A Compact Broadband Circularly Polarized Stacked Microstrip Antenna With Parasitic Elements

A compact broadband circularly polarized (CP) stacked microstrip antenna (SMPA) is proposed in this study. The CP SMPA is composed with a square‐loop sequential phasing feeding structure, two pairs of rectangular patches with different sizes, and two square patches as parasitic elements. For obtaining more CP resonant points, rectangular and square patches are etched on the upper and lower layers of two different substrates through a capacitively coupled connection. Utilizing CP resonant points produced by these parasitic elements, the bandwidth of CP SMPA is broadened. The designed CP SMPA has a wide 10‐dB return loss bandwidth of 19.6% (5.06–6.16 GHz, centered at 5.61 GHz), and a broad 3‐dB axial ratio bandwidth of 18% (5.05–6.05 GHz, centered at 5.55 GHz). The designed antenna features a circularly polarized bandwidth which could cover wireless local‐area network (5.725–5.85 GHz), intelligent transportation systems (5.8 GHz) and (5.85–5.925 GHz) band. Plain Language Summary A compact broadband circularly polarized (CP) stacked microstrip antenna (SMPA) is proposed in this paper. The CP SMPA is composed with a square‐loop feeding structure with feature of sequential phase, two pairs of rectangular patches with different sizes, and two square patches as parasitic elements. For obtaining more CP resonant modes, rectangular and square patches are etched on the upper and lower layers of two different substrates through a capacitively coupled connection way. Utilizing CP modes produced by these parasitic elements, the bandwidth of CP SMPA could be broadened. The designed CP SMPA has a wide 10‐dB return loss bandwidth of 19.6% (5.61 GHz, 5.06–6.16 GHz), and a broad 3‐dB axial ratio bandwidth of 18% (5.55 GHz, 5.05–6.05 GHz). Besides, the designed antenna features a circularly polarized bandwidth which could cover wireless local‐area network (5.725–5.85 GHz), intelligent transportation systems (5.8 GHz) and WIFI (5.85–5.925 GHz) band. Key Points A broadband circularly polarized (CP) stacked microstrip antenna (SMPA) with parasitic elements is proposed Utilizing CP resonant points produced by these parasitic elements, the bandwidth of CP SMPA is broadened