With the proliferation of smart devices, the Internet of Things (IoT) is rapidly expanding. This study proposes a miniaturized controllable metamaterial with low control voltage for achieving low-power and compact designs in IoT node devices. Operating at a target frequency of 2.4 GHz, the proposed metamaterial requires only a 3.3 V control voltage and occupies approximately one-third of the wavelength in size. Experimental validation demonstrates its excellent reflective control performance, positioning it as an ideal choice for low-power IoT systems, particularly in the context of miniaturized and low-power IoT node applications.

This paper proposes a 4-element multiple-input multiple-output (MIMO) antenna system, which is intended for ultra-wideband (UWB) applications. The antenna has a dimension of 92 × 70 × 1.6 mm3. It achieves element isolation via the defected ground structure (DGS) and symmetric E-shaped branch structures design. The realized operating bandwidth is from 3 GHz to 18 GHz, with 15 dB isolation within the whole wide band. The envelope correlation coefficient (ECC) is less than 0.01 with diversity gain (DG) greater than 9.95. The prototype is fabricated and measured to verify its potential applications for UWB MIMO communication.

Wireless sensor networks and nodes are faced with severe constraints in power capacity and lifespan, especially in harsh and cold environments. Electromagnetic radiation energy harvesters serve as a promising alternative power source for sensor nodes. However, the power output from reported energy harvesters remains limited, emphasizing the critical need to reduce power consumption in sensor nodes. Here, a miniaturized, low‐voltage, low‐power active frequency selective surface solution is proposed for backscatter communication under ice. It is designed for the 2.4 GHz wireless band and can operate under extreme conditions, such as sub‐ice environments, requiring only a 3.3 V control voltage and consuming approximately 0.3 of energy. Experimental results in sub‐ice scenarios demonstrate its reliable reflection control characteristics, making it particularly suitable for backscatter communication nodes in wireless sensor networks deployed in harsh environments.

Wireless sensor networks and nodes are faced with severe constraints in power capacity and lifespan, especially in harsh and cold environments. Electromagnetic radiation energy harvesters serve as a promising alternative power source for sensor nodes. However, the power output from reported energy harvesters remains limited, emphasizing the critical need to reduce power consumption in sensor nodes. In this study, we propose a miniaturized low-voltage controllable metamaterial. It is intended for 2.4 GHz wireless band and is capable of operating in extremely adverse conditions, for instance, beneath the ice, while requiring only 3.3 V control voltage and consumes about 0.3 μW energy. Measurements in sub-ice environment demonstrate its outstanding reflection control characteristics, making it highly suitable as a backscatter communication node in wireless sensor networks in harsh environments.

The rapidly increasing demand for compact, low-power electromagnetic components in Internet of Things (IoT) terminals has exposed the limitations of conventional active frequency selective surfaces (AFSS), such as large physical dimensions, high power consumption, and mechanical complexity. To overcome these challenges, this communication proposes an innovative compact three-dimensional (3D) AFSS design featuring helically arranged metallic strips on prismatic units. This configuration generates an upward-spiraling surface current path, substantially enhancing electromagnetic coupling and inductance while achieving miniaturization. The proposed structure represents a significant advancement in electronically tunable 3D AFSS, offering both extreme compactness and exceptionally wide continuous tunability. The fabricated prototype demonstrates an ultra-compact unit size of only 3.5 mm × 7 mm, a remarkable 95% fractional tuning range (920 MHz–2.58 GHz), and ultra-low power consumption of maximum 14.4 μW under 0–30 V bias. These features make the proposed AFSS a highly promising solution for low-power, highly integrated, and miniaturized wireless communication nodes in future IoT backscatter systems.