Our active magnetic shielding systems are used primarily for reducing powerline magnetic fields.
They are effective for both transmission and distribution lines, overhead or underground. Within a defined area, the magnetic field can often be reduced to a very
low level. While passive shielding using metal plates is commonly used for single rooms, active shielding is usually the only
practical approach to power line field mitigation at the whole-building level. Similar technology is commonly used for room-level
field reduction for scanning electron microscopes (SEMs) and other electron beam devices, but our work is limited to wide area,
building level applications. We currently have systems installed and operating throughout the U.S., Canada, Israel, and Sweden, in commercial, school, and residential environments.
Significant misconceptions exist about the true nature of active magnetic shielding
(active cancellation) and its use as a field reduction modality. This is partly because magnetic field remediation techniques are poorly
understood by many people, and partly because, until recent years, active shielding has seen limited use outside the laboratory environment.
The problem is exacerbated by the availability of outrageous products on the consumer market which claim to cancel EMF through various unexplained
means, but which in reality do nothing at all.
A magnetic field can be thought of as a force that has both strength and direction. If it is met with
an equal force of exactly opposite direction, the forces will cancel and the net force will be zero, within a defined area. This is the
basic principle of active cancellation. Fundamental principles of physics are applied in the real world to solve a problem. The term
"cancellation" is sometimes taken to mean complete elimination, but this is never achieved. Rather, EMF cancellation efficiencies of
65% to 90% are typical. From this perspective, the term "active magnetic shielding" is perhaps more appropriate, although both terms
can be used interchangeably.
The systems that we install consist of three basic elements: (1) a sensor to monitor the power line
field, (2) a control and power unit, and (3) an external loop network. The system tracks the power line field and instantaneously adjusts
to compensate for changes that normally occur due to load variation on the line. In large commercial or school applications, our systems
can supply virtually unlimited power, with adjustable phase compensation for improved stability and increased cancellation percentage.
In many cases, the external loop network can be placed underground where it is obscured from view. In other cases, above-ground components
such as poles and cables are required. We strive to harmonize the visual aesthetics of the design with the outdoor environment and architectural style prevailing at the site.
Total costs for a residential
system are typically in the $10,000 to $25,000 range. Systems for schools or commercial buildings can run from $20,000 to $250,000 or more,
depending on size and system complexity. This technology can represent a viable solution for powerline magnetic field reduction in cases where
no other possibilities exist.
For any active cancellation / active shielding system, the challenge to producing good
performance is design of the loop network that produces the counter field. This is completely unique to each job. The specialized
cancellation equipment is an essential element, but it is secondary to loop design. EMF Services has performed pioneering work to
develop field projection arrays which eliminate the need to surround the treated area with a cable loop. We have also addressed
issues of elliptical polarization, strong field gradients, inductive delay, and spatial phase variance, which in the past have
limited effective deployment of active EMF cancellation on a large scale.
The primary limitation to deployment of such a system is inadequate free space surrounding
the area where field reduction is desired. A preliminary determination of the applicability of active magnetic shielding for your
location can sometimes be made from a review of measurement data, photos, and a sketch showing building and lot dimensions.
However, this is not a packaged system that can be purchased and installed by the customer. Each application is unique because
field intensity, field angles, and available space vary widely. Therefore, all systems are custom designed to match the field
conditions at the site, and installed by local contractors under our direct supervision. Commercial, school, and residential
client references are available.
Active Shielding / EMF Cancellation Job Photos
Performance Examples:
