In this letter, a compact, via-assisted, circularly polarized antenna is presented for body-centric health monitoring, enabling frequency-dependent dual-mode radiation behavior without requiring reconfiguration or periodic structures. It covers the 2.45 and 5.8 GHz ISM bands with a size of $\bf {0.31\lambda _{0} \times 0.31\lambda _{0} \times 0.043\lambda _{0}}$. The stacked radiator is excited by a single CPW feed, while shorting vias introduce controlled inductive loading and mode perturbation to support miniaturization and stable CP. The proposed antenna produces a quasi-omnidirectional pattern at 2.45 GHz for on-body links and a more directive broadside pattern at 5.8 GHz for off-body communication. Measured $\bf {-10}$ dB bandwidths are 5.3% and 27.2%, with AR bandwidths of 15.1% and 21.2%. It achieves up to 80% radiation efficiency, peak gains of 2.94 dBi and 5.1 dBi, and low SAR of 0.049 W/kg and 0.074 W/kg, confirming a compact and versatile solution for wearable healthcare systems.

This paper proposes a device association strategy for rate-splitting multiple access (RSMA) communication aided with simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RISs), and investigates the ensuing system coverage performance. The device association is founded on the likelihood of line-of-sight links between the devices and the base station. Modeling the distributions of the devices and the STAR-RISs as Poisson point processes, and using stochastic geometry tools, closed-form and approximate expressions for the probability of LoS are obtained, enabling the classification of the devices into two categories: direct devices, which can be served directly by the base station, and indirect devices, which are to be served with the aid of STAR-RISs. Upon this classification and the proposed device association strategy, the coverage probability of the RSMA-based communication system is derived in closed form, considering the Nakagami-$m$ model for the channels' fading. Furthermore, comparisons with a NOMA-based benchmark are conducted. The numerical results validate the analytical findings and show that the proposed association strategy efficiently classifies the system's devices and leverages the STAR-RISs as needed to ensure full coverage for all devices. Finally, the impact of key system parameters on the coverage performance is analyzed, and the proposed RSMA-based approach is shown to outperform the benchmark in terms of coverage performance.

In this article, a dual-band frequency-selective surface (FSS) is proposed for wireless communication systems operating in the sub-6 GHz 5G band and emerging upper-mid-band frequencies considered for future wireless applications. The proposed FSS exhibits two passbands centered at 4.8 GHz and 6.9 GHz, with corresponding reflection coefficients of $-33$ dB and $-25$ dB, respectively. The associated $-10$ dB impedance bandwidths extend from 4.6–5.0 GHz and 6.6–7.2 GHz, providing efficient transmission within the desired operating bands. Between these passbands, the proposed structure exhibits a band-stop response centered at 5.5 GHz, where the transmission coefficient ($S_{21}$) reaches a minimum value of $-40$ dB over the frequency range of 5.2–5.8 GHz. This intermediate stopband suppresses unwanted signal transmission, particularly within the Wi-Fi band, thereby improving spectral selectivity and reducing potential interference in multi-band wireless communication environments. Furthermore, the proposed single-layer FSS maintains stable transmission and reflection characteristics under different polarization states and oblique incidence angles up to 60°. The measured results show good agreement with the simulated responses, demonstrating the suitability of the proposed design for applications requiring dual-band transmission and intermediate band-stop filtering in next-generation wireless communication systems.