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In this article, we present a new strategy to realize flexible and stretchable microwave (FSM) filter based on substrate integrated plasmonic waveguide (SIPW). To maintain the radio frequency (RF) performance under deformation, we developed lamp-strip-shaped spoof surface plasmon polariton (SSPP) units by adopting a strategy of shape preserving and combining them with serpentine interconnections through the “island-bridge” mechanism. The SSPP structure is etched on the upper surface of the serpentine patterned substrate integrated waveguide (SIW) assembled with elastic material to achieve the bandpass response. Meanwhile, a 2-D transmission line (TL)-based equivalent circuit model (ECM) is established to analyze the parasitic parameters of the serpentine structure caused at the RF level. The analysis and experiment verified that the introduction of the serpentine microstructure slows down the phase velocity in SIPW and therefore reduces the lateral size. In addition, owing to the unique electromagnetic (EM) transmission modes of SSPP/SIW and our special structural design, the fabricated filters cover the X-band of 8–12 GHz and maintain stable RF performance at conditions of the normal state, 180° bending, 90° twisting, and 120% stretching, which reveals that the proposed filter has potential applications in stretchable electronic systems.

This article introduces a multifunctional wireless power transfer (WPT) system, uniquely capable of self-sustaining power generation and automatic directional charging. This system integrates a retrodirective array (RDA), loaded with active radio frequency (RF) circuits, with solar cells (SCs), thus enabling the RDA to function as a transmitter in the WPT system independently, without reliance on external power sources. This integration facilitates direct solar-to-RF energy conversion while simultaneously achieving self-tracking and targeted RF energy transmission to the device requiring recharging. The proposed system comprises three primary components: the transmitter represented by solar antenna with retrodirective capability, the receiver at the terminal comprising a rectenna, and the power management circuit (PMC) designed for harvesting solar energy and energizing the RF active circuits. The feasibility of the proposed WPT system is substantiated through simulations, assemblies, and measurement processes. Both monostatic and bistatic radar cross section (RCS) measurements were conducted. The outcomes of these measurements demonstrate the WPT system’s proficiency in far-field tracking, facilitating both signal reception and transmission across a significant angular range of −40° to 40°. Furthermore, the rectifier antenna consistently maintains an optimal output voltage within this angular range. The system’s SC exhibits remarkable efficiency, fully charging a 70-mF supercapacitor within 30 s via the PMC. The proposed work holds the effective merge for multienergy synergy and interaction systems, opening up an ingenious pathway to the utilization of solar and RF energy in WPT systems.

In this communication, a fast algorithm based on artificial neural network (ANN) to noninvasively analyze and evaluate specific absorption rate (SAR) inside the equivalent head phantom is proposed. According to the fields outside of phantom, the inner fields of the phantom are calculated by field reconstruction. This process is accelerated by ANN. The network includes input/output layers and three essential hidden layers, representing fields and currents required for field reconstruction. The effectiveness of the proposed approach is validated by a case study of quick assessment of the SAR value within an equivalent human head phantom. The fast SAR prediction algorithm can control the error between the prediction result and the numerical calculation result within 4% in the range of 700 MHz–6 GHz, and at the same time reduce the solution time by more than 99%. Hence, the proposed algorithm can efficiently simplify the test process and reduce test time costs.

A slow time-delay assumption restricts the application of control approaches for numerous systems which are constantly affected by multiple uncertainties, including parameters, control coefficients, and the asymmetric dead-zone input. This work presents a new adaptive method for a class of high-order nonlinear delayed systems by removing the so-called slow time-delay assumption and multiple uncertainties. Remarkably, with a novel Lyapunov–Razumikhin (L-R) function and a direct fuzzy adaptive regulation scheme, a memoryless adaptive feedback controller is skillfully constructed to guarantee that the output tracks the given reference signal while keeping the boundedness of all closed-system signals. Finally, the presented scheme is applied to control a single-link robot system.

With the rapid expansion of wireless networks, the deployment and long-term maintenance of distributed microwave terminals have become increasingly challenging. To address these issues, we present a bio-inspired microwave system to constitute passive and maintenance-free wireless networks. Drawing inspiration from vertebrate skeletons and skins, we employ stimuli-responsive polymer with tunable stiffness to support and protect sensitive electromagnetic structures, and synthesize self-healable skin-like polymer for system encapsulation. Owing to the biomimetic strategy, our system combines outstanding flexibility, electromagnetic stability, structural robustness, and self-healable performance. On the other hand, to address power supply issues, our system modulates ambient electromagnetic waves to achieve long-range wireless communication, and the hybrid energy harvesting strategy allows the system to capture energy from ambient light and microwaves, thereby eliminating the need for batteries or power cables. Multidisciplinary innovation enables our system to be deployed almost anywhere and supports stable, battery-less, and maintenance-free wireless communication.This article presents a bio-inspired microwave system with stiffness-tunable ability, hybrid-energy harvesting, low-power backscatter communication and self-healable encapsulation, enabling battery-free wireless sensing across diverse conditions and harsh environments.