**5. Discussion**

Based on the obtained results, one can say:


### **6. Conclusions**

The proposed method of calibration improves the initial orientation of the radars relative to the north over the entire range of the initial errors. Moreover, it reduces the azimuth misalignment the bigger its initial value is. This is an undoubted advantage of the method and also has a great practical meaning, as it leads to a significant reduction of errors in determining the coordinates of the detected object (see Figure 5). Although there are cases when the azimuths misalignment increased after calibration, it has no practical meaning as it only concerned small initial errors. Therefore, after calibration, the orientation errors were still acceptable. The disadvantage of the method may be the need to perform a drone calibration flight along a fixed route. However, this appears to be a minor nuisance compared to other calibration methods.

**Author Contributions:** Conceptualization, A.N.; methodology, A.N., K.N. and D.M.; software, A.N.; validation, A.N., K.N. and D.M.; formal analysis, K.N.; writing—original draft preparation, A.N.; writing—review and editing, K.N. and D.M.; visualization, A.N. and D.M.

**Funding:** Own funds for the research activity of the Department of Geodesy, Faculty of Civil and Environmental Engineering of the Gdansk University of Technology.

**Acknowledgments:** The article was possible thanks to research on the use of remote sensing methods for the detection and classification of drones conducted in cooperation with the Gdansk University of Technology and the Naval Academy in Gdynia.

**Conflicts of Interest:** The authors declare no conflict of interest.
