spiral antenna is used as capsule endoscope system, a small sized antenna is required because capsule is small enough to be swallowed. The impedance bandwidth of the proposed antenna is 98MHz and it has isotropic radiation pattern [1]. A novel, miniaturized, biocompatible antenna at the medical implant communications service (MICS) band (402–405 MHz) for integration in wireless biotelemetry devices implanted in the human head was introduced by Asimina Kiourti et al. To reduce simulation time, the antenna is designed while in the center of a skin tissue simulating box and subsequently implanted inside the skin tissue of an anatomical human head model [2]. To analyze the performances of diverse biotelemetry links using the FDTD simulations, Jaehoon Kim et al simplified the human body model as cubic biological tissues whose dimensions are 16 x 16 x 16 cm 3 and the simplified body is filled with a skin tissue [3]. An article from Wei Xia, Kazuyuki Saito, Masaharu Takahashi and Koichi Ito shows proposed the cavity slot antenna with the H-shape slot for the implanted antenna. They analysed the performances of the proposed antenna which is embedded into the human body between the shoulder and the elbow [4]. II. METHODOLOGY Initially, the capsule antenna was designed using Computer Simulation Technology (CST). With the aid of CST, the antenna performance was analysed in order to achieve a final design that meets the specific requirements. The capsule antenna was simulated by place it at the centre with six different thicknesses of shell skin and BTSL. Those six models were simulated near the capsule antenna in two different positions; left-right and top-bottom. III. ANTENNA AND CAPSULE DESIGN A very compact peanut-shape patch antenna for the capsule antenna has been designed in free space using CST Microwave Studio software to determine the gain, operating frequency of the patch, and reflection coefficient [5]. The layouts of the peanut-shape antenna have shown in Figure 1 below. The dimension (W sub x L sub ) of the small antenna is 8 mm x 9.5 mm. All parameters value are the same as previous design except the radius of x-radius of the oval patch is more larger thus resulting larger bandwidth.