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abstract: Within the past two decades, metasurfaces, with their unique ability to tailor the wavefront, have attracted scientific attention. Along with many other research areas, RADAR cross-section (RCS)-reduction techniques have also benefited from metasurface technology. In this dissertation, a novel technique to synthesize the RCS-reduction metasurfaces is presented. This technique unifies the two most widely studied and two well-established modern RCS-reduction methods: checkerboard RCS-reduction andgradient-index RCS-reduction. It also overcomes the limitations associated with these RCS-reduction methods. It synthesizes the RCS-reduction metasurfaces, which can be juxtaposed with almost any existing metasurface, to reduce its RCS. The proposed technique is fundamentally based on scattering cancellation. Finally, an example of the RCS-reduction metasurface has been synthesized and introduced to reduce the RCS of an existing high-gain metasurface ground plane. After that, various ways of obtaining ultrabroadband RCS-reduction using the same technique are proposed, which overcome the fundamental limitation of the conventional checkerboard metasurfaces, where the reflection phase difference of (180+-37) degrees is required to achieve 10-dB RCS reduction. First, the guideline on how to select Artificial Magnetic Conductors (AMCs) is explained with an example of a blended checkerboard architecture where a 10-dB RCS reduction is observed over 83% of the bandwidth. Further, by modifying the architecture of the blended checkerboard metasurface, the 10-dB RCS reduction bandwidth increased to 91% fractional bandwidth. All the proposed architectures are validated using measured data for fabricated prototypes. Critical steps for designing the ultrabroadband RCS reduction checkerboard surface are summarized. Finally, a broadband technique to reduce the RCS of complex targets is presented. By using the proposed technique, the problem of reducing the RCS contribution from such multiple-bounces simplifies to identifying and implementing a set of orthogonal functions. Robust guidelines for avoiding grating lobes are provided using array theory. The 90 degree dihedral corner is used to verify the proposed technique. Measurements are reported for a fabricated prototype, where a 70% RCS-reduction bandwidth is observed. To generalize the method, a 45 degree dihedral corner, with a quadruple-bounce mechanism, is considered. Generalized guidelines are summarized and applied to reduce the RCS of complex targets using the proposed method. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2020

<p>Uppsatsen gör en första ansats till redogörelse för smygteknikens taktiska implikationer.</p><p>Vilka möjligheter finns med smygtekniken mot en kvalificerad motståndare under väpnad strid? Detta koncentreras till tre olika områden: duellstrid, underrättelseinhämtning och vilseledning. Med avstamp i flottans gamla reglemente, TRFL, via litteratur i ämnet, och slutligen med intervjuer dras slutsatser på huruvida sjötaktiken påverkats, eller kan påverkas av signaturanpassningen.</p><p>Slutsatserna är, förutom att fortsatt forskning behövs på området, att det är av största vikt att fartygschef har adekvata beslutsunderlag angående fartygets signaturer, och att signaturanpassningen, rätt nyttjad, ger taktiska fördelar.</p> / <p>This study examines how stealth technology affects Swedish tactics in the naval arena. Could stealth technology improve the chances of successful naval warfare? This puts focus on three underlying questions: how stealth technology affects your odds, in a duel, in deceptive action, and during reconnaissance/information gathering?</p><p>This requires a description of stealth technology, benefits and disadvantages, and a thorough picture of Swedish naval tactics. With this in mind, an analysis is conducted where the benefits of stealth technology are compared with Swedish naval tactics. The main results of this study shows that, firstly, the subject needs more careful research, secondly that stealth technology gives, if properly used, a tactical advantage.</p>

Uppsatsen gör en första ansats till redogörelse för smygteknikens taktiska implikationer. Vilka möjligheter finns med smygtekniken mot en kvalificerad motståndare under väpnad strid? Detta koncentreras till tre olika områden: duellstrid, underrättelseinhämtning och vilseledning. Med avstamp i flottans gamla reglemente, TRFL, via litteratur i ämnet, och slutligen med intervjuer dras slutsatser på huruvida sjötaktiken påverkats, eller kan påverkas av signaturanpassningen. Slutsatserna är, förutom att fortsatt forskning behövs på området, att det är av största vikt att fartygschef har adekvata beslutsunderlag angående fartygets signaturer, och att signaturanpassningen, rätt nyttjad, ger taktiska fördelar. / This study examines how stealth technology affects Swedish tactics in the naval arena. Could stealth technology improve the chances of successful naval warfare? This puts focus on three underlying questions: how stealth technology affects your odds, in a duel, in deceptive action, and during reconnaissance/information gathering? This requires a description of stealth technology, benefits and disadvantages, and a thorough picture of Swedish naval tactics. With this in mind, an analysis is conducted where the benefits of stealth technology are compared with Swedish naval tactics. The main results of this study shows that, firstly, the subject needs more careful research, secondly that stealth technology gives, if properly used, a tactical advantage.

Sedan radar började användas under första hälften av 1900-talet har duellen mellan radar och signalspaning pågått. Genom att utnyttja radar har alltid en medveten risk tagits, risken att bli upptäckt av motståndarens signalspaning. Duellen gavs möjlighet att ta en paus då radarsystem med låg uteffekt introducerades på marknaden under slutet av 1980-talet, nu fanns plötsligt en möjlighet att använda radar samtidigt som de samtida signalspaningssystemen inte kunde upptäcka dessa radarsystem. I föreliggande magisteruppsats i krigsvetenskap med militärteknisk inriktning undersöks räckviddsförhållanden mellan dessa radarsystem och signalspaningssystem. Genom scenarier i den marina arenan försöker jag värdera de taktiska vinster en användare av radar med låg uteffekt kan göra. Analysen visar på att det fram till dess att signalspaningssystem med förmåga att upptäcka radar som utnyttjar låg uteffekt finns tillgängligt är det möjligt att nå taktiska fördelar med dessa system. / Since the advent of radar during the early 20th century the duel between radar and electronic support measurement systems has been practised. Using radar has always been associated with a risk of being detected by an opponent’s electronic support measurement systems. The duel came to a halt when radar systems using low output power were introduced on the market during the late 1980s, now it was possible to use radar without being detected by contemporary electronic support measurement systems. The present master of science (one year) thesis in war science with specialization in military technology looks into the range relationships between radar and electronic support measurement systems. Through scenarios in the naval domain, I seek to assess the tactical benefits a user of low probability of intercept radar may have. The analysis indicates that until electronic support measurement systems with the ability to detect radar systems using low output power are available it is still possible to gain tactical advantages with such systems.