This paper proposes a low-profile wideband circularly polarized (CP) antenna using solar cell patches as radiation elements and a sequentially rotated feeding network for CubeSat applications. To realize a wide axial ratio (AR) bandwidth with a compact size, a sequentially rotated feeding network was designed by modifying a quadrature hybrid coupler and a rat-race coupler that has a small change in phase difference even when the frequency changes. A wideband CP patch array antenna was designed by combining a C-shaped slot-coupled solar cell patch in conjunction with a novel feeding network. The overall size of the proposed CP CubeSat antenna is 100 $\times 100\times7.2$ mm ³ ( $0.83\,\,\lambda _{\mathrm {o}} \times 0.83\,\,\lambda _{\mathrm {o}} \times 0.06\,\,\lambda _{\mathrm {o}}$ at 2.5 GHz). Solar cells occupy 79% of the antenna area, enabling efficient energy harvesting. The −10 dB impedance bandwidth is 1.98–3.0 GHz, which is a fractional bandwidth of approximately 41.0%. The 3-dB AR and 3-dB gain bandwidths are 1.98–3.0 GHz (41.0%) and 1.82–2.98 GHz (46.6%), respectively. The proposed CP solar patch array antenna demonstrates a constant radiation pattern within the −10 dB impedance bandwidth. The proposed CubeSat antenna is suitable for use in an Internet of Space Things (IoST) autonomous communication system.

This paper presents the effects of substrate dielectric constants on the performance characteristics of a circularly polarized (CP) metasurface-based patch antenna. The antenna structure is a modified patch with a step-like truncation sandwiched between a metasurface composed of a 4×4 lattices of periodic metallic patches and a ground plane. The effects on the performance variations are evaluated for two principal cases that include a uniform dielectric constant and a nonuniform dielectric constant for the upper and lower substrates of the antenna. Through careful computational analysis, the effects of the substrate dielectric constant on the antenna performance in terms of bandwidth and gain were investigated, and the results demonstrate that the antenna performance improves with a decrease in the substrate dielectric constant. For a uniform substrate material with dielectric constants of ε_r1=ε_r2=2.2, the fabricated antenna with an overall size of 54mm×54mm×3.0mm (0.76λ_o×0.76λ_o×0.042λ_o at 4.24GHz) demonstrates the following measured performance characteristics: a 10dB impedance bandwidth of 3.755.24GHz (33.14), a 3dB axial ratio (AR) bandwidth of 3.854.64GHz (18.61), a radiation efficiency >93, and a peak gain of 8.96dBic within the AR bandwidth.

We study the radar cross section (RCS) property of an aircraft considering the electromagnetic (EM) characteristics of a frequency selective surface (FSS) radome, mounted on the aircraft. Instead of full-wave methods, we utilize high-frequency methods, such as the shooting and bouncing rays (SBR), physical theory of diffraction (PTD), and flat model, taking a significant computational efficiency. Based on the developed algorithm, we analyze monostatic and bistatic RCSs of the aircraft equipped with either single- and multi-layer dielectric, FSS, or PEC radomes in terms of frequency and polarization. Our calculations are validated by comparing with those of the commercial EM simulator with significant computational efficiency. The present numerical study indicates that including the radome EM characteristics into the overall aircraft RCS study is crucial for the accurate RCS estimate

In this paper, we analyze the radar cross section (RCS) of an integrated mast and present the optimized mast shape for RCS reduction. The RCS is simulated using commercial electromagnetic (EM) software based on the shooting and bouncing rays (SBR) method and the diffraction fields at the edges are also considered. Threat frequencies, threat regions and cardinal points are first defined considering the operational environments of a naval vessel. We calculate and analyze the RCS of the integrated mast in terms of the threat frequencies, the shapes of the integrated mast and the direction and polarization of the incident waves. The shape of the integrated mast is optimized based on the shaping technique. The optimized mast has low RCS properties in the primary threat sectors except for the exceptional angle regions.

This paper presents a novel approach to integrating a wideband fat dipole antenna with a solar cell for both wireless communication and energy harvesting. The proposed design uses a uniplanar fat dipole structure incorporating a widened dipole arm and a pair of open stubs. The addition of these features compresses the first, third, and fifth-order modes, resulting in improved wideband characteristics and a high form factor. Moreover, integrating a dipole antenna with a solar cell provides dual functionality, enabling wireless communication and energy harvesting from the same device. The antenna and the solar cell were designed to operate independently using RF decoupler circuits. The proposed solar cell integrated antenna achieved a wide —10 dB impedance bandwidth of 105.8% (ranging from 0.98 to 3.18 GHz), and antenna gain varied from 2.1 to 4.7 dBi within the impedance bandwidth. The whole structure has a compact size of 102 mm × 52 mm × 0.571 mm (0.333 λ ₀ × 0.170 λ ₀ × 0.0019 λ ₀ at 0.98 GHz), with a form factor of 96.2% and an optical transparency of 100%.