چكيده به لاتين
Today, satellites play a key role in the world and a lot of money is paid for their design and construction, thus, increasing reliability and longevity is crucial in this industry. High-gain antennas are highly regarded in telecommunications because of their many advantages. There are many ways to make these antennas, the most famous of which are array antennas, parabolic antennas and reflect-array antennas. Parabolic antennas, despite having suitable radiation properties, are not used in many applications due to their bulkiness, and also array antennas in cases where the number of elements is high, leading to the complexity of the power supply network and thus increasing Construction costs and losses. Recently, reflectarray antennas have received lots of attentions due to their flatness and suitable radiation characteristics, but this type of antenna also has a relatively bulky structure due to the relatively large distance between the feed antenna and the antenna surface and so they are vulnerable to aerial maneuvers. In order to resolve the mentioned problems as well as to achieve the desired radiation properties, we use SSPP structures that support surface waves. These structures trap the wave and do not allow it to radiate. In the next step, by using phase gradient metasurface (PGM), we introduce a wave vector in the opposite direction of the SSPP structure which make these surface waves to radiate in the desired direction. As a result, we will have a compact antenna that contrary to conventional structures, its feed is on the surface of antenna.by proper design of either phase gradient metasurface or SSPP waveguide structure, we can have a high-gain antenna in the desired direction, which also have the ability to scan the beam with frequency. In this thesis, we present a structure consisting of metal grooves that support SSPP surface waves. on these metal grooves, the wave velocity is reduced and so it trapped on the surface of the grooves and as a result it is not possible to radiate. Then by using phase gradient metasurface which also play the role of polarization conversion, transform antenna surface wave to the free space wave at the desired angle. the proposed antenna in this thesis possess the impedance bandwidth of 8.2 GHz ~ 12 GHz. The results, confirm the generalized snell’s law in order to have radiation pattern with gain of 12.5dB in the direction of 15◦ at 10 GHz frequency.
