Coils vs Antennas in MR

Working within an MR environment, it's common to hear the terms "coil" and "antenna" being interchanged in daily conversation. Albeit, although these two devices are necessary for developing quality MR imaging, these two devices are not the same thing. With this, to provide an explanation, the antenna system is an RF transceiver, pairing both the RF transmission capability, and RF receiving capability into one electrical component. And, due to physics, relative to high quality medical MR image acquisition, the length of the given antenna serves an important role with appropriating the precessional frequency of hydrogen, which is 42.58 MHz / Tesla, in lieu of tuning the antenna's center frequency. Wherefore, to be specific, the RF transmitter component of the given antenna-transceiver needs to not be too short, as a means to radiate RF emissions with a long wavelength.

To get around this problem, where the problem is defined as how to make the RF transceiver as small as possible without diminishing the transmission-capability for generating an appropriate RF frequency relative to the precessional frequency of hydrogen, electrical engineers deploy coils. In short, coils are utilized for the process of "antenna loading", which is to electrically lengthen the RF transceiver (e.g. to not physically lengthen the antenna). Here, the purpose of coils relative to the process of antenna loading is that these coils serve as inductors, being placed at radiating elements within the RF transmission component of the given RF transceiver; to ameliorate the low frequency radiating-capability of a an RF transceiver, which is physically short, supporting the given antenna to radiate at the lower frequency being resolved by the chemical properties of hydrogen.

In conclusion, the underlying importance of coils, with respect to electrically lengthening the given RF transceiver, is in lieu of the fact that inductors act as storage devices for electrical circuits. Specifically, the idea storage is the implication of space. Wherefore, space gives the impression of length. Therefore, inductors (i.e. coils) allow RF transceivers to be electrically extended to accommodate lower RF frequencies through the deployment of unconventional space to achieve a desired end.