In this paper, a new multi-band PIFA antenna covering four frequency bands (GSM, Wifi/Bluetooth, 4G LTE and WIMAX) is presented. The proposed method in this work consists of two main phases. The first step consists in determining the electrical and radiation characteristics of the proposed antenna using HFSS simulator. The second step, the effects of this antenna on the human body is examined and the specific spatial peak absorption rate (SAR) in the human head caused by the use of mobile phone is reduced applying the adaptation technique. For this reason, experiments were carried out based on LC resonator placed between the generator and the load and put in series with the short circuit. After optimizing the values of L and C, theoretical and experimental results were compared and discussed to obtain a good compromise between some constraints: (1) simulation and measurement results are in good agreement on the return loss (RL) (= S11), (2) high bandwidth, (3) high radiation efficiency and (4) limited specific absorption rate.