Research On Multi-band Microstrip Reflectarray Antenna

The microstrip reflectarray antenna has gained significant attention due to its lightweight,easy processing,high gain,and spatial feeding capabilities.With the increasing demand for dual-band/multi-band performance in long-distance communication systems,researchers are seeking to achieve such characteristics while maintaining the inherent advantages of microstrip reflectarray antennas.This paper presents a comprehensive investigation of multi-band microstrip reflectarray antennas.The main research content of this paper includes the following two parts:(1)A single-layer microstrip reflectarray antenna operating in the C/X band is designed.The reflective surface of the antenna consists of two types of resonant elements-a low-frequency element comprising a square ring and four bent phase delay lines loaded on its periphery,and a high-frequency element consisting of two concentric square rings.By altering the peripheral delay line’s length and the inner double loop’s size,the phase change range of the antenna at 5.9 GHz and 10.4 GHz is obtained.Based on this reflect unit,a 10×10 scale reflectarray fed by a dual-band slot patch antenna is manufactured,and the antenna’s measured results show a 2.88%(5.84-6.01 GHz)and 2.98%(10.36-10.67GHz)impedance bandwidth.The peak gain of the antenna in the X-band is 17.1 d Bi,and in the C-band,it is 16.45 d Bi,thus achieving dual-band radiation performance.(2)A tri-band dual-layer microstrip reflectarray antenna is designed.The reflecting unit cell comprises two layers,with a circular ring structure loaded with two arc-shaped delay lines on the upper layer.The reflecting unit cell consists of a cross-shaped patch structure with phase delay lines loaded and a Phoenix square circular structure with a first-order Koch fractal on the lower layer.By changing the length of the delay line and the length of the square ring,the phase change range of the antenna at 4.8 GHz,5.2 GHz,and 6.2 GHz is obtained.The upper unit structure also introduces a frequency selective unit to achieve the transmission effect on the upper reflectarray,which consists of a circular ring loaded with a two-section open stub.Based on the reflecting unit cell,an11×11 scale reflectarray fed by ultra-wideband logarithmic periodic antennas is designed.The-10 d B impedance bandwidth of the antenna covers the frequency range from 4.76 GHz to 6.70 GHz,with a peak gain of 17.1 d Bi,18.7 d Bi,and 19.9 d Bi at 4.8 GHz,5.2GHz,and 6.2 GHz,respectively,achieving high directional performance at these frequencies.