In this paper, a new method for radar cross section reduction of a monopole antenna is proposed. In this method, a plasma helix like fluorescent bulbs is placed around the antenna element. The selected plasma parameter for this medium acts as an absorber without disturbing the antenna performance. The simulations show that radar cross section of simulated antenna is reduced in a wide frequency range. In this paper, the plasma parameter is chosen in such a way that reduces RCS at 4GHz. At this frequency, the radar cross section reduction is about 10dBsm. Due to the frequency dependent of the plasma medium, the plasma parameter must be changed for better result in the other frequencies. This change can be performed electrically without any change in the antenna structure. In this simulation, a PEC rode with 3cm diameter and 15cm height is chosen for the monopole antenna element. This monopole antenna resonates at 630 MHz. After placing the plasma helix around the antenna element, there is no significant change in the antenna performance.