الفهرس 
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Abstract
The main limitation of chipless Radio Frequency Identification (RFID) systems is their short reading range as the amplitude of the back-scattered tag signal is inversely proportional to the fourth root of the distance. In this thesis, a design of hybrid reflectarray (HRA) antenna consisting of five different unit cells working at 6GHz for chipless RFID reader applications is introduced. The proposed HRA has a narrow half-power beam width (HPBW) and a high gain. These characteristics significantly enhance the reader sensitivity, maximize the reader range, reduce the multipath effects, and improve the tag localization. The proposed HRA leads to efficient information transmission through the system channel. It is realized on a rectangular single-layer Rogers RT5880 lossy substrate of thicknessh=3.14mm and a relative permittivity ε= 2.2.The number of radiating cells in the design is 100 unit cells with a uniform element spacing =λ/2 . The elements are arranged on a rectangular substrate of dimensions (250×250)mm, and the array is fed by a pyramidal horn antenna with a gain of 12.3dBi,and a side-lobe level(SLL) of −18.4dB. The HPBW equals 46.7°and 42.8° in the E- and H-planes, respectively. The simulation results show that the proposed HRA gives a high gain up to 20.6 dBi, which is greater than the feeder gain by 8dBi and a four-times narrower HPBW of about 10°.It works over the ultra-wide band (UWB) frequency range from4.6GHz to 7.4GHz with47% fractional bandwidth (FBW),and it has an SLL= −14.8dB, which cannot be achieved by the conventional arrays. The main limitation of chipless Radio Frequency Identification (RFID) systems is their short reading range as the amplitude of the back-scattered tag signal is inversely proportional to the fourth root of the distance. In this thesis, a design of hybrid reflectarray (HRA) antenna consisting of five different unit cells working at 6GHz for chipless RFID reader applications is introduced. The proposed HRA has a narrow half-power beam width (HPBW) and a high gain. These characteristics significantly enhance the reader sensitivity, maximize the reader range, reduce the multipath effects, and improve the tag localization. The proposed HRA leads to efficient information transmission through the system channel. It is realized on a rectangular single-layer Rogers RT5880 lossy substrate of thicknessh=3.14mm and a relative permittivity ε= 2.2.The number of radiating cells in the design is 100 unit cells with a uniform element spacing =λ/2 . The elements are arranged on a rectangular substrate of dimensions (250×250)mm, and the array is fed by a pyramidal horn antenna with a gain of 12.3dBi,and a side-lobe level(SLL) of −18.4dB. The HPBW equals 46.7°and 42.8° in the E- and H-planes, respectively. The simulation results show that the proposed HRA gives a high gain up to 20.6 dBi, which is greater than the feeder gain by 8dBi and a four-times narrower HPBW of about 10°.It works over the ultra-wide band (UWB) frequency range from4.6GHz to 7.4GHz with47% fractional bandwidth (FBW),and it has an SLL= −14.8dB, which cannot be achieved by the conventional arrays.