A single H-coil can provide accurate measurements of magnetic field strengths. The accuracy of the measurement depends on several factors, including the design and construction of the H-coil, the sensitivity of the measurement equipment, and the environmental conditions in which the measurement is performed.
Using multiple H-coils can be beneficial in certain situations, such as when it is necessary to measure the magnetic field in three dimensions or to obtain a more precise measurement by averaging the results from multiple coils. However, it is not essential to use multiple H-coils to obtain accurate magnetic field strength measurements.
