The object of research is the process that forms an elliptical directional diagram of the H-sector horn antenna for flow irradiation of seeds with the electromagnetic field. The emitter of electromagnetic energy is presented as one of the main elements of installations for irradiating seeds with an electromagnetic field before sowing. This parameter was investigated by taking into account the values of the biotropic parameters of the low-energy electromagnetic field under the conditions of flow processing. This paper reports a study into the parameters of the H-sector horn emitter for irradiation of sugar beet seeds with a low-energy electromagnetic field at a frequency of 73...75 GHz in continuous flow. Thus, one should use the H-sectoral horn emitter with the following parameters: aperture width aa=20 mm; horn length RH=35 mm; b=1.8 mm. It is determined that in order to irradiate sugar beet seeds on the conveyor plane with a power flow density of P=100 μW/cm2, it is necessary to place two horns 1200 mm above the conveyor at a distance of 2540 mm from each other. It was checked that the treatment of sugar beet seeds with electromagnetic radiation in a continuous flow with a capacity of 300 kg/h is possible with a power of up to 2 W supplied to two horn antennas; the speed of the conveyor is 15 cm/s. The parameters of the sectoral horn for an elliptical directional diagram were studied by dividing the main task into internal and external. According to the results of the research, it is possible to build a base of geometric presets for adjusting installations for different types of seeds, the desired performance, the structural features of installations, as well as existing emitters