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 (MDSL) 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.