**1. Introduction**

In latest years, microwave antennas have performed an important role in implantable biomedical devices. Millions of people around the world improved and saved their lives with the help of implants [1]. Implantable antennas play a role in creating a simulation environment, checking results, and fulfilling diagnostic purposes. With population growth and health awareness, people are more concerned about their health. Implantable medical devices (IMD) play an important role now a days. It is used to continuous monitoring of human body temperature [2], implantable cardioverter defibrillators and pacemakers [3], for continuous glucose monitoring [4], to detect heart failure [5], rectenna [6], and so on. In IMD an antenna is one of the essential parts. To design biocompatible antennas according to parameters, consider the required size, shape, miniaturization, impedance matching, biocompatibility, patient safety, and low power consumption [7, 8].

In the twenty-first century flexible electronics developing towards bio-integrated electronics for curvilinear biological skin, tissue, and organs considering patient's safety [9]. Diagnosis and treatment are application areas of antenna, diagnosis can be done with help of magnetic resonance imaging (MRI), biomedical telemetry, and wireless capsule endoscopy [10]. Integrated implantable antenna plays important role in bi-directional communication for controlling and monitoring external

equipment. The implantable antenna must be biocompatible, human tissues are conductive and it can be short circuit while coming into contact with metallization [11].

These are operated in very low frequencies such as medical implants communication system (MICS) band (402–405GHz) & Industrial, Scientific and Medical (ISM) bands (2.4–2.4835GHz) [12–23]. In 1999, Federal Communications Commission (FCC) decided the frequency range of Medical Implant Communications Service (MICS) operating on frequency range 402–405 MHz. It consists of a lowpower, high-speed, non-voice transmission that is useful in the manufacture of implantable medical devices [24]. The design of an implantable antenna is challenging due to biocompatibility issues miniaturization, loss of transmission path in the human body, safety issues, and so on.
