Along with the current trend of wireless technology innovation, wideband, compact size, low-profile, lightweight and multiple functional antenna and array designs are becoming more attractive in many applications. Conventional wireless systems utilise omni-directional or sectored antenna systems. The disadvantage of such antenna systems is that the electromagnetic energy, required by a particular user located in a certain direction, is radiated unnecessarily in every direction within the entire cell, hence causing interference to other users in the system. In order to limit this source of interference and direct the energy to the desired user, smart antenna systems have been investigated and developed. This thesis presents the design, simulation, fabrication and full implementation of a novel smart antenna system for future mobile applications. The design and characterisation of a novel antenna structure and four-element liner array geometry for smart antenna systems are proposed in the first stage of this study. Firstly, a miniaturised microstrip-fed planar monopole antenna with Archimedean spiral slots to cover WiFi/Bluetooth and LTE mobile applications has been demonstrated. The fundamental structure of the proposed antenna element is a circular patch, which operates in high frequency range, for the purpose of miniaturising the circuit dimension. In order to achieve a multi-band performance, Archimedean spiral slots, acting as resonance paths, have been etched on the circular patch antenna. Different shapes of Archimedean spiral slots have been investigated and compared. The miniaturised and optimised antenna achieves a bandwidth of 2.2GHz to 2.9GHz covering WiFi/Bluetooth (2.45GHz) and LTE (2.6GHz) mobile standards. Then a four-element linear antenna array geometry utilising the planar monopole elements with Archimedean spiral slots has been described. All the relevant parameters have been studied and evaluated. Different phase shifts are excited for the array elements, and the main beam scanning range has been simulated and analysed. The second stage of the study presents several feeding network structures, which control the amplitude and phase excitations of the smart antenna elements. Research begins with the basic Wilkinson power divider configuration. Then this thesis presents a compact feeding network for circular antenna array, reconfigurable feeding networks for tuning the operating frequency and polarisations, a feeding network on high resistivity silicon (HRS), and an ultrawide-band (UWB) feeding network covering from 0.5GHz to 10GHz. The UWB feeding network is used to establish the smart antenna array system. Different topologies of phase shifters are discussed in the third stage, including ferrite phase shifters and planar phase shifters using switched delay line and loaded transmission line technologies. Diodes, FETs, MMIC and MEMS are integrated into different configurations. Based on the comparison, a low loss and high accurate Hittite MMIC analogue phase shifter has been selected and fully evaluated for this implementation. For the purpose of impedance matching and field matching, compact and ultra wideband CPW-to-Microstrip transitions are utilised between the phase shifters, feeding network and antenna elements. Finally, the fully integrated smart antenna array achieves a 10dB reflection coefficient from 2.25GHz to 2.8GHz, which covers WiFi/Bluetooth (2.45GHz) and LTE (2.6GHz) mobile applications. By appropriately controlling the voltage on the phase shifters, the main beam of the antenna array is steered ±50° and ±52°, for 2.45GHz and 2.6GHz, respectively. Furthermore, the smart antenna array demonstrates a gain of 8.5dBi with 40° 3dB bandwidth in broadside direction, and has more than 10dB side lobe level suppression across the scan. The final stage of the study investigates hardware and software automatic control systems for the smart antenna array. Two microcontrollers PIC18F4550 and LPC1768 are utilised to build the control PCBs. Using the graphical user interfaces provided in this thesis, it is able to configure the beam steering of the smart antenna array, which allows the user to analyse and optimise the signal strength of the received WiFi signals around the mobile device. The design strategies proposed in this thesis contribute to the realisation of adaptable and autonomous smart phone systems.

Since its invention, phased array has been extensively applied in both military and civil areas. The applications include target detecting and tracking, space probe communication, broadcasting, human-machine interfaces, and remote sensing. Although the phased array applications show a broad range of potential market, there are some limitations of phased array's development: high cost, complex structure, narrow bandwidth, and high power consumption. Therefore, novel ideas are needed to reduce these constraints. In this thesis, several new approaches about the design and application of phased array are presents. First, the principle of phased array and fundamental design equations are introduced. Second, a new application of phased array antenna for radar respiration measurement is presented. By integrating a 4×4 Butler matrix with four-element antenna array, there will be four distinct main beams in radiation pattern. This new approach can improve the measurement accuracy and realize a high detecting rate. Third, a compact phased array antenna system based on dual-band operations is introduced. Dual-band function can make N-antenna system obtain 2N unique radiation beams (N is an integer) and achieve a significant size reduction compared to the conventional single-band system. To verify the design concept, a four-element phased array antenna working at 5GHz and 8GHz is designed and fabricated. The measurement results make a good agreement with the simulations. Finally, a novel architecture of steering phase feeding network by using bi-directional series-fed topology is presented. This bi-directional series-fed network needs less phase shifters and realizes steering phase function by applying control voltage.

In this thesis the focus was on the design, fabrication, and tests of the feeding networks individually and within an array system. The array feeding network is a corporate-fed type utilizing equal-split, stepped-multiple sections of the conventional Wilkinson power divider in microstrip form with a unique topology. The feeding network was specifically designed for a broadside relatively small linearly-polarized wideband UHF non-scanning array for directed power applications that uses an array radiator with a new volumetric ribcage dipole configuration. The array has a large impedance bandwidth and consistent front lobe gain over the wide frequency band. Theoretical and experimental results describing the performance of the array feeding network and the array are presented and discussed.

This master thesis deals with a design of Vivaldi antenna due to its broadband properties suitable for radar applications. The folding of single Vivaldi antenna element into 2D antenna array we achieved required radiation properties. Appropriate design of feeding structure realized by SIW technology we obtained suppression of side lobes and deflection of the main lobe. The work also includes design of 3D Vivaldi antenna array. Modeling, simulation and optimization of antenna array were performed in CST Microwave Studio.

In this master´s thesis an issue of broadband planar antennas was analyzed. Firstly, the basic elements that affect bandwidth, such as the influence of the dieletric substrate, suitable shape or feeding network, were described. Furthermore technics that can be used to widen the band of the planar antennas were described. These technics were applied to a chosen type of a planar antenna. This antenna was modeled and simulated for desired dielectric substrate in CST STUDIO SUITE 2010 software. Feeding network with power dividers was designed for the antenna array. In order to obtain a higher gain, the antenna was implemented into the 2x2 element array. The results of the simulation are evaluated in the conclusion.

Power dividers are vital components and widely used in radio technology, such as antenna arrays, power amplifiers, multiplexers and mixers. A good example is the well-known Wilkinson power divider with its distinctive feeding network characteristics. A comprehensive review indicated that limited research is carried out in the area of planar multiport and reconfigurable power dividers in terms of the power levels between output ports. The main objectives of this work were to develop a small size power divider, a planer multi-output ports power divider and a power divider with a reconfigurable power division ratio. These power dividers were designed to operate over either an ultra-wideband frequency (3.1-10.6 GHz) or WLAN bands (2.4 or 5.2 GHz). A novel multi-layered topology solved the complexity of interconnecting isolation resistors by introducing an additional layer below the ground layer. The prototype was fabricated and tested to validate the results. The measurements and simulation were in good agreement. Finally, a novel uniplanar power divider with reconfigurable output power level difference was developed. The configurability feature was achieved by tuning the quarter wave transformer using one varactor diode. The power divider was applied to improve a full duplex system cancellation performance at the receiver element caused by interference from in-site transmitting antennas. This study investigated fixed power dividers, multi-output power dividers and reconfigurable power dividers. The measurements validated by the simulation results and applications proved the designed power dividers could be used in practical applications. / Higher Committee for Education Development (HCED), Iraq