Radio Frequency Identification (RFID) is one of the developed technologies, which is used in several applications, including for medical field applications. For patient monitoring purpose, the RFID system is consisted of a medical tag that is implanted into the human body and a reader unit that is installed away from the human either in proximity or far away from the human body. By this communication system, it can reduce medical error, the risk of the tag being lost, and can be used for uncooperative patient. The monitoring device will be connected to the existing network (wireless LAN and so on) allowing to provide the mobility of patient, the physicians or caregivers can get easily patient's medical information without spending a lot of time via such a network connection. In this study, it will propose a tiny dipole antenna for RFID tag that will be implanted into the body following it is enclosed by a silica glass to reduce the radiation effects on the human body. The antenna is numerically simulated by using a human arm model in the frequency of 924 MHz according to the RFID band allocation in Indonesia. This study also investigates two other different surrounding environment of the antenna in order to precisely understand about the antenna characteristics, i.e. antenna placed in free space and enclosed in silica glass material. Each environment gives effects on the antenna's resonant frequency including its bandwidth. Following the simulation, the antenna is fabricated and validated by the basic measurement. This paper will show the current results of the antenna characteristics in free space environment in order to validate its basic manner. The antenna is relatively very small dimension compared to the band wavelength with good performances in S parameter, sufficient bandwidth, and omnidirectional radiation pattern.