Abstract: A detectable device attachable to a movable item for detecting movement. Radio waves having a predetermined frequency are received by the detectable device, and radio waves having a harmonic frequency of the received waves are reradiated from the detectable device. The detectable device comprises a dipole antenna for receiving radio waves with said predetermined frequency, a diode connected in parallel to feed points of the dipole antenna for generating an electric current having a harmonic frequency of said received radio waves. A loop antenna is provided whose feed points are connected in parallel to feed points of the diode for converting the electric current having the harmonic frequency to radio waves for transmitting the radio waves at the harmonic frequency.

Abstract: A navigation apparatus utilizing a global positioning system having at least first and second satellite reception antennas installed on a navigation vehicle with a predetermined distance therebetween, a first azimuth computing unit for computing a first azimuth angle of the navigation vehicle from satellite radio waves received at the first and second antennas and a phase difference therebetween, a second azimuth computing unit for computing a second azimuth angle from a time change of antenna positions calculated from the satellite radio wave received at the first or second reception antenna, first and second multiplying units for multiplying outputs of the first and second azimuth computing units with predetermined coefficients respectively, an adding unit for adding outputs of the first and second multiplying units to produce a third azimuth angle, and a coefficient control unit for varying coefficient values of the first and second multiplying units in accordance with either the satellite arrangement or t

Abstract: A direction finding method and system for locating the direction of a transmission source based on an electromagnetic wave which is transmitted from the transmission source and is received by an antenna means at a receiving end apparatus. The transmission source transmits an angle-modulated wave. Meanwhile, the receiving end apparatus receives the transmitted wave, converts into electrical signals a beat frequency signal which is caused by direct and reflected waves contained in the received wave, and time-averaging the electrical signals, thus minimizing a angle error due to a multipass interference.

Abstract: The present invention pertains to a radiowave relay station in which image information or the like is transmitted by a helicopter from a first station to a second station. A direction finding device is provided which detects the direction of a transmitting source, i.e., a first station. The direction finding device calculates the vertical directional angle .phi. representing the direction of an incoming radiowave which is transmitted from the first station. This direction finding device allows the helicopter performing a relay function to fly rapidly to a contact point with the first station, i.e., in a vicinity of the first station. The direction finding device may also provide information to control an antenna driving portion for adjusting a receiving antenna located on the helicopter.

Abstract: A radome includes a radome member formed of a dielectric to protect an antenna element from outside space and a structural member formed of metal for supporting the antenna element at the center thereof and to which the radome member is joined at the periphery of the antenna element to support the radome member. When the radome member is formed of dielectric and the structural member is formed of metal, the junction therebetween serves as a kind of antenna and the radiation characteristic of the ordinary antenna element is disturbed. To solve this problem, a portion of the radome member through which an electric wave is transmitted is formed of material through which an electromagnetic wave having a frequency identical with that of the electric wave is transmitted and a junction formed between the radome member and the structural member has a structure for absorbing the electric wave.

Abstract: A high-frequency power divider having an input line, a pair of input-output lines, and a pair of high-impedance transmission lines diverging from the input line and interconnecting the first and second input-output lines. An isolation resistor is interposed between and connected to a pair of portions of the high-impedance transmission lines proximate the input-output lines. A capacitive component, corresponding to the capacitive component of the resistor, is provided at a diverging point at which the high-impedance transmission lines diverge from the first input-output line. The second capacitive component is defined by a capacitor or electrode surface.

Abstract: A high-frequency power synthesizing apparatus having a plurality of distributors arranged in a plurality of stages, a plurality of amplifiers which are supplied with outputs from a final stage of said power distributors and which amplify these outputs to a predetermined level, and a power synthesizing unit including initial-stage power synthesizers supplied with outputs from said amplifiers and a final-stage synthesizer which outputs power to an external load. The final-stage power distributors and the initial stage synthesizers are constituted by 0.degree.-hybrid modules. The output level of each amplifier is regulated and made constant by being compared with a predetermined level. The output levels of the amplifiers can be displayed on an external display.

Abstract: This invention relates to a push-pull transformer for use in a high frequency push-pull amplifier. This push-pull transformer has a coaxial line whose one end is connected to an input terminal, while the other end thereof is provided with an internal conductor and an outer conductor, the internal and outer conductors being grounded through stubs. A capacitor having a proper capacity is connected between the internal conductor and the outer conductor whereby the push-pull transformer can be properly actuated in a low frequency range other than the frequency used without any necessity to enlarge the size of the stubs.

Abstract: A slotted waveguide antenna assembly includes a slotted waveguide, a dielectric beam shaper and reflectors which are fixed and held by a holder member.The dielectric beam shaper is formed from a pair of dielectric plate members. The dielectric plate members are so arranged that they are slightly closer at the forward ends than the base ends, thus providing a nonparallel arrangement. The inclination of the dielectric plate members is selected within a range of 0.8.ltoreq.d/D<1 (D: a distance between the dielectric plate members at the base portions, d: a distance between the dielectric plate members at the forward portions).The dielectric plate members have a thickness which produces a phase difference, between electromagnetic waves reflected by inner surfaces of the respectivie dielectric plate members that are opposite each other.

Abstract: The present invention is applied to a slotted waveguide antenna assembly which comprises a slotted waveguide having a plurality of slots, a reflector having an aperture in front of the slotted waveguide and reflecting radiated electromagnetic wave for forming directive beam, and a mounting portion for mounting the antenna assembly onto a place where the antenna assembly is to be installed.In such an antenna assembly, a fixing member is provided on the reflector at a position spaced from the slotted waveguide. The fixing member extends between the opposite walls of the reflector and fixed thereto. The fixing member has an end which projects outwardly from the wall of the reflector to form the mounting portion. The fixing member is sufficiently thin as compared with the working wavelength.The slotted waveguide antenna assembly may have a dielectric wave-guiding arrangement.

Abstract: Described is an antenna structure which reduces the side lobe level of a slot array antenna of the type using a dielectric plate as a director mechanism. A slot radiator is mounted on the vertical side of a member composed of metal plates and having a C-shaped side sectional shape, and a pair of parallel dielectric plates are projected to extend in the direction of the open end of the C-shaped member. Also, a pair of metal pent roof plates are provided to spread upwardly and downwardly from the open end edges of the C-shaped member on the outer side of the dielectric plates. The metal pent roof plates serve as reflecting plates for the radiation power from the slot radiator and thus the side lobe level is reduced to a practical low level.