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This study presents a circularly polarised (CP) antenna with a wideband characteristic, which is caused by the interelement mutual coupling effect. The proposed antenna consists of a dipole array with four elements in centre symmetry and a wideband feed network. In order to extend the lowest working frequency, a strong mutual coupling effect is introduced to the adjacent co‐polarisation elements. What's more, the introduced effects of capacitive coupling reactance counteract the effects of the element's inductively reactive ground plane. Then, a small, tightly coupled array is formed that possesses wide impedance bandwidth and orthogonal polarisation component. A wideband feed network, including Wilkinson power dividers, phase shifters, and impedance converters, is designed to provide amplitudes and phases excitation that circular polarisation antenna required. Finally, a prototype is fabricated and tested. Measured results show a VSWR<2 impedance bandwidth of 102.7% (2.09–6.5 GHz) and a 3‐dB axial ratio bandwidth of 94.2% (2.25–6.25 GHz). Besides, a relatively stable gain is realised across the operating band. [ABSTRACT FROM AUTHOR]

In this study, the authors propose a new type of metasurface, namely a sandwiched anisotropic metasurface, for converting a linearly polarised elliptical patch antenna into a wideband circularly polarised antenna. A partially reflecting surface (PRS) as a superstrate is further used to enhance the gain of the antenna. The design rules of the antenna are also presented. The combined metasurface and the PRS‐based patch antenna is designed on a low‐cost substrate FR‐4. The realised 3 dB axial ratio bandwidth (ARBW) of the antenna is 1.01 GHz (3.55–4.56 GHz), its impedance matching bandwidth is 1.33 GHz (3.08–4.41 GHz), and its peak gain varies from 7 to 7.84 dB within the band. By placing the PRS superstrate above the antenna, gain further improves to 9.32 dBi without degrading the performance of the antenna. Measured results are presented to validate the antenna performance and results are compared against a large number of similarly available antenna. [ABSTRACT FROM AUTHOR]

A new design of a circularly polarised antenna based on the tightly coupled mechanism is presented. The proposed antenna consists of four tightly coupled dipoles, four impedance transforming networks and a wideband feeding network. Owing to the strong mutual coupling between coupled dipole elements, the proposed antenna realises a wide operating bandwidth. A prototype is manufactured and measured to validate the method. The measured results indicate that the proposed design provides a 10 dB return loss bandwidth of 101% (1.7–5.2 GHz) and a 3 dB axial ratio bandwidth of 77% (2.0–4.5 GHz). The design has a 3 dB gain bandwidth of 56% from 2.6 to 4.6 GHz with a peak gain of 10.4 dBic. Acceptable agreements can be obtained between the simulated and measured results. [ABSTRACT FROM AUTHOR]