A magnetoquasistatic field is a type of electromagnetic field characterized by a slowly oscillating magnetic field. Low-frequency induction from a magnetic dipole or a current loop is commonly used to generate a magnetoquasistatic field.
The term “magnetoquasistatic field” refers to a type of electromagnetic field that has both magnetic and electric field components, with the magnetic field being dominant and the electric field being relatively weak. This field is typically observed when the frequency of the electromagnetic waves involved is much lower than the characteristic frequency of the medium through which the waves propagate.
The magnetic near-field of such an emitter behaves differently than the far-field electromagnetic radiation that is more commonly used. Because the rate of change of the instantaneous field strength with each cycle is relatively slow at low frequencies, the term “magneto-quasistatic” was coined. The near field or quasistatic region typically extends no more than a wavelength from the antenna, and the electric and magnetic fields are approximately decoupled within this region.
The quasistatic approximation assumes that the electromagnetic field changes slowly with respect to time. This allows for simplifications in the mathematical description of field behavior. When it comes to the magnetoquasistatic field, it means that the time-varying magnetic field is dominant and the electric field can be ignored or considered negligible.
Weakly conducting non-magnetic bodies, such as the human body and many mineral rocks, are effectively transparent to magnetoquasistatic fields, allowing signals to be transmitted and received through such barriers. Long-wavelength (low-frequency) signals can also travel around corners more easily than shorter-wave signals. Communication does not have to be in direct line of sight.
The communication range of such signals is typically limited to a few tens of meters, depending on both the wavelength and the electromagnetic properties of the intervening medium at the chosen frequency.
Application
Practical applications of the magnetoquasistatic field include low-frequency magnetic field analysis, power distribution systems, electromagnetic compatibility studies, and certain types of magnetic sensors. It’s worth noting that the term “quasistatic” implies that the electromagnetic field varies slowly, but it doesn’t necessarily imply that it’s static.
Depending on the specific problem at hand, different mathematical models and techniques are used to analyze the behavior of a magnetoquasistatic field. Magnetic vector potential formulations, magnetostatic equations, and various numerical methods for solving the associated field equations are examples of these.
Overall, the concept of a magnetoquasistatic field is a useful approximation that simplifies the analysis of certain electromagnetic systems and phenomena, particularly those involving low-frequency magnetic fields.
