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With the roll out of new technologies and the worldbecoming more connected, there is a rising demand for higherbandwidth and new frequency bands. To meet the demand,higher frequencies are used in new communication systems.Higher frequencies come with the need for new antenna designsand one promising type of antenna is the lens antenna. In thispaper, a modulated geodesic Luneburg lens with a novel feedingmethod is proposed for use between 8-10 GHz. Furthermore, themanufacturing of the lens explores the possibility of 3D printingas a method of producing cheap antennas.The paper verifies the viability of using a patch antenna andhorn as a feeding method for a parallel-plate waveguide lens.First the lens is modeled and simulated in CST Microwave Studioand is then 3D-printed in PLA plastic and taped with coppertape. The antenna achieves -5 dB S11-parameter between 8-10GHz. The antenna also achieves 60 scanning in the azimuthplane. The antenna achieves a HPBW of 15. / Med utvecklingen av nya tekniker och envärld som blir allt mer digital är efterfrågan på större bandbreddoch nya frekvensband hög. För att möta efterfrågananvänds högre frekvenser i nya kommunikationssystem. Medanvändningen av högre frekvenser behövs nya antenndesigneroch en lovande typ av antenn är linsantennen. I den härartikeln föreslås en modulerad geodesic Luneburg lins med enny typ av matningsmetod för användning mellan 8-10 GHz. Förtillverkningen av linsen utforskas 3D-printning som en billig ochenkel metod.Artikeln verifierar användningen av en patch-antenn och etthorn som matningsmetod för en lins av parallella metallplattor.Först simuleras linsen i CST Microwave Studio och 3Dprintassedan i PLA-plast och tejpas med koppartejp. Antennenåstakommer -5 dB i S11-parameter mellan 8-10 GHz. Antennenhar en skanning av 60 i azimut-planet och har en HPBW av15. / Kandidatexjobb i elektroteknik 2021, KTH, Stockholm

The development of millimeter-wave (30-300 GHz) sensors and communications systems has a long history of interest, spanning back almost six decades. In particular, mm-wave radars have applications as automotive radars, in remote atmospheric sensing applications, as landing radars for air and spacecraft, and for high precision imaging applications. Mm-wave radar systems have high angular accuracy and range resolution, and, while susceptible to atmospheric attenuation, are less susceptible to optically opaque conditions, such as smoke or dust. This dissertation document will present the initial steps towards a new approach to the creation of a mm-wave radar system at 94 GHz. Specifically, this dissertation presents the design, fabrication and testing of various components of a highly integrated mm-wave a 94 Ghz monopulse radar transmitter/receiver. Several architectural approaches are considered, including passive and active implementations of RF monopulse comparator networks. These architectures are enabled by a high-performance three-dimensional rectangular coaxial microwave transmission line technology known as PolyStrataTM as well as silicon-based IC technologies. A number of specific components are examined in detail, including: a 2x2 PolyStrata antenna array, a passive monopulse comparator network, a 94 GHz SiGe two-port active comparator MMIC, a 24 GHz RF-CMOS 4-port active monopulse comparator IC, and a series of V- and W-band corporate combining structures for use in transmitter power combining applications. The 94 GHz cavity-backed antennas based on a rectangular coaxial feeding network have been designed, fabricated, and tested. 13 dB gain for a 2 x 2 array, as well as antenna patterns are reported. In an effort to facilitate high-accuracy measurement of the antenna array, an E-probe transition to waveguide and PolyStrata diode detectors were also designed and fabricated. AW-band rectangular coaxial passive monopulse comparator with integrated antenna array and diode detectors have also been presented. Measured monopulse nulls of 31.4 dB in the ΔAZ plane have been demonstrated. 94-GHz SiGe active monopulse comparator IC and 24 GHz RF-CMOS active monopulse comparator RFIC designs are presented, including detailed simulations of monopulse nulls and performance over frequency. Simulations of the W-band SiGe active monopulse comparator IC indicate potential for wideband operation, with 30 dB monopulse nulls from 75-105 GHz. For the 24-GHz active monopulse comparator IC, simulated monopulse nulls of 71 dB and 68 dB were reported for the azimuthal and elevational sweeps. Measurements of these ICs were unsuccessful due to layout errors and incomplete accounting for parasitics. Simulated results from a series of rectangular coaxial power corporate power combining structures have been presented, and their relative merits discussed. These designs include 2-1 and 4-1 reactive, Wilkinson, and Gysel combiners at V- and W-band. Measured back-to-back results from Gysel combiners at 60 GHz included insertion loss of 0.13 dB per division for a 2-1 combination, and an insertion loss of 0.3 dB and 0.14 dB for "planar" and "direct" 4-1 combinations, respectively. At 94 GHz, a measured insertion loss of 0.1 dB per division has been presented for a 2-1 Gysel combination, using a back-to-back structure. Preliminary designs for a solid-state power amplifier (SSPA) structure have also been presented. Finally, two conceptual monopulse transceivers will be presented, as a vehicle for integrating the various components demonstrated in this dissertation. / Ph. D.

With the advances in wireless communication systems, antennas with different shapes and design have achieved great demand and are desirable for many uses such as personal communication systems, and other applications involving wireless communication. This has resulted in different shapes and types of antenna design in order to achieve different antenna characteristic. One attractive approach to the design of antennas is to suppress or attenuate harmonic contents due to the non-linear operation of the Radio Frequency (RF) front end. The objectives of this work were to investigate, design and implement antennas for harmonic suppression with the aid of a genetic algorithm (GA). Several microstrip patch antennas were designed to operate at frequencies 1.0, 1.8 and 2.4 GHz respectively. The microstrip patch antenna with stub tuned microstrip lines was also employed at 1.0 and 1.8 GHz to meet the design objectives. A new sensing patch technique is introduced and applied in order to find the accepted power at harmonic frequencies. The evaluation of the measured power accepted at the antenna feed port was done using an electromagnetic (EM) simulator, Ansoft Designer, in terms of current distribution. A two sensors method is presented on one antenna prototype to estimate the accepted power at three frequencies. The computational method is based on an integral equation solver using adaptive surface meshing driven by a genetic algorithm. Several examples are demonstrated, including design of coaxially-fed, air-dielectric patch antennas implanted with shorting and folded walls. The characteristics of the antennas in terms of the impedance responses and far field radiation patterns are discussed. The results in terms of the radiation performance are addressed, and compared to measurements. The presented results of these antennas show a good impedance matching at the fundamental frequency with good suppression achieved at the second and third harmonic frequencies.

This thesis includes the design, production and measurement of a wideband dualpolarized X-band aperture-coupled microstrip patch antenna. The wideband and dual-polarized operation is achieved through the use of H-shaped coupling slots. Therefore, the equivalent circuit modeling of a microstrip line fed H-shaped slot is also studied in this thesis. A step-by-step procedure is followed during the design process of the dual-polarized aperture-coupled microstrip antenna. First, an aperture-coupled microstrip antenna with a single rectangular slot, that exhibits a wideband characteristic for single polarization, is designed. Then, the design procedure is repeated for an antenna with H-shaped slot in order to satisfy the same specifications with a shorter slot. Finally, dual-polarized aperture-coupled microstrip antenna is designed. At this configuration, two H-shaped slots are used and they are placed orthogonal to each other. During the design process, the effects of antenna parameters on the input impedance characteristics of the antenna are investigated. These parametric analyses are done in CST Microwave Studio&reg / . The v designed dual-polarized wideband aperture-coupled microstrip antenna is manufactured. Simulation results and measurement results are compared. During the equivalent circuit modeling of an H-shaped slot fed by a microstrip line, an approach based on the reciprocity theorem is utilized. The method was originally proposed for rectangular shaped slots, in this thesis it is generalized for arbitrarily shaped slots. Software codes are developed in MATLAB to calculate the equivalent impedance of the slot.

The main objective of this research is to design, model and implement several antenna geometries using electromagnetic band gap (EBG) material and a defected ground plane. Several antenna applications are addressed with the aim of improving performance, particularly the mutual coupling between the elements. The EBG structures have the unique capability to prevent or assist the propagation of electromagnetic waves in a specific band of frequencies, and have been incorporated here in antenna structures to improve patterns and reduce mutual coupling in multielement arrays. A neutralization technique and defected ground plane structures have also been investigated as alternative approaches, and may be more practical in real applications. A new Uni-planar Compact EBG (UC-EBG) formed from a compact unit cell was presented, giving a stop band in the 2.4 GHz WLAN range. Dual band forms of the neutralization and defected ground plane techniques have also been developed and measured. The recorded results for all antenna configurations show good improvement in terms of the mutual coupling effect. The MIMO antenna performance with EBG, neutralization and defected ground of several wireless communication applications were analysed and evaluated. The correlation coefficient, total active reflection coefficient (TARC), channel capacity and capacity loss of the array antenna were computed and the results compared to measurements with good agreement. In addition, a computational method combining Genetic Algorithm (GA) with surface meshing code for the analysis of a 2×2 antenna arrays on EBG was developed. Here the impedance matrix resulting from the meshing analysis is manipulated by the GA process in order to find the optimal antenna and EBG operated at 2.4 GHz with the goal of targeting a specific fitness function. Furthermore, an investigation of GA on 2×2 printed slot on DGS was also done.

The continuous advancement in wireless communications technology demands new approaches to improving the capacity of existing radio links. The high data throughput required can be achieved by the complete utilization of space, time and polarization diversities inherent in any propagation environment. Among the different propagation scenarios, the indoor channels represent a particularly challenging problem given the number and complexity of interactions between the transmitted signal and the environment. This dissertation explores the interrelation between propagation physics and space-time-polarization diversity based on a novel high resolution channel sounding and reconstruction technique. First, a method to reconstruct the indoor complex channel response based on a limited set of samples and the elimination of the interference using deconvolution techniques is presented. Then, the results for the joint angle-of-arrival, delay characterization and depolarization of electromagnetic waves are presented. Finally, a novel approach to using depolarized multipath signals to boost the receiver signal-to-noise performance is presented. The current study shows that full utilization of the diversities of channel novel wireless systems can be proposed with significant improvement in capacity.

The continuous advancement in wireless communications technology demands new approaches to improving the capacity of existing radio links. The high data throughput required can be achieved by the complete utilization of space, time and polarization diversities inherent in any propagation environment. Among the different propagation scenarios, the indoor channels represent a particularly challenging problem given the number and complexity of interactions between the transmitted signal and the environment. This dissertation explores the interrelation between propagation physics and space-time-polarization diversity based on a novel high resolution channel sounding and reconstruction technique. First, a method to reconstruct the indoor complex channel response based on a limited set of samples and the elimination of the interference using deconvolution techniques is presented. Then, the results for the joint angle-of-arrival, delay characterization and depolarization of electromagnetic waves are presented. Finally, a novel approach to using depolarized multipath signals to boost the receiver signal-to-noise performance is presented. The current study shows that full utilization of the diversities of channel novel wireless systems can be proposed with significant improvement in capacity.

This diploma thesis deals with the modeling of planar antennas with special superstrates in the CST Microwave Studio. Attention is given to the electromagnetic bandgap (EBG) substrates. Firstly, the working principle of these special substrates and generally physical phenomena accompanying electromagnetic waves propagation in a periodic medium are analyzed. By modeling of basic EBG structures in CST their dispersion diagrams were obtained and afterwards compared to one another. The object of the second part of this thesis was modeling of a chosen antenna in CST. An Antenna placed first on the conventional and then on the EBG substrate - in both cases with special superstrates - is analyzed and compared to each other. In the third part of this thesis, the particle swarm optimization (PSO) technique was implemented in CST (VBA language), and was applied to the original design of the chosen antenna. In the final part of this thesis, the optimized antenna was modeled and analyzed in ANSOFT HFSS, and the results from both simulation programs are compared to each other.

The thesis is focused on the design of a planar resonant-type antenna, which exploits a proper combination of left- and right-handed properties of transmission lines. This transmission line is called CRLH TL and is based on Sievenpiper mushroom structure. Advantages of the proposed antenna concept are demonstrated by a detailed comparison of its basic properties with the properties of a conventional patch antenna.