A novel ultrathin linear to cross-polarization transmission metasurface (MS) converter with a periodicity of 8 mm ( $\lambda_0$ /4.26, where $\lambda_0$ is free space wavelength at 8.8 GHz) is proposed which gives perfect transmission. The proposed MS is a single layer with a thickness of 0.8 mm (0.0235 $\lambda_0$ ). The conversion efficiency is near unity due to Fabry-Perot resonator like condition formed, thus giving the perfect cross-polarized wave. The bandwidth of conversion efficiency greater than 80 % is 4.31%. As the top and bottom surface has the same patterns, the proposed design shows the same conversion with x- or y-polarized incident wave. Due to the ease of fabrication and lightweight, the proposed design is a better candidate for applications like remote sensing, microwave communications than the multilayer transmission converters.

In this letter, the far-field wireless power transfer up to 6-m distance from the transmitting horn antenna (Tx) aperture using a new design gradient refractive index lens metamaterial (GRIN MM) is proposed for the first time, which increases the efficiency of power transfer. Double-sided-S-shaped GRIN MM unit cell dimensions are optimized for the operating frequency of 2.45 GHz. The D-dot sensor is placed at 6-m distance from the Tx aperture to measure the electric field without and with the proposed GRIN MM and hence the power density. The same amount of power is received experimentally without GRIN MM as obtained by the Friis transmission equation, thus validating the theoretical and experimental analysis. Experimentally, it is observed that due to the point directive beam obtained after passing through the GRIN MM array, 86% more power is received with it compared to without it, thus increasing the maximum theoretical power received.

As wireless communication technology advances towards faster and higher transmission rates such as Fifth Generation (5G) and beyond, the need for multiple access points increases. The growing demand for access points often results in them occupying any available surface area and potentially disrupting the existing scenery. In order to address this issue, Optically Transparent Antennas (OTAs) emerge as an optimal solution for balancing the aesthetics of a specific setting with the desired communication system requirements. These antennas can be integrated into various infrastructures without interfering with the design of the objects on which they are installed. Research on the techniques and materials for OTA fabrication, which is proposed as a solution to the 5G wireless communication demand for access points, is presented. This work will highlight key antenna characteristics such as gain, bandwidth, efficiency, and transparency, and how the materials used for OTA implementation influence these parameters. Techniques like Metal Mesh (MM), Transparent Conductive Film (TCF), and Transparent Conductive Oxide (TCO) will be explained. The performance of the OTAs will be analyzed based on gain, bandwidth, transparency, and efficiency. This paper also addresses the challenges and limitations associated with OTAs. Finally, it confirms that OTAs offer a compelling solution for this scenario by balancing aesthetics with high antenna performance, making them an innovation for future wireless networks.

In this paper, the authors, for the first time, have shown the use of 2D conformal microwave absorbing material (MAM) in the design and fabrication of a portable Anechoic chamber (AC). The MAM is fabricated on the transparent and conductive metal oxide layer named indium-tin-oxide (ITO) with Polyethylene terephthalate as the substrate and the ground plane for zero transmission having overall thickness of 0.012 $$\lambda$$λ where $$\lambda$$λ is calculated at 0.7 GHz. The MAM is characterized for 0.7 to 18 GHz for both TE- and TM-polarisation and oblique incidence. High sheet resistance, dipole-like resonance structure patterned on the ITO, and the air-spacing between the layers is optimized to achieve broadband absorption. The MAM is used to line the six sides of the rectangular anechoic chamber having inner dimensions of: (L × W × H: 850 × 650 × 720 mm³). The return loss (RL), gain, and radiation pattern of three antenna working at 1.56, 2.43, and 4.93 GHz are analyzed inside the AC. The measurement results for all frequencies very well match with the simulation studies, thus validating and opening the door for the future use of ultra-thin and planar MAM in the AC.

Wireless Power Transfer (WPT) promises to revolutionize energy distribution, being especially important in space exploration. By enabling previously impossible mission designs while avoiding interference concerns with living beings, the first widescale implementation of high-power WPT may happen here. To achieve long-distances, energy is transferred via electromagnetic waves, whose efficiency can be increased by focusing into a beam. In this paper we discuss various aspects, from the theory of quasioptics, usage of focusing components, the promise of time-modulated arrays, the importance of transparency in space and finalize with energy rectification back into DC. We hope to cover here the most important points required to make radiative WPT a reality in space applications.