Ultrawideband Antennas for Magnetic Resonance Imaging Navigator Techniques

Due to its high appreciation for medical diagnostics worldwide, recent developments in magnetic resonance imaging (MRI) aim at adding the capability of creating focused images of moving objects. Among the potential navigator techniques required for such an improved MRI is ultrawideband (UWB) radar. We have studied the performance of UWB antennas for biomedical imaging inside the 3-Tesla MRI system at PTB Berlin. The strong static and time variant magnetic fields give rise to severe mechanical and electrical interactions due to the induced electromagnetic forces. On the other side, the high magnetic field homogeneity required for MR scans can also be affected adversely by the presence of the UWB antennas. The requirements resulting for the design of MRI compatible antennas have been identified and implemented in terms of a novel type of double-ridged horn antennas. We describe the general design strategy and the successful experimental verification of the antenna concept as well as biomedical results achieved with a combination of both UWB and MRI systems.