Abstract: An antenna device for a direction finder includes a substantially grounded conductive base plate, a plurality of web-shaped antenna elements mounted in spaced relation on the base plate and having central portions extending in crisscross relation and insulated from each other, an electronic switching circuit for alternately grounding ends of the antenna elements and picking up reception outputs from opposite ends of the antenna elements at a constant period with the antenna elements being switched out of phase at an angle corresponding to the angle at which the antenna elements extend across each other, and a circuit for combining outputs from the antenna elements. According to another embodiment, the antenna elements comprise the web-shaped antenna elements and a vertical antenna element disposed substantially centrally in the web-shaped antenna elements.

Abstract: An automatic direction finder capable of measuring a direction with a higher accuracy is disclosed. In an initial measurement, loop antennas and a vertical antenna are used in a conventional manner. However, in a final measurement the vertical antenna adversely affected by the surrounding disturbances is not employed and only the loop antennas are used. The disclosed finder includes a switching device for disconnecting the vertical antenna in the final measurement. The finder is also provided with a pair of search coils disposed perpendicular to each other. One of the search coils is connected to a combining circuit via the switching device, while the other is connected to the combining circuit via a balanced modulator.

Abstract: In an antenna device for a direction finder including an electrically conductive antenna plate of a configuration symmetrical around its center and disposed in parallel with a base plate with a predetermined distance maintained therebetween, a plurality of pairs of connecting portions are provided around the antenna plate so that one in each pair is provided opposite to the other with respect to the center. An electronic switch provided in the device transfers the connection in order that one in a pair thus transferred is grounded through a resistor having the characteristic impedance of the antenna plate while the other in the pair is connected to the receiver of the direction finder through a cable having the characteristic impedance.

Abstract: A radio direction finder, which is designed to determine the direction of arrival of a radio wave by causing the rotation of a directional antenna arrangement or a goniometer, to which the output of the directional antenna arrangement is coupled, or rotating the directivity by an electric means and combining the output of the directional antenna arrangement or goniometer and the output of a non-directional antenna. With this system, it is possible to detect and display the bearing of the received radio wave with a higher place counter and precisely track and display the second bearing of the wave with a lower place counter.

Abstract: A bearing measuring system for determining the direction of arrival of a wave by rotating directional antennas or a goniometer to which the directional antennas are connected or rotating the directivity of such directional antennas or goniometer by electric means. The receiver of bearing measuring system of the type disclosed is usually constructed to determine the bearing of an amplitude modulated wave while confirming information about arriving waves. With a single receiver for frequency modulated waves it has been difficult to determine the bearing from adding the outputs of the directional antennas and the output of a nondirectional antenna while confirming information about arriving waves. With the system according to the present invention, it is possible with a single receiver to determine the bearing of the aforementioned frequency modulated waves while confirming information about the waves.

Abstract: A radio direction finder, designed to determine the direction of arrival of radio waves utilizing a nondirectional antenna and a plurality of directional antennas having respective directivities, comprises an oscillator for producing A.C. signals having a phase angle in correspondence to the configuration of each of the directional antennas, modulators for modulating the respective outputs of the directional antennas with respective A.C. signals, a additive circuit for superimposing the respective modulation outputs on the phase-shifted output of the nondirectional antenna, and a receiving circuit for demodulating the added output of the additive circuit to recover the A.C. signals. The radio direction finder is further characterized by an automatic phase tracking counter for following the phase of the output of the receiving circuit, and a display unit for displaying the bearing of the received radio wave numerically.