Abstract: In this paper, a broadband balun model based on a coaxial line structure loaded with ferrite beads is proposed for the problem of differential feeding and impedance matching of high-power antennas. The dual coaxial line has impedance transformation function and better power carrying capacity, and the ferrite magnetic beads improve the input matching and the balance of the two output ports at low frequencies of the balun. Simulations and measurements show that the return loss is less than -10 dB, single-ended insertion loss is within 1. 5 dB after removal of 3. 0 dB system insertion loss, the phase imbalance is within 5° and the amplitude imbalance is within 2% at both outputs from 0. 05 GHz to 1. 24 GHz. The operating performance of the balun at high power feeds is verified by analyzing the electromagnetic heat loss field, temperature field and stress deformation field of the balun, and the results show that this balun can withstand 500 W power in the operating frequency band.