Blockers working principle is as follows: At a certain frequency range, cell phones and base stations linked by radio waves, in a certain way of baud rate and modulation complete data and voice transmission.
Meaning: the influence of the external electric field of instruments and equipment in order to avoid, or to avoid electrical equipment of the electric field to the outside world, the influence of the electric field with a cavity conductor cover, make its internal is not affected, nor make electrical equipment affect the outside world, this is called the electrostatic shielding. Outside the cavity is not grounded conductor shielding for shielding, cavity within the conductor earthed shielding for shielding.
In the condition of electrostatic equilibrium, whether it's hollow conductor or solid conductor; No matter how much charged conductor itself, or whether the conductor in electric field, equipotential body, for its internal field intensity is zero, this is the basic theory of electrostatic shielding.
Electrostatic shielding are of significance of two aspects, one is of practical significance: block to make the working condition of the instrument or a metallic shell is not affected by external electric field, also does not influence the external electric field. Some electronic devices or measuring equipment for interference cancellation, all want to practice the electrostatic shielding, such as indoor high voltage equipment hood grounded metal hood or relatively dense metal net, electronic worked metal shell. And as a full-wave rectifier or bridge rectifier Power transformer, between the primary and secondary windings wound a layer of metal chips on the package or enameled wire and grounding, shielding effect. In the high voltage live working, workers put on a metal wire or conductive fibers are brought, can shield effect to human body. In that time we need Indoor Jammers .In the static experiments, because there are about 100 v/m near the earth vertical electric field. To exclude the electric field research on the role of electronics, electronic under gravity movement only, you must have the eE < 10-10 v/m, this is a little "electrostatic vacuum electrostatic field, the only to draw into a vacuum cavity for electrostatic shielding can be achieved. In fact, from a closed cavity conductor implementation of electrostatic shielding is very effective.