Abstract: A resistive-coupling type beam forming network for a multibeam array antenna involving symmetry in the arrangement of antenna elements and/or the arrangement of beams. In the network, a matrix is formed of distribution lines from four-phase splitters each receiving two input signals in the relationship of mutual complex conjugates and outputting four-phase signals, output summing lines and coupling resistors for coupling specific distribution lines with output summing lines. Owing to the fact that each four-phase splitter and each set of four distribution lines per splitter can be shared for two input signals of complex conjugates, and where the arrangement of beams or antenna elements on the output side has symmetry, each coupling resistor can be shared for two output signals of complex conjugates, the number of coupling points of the matrix is notably decreased, beam forming characteristics are improved and the size and weight of the whole network are reduced accordingly.

Abstract: A circular polarization antenna having wide-band circular polarization characteristics and impedance characteristics is accomplished by feedng N-antenna elements which are shifted at an interval of .pi./N rad. with respect to the boresight direction with differential phase shift of an interval of .pi./N rad. corresponding to the angular orientation of the antenna elements so as to obtain perfect circular polarization with respect to the boresight direction. This antenna construction can be applied to circular polarization antennas of various types, thereby allowing a wide-band circular polarization array antenna or an array antenna for dual orthogonal circular polarizations having high polarization discrimination to be achieved.

Abstract: The stability of reception of information signals in a low-quality radio communication circuit is notably improved by a method and apparatus of diversity reception which, by means of the local oscillation frequencies of a plurality of receiving systems, permits one or more coherently interrelated received signals to be phase-locked in the phase-lock loops of the respective receiving systems and which, when any of the phase-lock loops has accidentally lost the phase-lock of the received signals, enables the lost phase-lock loop to resume normal phase-lock by borrowing and using, as its own local oscillation frequency, the local oscillation frequency of the phase-lock loop of one of the remaining receiving systems still locking the phases of the received signals.

Abstract: An acoustic wave source and a radio wave source are installed close to each other on the ground. When an acoustic wave pulse is transmitted vertically into the atmosphere by the acoustic wave source, spherical wavefronts formed in the atmosphere by the acoustic wave are propagated upwardly at the velocity of sound. When a continuous radio wave is transmitted from the radio wave source toward the spherical wavefronts, it is reflected by the wavefronts and the reflected radio waves are converged to form a focusing spot on the ground. The position where the spot due to the convergence of the reflected radio waves is formed with the maximum intensity is detected by means of an antenna network formed of a multiplicity of receiving antennas laid out in the pattern of a lattice. The time-course change of such positions of the spots is traced to realize remote measurement of the height distribution of wind direction and speed in the atmosphere under surveillance.

Abstract: In digital telecommunication, the suppression of digital error noise contained in the signals received by the receiver is accomplished by subjecting the received signals to Fourier transform thereby to obtain a frequency spectrum, subtracting a predetermined flat spectrum from the amplitude spectrum of the frequency spectrum, subjecting the resulting difference to invert Fourier transform thereby to extract any digital error noise component and correcting the particular sampled signal containing the noise component by use of interpolation with respect to the preceding and following sets each of several sampled signals between which the particular sampled signal is interposed, whereby sampled signals free from the digital error noise are delivered as output signals.