Proposal and theoretical evaluation of the active shield with self-tunable loop current array

Goleman, K.; Sasada, I.

doi:10.1109/tmag.2005.855193

Cited by 6 publications

(5 citation statements)

References 1 publication

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“…In the shield design, overcompensation factor k has to be found in iterative calculations using method described in [4]. An important assumption in the simulations was that the locations of the disturbing source placement and area to the shielded are known.…”

Section: Self-tunable Loop-current Array Shielding Modulementioning

confidence: 99%

“…An axial component of the magnetic field generated by loop current can be calculated using following expression [4]:…”

Section: Improvement Of the Cancellation Performancementioning

confidence: 99%

“…A self-tunable loop-current array active shielding module was proposed in [3] and preliminary numerical verification was presented in [4]. The idea of this system is that disturbing magnetic fields coming to the shielded area are superimposed by an inverse magnetic field generated by the array consisting of several loop-currents.…”

Section: Introductionmentioning

confidence: 99%

“…This will provide shift of the best cancellation area largely apart from the array. In our previous investigations shown in [3][4][5], we used small overcompensation coils of the radius Rover and having n turns wound around magnetometers in the opposite direction and connected in series with the main loop-current (see Fig. 1b).…”

Section: Introductionmentioning

confidence: 99%

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Improvement of the cancellation performance of the loop-current array shielding module

Goleman

Sasada

2007

J. Magn. Soc. Jpn.

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Cancellation performance of a loop-current array shielding module depends on the overcompensation method used to adjust current in the loops. In previous experiments we used a single value as an overcompensation factor to all of the loops in the array. In this paper a new method of the overcompensation is proposed and verified numerically. In this method overcompensation factors are calculated independently for each of the loop-current. Simulation results show almost two times improvement in the attenuation ratio and 6-8 times expanding of the best cancellation area by the new method. An example of the implementation of the proposed overcompensation method is described in the paper.

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Section: Self-tunable Loop-current Array Shielding Modulementioning

confidence: 99%

“…An axial component of the magnetic field generated by loop current can be calculated using following expression [4]:…”

Section: Improvement Of the Cancellation Performancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Improvement of the cancellation performance of the loop-current array shielding module

Goleman

Sasada

2007

J. Magn. Soc. Jpn.

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“…, attenuation of high‐power pulses and transmission of low‐power continuous waves have been simultaneously obtained in a shielding with the implementation of diodes and RC circuits. In the kilohertz range, a magnetometer‐loaded metallic loop array was presented as an active shielding . In addition, variable‐capacitor loaded loop arrays were stacked as an anisotropic medium for enhancing the shielding effect .…”

Section: Introductionmentioning

confidence: 99%

Null‐spot control of magnetic field enabled by manipulating current distribution in metallic loop array

Banerjee¹,

Tanaka

Iizuka

2015

Micro & Optical Tech Letters

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Loading a capacitor into a metallic loop allows one to tune the resonance frequency of the induced current on the loop and enhance the current amplitude for the normally incident magnetic field. We show that in an array of variable‐capacitor‐loaded loops, a null spot of the magnetic field generated some distance away can be moved laterally and crossed the array by manipulating current amplitude of each loop via the variable capacitor. We develop an analytic model for expressing the curl of the current source on the loop by using the delta function so that the magnetic field behavior in the vicinity of the array is characterized together with physical insight. Moreover, the control of a null spot is explained by the decomposition of the curl of current sources. The concept of a null‐spot control is crucial for manipulating the kilohertz/megahertz magnetic field. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2891–2895, 2015

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Experimental verification of the performance of the self-tunable loop-current array shielding module

Goleman

Yamato

Sasada

2006

Journal of Applied Physics

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An active shielding module consisting of a self-tunable loop-current array is verified experimentally. Loop currents in the array are independently controlled by the magnetometer dedicated to each of them. Since magnetic field decays as 1∕z3 along the distance z from the loop, the magnetic noise should be overcompensated at the location of the loop-current array to provide a good cancellation in the shielded area. In order to enable overcompensation in a stable feedback system, a small additional loop is combined to the magnetometer that reduces the magnetic direct coupling from the main loop current to the magnetometer. A feedback electronic circuit with a proportional-integral (PI) controller is combined with each of the array element to establish a stable canceling operation. An orthogonal fluxgate magnetometer is used to monitor incident magnetic noise. Shielding performance of an array consisting of nine loop currents arranged in a 3×3 grid was evaluated numerically and confirmed by experiments. Evaluation and measurements are done over the 1.5×1.5m2 area 2m in front of the array. The magnetic dipole disturbance source is placed 2m further beyond the array. Attenuation of the magnetic field is calculated as 1∕15. Experimental data show 1∕10 attenuation.

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Proposal and theoretical evaluation of the active shield with self-tunable loop current array

Cited by 6 publications

References 1 publication

Improvement of the cancellation performance of the loop-current array shielding module

Improvement of the cancellation performance of the loop-current array shielding module

Null‐spot control of magnetic field enabled by manipulating current distribution in metallic loop array

Experimental verification of the performance of the self-tunable loop-current array shielding module

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