Abstract: An electronic game apparatus which includes a playing board having a playing surface and playing areas and is capable of identifying game pieces and their position on the playing surface. First and second sets of parallel transmission lines are located beneath the playing surface of the playing board. The second set of parallel transmission lines is orthogonal to the first set of transmission lines. The first and second sets of transmission lines form intersecting points which are positioned proximate to a playing area of the playing surface. A source of electromagnetic energy has a plurality of predetermined different frequencies within a predetermined frequency range. A plurality of game pieces, each containing a resonant circuit having a predetermined resonant frequency, correspond to a frequency within a predetermined frequency range. A selector sequentially supplies electromagnetic energy at a selected frequency within the predetermined frequency range to the first set of transmission lines.

Abstract: A phase-locked semiconductor laser array having a plurality of lasing regions includes phase-shifting means on the emitting surface thereof through which laser light is emitted. The phase-shifting means provide a phase shift for those laser beams passing therethrough so that the phases of all the emitted laser beams are substantially the same. The phase-shifting means include a coating on the emitting surface which has a spatially varying thickness in the lateral direction.

Abstract: A composition providing effective electromagnetic/radio frequency interference (EMI/RFI) shielding is disclosed. The composition comprises a plastic material, preferably a thermoplastic resin, suitable additives such as lubricants, stabilizers and the like, and a conductive component consisting of a mixture of finely divided conductive carbon black and graphite.

Abstract: In a record playback system, such as a video disc player, there is tendency to radiate energy at a given frequency from the vicinity of the stylus where the stylus passes through the carriage bottom during playback. A first radial transmission waveguide path is provided in association with the carriage bottom. A second radial transmission waveguide path is provided between the carriage bottom and the record. The first and second paths are made to differ from one another by 180 electrical degrees. There is thus a reduction in radiated energy at the given frequency in the radial location which forms the common end of the first and second paths by signal cancellation at this common location.

Abstract: An RF gasket for reducing the flow of energy in the interface area between two conductive surfaces includes a plurality of stub pairs. These stub-pairs are dimensioned to form sub-groups of low impedance paths between the two conductive surfaces with each sub-group being effective in a different frequency sub-band of a large frequency range. The low impedance paths are established without the use of direct current connections between the two conductive surfaces. Such a gasket provides a broadband, non-contacting RF shield in the interface area between the two conductive surfaces.

Abstract: An RF shielding gasket is provided for establishing low impedance paths, in a given frequency range, in the interface area between two conductive surfaces. The gasket includes a first and second plurality of stubs. The stubs are joined to one another by a conductive member. The stubs are open circuited at one end and connected to the conductive member on the other end. Each stub is folded back upon itself between the two ends. In the interface area, portions of each of the conductive surfaces function as ground planes and a first and second plurality of microstrip lines are thus provided. The open circuits are transformed into low impedance paths, in the frequency range of interest, between the second end of the stubs and the portions of the first and second conductive surfaces. In one embodiment, the stubs and conductive member are formed into a substantial U-shape with a resilient core in the central volume to form a compact RF gasket.