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Doty RF Litz Coils What is A Litz coil? The Litz (woven) coil utilizes etched foil patterns with insulated crossovers to obtain rf flux transparency and improved S/N. Special symmetries permit an ideal current distribution that is compatible with high-frequency operation and is independent (to first order) of tuning, balancing, and matching adjustments. Homogeneity is excellent and tuning is simple. How does a Linear Litz coil compare to a Linear Birdcage? • Much Easier Tuning. Easily tuned and matched to a wide range of samples. Compatible with double-resonance multinuclear tuning, with little loss in efficiency or homogeneity. • B1 homogeneity is 10-40% better. • SNR is at least 10% higher - up to 30% higher. Up to 50% higher S/N in small 1H coils (below 30 mm), and up to twice the S/N for double-resonance. • Enormous B0 homogeneity advantage in small coils. Linewidth generally less than 0 .02 ppm, which may be an order of magnitude better than what is often seen in small birdcages. • Substantial cost advantage. When is a linear Litz Coil recommended over a CP Litzcage? The Litz coil is usually preferred for double-tuned coils. Also, small Litz coils at lower frequencies have equal or better homogeneity and S/N than quadrature coils. The ease of tuning and lower cost often make them the best choice for small coils. When is a CP Litzcage recommended over a linear Litz Coil? Usually for single resonance where the frequency-diameter product is greater than 9 MHz-m (e.g. a 30 mm coil at 300 MHz), but other factors include available space and budget. Preprint
available – RF
Coil Technology for Small-Animal MRI. Please contact sales with questions or quote requests. |
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