In this article, we present a dual‐band linear‐to‐circular transparent converter by bi‐layered chiral metamaterial (CMM) with an inverted “G” array in microwave region. The proposed metasurface consists of three layers which are the upper layer of the metasurface with a periodic regular metallic inverted “G” and wire array, the dielectric layer, and the bottom layer operating as chiral symmetric structure of the upper. The simulation results show that the transmitted right‐circular polarized wave with the axial ratio of 3 dB or less is in the range of 8.6‐10.9 GHz and the left‐circular polarized wave is within 18.1‐22.5 GHz when y‐polarized forward wave is normally incident. Specifically, the polarization conversion transmission can be maintained at over 85% at angle of incidence up to 40°. Therefore, the proposed CMM device is useful for the development of the integrated polarization manipulation devices.
An asymmetric U-shaped millimeter-wave (MMW) metasurface (MS) transmitarray (TA) antenna is proposed based on characteristic mode analysis (CMA). The CMA of U-type unit shows two modes in the required frequency band and excites these two modes with a certain phase difference, so that the transmittance of the unit in the working band is greater than 0.8. The difference of lens unit is 360° by controlling the size change of the unit, and the transmission array is designed according to the phase distribution of the array. Through optimization simulation, the total size of the lens is
92.4
×
92.4
mm2, composed of
21
×
21
components and focal ratio of 0.85. The feed source is a SIW antenna, and then, the MS converts the quasispherical wave emitted from this feed source into a plane wave. The measured results show that the peak gain at 28 GHz is 22.3 dBi, the gain bandwidth at 3 dB is 5.8°, and the radiation efficiency is 81.6%. Due to the high gain and low-cost design, the proposed MS transmitarray antenna is suitable for MMW communication.
This article proposes and designs a low-sidelobe planar reflectarray antenna based on particle swarm optimization (PSO). It is composed of a feed antenna and a plane reflectarray based on metasurface, and the center frequency is 5.8 GHz. The operating frequency range of the feed antenna is 5.4-6.3 GHz, and the maximum gain is 6.3 dB. The planar reflectarray based on PSO is composed of reflector elements of different sizes. The planar reflectarray antenna optimized by the PSO achieves the optimization goal of sidelobe level less than À30 dB, and the sidelobe level can be further reduced as the number of iterations increases. The antenna array adopts a side-fed feed mode to achieve a maximum gain of 22.6 dB, and 1 dB gain relative to the bandwidth accounted for 15.8%. It has great application value in scanning and multi-beam radiation for wireless communication.
A wideband millimeter‐wave circularly polarized (CP) antenna based on metasurface (MS) is proposed. The antenna consists of a two‐layer substrate integrated waveguide (SIW) feed structure and a layer of MS with a 2 × 2 rectangular truncated corner. As a polarization conversion structure, the MS converts the linearly polarized wave generated by the SIW into a CP wave, and four metal pins are placed in the middle to improve the impedance and the axial ratio (AR) bandwidth. Based on this antenna element, a SIW‐fed 2 × 2 array using the sequentially rotating phase (SRP) feed technique is designed, which further improves the AR bandwidth and the gain level of the antenna. The results of the measurements show that the array maintains a low profile with an impedance bandwidth of 40.3% from 25.05 to 37.14 GHz, and an AR bandwidth of 31.3% from 23.14 to 32.54 GHz, and a peak gain of 14.3 dBi.
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