## 1 Introduction
Nowadays, several methods and devices are used to measure the magnetic properties of ferromagnetic materials in the form of magnetic hysteresis curves. Most of them are based on the measurement using a toroidal-shaped specimen or Epstein frame device [31, 32, 33, 34]. Occasionally, a single-yoke open configuration is used [35]. However, many experimental methods are particularly designed to measure the magnetic characteristics of ferromagneticmaterials with specific properties or with use in highly specialized applications [36; 37; 38; 39; 40]. Therefore, our original measuring workstation, using a flux gate VEMA magnetometer, was redesigned in 2022 to determine the magnetization state of an open-ended actuator core for the complete magnetization reversal cycle. The measurement process is fully automated by implemented software algorithms, which output a complex hysteresis curve as a functional dependence of a material magnetic polarization on an excitation magnetic field. The usage of the measuring method, based on stray magnetic field measurement, is not limited only to the space sector. The proposed method with the designed workstation can be used for measuring the hysteresis curves of various ferromagnetic and paramagnetic components of industrial and security sensor systems. Regarding security sensor systems, the magnetic field represents an information medium that is hard to manipulate without conspicuous notice. The fluctuations of the magnetic field can be caused by various sources in the monitored area of interest. One of the most common is the object's movement in a geomagnetic field or an ambient magnetic field, given as the superposition of surrounded devices. Since such variations of the magnetic field can be relatively easy to measure with the proper devices, various experimental measurements using the magnetic field as the medium to secure the given protective perimeter were already performed; for example, possibilities of indoor technical security by the magnetic field, measured with a magnetometer insensitive to industrial frequencies (50 Hz) [41]. The magnetometer, in the function of security devices, can also be used in open spaces to protect a given perimeter against ground vehicles or flying objects. Concerning the flying objects, there is a proof of concept utilizing a small unmanned aerial vehicle (UAV) with an attached magnetometer to secure the surrounding area against a potential flying intruder--another small multirotor UAV [42]. Experimental measurements have also been performed using the UAV with an integrated magnetometer for an indoor mapping of the ambient magnetic field [43]. The purposeful ambient magnetic field measurements intended for the security applications (such as those mentioned above) are usually based on a relatively simple method using a relax-type fluxgate magnetometer. One of the primary sensing elements of the relax-type magnetometer probes is an open-ended ferromagnetic core, which is periodically saturated by an excitation coil during a measurement process. The time between the saturation state and the relaxed state of the core, conditioned by the measured ambient magnetic field, represents a parameter used to calculate sensed magnetic flux density in a given direction. Therefore, the ferromagnetic core with a suitable magnetic characteristic must be considered to acquire the desired measurement parameters of the relax-type fluxgate magnetometer. In accordance with this fact, the presented measuring workstation, based on the stray magnetic field method, can also be used to measure the magnetic properties of the ferromagnetic core utilized as the sensing element of the relax-type magnetometer probe. Consequently, in order to demonstrate the capabilities and potential spectrum of use of the presented measuring workstation, the magnetic hysteresis curve of the open-ended ferromagnetic core, used as the sensing element of the relax-type VEMA magnetometer probes, is also discussed.