Abstract-In this paper, the most adequate architecture to implement dual frequency amplifiers is shown. Composite Right/Left Hand (CRLH) and Extended Composite Right/Left Hand (ECRLH) transmission lines are studied and evaluated to find the most suitable structure for dual band power amplifiers. As an example, the performance of a class CE amplifier, working in TETRA and GSM frequency bands, is compared with simulations and measurement, showing good agreement. INTRODUCTIONThe increasing demand for wireless systems requires the use of higher frequency spectrum. Such high frequencies entail two major drawbacks: First, line transmission losses increase significantly. And second, solid state devices present power limitations at radio frequency (RF). Besides, when high RF power is demanded, there are some problems related with conventional system design and implementation, which can be overcome combining several RF devices to achieve the desired level. Another problem arises from the need of multifunction transponders to cope with several services, usually allocated at different frequencies, in the only terminal, being a well known example multiband or even GPS mobile phones. As a result of all these drawbacks, the development and use of multi-frequency highperformance power amplifiers is required. In this paper, TETRA Corresponding author: V. Gonzalez-Posadas (vgonzalz@diac.upm.es).

High-power (HP) UV-LEDs can replace UV lamps for real-time fluoro-sensing applications by allowing portable and autonomous systems. However, HP UV-LEDs are not a mature technology, and there are still open issues regarding their performance evolution over time. This paper presents a reliability study of 3 W UV-LEDs, with special focus on LED degradation for two working conditions: continuous and cycled (30 s ON and 30 s OFF). Accelerated Ufe tests are developed to evalúate the influence of temperature and electrical working conditions in high-power LEDs degradation, being the predominant failure mechanism the degradation of the package. An analysis that includes dynamic thermal and optical HP UV-LED measurements has been performed. Static thermal and stress simulation analysis with the finite element method (FEM) identifies the causes of package degradation. Accelerated Ufe test results prove that HP UV-LEDs working in cycled condition have a better performance than those working in continuous condition.

This work analyzes the long-term functionality of HP (High-power) UV-LEDs (Ultraviolet Light Emitting Diodes) as the exciting light source in non-contact, continuous 24/7 real-time fluoro-sensing pollutant identification in inland water. Fluorescence is an effective alternative in the detection and identification of hydrocarbons. The HP UV-LEDs are more advantageous than classical light sources (xenon and mercury lamps) and helps in the development of a low cost, non-contact, and compact system for continuous real-time fieldwork. This work analyzes the wavelength, output optical power, and the effects of viscosity, temperature of the water pollutants, and the functional consistency for long-term HP UV-LED working operation. To accomplish the latter, an analysis of the influence of two types 365 nm HP UV-LEDs degradation under two continuous real-system working mode conditions was done, by temperature Accelerated Life Tests (ALTs). These tests estimate the mean life under continuous working conditions of 6200 h and for cycled working conditions (30 s ON & 30 s OFF) of 66,000 h, over 7 years of 24/7 operating life of hydrocarbon pollution monitoring. In addition, the durability in the face of the internal and external parameter system variations is evaluated.

No abstract

This paper presents the detection and identification of hydrocarbons through flu oro-sensing by developing a simple and inexpensive detector for inland water, in contrast to current systems, designed to be used for marine waters at large distances and being extremely costly. To validate the proposed system, three test-benches have been mounted, with various UV-Iight sources. Main application of this system would be detect hydrocarbons pollution in rivers, lakes or dams, which in fact, is of growing interest by administrations.Another fact that damages the quality of the rivers is referred to the presence of pollutants, which due to its hazard, should never be present, such as hydrocarbons (Figure 1. ). Therefore detection and control becomes is a basic need.