Abstract: Passive electrically small antennas follow the Bode-Fano constraint criteria, and the volume, bandwidth, and efficiency constitute a constraint relationship with each other, so it is difficult for antennas to achieve a wide frequency band while being miniaturized. The negative impedance element realized by a non-Foster circuit can effectively offset the large reactance of the electrically small antenna, thereby breaking the limitation of the above-mentioned criterion, improving the radiation performance of the antenna. The butterfly slot antenna is selected as the non-foster circuit matching object, and the circuit is welded on the back of the antenna for integrated design, so that the integration degree of active antenna is higher. By analyzing the feed network of the integrated active butterfly antenna, the effects of different feed positions and feed modes on the performance of the antenna are compared. The S11 parameters of the optimized active antenna are less than -10 dB in the operating frequency band of 250 MHz~850 MHz, reaching -24 dB at the resonance point, the relative bandwidth is increased by 109?? and the gain is increased by 5. 8 dB. The active antenna is processed and tested, and the test results are consistent with the simulation ones.