Parallel‐plate split‐conductor surface coil: Analysis and design

Abstract

A split-conductor circular parallel-plate resonator with one end shorted to ground can be used to one's advantage as a surface coil for NMR imaging experiments. It can be easily constructed by a printed-circuit method and possesses a relatively high loaded Q with negligible frequency detuning. From the proposed equivalent circuit, an equation was derived that relates the self-resonance frequency of the resonator to the split distance measured from a reference point. An example of a 101-mm-diameter surface coil operating at 26 MHz for 31P in vivo spectroscopy is given to illustrate the concordance between calculated and experimental results. Complementary equations and formulas are also included to assist researchers in designing their own antennas to meet specific requirements.

A high-impedance detector-array glove for magnetic resonance imaging of the hand

“…Over the years, several other designs have been proposed to eliminate lumped elements from the coil and enhance the mechanical flexibility [18, 19, 20, 21, 24]. The elegant printed coil design proposed by Corea et al [21], achieves a high degree of flexibility by printing conductive ink onto a flexible substrate.…”

“…S2). The lack of lumped elements [18, 19, 20], [21, 22, 23] in combination with the coaxial design [24] suggests that a high degree of mechanical flexibility may be possible with HIC coils. Given the possibility to make a more flexible coil in addition to leveraging the desirable decoupling properties of HICs, we settled on a 0.7 mm separation between the inner and outer conductor, the effective resolution limit of our printer for this type of structure, leading to a coil diameter of 8.0 cm when tuned to 123 MHz, the proton Larmor frequency of our 3 Tesla MRI scanner (Siemens, Erlangen, Germany).…”

Multi-Loop Radio Frequency Coil Elements for Magnetic Resonance Imaging: Theory, Simulation, and Experimental Investigation

“…One can notice that when employing other technologies than that of lumped components to fabricate the coil, the two above mentioned noise sources are still of concern. Considering the case of self-resonant coils based on the transmission line principle (e.g., [28]), losses within the substrate, similarly to capacitors losses, may contribute to the overall coil noise and should be considered. This is particularly of concern when using low quality substrates, such as FR4 or Polyimide (e.g., Kapton R ) whose loss tangent limits the achievable overall quality factor of the coil.…”

Novel inductive decoupling technique for flexible transceiver arrays of monolithic transmission line resonators

“…This is especially important at ultrahigh field, where multiple lumped capacitors per coil are needed to generate a uniform current distribution along the loop . These constraints can be overcome by the concept of monolithic transmission line resonators (TLRs) . TLRs consist of two circular conducting bands intersected by diagonally opposite gaps and deposited on both sides of a low‐loss dielectric substrate, which may be flexible.…”