We have developed a new multiantenna rf ion source for neutral beam injection and studied the effects of different antennas, connected in parallel, on the hydrogen plasma characteristics. The four-antenna elements 20 cm long are installed inside the 35×35×21 cm3 rectangular bucket chamber. The maximum rf power of 40 kW at 9 MHz is used. The ion current, electron temperature, and plasma potential for the hydrogen pressure of a few mtorr are 20–70 mA/cm2, 3–10 eV, and 0–10 V, respectively. The increasing numbers of parallel antennas improve the available rf power input and change the plasma parameters. The calculation demonstrates that the uniform density profile can be obtained by controlling the rf current of antenna array.