| Abstract [eng] |
The use of metamaterials in the manufacture of antennas has number of advantages. With the help of metamaterials, we can reduce the dimensions of the antenna, also improve some parameters of antennas, such as gain, reflection, directivity, bandwidth, radiation direction. Metamaterials are artificially created composite materials, usually consisting of periodic sub-wavelength metallic and/or dielectric structures, which resonantly connect with the electric and magnetic fields of incident electromagnetic waves and acquire unusual electromagnetic properties not found in the natural environment. These materials due to their precise shape, geometry, size, orientation, and arrangement have special ability to manipulate electromagnetic waves: block, absorb, or bend. The aim of this work is to theoretically and experimentally analyze the effect of the metasurface on the radiation and control of two microstrip antennas. Two metasurface antennas using photolithography method were fabricated and measurements have been performed. Measured results were compared with the theoretically calculated ones with CST Microwave Studio software. The results of this work have shown that by increasing the width and length of the microstrip antenna increases the reflection of the antenna and shifts the resonant frequency towards the lower frequency range. This is due to the fact that increasing the dimensions of the antenna increases the length of the radiated waves, which is inversely proportional to the resonant frequency. Moreover, after analyzing how the resonant frequency and reflection of the antenna changes depending on the gap width of the slotted antenna, it was observed that as the gap narrows, a smaller antenna reflection is obtained, and the resonant frequency moves towards lower frequencies, these parameter variations are caused due to better antenna impedance matching. In addition, investigating how the resonant frequency and reflection change depending on the thickness of the antenna substrate, it was noticed that increasing the thickness in the case of both antennas the resonant frequency and the reflection increases. These changes are due to the increasing effective dielectric constant, which is inversely proportional to the resonant frequency. Also, after experimentally analyzing the dependence of the microstrip antenna gain on the distance to the metasurface, it is shown that when the metasurface is at a distance of 15 mm from the microstrip antenna, the gain is high and increases by 2.4 dB compared to the antenna without a metasurface. Furthermore, analyzing the directional dependences of the microstrip antenna controlled by water, it was found that when two channels are filled with water, the radiation direction of the antenna turns by 6 degrees. Direction change of microwaves radiated by the antenna occurs due to the interaction between water and the metasurface. |
