**3.1 Miniaturization**

In the case of an implantable antenna, an antenna supposes to be implanted in the human body, therefore the size must be should be minimized. Miniaturization becomes very important today because dimensions of half-wavelength (λ/2) and quarter wavelength (λ/4) antennas at low-frequency bands, ISM, MICS band makes them useless for designing implantable antennas. Generally, for the implantable antenna design MICS (402–405 MHz), ISM (Industrial, Scientific, and Medical 2.4–2.48 GHz) and Med Radio (401–406 MHz) bands are useful. While design, human tissue is designed with high relative permittivity, due to this antenna miniaturization being challenging. When a biocompatible layer with low permittivity is inserted around the antenna, the effective permittivity decreases. Various miniaturization methods are shown below.
