An array coil combines the advantages of smaller coils (high SNR) with those of larger coils (large measurement field).
This type of RF coil is composed of separate multiple smaller coils, which can be used individually (switchable coil) or combined.
When used simultaneously, the elements can either be:
coupled array coils - electrically coupled to each other through common transmission lines or mutual
isolated array coils - electrically isolated from each other with separate transmission lines and receivers and minimum effective
mutual inductance, and with the signals from each transmission line processed independently or at different frequencies
phased array coils - multiple small coils arranged to efficiently cover a specific anatomic region and obtain high-resolution, high-SNR images of a larger volume. The data from the individual coils is integrated by special software to produce the high-resolution images.