A microstrip reflectarray antenna with the properties of wide bandwidth and low side-lobe level

A portable radar substitutes the microstrip reflectarray antenna for the traditional paraboloid antenna to realize the intent of its portability and miniaturization. The difficulty of the design of the antenna is how to keep the low side-lobe property in the whole working band of the radar. A phase shifter scheme of the microstrip delay-line was used to realize the property of low side-lobe of the microstrip reflectarray antenna. The match fundamental that the microstrip patch and delay-line were satisfied with the relationship of linear phase shifter was adopted to realize the property of wide bandwidth and low side-lobe level of the antenna. It was proved in the testing result that the side-lobe level of the microstrip reflectarray was below -25dB in the 3.2% bandwidth of the X-band in the base of the more 50% efficiency of the antenna.