UWB Antennas for Medical Imaging

Ultra-Wide Band (UWB) Microwave for imaging applications; especially in the medical field, is a new method to overcome the inherent invasive features of X-ray imaging. In this work a new systematic and detailed design for the Tapered Slot Antenna (TSA) as a UWB antenna in microwave imaging systems for medical applications is presented. Among TSAs, the Vivaldi antenna was selected and the reasons to replace the horn antenna imaging systems are illustrated. In the first chapter the previous designs for microwave imaging and the outline of this work are given, Chapter Two covers the design of the Vivaldi antenna\u27s different parts design by concentration on previous researches, the third chapter presents the antenna deign for this project, Chapter Four a method based on a closed form equation to design the antenna taper for reduced reflection is presented, the fifth chapter is a method to design the Vivaldi antenna taper to penetrate tissue like objects, and in the last chapter the UWB performance of the designed Vivaldi antenna and its impulse response are analyzed. In this work the theorical designs are verified experimentally and the results and design justifications are provided for each par

Magneto-Electric Effects on Sr Z-type Hexaferrite at Room Temperature

In this paper, magnetoelectric effects of Sr Z-type hexaferrite, Sr3Fe24Co2O41, at room temperature is measured. The change in remanence magnetization was measured by applying a DC voltage or electric field across a slab of hexaferrite. Changes of ~ 18% in remanence was observed in an electric field of 10,000V/cm implying a similar change in the microwave permeability at frequencies below 3GHz. Also, a change in dielectric constant at 1 GHz of ~16% in a magnetic field of only 320 Oe was measured. In these types of measurements high resistivity is critical in order to reduce current flow in the hexaferrite. The resistivity of the hexaferrite was raised to 4.28x10^8 ohm-cm by annealing under oxygen pressure. The measurements indicate that indeed electric polarization and magnetization changes were induced by the application of magnetic and electric fields, respectively. The implications for microwave applications appear to be very promising at room temperature.Comment: 8 pages, 3 figures, MMM conference and Journal of applied Physic

Converse Magnetoelectric Experiments on a Room Temperature Spirally Ordered Hexaferrite

Experiments have been performed to measure magnetoelectric properties of room temperature spirally ordered Sr3Co2Fe24O41 hexaferrite slabs. The measured properties include the magnetic permeability, the magnetization and the strain all as a function of the electric field E and the magnetic intensity H. The material hexaferrite Sr3Co2Fe24O41 exhibits broken symmetries for both time reversal and parity. The product of the two symmetries remains unbroken. This is the central feature of these magnetoelectric materials. A simple physical model is proposed to explain the magnetoelectric effect in these materials.Comment: 6 pages, 5 figure