JultikaUniversity of Oulu repository

In this thesis, a steerable antenna system which is able to maintain high connectivity through beamforming towards the strongest base station signal is presented. Main objective of the thesis is to design an antenna system for vehicles operating in poor coverage region or even in no coverage region, in order to enable these vehicles to make a reliable communication link with far away base stations. To achieve this high performance antenna system, several antenna designs were considered and evaluated for their performance. This thesis provides an overview of different antenna designs considered and their pros and cons. Among these designs, the concept of stacked patch antenna was selected for prototype manufacturing because of its good performance in terms of bandwidth, efficiency, gain, impedance matching and ease of fabrication because of its simple structure. Stacked patch antenna was optimized for lower GSM band covering frequencies from 824 MHz to 960 MHz by using electromagnetic simulation software CST Microwave Studio. Finally the stacked patch antenna was fabricated and measurements were performed. The results for both the prototype measurement and simulations are presented and compared. From the comparison, it is concluded that the manufactured antenna element prototype gives high performance as promised by simulation results and is suitable for the adaptive vehicular antenna system.