The main aim of this study is to design an Ultra-Wide Band antenna with an almost constant level of gain over 3.1-10.6 GHz. A modified antipodal Vivaldi antenna with rake-like wires (called MAVARW-III), is designed for this goal. The MAVARW-III has two flared metal arms with rake-like wires printed on a dielectric substrate. Rake-like wires are primarily associated with balancing the gain over the operating bandwidth of the antenna. The proposed MAVARW-III has 7.90 dB minimum gain level over the bandwidth in simulations. The difference between the minimum and maximum value of the gain is <1.55 dB over whole frequency range in simulations. The proposed MAVARW-III is characterized both numerically and experimentally with a good agreement. The given design approach can be extended to relatively larger or smaller MAVARWIIIs to achieve almost constant gain level over desired other frequency bands.