The aim of this study is to investigate the effects of changes in the physical parameters of tapered slot antennas (TSA) on their radiation characteristics and also to explore the possibility of reconfiguration in the radiation pattern of TSA by switching between two different types of tapering. There are mainly three physical parameters that affect the radiation pattern of TSAs. These are antenna length, aperture width and the ground extension. After designing a wideband microstrip line to slot line transition, the effect of antenna parameter variations on the beamwidth and sidelobe level of the antenna are investigated through the use of a commercially available electromagnetic simulation software HFSS by ANSOFT. The radiation characteristics of constant width slot antennas (CWSA) and linearly tapered slot antennas (LTSA) are compared. It is observed that CWSAs exhibit narrower beamwidth and higher sidelobe level whereas linearly tapered slot antennas (LTSA) have wider beamwidth with lower sidelobe level compared to each other. A novel switching architecture between CWSA and LTSA is proposed to obtain a reconfigurable antenna.

An active, broadband antenna module amenable for use in low cost phased arrays is proposed. The module consists of a Vivaldi antenna integrated with a frequency conversion integrated circuit. A method of orthogonally mounting endfire antennas onto an array motherboard is developed using castellated vias. A castellated active isolated Vivaldi antenna package is designed, fabricated, and measured. An 8x1 phased array of castellated, active Vivaldi antenna packages is designed and assembled. Each element has approximately one octave of bandwidth centered in X-band, and each is mounted onto a coplanar waveguide motherboard. Radiation patterns of the array are measured at several frequencies and scan angles.

This thesis presents various integrated antenna solutions for different types of systems and applications, e.g. wireless sensors, broadband handsets, advanced base stations, MEMS-based reconfigurable front-ends, automotive anti-collision radars, and large area electronics. For wireless sensor applications, a T-matched dipole is proposed and integrated in an electrically small body-worn sensor node. Measurement techniques are developed to characterize the port impedance and radiation properties. Possibilities and limitations of the planar inverted cone antenna (PICA) for small handsets are studied experimentally. Printed slot-type and folded PICAs are demonstrated for UWB handheld terminals. Both monolithic and hybrid integration are applied for electrically steerable array antennas. Compact phase shifters within a traveling wave array antenna architecture, on single layer substrate, is investigated for the first time. Radio frequency MEMS switches are utilized to improve the performance of reconfigurable antennas at higher frequencies. Using monolithic integration, a 20 GHz switched beam antenna based on MEMS switches is implemented and evaluated. Compared to similar work published previously, complete experimental results are here for the first time reported. Moreover, a hybrid approach is used for a 24 GHz switched beam traveling wave array antenna. A MEMS router is fabricated on silicon substrate for switching two array antennas on a LTCC chip. A concept of nano-wire based substrate integrated waveguides (SIW) is proposed for millimeter-wave applications. Antenna prototypes based on this concept are successfully demonstrated for automotive radar applications. W-band body-worn nonlinear harmonic radar reflectors are proposed as a means to improve automotive radar functionality. Passive, semi-passive and active nonlinear reflectors consisting of array antennas and nonlinear circuitry on flex foils are investigated. A new stretchable RF electronics concept for large area electronics is demonstrated. It incorporates liquid metal into microstructured elastic channels. The prototypes exhibit high stretchability, foldability, and twistability, with maintained electrical properties. / wisenet