Abstract: An electromagnetic wave absorbing sheet S is disclosed. The absorbing sheet S includes a laminated-structural layer of a nonwoven fabric sheet 10 and a metallic layer 22 such as iron, aluminums, copper or their alloy which is disposed on a bottom surface of the metallic layer 22. The nonwoven fabric sheet 10 includes non-metallic fibers 16 having no binding faculty, non-metallic binding fibers 14 having binding faculty which are melted by heat to bind neighboring fibers, and metallic fibers 12 having an irregular cross-section and being produced by shaving a metallic wire or rod, that are dispersed uniformly in the nonwoven fiber layer or layers.

Abstract: An electromagnetic wave absorbing sheet S is disclosed. The absorbing sheet S comprises a laminated-structural layer of a nonwoven fabric sheet 10 and a metallic layer 22 such as iron, aluminums, copper or their alloy which is disposed on a bottom surface of the metallic layer 22. The nonwoven fabric sheet 10 includes non-metallic fibers 16 having no binding faculty, non-metallic binding fibers 14 having binding faculty which are melted by heat to bind neighboring fibers, and metallic fibers 12 having an irregular cross-section and being produced by shaving a metallic wire or rod, that are dispersed uniformly in the nonwoven fiber layer or layers.

Abstract: An oscillation detecting apparatus for detecting an oscillation of a wireless repeater intervening between a base station and a mobile station brought in communication with each other through a TDMA system. The wireless repeater produces an input signal based on a radio wave transmitted from one of the base station and the mobile stations, and amplifies the input signal to produce an output signal. The output signal is transmitted from the wireless repeater to the other of the base station and the mobile station. The oscillation detecting apparatus comprises producing apparatus for producing a power level signal varied in proportion with an amplitude of the output signal. The power level signal is formed by, for example, an envelope of the output signal.

Abstract: In a roadside beacon system for transmitting to vehicles moving along roads, signals on position and direction, linearly polarizing antennas mounted to be stationarey either beside or above the roads and other linearly polarizing antennas mounted to be mobile on the vehicles. The downwardly transmitting stationary and the upwardly receiving mobile antennas have matching linear polarizations when the vehicle is traveling on the road adjacent to the antenna but a mobile antenna will have reduced sensitivity when moving on a road at a different angle.

Abstract: An antenna for vehicle mounting in a roadside beacon system comprising a ground plane, a shorting board transverse to the grounding plane and two antenna boards attached to the top of the shorting boards in parallel to the ground plane. Two signal feeding points are symmetrically placed in the ground plane on either side of the shorting board. Depending on whether the two signals are phase shifted with respect to each other the antenna gain pattern is directed sidewardly with high gain or upwardly with low gain.

Abstract: A roadside antenna system permitting the transmission of data to a vehicular navigation system and providing for the recalibration of positional data carried by the navigation system includes an antenna structure and transmitter system which permits the data transmission signal to be broadcast in a wide pattern. Meanwhile, the signal that provides for positional recalibration is broadcast in a high directivity signal or split beam. The positional accuracy of the navigator system is improved by performing the positional calibration only when intercepting the narrow beam pattern. Data transmission and reception can be carried out within a larger effective reception area without affecting the positional accuracy.

Abstract: A roadside beacon system having improved reliability in the face of multi-path fading and the presence of large vehicles or the like which shield or scatter the received signal. The roadside antenna is of the split beam type. In the navigation system on the vehicle, the received signal is divided into two parts. The first part is smoothed and its level detected to determine when the vehicle is approaching an antenna. The remaining signal is then employed directly to detect the null in the transmitted beam when the vehicle passes directly in front of the antenna.

Abstract: A protective lid is provided in front of an image-forming lens mounted on the forward end of a picture image transmission line which comprises plural optical fibers bundled in alignment to be remotely controlled from the back end of the transmission line for opening/closing so that the image-forming lens may be protected from particles, vapor or poisonous gas when the transmission line is used in such atmosphere, thereby preventing deterioration of the quality of picture images to be formed.

Abstract: Signals for controlling the discharge current and laser gas pressure are provided in predetermined combination in accordance with a selected laser output level.