# Development of a Metalens for Radio Wave Ground- Penetrating Radars
## 1 Introduction
At present, numerous studies are aimed at developing technologies for applying metamaterials to antenna systems for various purposes [10; 11; 12; 13; 14; 15; 16]. However, despite the intensive development of this topic, the technology was narrowband for a long time, and only in the last five years, work has been carried out on the use of metamaterials with an extended operating frequency band. Existing antenna systems for georadio sounding have a number of disadvantages, for example the radiation pattern of traditional antennas is determined by the relative size of the aperture. A large aperture is required to obtain a needle chart. There are difficulties with matching the elements of antenna arrays, and this and other circumstances lead to high material costs. Metamaterials provide an unprecedented ability to manipulate electromagnetic waves and enable technology for new devices ranging from flat lenses that focus light beyond diffraction to coatings that can mask an object. However, narrow bandwidths and high internal losses due to the resonant properties of metamaterials make it difficult to expand their scope. New design approaches seek to turn perceived dispersion disadvantages into assets that enhance device performance. One way is to create a focusing device from a metamaterial with a negative refractive index. Modern methods for creating metamaterials are being intensively developed, but so far, little attention has been paid to important effects due to the near-field interaction of the basic elements of metamaterials. According to the methods proposed in the literature for creating metamaterials, many experimental prototypes of composite structures with negative permittivity and magnetic permeability have been developed to date. Thus, the work of [PERSON], [PERSON], and others [17] proposes the creation of a material based on a resonant structure of the RLC circuit type. In this work, negative refractive readings were obtained at resonant frequencies of 2.02, 6.985, 9.985, and 14.425 GHz. In [18], a metamaterial was presented, which is a printed circuit board with a resonant pattern on it. Like the previous version, it is an RLC type, which is based on the resonant negative value of the dielectric and magnetic permeability. This structure changes its value of dielectric and magnetic permeability with a change in the substrate, as well as with a change in the wave incidence on this structure. Negative values were obtained at resonances at frequencies of 10.2 and 4.3. In addition to negative metamaterials, materials with a zero refractive index are also being created [19]. The modern literature provides examples of the creation of focusing devices with an operating frequency of 3.5 GHz [20]. The miniaturization of antenna systems with improved signal transmission was considered in [21]. It was claimed that the operating frequency range of such antennas extends from 7 to 8 GHz (1 GHz band). The reduction in overall dimensions and improvement in performance using metamaterials was demonstrated in the work of [PERSON] et al. [22] for widely used GPS, WLAN, and WiMAX antennas. The study of the decrease in the effective scattering area of an object covered with a metamaterial was carried out in [23; 21; 24; 25]. It is noted that this decrease occurs only when the wavelength is 632.8 nm. In addition, the following are actively discussed in the literature: the possibility of synthesizing nanoscale circuits using metamaterials [26], the creation of optical-range metamaterials based on nanotechnologies [27], and the problems of improving the characteristics of already existing strip antennas. However, the papers [26; 27; 28] also dealt with the use of not very broadband metamaterials. Therefore, for example, from the analysis of the content of [28], it follows that the antenna described in it becomes more efficient only at two resonant frequencies of 12.5 GHz and 14.25 GHz. Metamaterials are also used in the space industry, as in [29], where the calculations of a horn antenna were presented.