This doctoral thesis deals with designs and developments of multi(wide)-band multifunctional antennas based on folded dipoles. In the beginning, the concept of Orthogonal Folded Dipoles (OFD) are put forward. Orthogonal folded dipoles are formed by two identical two-port folded dipoles orthogonally joining with each other at the center, and can be fed through different combinations of feed nodes to offer dual- and wide-band modes, respectively. The impedances of the 2 modes are studied both by analytical models and by commercial electromagnetic simulation tools. The properties of the linearly polarized radiation patterns in the two modes vary quite little, except for ±45◦  rotation of two principal planes. In this way, orthogonal folded dipoles can possibly provide pattern reconfigurability in a context of switchable types and orientations of polarizations. Next, the concept of Log-Periodic Folded Dipole Array (LPFDA) is proposed. It stems from the traditional log-periodic dipole array, whereas folded dipoles instead of straight dipoles are applied as the elements of the array. Two configurations, i.e. partly-scaled LPFDA and fully-scaled LPFDA, are studied through simulations and optimizations. The comparison shows that the latter outperforms the former in terms of higher directivity, reduced front-to-back ratio and lower crosspolar level. The key parts of this thesis focus on exploiting Eleven antennas, based on the LPFDAs, in a variety of applications. First, the 4-port L-band lab model for use in satellite terminals demonstrates that the radiation patterns for monopulse tracking can be achieved through different excitation combinations of the multiport Eleven antenna. Second, a decade bandwidth, an unchanged phase center and nearly constant directivities over the whole band can be regarded as the major figure-of-merit of the Eleven antenna, which makes it suitable as feed for prime-fed reflector antennas. Through endeavors of using Genetic Algorithms, the wideband Eleven antennas have been gradually optimized in term of matching as well as efficiencies. Besides, the rotationally symmetric circular Eleven feed is a very promising solution for improving the BOR1 efficiency and therefore the aperture efficiency by a fraction of dB. Last but not least, the two multiport L-band lab models measured in a reverberation chamber demonstrate that the Eleven antenna with MIMO diversity ports can possibly overcome narrowband multipath fading in a real radio link and improve the link quality in terms of a significant diversity gain and high maximum available capacity.

Online food delivery (OFD) services have become increasingly popular and accessible, allowing customers to choose between a wide range of restaurants conveniently, compare meals and prices effectively, and arrange the delivery of the meal immediately. Thus, the number of last-mile online food deliveries has increased, creating challenges for urban cities. Based on the goal that the City Council of Stockholm has set up regarding becoming fossil-free by 2040, this report examines the effects of the last-mile deliveries in the food delivery sector, particularly how the food is delivered to consumers today, and what challenges the OFD companies are facing in relation to lowering emissions from last-mile deliveries in the urban area. The study consists of empirical data collected from a quantitative survey answered by food delivery consumers in Stockholm, a qualitative interview with Sofia Leffler Moberg, Head of Sustainable Transformation at PostNord, and secondary data published online. The results show that there is a discrepancy between how the food was delivered to the customer and what the respective OFD platform recounted in their application to be the delivery method. The in-app visualization shows that the predominant vehicle used for delivery was bicycle, however, the answers from the participants in the investigation indicate that fossil-driven vehicles such as cars and mopeds are used for delivering. The findings also indicate that there is, to a certain extent, an awareness and a presence of sustainability work in relation to carbon dioxide emissions, however, the work is argued to be limited in relation to what is actually needed in order to contribute to becoming a fossil-free city. Therefore, a large commitment by both the OFD companies and the City Council of Stockholm is needed to accelerate the transition from fossil-driven to fossil-free delivery fleets in order to reduce the GHG emissions from the last-mile deliveries within the sector. / Matleveranstjänster har blivit alltmer populära och tillgängliga, vilket gör att kunderna enkelt kan välja mellan ett brett utbud av restauranger, jämföra måltider och priser effektivt och ordna leveransen av maten direkt. Således har antalet sista mil matleveranser ökat och skapat utmaningar för städerna. Baserat på det mål som Stockholms Stad har satt upp om att bli fossilfritt till år 2040, undersöker denna rapport effekterna av leveranserna i sista milen inom matleveranssektorn, särskilt hur maten levereras till konsumenterna idag och vilka utmaningar matleveransföretagen står inför i förhållande till att minska utsläppen från sista milen leveranser i stadsområdet. Studien består av empirisk data insamlad från en kvantitativ undersökning besvarad av personer som konsumerar matleveranstjänster i Stockholm, en kvalitativ intervju med Sofia Leffler Moberg, hållbarhetschef på PostNord, och sekundära data publicerade på nätet. Resultaten visar att det finns en avvikelse mellan hur maten levererades till kunden och vilken leveransmetod respektive matleverans-plattform angav i sin applikation. Visualiseringen i applikationen visade att cykel var vanligast för matleveranser i Stockholm, men deltagarna i undersökningen indikerade att fossila fordon som bilar och mopeder används oftare än cykel. Resultaten tyder också på att det till viss del finns en medvetenhet och närvaro av hållbarhetsarbete i förhållande till koldioxidutsläpp, men arbetet är begränsat i relation till vad som behövs göras för att uppnå målet om att bli en fossilfri stad. Därför behövs ett stort åtagande från både matleverans-företagen och Stockholms Stad för att påskynda övergången från fossildrivna till elektriska leveransflottor för att minska växthusgasutsläppen från sista milen leveranser inom sektorn.