Broadband Low-Cost Reflectarray Using Modified Double Square Loop Loaded by Spiral Stubs

An X-band reflectarray, which consists of double square loop loaded by spiral stubs (DSL-SS) unit, is investigated in this communication. The DSL-SS unit is composed of a modified double square loop loaded by four spiral stubs and is analyzed by a simple circuit approach, which can analyze the complex multiple resonance structure and guide the design, to reveal its characteristic. The reflectarray is designed according to a detailed design procedure and is then fabricated on a single-layer FR-4 substrate, which covers an area of 192×192 mm2 . The proposed reflectarray has a wider gain bandwidth and lower cross-polarization when compared with the conventional single-layer reflectarrays, and its measured gain, the aperture efficiency and 1-dB gain bandwidth are 24.4 dBi, 53.5% at the center 10 GHz, and about 38% (9.4~13.2 GHz), respectively. This new reflectarray antenna is especially useful for low-cost broadband communication applications.