RF Solenoid with Extended Equiripple Field Profile

Field modulation effects induced by sample spinning: application to high-resolution magic angle spinning NMR

“…One approach to increase the RF homogeneity of the solenoidal coil was to vary the pitch angle of the solenoidal windings or the width of the coil wire [51][52][53]. Leifer [54] proposed an inverse strategy to optimize homogeneity of the RF-field in 6 and 10 turn coils with diameters larger than 10 mm operating at frequencies of 85 and 21 MHz, respectively. By using Chebyshev polynomials to describe the field, he uses an inverse technique proposed by Turner [55] to derive the current distribution that generates the desired field and, in turn, from the current distribution the positioning of the nonequidistant windings can be derived.…”

A large volume flat coil probe for oriented membrane proteins

“…Proper balancing of the RF circuit was essential for maintaining good 1 H B 1 field homogeneity in such an electrically long coil during cross-polarization experiments. If desired, B 1 uniformity at both frequencies can be further improved (at some expense to the 15 N channel efficiency) by varying the pitch of sample coil [30][31][32] with the wider gap between the 2nd and 3rd turns of the sample solenoid.…”

A novel low-E field coil to minimize heating of biological samples in solid-state multinuclear NMR experiments

“…5, the solenoidal coil with a variable pitch has a higher B 1 homogeneity than the regular solenoid [12,35], but also a slightly decreased maximum value. The improved homogeneous plateau of the Z coil exhibits simultaneously a slight decrease of the maximum value of the ball shift in the coil center when compared to the regular solenoidal coil.…”