The Faraday Screen

The Faraday Screen, also known as the Faraday shield, is an electrostatic shield commonly employed in receiver circuits to counteract capacitive coupling, a phenomenon where electrical signals unintentionally transfer between adjacent elements. This shield effectively isolates the receiver's sensitive components from external electromagnetic interference, ensuring the integrity of the received signal.

A typical Faraday Screen comprises a series of closely spaced metallic wires, each connected to a common grounding point at one end. This arrangement creates a conductive barrier that disrupts the electric field lines responsible for capacitive coupling. By grounding only one end of the wires, eddy current losses, which arise from the flow of induced currents within the conductive material, are minimized. As a result, the Faraday Screen effectively shields the receiver from external electromagnetic disturbances without introducing significant signal loss.

A Faraday screen can block out interference from nearby sources, such as other electronic devices or power lines. This can improve the quality of the received signal.

A Faraday Screen can be constructed by winding a large number of turns of very small insulated wire on a cardboard drum, which has first been treated with insulating varnish. The wire is wound as on any ordinary coil, then a coating of insulating varnish is applied to the winding. After it has dried, the coil is cut in half, along its length, and flattened out. The insulation is then removed from one end and the wires soldered together, as shown in figure 1.

Materials:

• Cardboard drum

• Insulating varnish

• Very small insulated wire

• Soldering iron

• Solder