Abstract: A multiple layer printed circuit board and a method of manufacturing multiple layer printed circuit boards which incorporate integral edge shielding in combination with top and bottom shielding to effectively provide a sandwich arrangement within a Faraday Cage. Electromagnetic emissions radiating from an outside surface of either the top or bottom shielding layer are substantially reduced. In one structure, a multiple layer printed circuit board having a sandwich arrangement which includes at least one inner conductive layer for providing a ground plane disposed between the outer shielding layers, the inner conductive layer being electrically connected directly to the edge shielding means and hence to the outer conductive layers. The larger and more continuous surface area provided by the direct connection to the edge shielding effectively provides an electrical connection having a low inductance and hence in operation results in all ground planes having a more constant non-varying potential.

Abstract: A multiple layer printed circuit board and a method of manufacturing multiple layer printed circuit boards which incorporate integral edge shielding in combination with top and bottom shielding to effectively provide a sandwich arrangement within a Faraday Cage. Electromagnetic emissions radiating from an outside surface of either the top or bottom shielding layer are substantially reduced. In one structure, a multiple layer printed circuit board having a sandwich arrangement which includes at least one inner conductive layer for providing a ground plane disposed between the outer shielding layers, the inner conductive layer being electrically connected directly to the edge shield and hence to the outer conductive layers. The larger and more continuous surface area provided by the direct connection to the edge shielding effectively provides an electrical connection having a low inductance and hence in operation results in all ground planes having a more constant non-varying potential.

Abstract: An interface for differentially driven twisted pair cable provides for inductive and capacitive coupling of a differential drive signal to respective conductors of the twisted pair. Two input tracks have a terminating resistor at a far end whose value equals the characteristic impedance of the respective track. An output track having two branches provides connection at the near end to the twisted pair cable, the far ends being connected by a terminating resistor whose value is equal to the impedance of the twisted pair cable. The output branches parallel the input tracks for a coupling length L.sub.C.

Abstract: A backplane databus and bussing method provide multidrop signal distribution using capacitive and inductive coupling of a main signal. A main signal loop on the backplane has a plurality of coupling loops coupled thereto for a respective length L.sub.C. The main signal, typically a NRZ trapezoidal shaped waveform is coupled into the coupling loops as a bipolar signal. The main signal loop is terminated by a resistor having a resistance equal to the characteristic impedance of the track forming the main signal loop. Similarly, the coupling loops are terminated at a far end by resistors whose impedance is equal to the characteristic of the track forming the coupling loop. The near end of the loop is connected to a receiver having a matching input impedance.

Abstract: Apparatus for measuring electromagnetic radiation from an electronic component in which a transverse electromagnetic cell has a coaxial connector for receiving radiation, a septum extending from the connector to a facing wall of the apparatus, the facing wall having a flat surface and formed from ferrite particles dispersed through rigid material. The rigid material is ceramic and conveniently the facing wall is made from ceramic tiles incorporating the ferrite particles. With this wall structure, the apparatus may be of small size suitable for measuring radiation or electronic chips or connector assemblies.