# Optimal Design of a New Rotating Magnetic Beacon Structure Based on Halbach Array
## 1 Introduction
However, the current magnetic signals generated by the existing magnetic beacons are all sinusoidal periodic changes, and there is a multi-value problem when using the phase information of the signal to measure the angle. Therefore, it is necessary to re-design the beacon so that it can generate the characteristic strong magnetic signal with only one maximum value within the period. A Halbach array is a kind of magnet structure that generates the strongest magnetic fields by arranging magnets with different magnetization directions in a certain pattern. [PERSON] [19] an American scholar, discovered this special structure in an electron acceleration experiment and gradually improved it, and finally formed the Halbach magnetic array, which enhanced the field strength in one direction and weakened the field strength on the other side. [PERSON] and [PERSON] [20] calculated and analyzed the performance and potential applications of radial and axial fields, slotted and non-slotted, rotating and linear, and spherical Halbach magnetization arrays on the basis of commonly used Halbach arrays. [PERSON], [PERSON], and [PERSON] [21] established the magnetic field model with the Fourier series method, analyzed the one-sided flux density characteristics of the Halbach array, and studied a new type of magnetic switchable device based on the Halbach array, which improved the utilization rate of a magnet. [PERSON] [22] innovated the traditional Halbach array by placing the Halbach magnetic array on the upper and lower sides of the conductive plate and derived a three-dimensional analysis of the model. By optimizing the geometric parameters of the model, the applicability of the model on the point dynamic suspension device was verified. With the development of magnetic material technology, [PERSON]. [23] studied the tunable linear Halbach array of a kind of conductive nanoparticle. By adjusting the magnetization mode and field distribution of the particles in the array, a relatively large area of a high magnetic field could be generated. Currently, Halbach arrays are mostly used in magnetic levitation and motor technologies, which are dedicated to unilateral magnetization enhancement capability and magnetic field utilization efficiency, but the characteristics of such magnetic fields are not strong enough to meet the signal requirements of phase-based goniometry methods. In this paper, a fiducial model consisting of seven permanent magnets is established by deriving the magnetic field distribution of the Halbach array, then changing the magnetization direction of permanent magnets in the structure and analyzing the variation of magnetic fields on both sides of the array, so that a magnetization angle with better unilateral magnetic aggregation effect is determined. On this basis, the particle swarm optimization algorithm is used to adjust and optimize the size of the permanent magnets in the structure to obtain a set of structural parameters with the strongest magnetic field characteristics. Finally, the modeling data of the optimized structure are compared with the COMSOL finite element simulation results to prove the usability of the structure. The new beacon structure proposed in this paper has more important implications for further research based on the principle of artificial magnetic beacon direction finding.