Novel printing techniques to print flexible radio frequency devices such as antennas

Energy harvesting devices such as solar panels and wind generators collect energy sources and convert them to generate power. Such devices are economical and efficient and also allow energy to be generated and devices and applications powered in places without conventional power sources, such as underwater. Energy harvesting also has the potential to be used to satisfy the need for energy autonomy that autonomous electronics, the Internet of Things (IoT) and wearable devices demand. At the University of Surrey, UK, Dr Simon King is collaborating with Dr Bilal Malik, Dr Maxim Shkunov and Dr Pavlos Giannakou on a project called flexible smart SURFaces for Augmented indoor communicationS (SURFAS) to design energy harvesting surfaces (antennas) for zero-power consuming electronic devices. Each team member has their own speciality and all share the common goal of revolutioning the ways that devices access and consume energy. The goal is to reduce energy consumption and provide cost benefits. Part of the team's current work involves the use of novel printing techniques to fabricate flexible radio frequency (RF) devices, such as rectifying antennas. The team believes the development of fully integrated printed energy harvesting devices will lead to countless future IoT applications. The ultimate objective of SURFAS is to enable zero-power consumption electronic devices and smart surfaces that are capable of optimally redirecting Wi-Fi signals and enhancing the performance of receivers. The team is also working to develop a manufacturing process for rapidly and cost-effectively producing such devices.

Influence of Microcracks on Silver/Polydimethylsiloxane-Based Flexible Microstrip Transmission Lines

Microcrack is commonly seen as a defect in materials that affects the performance of flexible radio frequency (RF) devices. Here, we investigate the influence of microcracks on the RF characteristics of flexible microstrip by stretching flexible microstrip that is based on polydimethylsiloxane (PDMS) substrate and an Ag microparticles/PDMS (AgMP/PDMS) composite conductor. The RF characteristics of the microstrip were monitored with a variety of tensile displacements. An equivalent circuit model of the microstrip with microcracks was proposed to reveal the mechanisms. The fitting results matched the actual measurement well. In addition, the morphology of the microcracks was characterized by SEM and the direct-current (DC) resistance was monitored. The results show that the changes in equivalent circuit element parameters (R, L, C) are due to the change in the conductive pathways, which affect the transmission and reflection of the RF signals.

Flexible Radio Array for Ionospheric and Atmospheric research (FRAIA)

<p>We present the Flexible Radio Array for Ionospheric and Atmospheric<br>research (FRAIA). FRAIA consists of 18 relocatable RF receiver<br>stations with the capability to receive in the VLF band (0-50 kHz),<br>the HF/VHF band (3-85 MHz), as well as at discrete beacon satellite<br>frequencies 150, 400, and 1067 MHz. The antennas are monopole for the<br>VLF reception, all-sky broad-band crossed dipoles for the HF/VHF band,<br>and co-centric all-sky quadrifilar antennas for the beacon satellite<br>bands. Each station contains a 8-core CPU and a high-end<br>software-defined radio for real-time sampling and processing of the RF<br>signals. Each station include GPS timing to 50 ns, and three<br>synchronization devices allows for the 18 stations to be used together<br>in a single phased array or up to three phased arrays. FRAIA stations<br>can be used for observing VLF whistler waves, receiving standard<br>VHF/UHF beacon satellite signals for ionospheric tomography, for<br>riometry, for lightning observations and lightning interferometry, as<br>ionosonde receivers, HF radar receivers, over-the-horizon radar<br>receivers, and receivers for a future HF beacon satellite which we<br>propose, for ionospheric tomography.</p>