Broadband cloaking with volumetric structures composed of two-dimensional transmission-line networks

The cloaking performance of two microwave cloaks, both based on the recently proposed transmission-line approach, are studied using commercial full-wave simulation software. The cloaks are shown to be able to reduce the total scattering cross sections of metallic objects of some restricted shapes and sizes. One of the studied cloaks is electrically small in diameter, and the other is electrically large, with the diameter equal to several wavelengths.Comment: 6 pages, 7 figure

Impedance-matched microwave lens

A microwave lens with highly reduced reflectance, as compared to conventional dielectric lenses, is proposed. The lens is based on two-dimensional or three-dimensional transmission-line networks that can be designed to have an effective refractive index larger than one, while having almost perfect impedance matching with free space. The design principles are presented and an example lens is studied using commercial simulation software.Comment: 11 pages, 8 figure

Artificial impedance surfaces

In this doctoral thesis the properties of certain artificial impedance surfaces and electromagnetic materials are studied. In the context of the thesis the word artificial refers to the electromagnetic properties of homogeneous surfaces and materials, that are not naturally observed in nature. The macroscopic electromagnetic properties of these homogeneous materials are determined by their microscopic structures. Therefore it is convenient to call these surfaces and materials also as metasurfaces and metamaterials, which are the common names in the literature for the surfaces and materials studied in this doctoral thesis. This work concentrates on the analytical modeling and applications of such structures. The purpose of the analytical models of artificial impedance surfaces is to understand the physical properties of the structures and to facilitate the use of these structures in different applications. Sometimes the information given by the analytical models leads to innovations and new findings. For the artificial impedance surfaces studied in this doctoral thesis there have been no accurate and physically exact models available in the literature. In this work we have derived analytical models for various artificial surfaces and verified them to be accurate by numerical and experimental methods. We have used these models in the thesis work to study the properties of these surfaces. Further, we have used the derived analytical models to design different applications based on the artificial impedance surfaces. I have also been able to show the existence of previously unknown plasmonic resonance in electrically thin artificial impedance surface structures. The results of this doctoral thesis bring more insight into the properties of artificial impedance surfaces. These results are important when designing novel impedance surfaces and applications based on these surfaces

Ensiapukoulutus Lammintuvan henkilökunnalle

Tiivistelmä Tekijä: Luukkonen Olli Työn nimi: Ensiapukoulutus Lammintuvan henkilökunnalle Tutkintonimike: Sairaanhoitaja (AMK) Asiasanat: Ensiapu, tapaturmat, turvallisuus, opettaminen Harvaan asutulla seudulla maallikoiden antamalla ensiavulla on vielä isompi rooli kuin kaupun-kiympäristössä. Opinnäytetyössä suunnittelin ja toteutin ensiapukoulutuksen matkailu- ja ravinto-lapalveluita tuottavalle Lammintuvalle. Opinnäytetyön tarkoitus oli suunnitella ja toteuttaa Lam-mintuvan henkilökunnan tarpeisiin sopiva ensiapukoulutus. Opinnäytetyön tavoite oli lisätä Lam-mintuvan henkilökunnan valmiuksia toimia yllättävissä ja haastavissa hätätilanteissa. Lammintupa sijaitsee puolen tunnin ajomatkan päässä Kuusamosta, joten ammattiavun saapuminen kestää kauan. Tutkimustehtävät opinnäytetyössäni olivat: Millaiset ovat Lammintuvan henkilökunnan ensiaputaidot ja valmiudet? Millainen ensiapukoulutus parantaa Lammintuvan henkilökunnan en-siaputaitoja? Otin huomioon ensiapukoulutuksen suunnittelussa toimeksiantajan kanssa kartoitetut Lammintu-van erityispiirteet. Ensiapukoulutuspäivä järjestettiin toimeksiantajan tiloissa, ensiapukoulutuksen kesto oli kuusi tuntia. Päivä koostui teoriaosuudesta sekä käytännön harjoittelusta. Matkailuala on sesonkiluontoista työtä, työntekijät vaihtuvat paljon. Haasteita opinnäytetyön suunnitteluun toi se, että toimeksiantaja ei tiennyt osallistujien määrää etukäteen. Koulutukseen osallistui lopulta 12 Lammintuvan työntekijää. Opinnäytetyön toiminnallista osuutta osallistujat arvioivat kirjallisella palautteella. Palautteen pe-rusteella onnistuin koulutustapahtumassa suunnitelman mukaisesti ja se oli kohderyhmälle sopi-va. Saamani palaute oli erinomaista ja siitä selvisi, että osasin opettaa asiat ymmärrettävästi. Toimeksiantaja haluaisi, että pitäisin heille ensiapukoulutusta vuosittain.Abstract Author: Luukkonen Olli Title of the publication: First Aid Training for Lammintupa Staff Degree title: Bachelor of Health care, Nursing Keywords: First Aid, accidents, safety, teaching In sparsely populated areas, first aid given by ordinary people is more significant than in urban environments. This thesis introduces first aid training planned and organized for Lammintupa, a company providing tourism and restaurant services in Kuusamo. The purpose of this thesis was to plan and organize first aid training suitable for the needs of the Lammintupa staff. The aim of the thesis was to increase the capability of the Lammintupa staff to act in sudden and unex-pected emergency situations. Lammintupa is located a half an hour’s drive from Kuusamo town center, so it takes a long time for professional emergency assistance to arrive in the scene. The research tasks were the following: what were the first aid skills and capabilities of the Lammintu-pa staff and what kind of first aid training would improve the first aid skills of the Lammintupa staff? The special features of Lammintupa were taken into account in the contents of the first aid train-ing day. The training day, which consisted of a theoretical part and practical training, was ar-ranged on the client’s premises and lasted for six hours. The tourism business is seasonal, and the employee turnover is high. Therefore, it was challenging to plan the training day because the client did not know the number of participants in advance. Eventually 12 Lammintupa employees participated in the training. The participants evaluated the functional part of the thesis by giving written feedback. According to the feedback, the training day was successful and suitable for the target group. The feedback received was excellent and indicated that matters were taught in an understandable way. The cli-ent would like to have similar first aid training annually

Simple and accurate analytical model of planar grids and high-impedance surfaces comprising metal strips or patches

This paper introduces simple analytical formulas for the grid impedance of electrically dense arrays of square patches and for the surface impedance of high-impedance surfaces based on the dense arrays of metal strips or square patches over ground planes. Emphasis is on the oblique-incidence excitation. The approach is based on the known analytical models for strip grids combined with the approximate Babinet principle for planar grids located at a dielectric interface. Analytical expressions for the surface impedance and reflection coefficient resulting from our analysis are thoroughly verified by full-wave simulations and compared with available data in open literature for particular cases. The results can be used in the design of various antennas and microwave or millimeter wave devices which use artificial impedance surfaces and artificial magnetic conductors (reflect-array antennas, tunable phase shifters, etc.), as well as for the derivation of accurate higher-order impedance boundary conditions for artificial (high-) impedance surfaces. As an example, the propagation properties of surface waves along the high-impedance surfaces are studied.Comment: 12 pages, 10 figures, submitted to IEEE Transactions on Antennas and Propagatio

A three-dimensional backward-wave network matched with free space

A backward-wave slab based on a capacitively and inductively loaded three-dimensional transmission-line network is designed in such a way that impedance-matching with free space is obtained. To enable field propagation from free space to the network and vice versa, the use of a transition layer is proposed. Matching of the designed network with free space and negative refraction occurring at the slab interfaces are confirmed with full-wave simulations.Comment: 8 pages, 5 figure