Introduction Recently the concept of traveling wave excitation was demonstrated for high field MRI (1). In these experiments RF excitation and reception was done by using a patch antenna, suited for this task. The disadvantage of this antenna, however, is its size. A proper patch antenna for 7 T MRI is almost as large as the diameter of the bore. This limits the location of the antenna to the e...

In this thesis micromachined antennas suitable for on-chip integration with silicon based active devices are treated. The emphasis is put on compact 24 GHz antennas, capable of being integrated in commercial SiliconGermanium (SiGe) processes using low temperature post processing micromachining techniques. Antenna types covered are the slot loop antenna, wire loop antenna, meandered dipole and t...

Electromagnetic models based on antenna theory have been recently applied in lightning studies. Their practical use is facilitated by existing thin-wire antenna numerical codes that utilize localized voltage sources. Such voltage sources have to be tuned to provide the lightning channel-base current for which experimental data are available. This involves some preparatory steps, such as the det...

SOORA, SHRUTHI. A Comparison of Two and Three Dimensional Wire Antennas for Biomedical Applications. (Under the direction of Prof. Gianluca Lazzi.) Miniature antennas are necessary to reduce the size of communications and biomedical devices, specifically for a retinal prosthesis. A comparison of two dimensional and three dimensional antennas are presented as an attempt to miniaturize and reduce...

The electromagnetic equivalence of an infinitely long loaded wire-cage structure and loaded hollow cylindrical geometry is established based on the same radiated fields under identical conditions. Analysis of the canonical infinitely long loaded wire geometries are given by treatment as boundary-value antenna prob1ems. An expression for the equivalent radius of the wire cage and an equivalent i...

An optimal design of a linear antenna array is presented. The antenna array is optimized under the restriction of uniform excitation distribution using a particle swarm optimization based method. The optimization procedure is applied under the requirements for the minimum possible side lobe level and the maximum possible power gain at the desired direction. The method has been applied to collin...

-The problem of sensitivity in the wire antennas designed by genetic algorithm (GA) causes the results to be unfeasible to be constructed successfully. This problem is due to great variation of final objective (cost function) when the antenna has some physical variations. Moreover, these GA results are not reliable because of the fact that, usually cost functions of the well-done results show h...

The wireless communication serves the efficient information among two or more points wirelessly. Antenna is the main component in the communication, which radiates and receives the radio waves or in broad way. The antenna also plays a role of impedance matching device, which performs the matching of impedances like free-space & transmitter and receiver impedances at receiver end. The antennas c...

New methods are presented for increasing the bandwidth of wire antennas using impedance loading. This paper extends the seminal Wu-King theory of the internal impedance profile that produces travelling-wave only current modes on a center-fed dipole antenna. It also presents a numerical optimization methodology based on Central Force Optimization, a new deterministic multidimensional search and ...

New emerging wireless systems that operate at millimeter wave frequencies, such as high data rate 60-GHz transceivers for wireless personal area networks (WPAN), use integrated antennas. The small wavelength at 60-GHz enables the antenna to be integrated either in the package or on the chip. However, on-chip integrated antennas for 60-GHz systems, built on a conductive substrate, such as comple...