Ahmet Hulusi Gülseren

A small-sized reflectarray antenna array with compact production specifications is designed and fabricated for high-speed Ka-band communication systems. In the design phase, firstly, the reflection characteristics of unit cells used in the reflective surface are obtained by the full wave computational analysis tool, CST Microwave Studio. Secondly, an aperture efficiency analysis is carried out to determine the physical size of the reflectarray and the distances between the feeding antenna and the individual unit cells. Then, the entire reflectarray antenna is analyzed by array theory to obtain geometrical dimensions to be used in the fabrication phase. These results are verified by CST Microwave Studio and similar fabrication guidelines are obtained for both TE and TM polarizations. In the fabrication phase, the carefully tailored design parameters of the unit cells are used to build the antenna and measure important parameters such as radiation patterns, gain, cross polarization levels and S11 parameters, which agree with the results obtained in the design phase. The proposed reflectarray antenna makes it possible to support dual-polarized multi-beams in the range 18-20 GHz with stable gain behavior, which makes it possible to use it in high speed 5G satellite communication systems.

A dual-band, dual-polarized frequency selective surface (FSS)-backed multilayer reflectarray antenna is designed for 5G high-speed satellites operating at Ka-band uplink and downlink frequencies (20/30 GHz). A reflectarray antenna system consists of two reflectarrays that are separated from each other by an FSS layer that behaves as a planar bandpass filter at Ka-band satellite uplink frequencies. Each reflectarray antenna is designed with dual-polarized unit cells. In order to achieve a uniform phase distribution across the reflectarray surface, physical dimensions and positions of the unit cells with a fixed periodicity are carefully chosen. The FSS conductor is etched to the bottom layer of the 30 GHz reflectarray substrate to save cost and weight. The reflectarray performance is analyzed by using CST Microwave Studio and array theory. A prototype is fabricated, and the results are experimentally verified. The gain of the reflectarray is measured as 21.13 dBi and 26.94 dBi at 20 and 30 GHz, respectively. A crosspol level of more than 35 dB is observed at both frequencies. The simulated and measured results show that the proposed reflectarray is suitable for high-speed Ka-band satellites.