|Implanted antennas are widely used in hyperthermia and biomedical applications. The
antenna needs to be extremely small while maintaining a permissible Speci¯c Absorption Rate (SAR)
and being able to cope with the detuning e®ects due to the dielectric properties of human body tissues.
Most of the proposed antennas for implanted applications are electric ¯eld antennas such as Planner
Inverted-F Antennas (PIFA) and micro-strip patch antennas. By minimizing the size of an electric
¯eld antenna, the near zone electric ¯eld will increase, resulting in higher SAR. This work is devoted
to design a miniaturized magnetic ¯eld antenna to overcome the above limitations. The proposed
electrically coupled loop antenna (ECLA) has high magnetic ¯eld and low electric ¯eld in the near
zone and therefore, has a small SAR and is less sensitive to detuning e®ects. ECLA is designed at the
Medical Implanted Communication Service (MICS) band with dimensions of (5£5£3 mm3). 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 e±ciency of 0.525%. The 1 g average SAR inside the human
body for 10 mW input power is about 1W/kg which is 7 times lower than the SAR for a patch antenna
of the same size with the same accepted power.