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This article presents a switchable phase‐modulated metasurface (PMM) whose reflection phase can be modulated between two states using PIN diodes. The PMM is composed of a switchable surface loaded with four PIN diodes in each unit cell, as well as a ground plane and an air spacer. The reflection phase can be modulated when the PIN diodes are switched between two states (ON and OFF). Theoretical analysis indicates that the phase‐modulation bandwidth is determined by the thickness of the PMM. The phase‐modulation bandwidth with a phase difference of 180 ± 37° achieves 2.6–4.25 GHz and a fractional bandwidth of 48.2%. [ABSTRACT FROM AUTHOR]

A metasurface-based low-profile crossed dipole antenna with wide circularly polarized bandwidth for 2.45 GHz ISM band wireless communications is proposed and fabricated in this article. Consisting of four slit-loaded rectangular patches, the double-sided printing crossed dipoles are fed by a pair of vacant-quarter printed rings which circularly polarized (CP) radiation could be generated. With slits loaded, by properly combining the fundamental mode of the two inverted L-shaped dipole, the slot mode and extra resonance generated by the AMC surface, a wideband circularly polarized operation can be obtained. After optimization, the final design with an overall size of 0.44λ0 × 0.44λ0 × 0.1448λ0 at 2.4 GHz had measured a 31.6% (2-2.75 GHz) impedance bandwidth and 3 dB axial ratio bandwidths of measured were 23.2% (2.1-2.65 GHz), respectively. In addition, the antenna performed a small gain variation (7.0-7.5 dBic) and a front-to-back ratio (FBR) of over 25 dB across the whole CP region. [ABSTRACT FROM AUTHOR]

A wideband circularly polarized printed antenna is proposed and fabricated, which employs monofilar spiral stubs and a slit in the asymmetrical ground plane which are fed by an inverted L-shaped microstrip feedline. The CP operation is realized by embedding an inverted-L shaped strip and modified ground plane and can be markedly improved by loading monofilar spiral stubs asymmetrically connected at the edge of the ground plane. After optimization, the measured results of the finally structure demonstrate that a 10-dB bandwidth of 67.6% from 4.6 to 9.3 GHz and a 3-dB axial-ratio bandwidth (ARBW) for circular polarization (CP) of 60.1% from 5 to 9.3 GHz could be achieved which could completely cover the WLAN (5.725-5.85 GHz) band. Therefore, the proposed antenna is suitable for circular polarization applications in C band. To explain the mechanism of broadband circular polarization operation, the analysis of magnetic fields distributions and a parametric study of the design are given. Compared to other recent works, a simpler structure, wider axial ratio and impedance bandwidths and a more compact size are the key features of the proposed antenna. [ABSTRACT FROM AUTHOR]

A wideband circularly polarized printed antenna is proposed and fabricated, which employs monofilar spiral stubs and a slit in the asymmetrical ground plane which is fed by an asymmetrical microstrip feedline using a via. The CP operation is realized by embedding an inverted-L shaped strip and a modified ground plane and can be markedly improved by loading monofilar spiral stubs connected to the asymmetric feedline by means of a via. A parametric study of the key parameters is made and the mechanism for circular polarization is described. After optimization, the impedance bandwidth is approximately 3.6 GHz (4.4-8 GHz) and the 3 dB axial ratio bandwidth is approximately 3.3 GHz (4.7-8 GHz), which represent fractional bandwidths of approximately 58.1% and 52%, respectively. Therefore, the proposed antenna is suitable for circular polarization applications in C (4-8 GHz) band. Compared with other recent works, the simpler structure, wider axial ratio, impedance bandwidths, and more compact size are the key features of the proposed antenna. [ABSTRACT FROM AUTHOR]

This study investigates the use of a polarization rotation reflective surface (PRRS) to construct a wideband, wide‐beam, low‐profile circularly polarized (CP) patch antenna. The device is composed of a feeding monopole antenna and a novel PRRS‐based dual‐patch artificial magnetic conductor (AMC) cell structure. The PRRS has two polarization rotation (PR) frequency points, generated by properly adjusting the width between square and L‐shaped metallic patches. A large PR band of 35.5% (5.1‐7.3 GHz) was achieved by combining two adjacent PR frequency points. The PRRS‐based patch antenna impedance bandwidth was measured to be 28.6% (5.1‐6.35 GHz), with a 3 dB axial ratio (AR) bandwidth of 21.8% (4.8‐6.4 GHz) and a profile of 0.045λ0. Additionally, the proposed antenna exhibited the largest AR beamwidth (to our knowledge) of 175° and 128° in the xoz and yoz planes, respectively. It also produced a high broadside gain of 6.7 dBic within the operational bandwidth. [ABSTRACT FROM AUTHOR]