Performance of an Implanted Electrically Coupled Loop Antenna Inside Human Body

Abstract

Abstract-Implanted antennas are widely used in hyperthermia and biomedical applications. The antenna needs to be extremely small while maintaining a permissible Specific Absorption Rate (SAR) and being able to cope with the detuning effects due to the dielectric properties of human body tissues. Most of the proposed antennas for implanted applications are electric field antennas such as Planner Inverted-F Antennas (PIFA) and micro-strip patch antennas. By minimizing the size of an electric field antenna, the near zone electric field will increase, resulting in higher SAR. This work is devoted to design a miniaturized magnetic field antenna to overcome the above limitations. The proposed electrically coupled loop antenna (ECLA) has high magnetic field and low electric field in the near zone and therefore, has a small SAR and is less sensitive to detuning effects. ECLA is designed at the Medical Implanted Communication Service (MICS) band with dimensions of (5×5×3 mm 3 ). ECLA has been simulated inside one-layer human body model, three-layer spherical human head model, human head and human body. From the simulation results, ECLA inside the human body has a 5 MHz-3 dB bandwidth, −14 dB gain, and radiation efficiency of 0.525%. The 1 g average SAR inside the human body for 10 mW input power is about 1 W/kg which is 7 times lower than the SAR for a patch antenna of the same size with the same accepted power.

Low profile UHF loop antenna prototyped and investigated by circuit modeling

“…This antenna operates above a metallic ground plane with an air spacing between the antenna and the ground plane. This type of antenna has been used formerly in VHF and UHF band but in comparison to our work these former types provided very limited bandwidth and gain. With some modifications, the bandwidth and gain is increased, dimensions adapted for UHF application, also radiation pattern improved for proper communication.…”

“…Therefore, approximately the entire loss through the living being is associated with the electric field within a complicated medium with complex conductance . The desired antennas operating near human bodies should have a low electric field in the near zone to reduce the ohmic loss inside the human body. The H‐field antenna is virtually insensitive to precipitation static effects.…”

Systemic Overview of Microstrip Patch Antenna’s for Different Biomedical Applications

“…They cannot communicate where the range is long between transmitter and receiver (the signals transferred from transmitter to receiver shown in Figure 1 below). 60…”

Implantable ferrite antenna for biomedical applications

“…These configuration types have led to efficient implantable antenna designs by other authors [12][13]; however the non-planar profile of these models can make antenna miniaturization more difficult. With this in mind, we chose the microstrip patch antenna configuration as the preferred starting model for our implantable antenna design.…”