دانلود رایگان مقاله بازتابی شبکه مارپیچ لگاریتمی از آنتن های پایه اى در دهانه آن

Abstract

A reflectarray with logarithmic spiral lattice of elementary antennas on its aperture is presented. In a logarithmic spiral lattice, elementary antennas are arranged in a grid of an outwardly spiral so as to have no translational periodicity. Infinite array approach has been used to determine reflection phase curve since in the aperiodic logarithmic spiral lattice, the effective unit cell area remains the same. Based on this lattice, a prime focus fed reflectarray centered at 16 GHz has been designed and developed. The measured gain is 30.5 dBi and side lobe levels are −29 dB and −22 dB in E- and H-plane respectively. Aperture efficiency of the proposed reflectarray is 37% and its 1-dB gain bandwidth is 4.1%. Good agreement between measured and simulated results reinforces the validity of the design process. A comprehensive investigation of reflectarrays’ performance with different lattices is conducted which shows lower side lobe levels for reflectarray with logarithmic spiral lattice.

5. Conclusion

The design and analysis of reflectarray with logarithmic spiral lattice of elementary antennas on its aperture has been presented. Design equations of logarithmic spiral have been used to obtain grid points of elementary antennas on reflectarray aperture. Designed reflectarray is fabricated and measured for radiation pat- terns. Overall gain of the reflectarray has been measured to be 30.5 dBi with SLL of
29 dB in E-plane and
22 dB in H-plane. A performance comparison of this reflectarray has been carried out with reflectarrays having conventional (rectangular and circular) lattices. An improvement in gain of about 1.5 dBi and improve- ments in SLL of 6.2 dB in E-plane and 6.3 dB in H-plane have been achieved for proposed reflectarray as compared to reflectarray with conventional rectangular lattice.