Meeting Banner
Abstract #4363

Investigation of the Transition from Travelling Wave to Near Field Excitation Using Crossed Dipole Antennas

Karthik Lakshmanan1, Martijn A. Cloos2, Graham C. Wiggins1

1NYU, Newyork, United States; 2New York University School of Medicine, Newyork, United States

Crossed Dipoles have been used to create travelling waves in the bore of the magnet which can be used for MR imaging. Travelling wave excitation is relatively inefficient compared to conventional volume resonators. If the crossed dipole is placed close to the object, however, efficiency increases while excitation pattern changes. In this study we compared the excitation profile and efficiency of a crossed dipole antenna pair as a function of distance between the antenna and the object imaged. The efficiency of the antenna configuration showed an inverse proportionality to the distance between the antenna and the Imaging object. When the distance between the antenna pair and the imaging object was less than quarter wavelength the excitation pattern changed from a travelling pattern with peak low in the head and with neck excitation to more of a near field excitation with the excitation primarily confined to the top of the head.

Abstract PDF Presentation Video

Keywords

able achieve actual antenna antennas application appropriate around believe better board body bore boxes built capacitor channel choosing circuit classic closer coil coils confined connected constructed coupling crossed decreasing dipole dipoles distance distances distribution dominate efficiency element elements excitation exhibiting experimental explored fabricated favorable field fixed free frequency function generated getting graham head house indicated inductor inefficient interface investigation isotropic landmark lattice load located long magnet maps match matched matching matrix medical move nature near neck needs note object pair parallel patch patient pattern peak phantom placed please practical primarily profile proximity quarter realm reduced relationship relatively resolution resonators sample scaling scanner sensitive setup shaped shield shortened simple solutions space starts strength strong subject sustained system systems table traces transition transmit tune tuning typically voltage voltages volume wave wavelength waves whole wide wires