https://www.um.edu.mt/library/oar/handle/123456789/68074 Mon, 20 Apr 2026 01:35:39 GMT 2026-04-20T01:35:39Z https://www.um.edu.mt/library/oar/handle/123456789/101264 Title: A planar circuit model for the analysis of pixel microstrip antennas Abstract: A mobile handset needs to transmit/receive data on multiple frequency bands to access a diverse range of services. This implies both an increase in real estate for mobile terminal antennas as well as ever escalating challenges for the antenna design and manufacturing departments. The pixel patch antenna has been proposed as a possible solution. The pixel patch antenna is made up of a large number of pixels which by themselves do not resonate at any frequency of practical interest. However, when a set of selected pixels are connected/switched together, antennas of different shapes are synthesized to deliver the required electrical characteristics. Ideally these properties are optimized for a given operating environment in real-time. Given the antenna hardware architecture, the problem of synthesizing the various shapes can be casted as a search among many configurations, which is not a trivial problem because of the large search space defined by the pixel array. Early research has focused mostly on the physical construction and architecture of the pixel patch antenna and it is only recently that attention has increased on the search algorithm. A series of experiments using shorting ports, switches and varactor diodes are carried out as part of the literature review, to study tuning techniques. As a result of this study, novel architectures are proposed. The model based search algorithm is reviewed and its performance is compared to the Genetic Algorithm with and without pruning methods. This thesis builds upon the idea of making use of an antenna model in the search and optimization loop. To this end the known planar circuit model, augmented with segmentation and desegmentation methods, is further developed to yield an efficient model that is used to analyse a given arbitrary pixel antenna configuration. In the model's formulation, the Green's function approach is chosen to analyse the planar circuit. The Green's function is available for regular shapes only, and for arbitrary shaped structures, segmentation techniques are used to connect regular shapes together. The Generalized Cavity Model is used to model radiation and the fields beneath the patch. In order to realize the model several studies and novel methods had to be developed. An analysis of the behaviour of the Green's function with respect to the number of modes needed for convergence was carried out. It was determined that that the number of modes needed is a function of frequency and the permittivity of the substrate Er, at which the Green's function is evaluated. It was also found that the maximum number of modes is needed when the value of effective loss tangent is zero. These studies are used to dynamically estimate the number of modes needed per segment. A study is performed on the errors generated by multiple applications of the segmentation technique. The results from this study indicate that the number of segments used to represent the pixel patch antenna should be minimized. This is implemented in the Model Order Reduction algorithm. The relationships between the pixels are represented in a tree and a graph. This tree is traversed in order to build the order of segmentation. The use of these data structures allows the analysis of any arbitrary pixel patch antenna. A novel method to calculate the current passing through a number of n-port networks is developed and described. This method is more computationally efficient than the method used in the original segmentation method. The graph is used to determine the edges of the segments that will be used in the segmentation algorithm. A set of solvers are developed and their application in terms of efficiency are studied. In particular an algorithm that evaluates the input impedance of the antenna only in a set of intervals and interpolates between these points to find the minimum value of the input reflection coefficient is developed. The fields are only evaluated once the resonant frequency is found. The results obtained from this model are compared to CST microwave studio simulations. A set of pixel patch antennas configured in regular shapes, and a set of arbitrary shaped pixel patch configurations are used in the evaluation. The planar circuit model yields accurate results for the resonant frequency while it gives a good estimate of the impedance matching. The different variants of the model are considered to study the trade-off between accuracy and computational efficiency. Finally, developments to the model that potentially improve computational efficiency are suggested and discussed. Description: PH.D. Wed, 01 Jan 2014 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/101264 2014-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/95233 Title: AR games on an FPGA Abstract: Image processing and computer vision techniques form the basis of augmented reality applications. AR is becoming a very pliable and versatile concept appearing in a vast range of products developed by both large companies and hobbyists alike. It follows the idea of superimposing computer-generated data on real-time imagery in order to submerse a user in an environment where the real world and a virtual one seamlessly blend together. This thesis aims to produce two sample augmented reality games and discuss some concepts that are enveloped in this expanding field. The first is a 2-player game, where user A is able to draw a maze "directly" into the game using a white board as the canvas. User B has to manipulate a ball object out of this maze in the fewest amount of moves possible. The concept revolves around a basic system of a camcorder-transducer that will extract the image off the white board, pass it through various filtering techniques, and display it onto the VGA monitor. In this way, a user is able to completely control the difficulty factor of the game and challenge fellow players in a new way every game. The second game is similar to the first but has an added twist - there is a limited number allowed collisions and once this value is reached the ball disappears and the game is over. The user that gets farthest through the maze and obtains the best time result is declared the winner. Description: B.SC.(HONS)COMPUTER ENG. Wed, 01 Jan 2014 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/95233 2014-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/95106 Title: Car tracking in video surveillance Abstract: Technology has reached a stage where mounting cameras to capture video imagery is quite affordable, but finding available human resources to sit and watch the imagery is very expensive, due to the continuous monitoring that is required. The massive amount of data involved makes it unfeasible to guarantee attentive monitoring by human operators for long periods of time due to monotony and fatigue. Therefore, to assist human operators with identification of important events in videos, an intelligent visual surveillance system can be used. The goal of such implementations is not just to use cameras in the place of human eyes, but mainly to achieve the entire surveillance task as automatically as possible. There are three basic key steps in object tracking, which are detection of interesting moving objects, tracking of such objects from frame to frame, and the analysis of object tracks to so that their behaviour can be recognized. In this project, a tracking algorithm is designed to identify moving cars from a video sequence which is captured by a stationary camera. The algorithm is divided into two main parts, motion detection and tracking. Initially, the system detects any motion present in the scene by using the background subtraction technique. Finally, it keeps track of each moving car and associates the detections which correspond to the same car over a period of time together, and displays a car identification number for each track. The system was tested with different test sequences, and values for the thresholds used in the algorithm were selected experimentally. Tests showed that the algorithm can track cars from a stationary camera effectively. Description: B.SC.(HONS)COMPUTER ENG. Wed, 01 Jan 2014 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/95106 2014-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/95031 Title: Immersive AR/VR spaces Abstract: Augmented reality is a modem term that is most often mistaken for virtual reality. Although these seem interchangeable, there is a distinct difference these two terms. For the Augmented reality case, the system creates an environment, where information is superimposed over the real world. While, for virtual reality, all of the modifications and actions that take place are related to the virtual world. In this final year project, the designed system was split up into two main sections. The first case is a purely augmented reality system (AR). The idea behind this is to create an environment where the user is able to detect a specific pattern, on which a desired augmented object is portrayed. Also the end-user will have the capability of modifying such an item. While the second aspect of this thesis, was that of an augmented virtualized reality (A VR) system. This can be perceived as an amalgamation of both augmented and virtual reality. The idea behind such a concept is that of creating an area where the user has the facility of creating and modifying virtual objects. One must note that, although these are two different scenarios, there are still some core items that must be implemented in both cases. One of which is the display headset. The purpose of this item is to provide an interface between the user and the processing system. Generally this is achieved by means of a virtual monitor. This is presented as two separate vision slots for the user. One can perceive this display headset as a pair of glasses. Also a feature that is this generally incorporated in such designs, is that of video cameras. Their purpose is to provide a live video stream back to the processing system. While another item that is common in both of the AR and A VR case is that of tracking. The idea behind this term is that the system is able to determine the location of an entity. Some of the most common typos of tracking systems arc GPS, QR codes and image tracking. For this project, the latter case is used for both designs. For the AR scenario, the system is programmed to track certain images of real world items. When such an items comes into the field of vision of the system, the assigned augmented object is created. As for the AVR design, the image tracking is used to determine the position of the user, relative to certain markers. Description: B.SC.(HONS)COMPUTER ENG. Wed, 01 Jan 2014 00:00:00 GMT https://www.um.edu.mt/library/oar/handle/123456789/95031 2014-01-01T00:00:00Z