Experimentalstudy of spiral antennas with various additional decelerationoptions

Background. The work is aimed at the development and research of flat spiral antennas with additional slowdown. The use of slowdown structures allows to change the operating frequency range of antennas and the electrodynamic characteristics of antennas. Three variants of the retarding structure implementation are considered: a planar dielectric plate, a planar metal-dielectric plate with metallized holes, and a planar metal-dielectric plate with metal pins. The results of measurements of the sample parameters were compared with a reference antenna sample. Aim. The work measures the electrical parameters of flat spiral antennas with additional deceleration. The standing wave coefficient, the width of the radiation pattern and the gain are determined for a practical assessment of the degree of influence of design solutions for the construction of decelerating plates on the functioning of the antenna. Methods. Planar deceleration plates are installed directly in front of the radiating structure. Platines are implemented as a multilayer structure of dielectric substrates with variable dielectric permittivity. Additional elements are provided in the construction of metal-dielectric plates: metallized holes and metal pins. The experiment is based on rigorous measurement techniques and quantitative methods for evaluating research results. The parameters of the antenna devices were measured under the same conditions at the same workplaces, which ensures the reliability and stability of measurements. Results. The proposed design options for the deceleration plates provide better matching and an increase in the gain in the lower part of the operating range, and a decrease in the lower operating frequency of the antenna is observed. At the same time, the best matching is provided by a planar dielectric plate, and a retarding plate with metallized holes has the least effect on the uniformity of the radiation pattern. The use of such structures with a spiral diameter of more than one and a half wavelengths requires careful coordination of the design of the plate layers (their shape and thickness; sequence, gradient of change in dielectric constant; size and location of additional retarding elements). Conclusion. From a practical point of view, it has been shown that planar dielectric and metal-dielectric plates slow down electromagnetic waves in flat spiral antennas and allow them to shift the operating range to lower frequencies without increasing overall dimensions.