A novel miniaturized printed monopole antenna for ultra-wideband (UWB) bidirectional brain machine interface (Bi-BMI) applications, based on defected feed line and parasitic structures, is designed and tested. The proposed antenna structure consists of a rectangular radiating patch and two inverted L-shaped slots located in the transition distance between patch and feed line, with a meander line parasitic structure in which a resonance frequency with narrow bandwidth nearly to 2.4 GHz and a running fractional bandwidth of more than 100% are provided (3.19–10.63 GHz). Inserting a meander line parasitic structure caused the antenna to resonate in 2.4 lower frequency bands in order to transfer controlling command in BMI application. In addition, by inserting a pair of inverted slots on the feed line and radiating patch’s corners, an excitation has been taken further in the resonance; therefore, a much wider impedance bandwidth is possible to be processed. To illustrate the usefulness of the proposed antenna for BMI applications, the Specific Absorption Rate (SAR) distribution, one of the most important characteristics in the implanted sensors, in the mode of an implanted antenna inside the full head voxel model, under Dura matter, and external antenna with the distance of 20 cm from the implanted antenna, is presented. The proposed antenna has great radiation characteristics, such as very low SAR, high fidelity and almost omnidirectional radiation patterns over the whole band.