Low-mutual-coupling reflectarray antenna based on random fragmented elements with square loops

ABSTRACT

A novel microstrip reflectarray antenna constructed by elements of random fragmented patches with square loops attached to the edge is proposed in this paper. The fragmented patch is gridded into 2 N × 2 N pixels, each of which is randomly assigned either conducting or non-conducting property. In this case, a variety of different reflection phases can be obtained due to the structural differences between the elements. To suppress the mutual coupling between elements, each fragmented unit is integrated with a metal square loop, and the reduction of the mutual coupling is indirectly analyzed across the frequency characteristics of the reflection phase for the combined elements. A prototype antenna with 7 × 7 elements was designed, fabricated, and measured. Both the simulation and measurement results show that the microstrip reflectarray antenna possesses a high gain of 19.7 dBi at its working frequency of 5.8 GHz, which is 2 dB higher than that of the reflectarray elements without square loops. Meanwhile, this antenna achieves an impedance bandwidth (|S| < − 10 dB) of 5.6%, side-lobes 13.1 dB below the main lobe, and with the cross-polarization level less than −18 dB.

KEYWORDS:

• Reflectarray antenna
• fragmented
• mutual coupling
• reflection phase

Acknowledgments

This work was supported by the Natural Science Foundation of Shanxi Province (201901D111026)