Measuring and filtering microwave radiations using frequency selective surface through energy saving glass

This thesis presents the results of our investigation into the measurement and filtering of microwave radiation, and the subsequent development of a microwave reduction solution for modern building architecture utilising Energy Saving Glass (ESG), in conjunction with Frequency Selective (FSS) surfaces through which useful signals can be filtered. In the investigation, radiation power density levels arising from the three common microwave sources (radio base stations, mobile phones, and microwave ovens) were measured, and the results were compared with the standards provided by the Australian Radiation Protection and Nuclear Safety Agency. For the radio base stations, the relationship between radiation intensity levels and the important location parameters at the measurement point, e.g., line of sight, distance and elevation, are discussed in detail. Our results show that locations having the same elevation level as the RBS receive higher level of radiation, compared to those locations not at the same level. Power density of the radiation from microwave ovens was measured at various distances and angles. The results indicate that most of the radiation is emitted through the main door of the ovens, with the doors normally being assembled utilising simple float glass. ESG was found to have desirable radiation attenuating characteristics, and was identified as an effective replacement for float glass in microwave oven doors. In our investigation of the third potentially hazardous source of microwave radiation, the mobile handset, measurements were carried out in order to analyse power density levels during both call and idle times. Our results confirm that some handsets do not change power level, while others use higher power to communicate with the base station during a call. It is our recommendation that the manufacturers label each handset with the specific transmission power level in order to provide users with the relevant information. The conclusions drawn from our investigations lead us to recommend that ESG be used in buildings close to RBS, so that the levels of unnecessary radiation are reduced. However, useful signals would still be transmitted by utilising the dual bandpass FSS filters designed as part of this work. We designed two distinct models of bandpass FSS filters on hard coated ESG. The first filter that we designed will block microwave signals coming from weather radar, personal communication devices, power transmission lines and emergency service radios, while transmitting useful UMTS and Wi-Fi signals; minimising the radiation impact. Only 7.30% of the coating area of the glass was removed to enable transmission in the U850 and U2100 frequency bands. The second design requires the removal of 12.35% of the coating area to enable transmission in the U800, U850, U1900 and U2100 frequency bands. Simulation results for the two designs show stable frequency responses for both TE and TM polarisations at normal and oblique incident angles, with attenuation\u27s below 10 dB within the passbands. Parametric studies on geometrical dimensions, substrate permittivity, and thickness help clarify the effects of these parameters upon the overall performance of FSS on hard coating ESG, and help the process of FSS design optimisation

Uncommon ossicle in Holothuria (Mertensiothuria) leucospilota from Teluk Nipah, Pangkor Island

The high popularity of a commercial sea cucumber species on Pangkor Island (i.e. Stichopus horrens) has resulted in a lack of studies on Holothuria (Mertensiothuria) leucospilota from Pangkor Island, Perak, Malaysia. S. horrens is the main ingredient of gamat-based traditional medicine on the resort island, while H. leucospilota is the most dominant species. For that reason, this study aimed to isolate ossicles from a specimen of morphospecies H. leucospilota collected from Teluk Nipah Beach, Pangkor Island; and to determine the shapes of the ossicles for species verification. A number of six ossicle shapes were observed. Beside buttons and tables as the common ossicle shapes; I-shaped rod, long I-shaped rod, branched rod, and spider-shaped rod were also documented. Nonetheless, the spider-shaped rod is an unusual ossicle shape in H. leucospilota as there was no previous record on it, thus it could be considered as a new finding. In summary, the results of this research indicate the uniqueness of the specimen of morphospecies H. leucospilota as a result of the presence of the spider-shaped rod. More studies with more samples, more morphological approaches as well as more molecular techniques need to be incorporated in future for a better insight

Elektromagnetische velden in arbeidssituaties

NB Nederlandstalige versie verschenen onder nummer 610015001N De EU heeft richtlijn 2004/40/EG uitgevaardigd om de werknemer te beschermen tegen gezondheidsrisico's door blootstelling aan elektromagnetische velden op het werk. Deze richtlijn moet uiterlijk 30 april 2008 zijn omgezet in nationale wetgeving. Ter voorbereiding hiervan heeft het RIVM in opdracht van het Ministerie van SZW de blootstelling in Nederlandse arbeidssituaties geinventariseerd en geanalyseerd. Het doel van dit rapport is de werkgevers een handreiking te geven om vast te stellen of aan de eisen uit de richtlijn wordt voldaan en om de risico-inventarisatie en -evaluatie (RI&E) voor elektromagnetische velden op te stellen. Totdat er geharmoniseerde Europese normen van het Europees Comiti voor elektrotechnische normalisatie (CENELEC) beschikbaar zijn voor alle situaties die moeten worden beoordeeld, gemeten en berekend, mag dit rapport als richtsnoer gebruikt worden. Gebruik van dit rapport is dus geen verplichting. Voor de meeste werkgevers is het voldoende om de eerste twee hoofdstukken door te nemen. De volgende drie hoofdstukken bevatten voor een aantal arbeidssituaties informatie over de blootstelling, de rekenregels waarmee de situatie kan worden ingeschat en de mogelijke beheersmaatregelen. Het laatste hoofdstuk geeft een overzicht van de kosten die met invoering van de richtlijn samenhangen. Om te kunnen toetsen of de blootstelling onder de limieten van de richtlijn blijft, moeten CENELEC-normen worden gebruikt, voor zover ze bestaan. Deze normen zijn zonder specialistische kennis niet eenvoudig toe te passen. Ook hoeft niet alle apparatuur even uitgebreid beoordeeld te worden of zijn even zware maatregelen nodig. Om de beoordeling te vergemakkelijken geeft dit rapport een beoordelingsschema en tabellen met een indeling van alle relevante werkomgevingen in drie categorieen. Voor iedere categorie geldt een ander beoordelingstraject.The EU has issued Directive 2004/40/EC on the protection of workers from health and safety risks arising from exposure to electromagnetic fields in the workplace. This directive must be implemented in national legislation no later than 30 April 2008. To prepare for implementation, RIVM has, on commission of the Ministry of Social Affairs and Employment, investigated and analysed the exposure in Dutch working environments. The purpose of this report is to provide assistance to employers to assess whether compliance is met and to carry out the inventory and evaluation of risks (RI&E) due to electromagnetic fields. Until harmonised European standards from CENELEC cover all relevant assessment, measurement and calculation situations, this report may serve as a guide. It is not mandatory to use this report. It will be sufficient for most of the employers to confine themselves to the first two chapters. Subsequent chapters deal with the exposure found in several working environments and provide guidelines for assessing risks and possible measures in these working environments. Costs for implementing the directive are discussed in the last chapter. CENELEC standards, if available, are mandatory for assessing whether exposure occurs below the limits in the directive. However, these standards are not easy to use without specialist knowledge. Furthermore, not all equipment needs to be assessed to the same extent nor are the same measures needed. A flow chart and tables of relevant working environments, classified into three categories, are provided to facilitate the assessment. Each category has its own assessment path.SZ

A personal, distributed exposimeter: procedure for design, calibration, validation, and application

This paper describes, for the first time, the procedure for the full design, calibration, uncertainty analysis, and practical application of a personal, distributed exposimeter (PDE) for the detection of personal exposure in the Global System for Mobile Communications (GSM) downlink (DL) band around 900 MHz (GSM 900 DL). The PDE is a sensor that consists of several body-worn antennas. The on-body location of these antennas is investigated using numerical simulations and calibration measurements in an anechoic chamber. The calibration measurements and the simulations result in a design (or on-body setup) of the PDE. This is used for validation measurements and indoor radio frequency (RF) exposure measurements in Ghent, Belgium. The main achievements of this paper are: first, the demonstration, using both measurements and simulations, that a PDE consisting of multiple on-body textile antennas will have a lower measurement uncertainty for personal RF exposure than existing on-body sensors; second, a validation of the PDE, which proves that the device correctly estimates the incident power densities; and third, a demonstration of the usability of the PDE for real exposure assessment measurements. To this aim, the validated PDE is used for indoor measurements in a residential building in Ghent, Belgium, which yield an average incident power density of 0.018 mW/m(2)