This article shows the development of a photonic detector of low-frequency ultrasonic signals. These signals latter reach a sensitive single-mode optical fiber as an acoustic guide conveying the signals (around 43 kHz) over 70 cm to a distant and protected in-fiber Bragg grating. The grating reflects a spectrum centered around 1550 and 2.6 nm bandwidth and is interrogated by a tunable laser in their linear and most sensitive region. As a result, real-time passive demodulation of communication or monitoring of ultrasonic signals propagating through solid materials is possible. The detector may also be applied to other physical media. In this study, a new passive technique to thermally desensitize the fiber-Bragg gratings (FBG) is also proposed, though the proposed technique is not experimentally tested. K E Y W O R D S acoustic communications, acoustic guide, acoustic monitoring, fiber Bragg grating, optical fiber, ultrasound AbstractThis article presents a novel multi-band rectifier utilizing modified hybrid structure for radio frequency (RF) energy harvesting. The proposed multi-band rectifier consists of a modified hybrid junction and three rectifying branches. The rectifying branches are placed inside the modified hybrid to reduce the layout size. The proposed multi-band rectifier is designed for GSM-1800, UMTS-2100, and Wi-Fi bands. Measured peak efficiency of the proposed rectifier reaches 61.7% at 9 dBm input power level. The results show a good overall performance on operation bands, LI ET AL. | 817

Abstract-The latency effect in long-distance gigabit links and networks may lead to some transmission penalties, as here discussed and illustrated through various examples. When transcontinental or overseas connections are considered, these penalties may become remarkably severe. By evaluating and discussing realistic cases, some countermeasures are suggested. These last may include an important conceptual change in several well-established protocols and a substantial increase in the data packet sizes together with some other modifications concerning the physical layer management.Resumo -0 efeito de latencia em enlaces e redes de alta velocidade e longa distancia podem levar a algumas penalidades de transmissao, como e aqui discutido e ilustrado por meio de varios exemplos. Quando conex6es transcontinentais sao consideradas, estas penas podem se tamar particularmente severas. Pela avalia<;ao e discussao de casos realfsticos, algumas medidas preventivas sao sugeridas. Estas medidas podem incluir uma importante altera<;ao conceitual em varios protocolos bern estabelecidos e urn aumento substancial nos comprimentos de pacotes, assim como algumas modifica<;6es relativas ao gerenciamento de camada ffsica.

Resumo Este artigo apresenta o projeto de um divisor de potência do tipo Wilkinson banda larga impresso e de dimensões reduzidas realizado no substrato FR-4 objetivando os serviços RFID e 5G. Os resultados, prático e simulado, mostram perda de transmissão de 3,5 e 4 dB, nas portadoras dos serviços desejados, além de um isolamento entre as portas de saída de 10 dB. Inclui também aplicações do divisor em sistema de transmissão full duplex e na alimentação de painel com antenas elípticas. Os resultados apresentados mostram um bom comportamento alcançando, em ambos os casos, até 160 MHz de largura de banda.

This paper shows for the first time, to the best of our knowledge, the design of a simple, non-invasive, bidirectional and inexpensive optical power monitor (OPMo) for WDM over PMMA-based polymer optical fibre (POF) links transmitting 470 nm and 650 nm wavelengths light carriers. Low-cost cellophane plastic optical filters were used for each WDM channel aiming to demonstrate the OPMo operational principle. The OPMo is non-invasive because it does not tap any guided light from the fibre core; rather, it collects and detects the spontaneous side-scattered light. A sensitivity of  −32 dBm and dynamic range of 38.8 dB were measured. A crosstalk rejection better than 25 dB was achieved when both light carriers are of the same power.

Resumo-Este artigo apresenta o desenvolvimento de um dispositivo que funciona como um detector de luz na faixa visível -"antena óptica". A idéia central é utilizar um pequeno segmento de fibra óptica plástica de PMMA ou de poliestireno fluorescente para recepção em enlaces LiFi (Light Fidelity).Palavras-Chave-comunicações por luz visível; fibra óptica plástica; espalhamento; fluorescência.