A dual‐band planar antenna based on composite right and left handed (CRLH) metamaterial is presented. The proposed antenna is comprised of a host folded planar monopole antenna and a CRLH transmission line unit cell. Due to another resonance frequency generated from the loaded CRLH unit cell, the presented antenna is actually a planar antenna with dual resonance bands at the centre frequency of 2.50 and 5.80 GHz, respectively, which can be regulated independently. The developed antenna also has different polarisations, the linear polarisation at the lower band and the circular polarisation at the upper resonance band. Rather than the complicated structure as before, this antenna is fabricated easily for the simple configuration without holes and the interdigital capacitances. The results of this study show that the reflection coefficient and radiation pattern have a good agreement between the simulation and measurement, the simulated relative bandwidth is 22.8% (2.22–2.79 GHz) and 10.8% (5.42–6.04 GHz), which meet the Wi‐Fi/Worldwide Interoperability for Microwave Access (WiMAX) specification very well.

A wideband and high-efficiency polarization conversion metasurface (PCM) is proposed and applied to reduce radar cross section (RCS). The proposed PCM unit is composed of two oblique asymmetry triangle split rings, which generate multiple plasmon resonances. Simulated and measured results demonstrate that it achieves polarization conversion over 90% from 9.24 to 17.64 GHz. Besides square checkerboard, the proposed PCM units and mirror units are arranged in triangle checkerboard. The mechanisms of both checkerboard PCMs are analyzed based on standard array theory, including the relationship between RCS reduction value and polarization conversion ratio value. The derived formulas provide a guideline to design checkerboard structure based on PCM. Simulated results demonstrate that both checkerboard PCMs achieve over 62% relative bandwidth of 10 dB RCS reduction under normal incidence with respect to the equal-sized metallic plate, which also means that the triangle one could be an alternative solution to reduce RCS. To verify the analyzed and simulated results, the fabricated sample and measured results of both checkerboard PCMs are presented. Good agreements are achieved between measurements, simulations and numerical analysis.

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In this study, a new microstrip patch antenna with wideband radar cross-section (RCS) reduction is presented. The RCS of the proposed antenna was reduced by subtracting the current-direction slots of the patch, with the radiation performance sustained not only for the current-direction subtraction, but also for the no modification in the ground plane. Modified and reference antenna were fabricated and measured. The simulation and measurement results showed that the modified antenna reduced the in-band and out-band RCS simultaneously with no detriment to the radiation performance. In the frequency band from 3.9 to 8.1 GHz, the RCS of the modified antenna was reduced in the whole band compared with the RCS of the reference antenna. The maximum RCS reduction was 7 dB at a frequency of 6.7 GHz.

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