Unmanned aerial vehicles (UAV) have become common in commercial and recreational fields, but also in the hands of criminals. UAVs are used for plural of crimes. Most notably they are used to smuggle contrabands over perimeters, for example to prisons. Presently the industry of neutralizing misused UAVs is growing and testing different methods. Four electromagnetic methods can be distinguished at the moment, which are jamming, spoofing, high-power laser and electromagnetic pulse (EMP).

This thesis presents theory on high power microwave (HPM) systems required to design directed EMP system to disable commercial unmanned aerial vehicles and presents a prototype design for high-power circularly polarized directive antenna for the specific purpose. Research of the theory was conducted as a literature review and the design of the antenna was confirmed through electromagnetic simulations on CST Microwave® Studio.

Literature review presents basic radiation characteristics of magnetrons, klystrons and backward wave oscillators (BWO), techniques and components for HPM transmission and directive antennas with high power capacity. The different microwave sources are capable of producing microwaves at gigawatt power levels and on frequencies of over 10 GHz. The sole transmission components for HPM are the multitude of different waveguides.

The surveyed antennas are the horn antenna, the parabolic antenna, the slotted array waveguide antenna, the helical array antenna and the radial line slotted array (RLSA) antenna. The RLSA was chosen to be designed, because of its low profile.

The designed antenna has maximum directivity of 32.8 dB and the system from the magnetron interface to the antenna has a total efficiency of 0.9026=-0.45 dB. The range of the system is estimated to be 130 m with 325 kW input power, within which a commercial UAV is neutralized by the EMP from the antenna.