Decoupling of Two Closely Located Dipoles by a Single Passive Scatterer for Ultra-High Field MRI

TL;DR

This paper demonstrates that a single passive scatterer can effectively decouple two closely spaced dipole antennas used in ultra-high field MRI, with the decoupling performance influenced by the presence of a body phantom.

Contribution

It introduces a passive scatterer-based decoupling method for MRI antennas and compares the effectiveness of a dipole and a split-loop resonator in realistic conditions.

Findings

Passive scatterer achieves effective decoupling below 1/30 wavelength gap.

Decoupling performance is significantly affected by the presence of a body phantom.

Dipole scatterer is more advantageous than SLR in realistic MRI scenarios.

Abstract

We report decoupling of two closely located resonant dipole antennas dedicated for ultra-high field magnetic resonance imaging (MRI). We show that a scatterer slightly raised over the plane of antennas grants a sufficient decoupling even for antennas separated by very small gap (below 1/30 of the wavelength). We compare the operation of two decoupling scatterers. One of them is a shortcut resonant dipole and another is a split-loop resonator (SLR). Previously, we have shown that the SLR offers a wider operational band than the dipole and the same level of decoupling. However, it was so for an array in free space. The presence of the body phantom drastically changes the decoupling conditions. Moreover, the requirement to minimize the parasitic scattering from the decoupling element into the body makes the decoupling dipole much more advantageous compared to the SLR.