JPS6217673A - Antenna apparatus of direction finder - Google Patents

Abstract

PURPOSE:To enable the taking-out of a use frequency signal with high sensitivity by earthing signal with low frequency such as atmospherics and selecting a shortcircuit bar setting point, by respectively earthing doublet antennae to the housing at the central part of the antenna apparatus by feeders. CONSTITUTION:In order to measure a radio wave arrival direction, the doublet antennae 3 of plural sets of antenna elements are arranged in a ring form. These doublet antennae 3 are respectively earched to the housing 1 provided to the central part of an antenna apparatus by feeders 2a, 2b through a shortcircuit bar 5. The nodes of the antennae 3 and the feeders 2a, 2b are set as the take-out points of receiving signals through a coaxial cable 7 and the impedances at said points are matched corresponding to use frequency by an impedance matching part 6 such as a matching transformer. By this constitution, a signal having low frequency such as atmospherics is earthed and no induced voltage is generated and the damage of electronic parts is prevented. Further, the impedance of each antenna is optimumly selected and a signal with use frequency is led out with high sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an antenna device for a radio direction finder that measures the arrival direction of radio waves.

[Conventional technology]

So-called Doppler direction finding has been put into practical use by sequentially electronically switching the receiving output of multiple vertical omnidirectional antennas arranged in a ring, amplifying and detecting the phase changes in the received signals of each antenna, and determining the direction of arrival of radio waves. There is.

[Problem that the invention seeks to solve]

The antenna electronic switching device used in this type of direction finder mainly uses semiconductor elements such as diodes, which has the problem of being damaged by static electricity and electromotive force of radio waves.

Due to the characteristics of radio waves, airborne loose equipment in particular in high frequency bands is often installed at high places, so this type of accident inevitably increases, and repair is extremely difficult because it is installed at high places. Currently, countermeasures against these accidents are required.

The present invention eliminates the above problems and provides an antenna device for a direction finder that can be used with peace of mind.

[Means for solving problems]

The present invention comprises each antenna constituting an antenna device as a doublet antenna, and provides a feeder consisting of two parallel conductor rods that are commonly grounded at the center at the output points of each of the seven antennas, and a specific point of this feeder. The above-mentioned problem can be solved by providing means for short-circuiting with a short-circuiting bar.

[Effect]

By grounding each antenna in common at the center of the antenna device, relatively low frequency signals such as static electricity can be completely grounded, and by selecting the setting point of the shorting bar, signals in the frequency band used can be detected with high sensitivity. Make it available.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings.

tlS1 and FIG. 3 show the antenna device of the present invention,
A structural schematic diagram showing one embodiment of a plurality of antenna elements having the same structure. 1 shows a part of the metal casing which is located in the center of the antenna device and houses an electronic switching device etc. 2 shows an aluminum tube. The feeder is constituted by a conductor rod such as, and one end is grounded to the central casing, and the other end is connected to the doublet antenna element 3 with screws 4 or the like. Reference numeral 5 denotes a shorting bar of the feeder 2, which can be moved and fixed at a desired position on the feeder. 6 is an impedance matching section composed of a matching transformer, etc., which connects the doublet antenna 3, the feeder 2a,
It is inserted between the connection point of 2b and the coaxial cable 7.

The other end of the coaxial cable 7 is connected to an electronic switching device (not shown). 8 is an arm made of insulating material that protrudes from the central housing 1 and supports the feeders 2a, 2b, gables 3, etc. 9 is a hollow metal pipe through which the coaxial cable 7 is passed.

FIG. 2 is an electrical system diagram showing one embodiment of the antenna device of the present invention. 11 indicates a doublet antenna element;
Reference numeral 12 indicates a feeder arranged radially from the central housing. Reference numeral 13 indicates a shorting bar of the feeder 2. The shorting bar 13 is moved over the feeder 12 to connect the doublet antenna 11 and the feeder 12 between the junction points a and a'. Impedance can be optimally adjusted for the frequency band used. A matching transformer 14 impedance-matches the received output of the doublet antenna 11 and sends it to the coaxial cable 15. Reference numeral 16 denotes an electronic switching device, which is composed of a switching circuit such as a diode, and 17, a plurality of sets of antenna element circuits, each of which is composed of the same circuit. With the above configuration, the output of the doublet antenna 11 is completely grounded by the feeder 12 at low frequencies, so relatively low frequency signals such as static electricity and radio waves are almost completely grounded, and are caused by static electricity and high power radio waves. Since the induced voltage is kept extremely low, damage to the diode of the electronic switching device in the antenna device can be prevented.

Figure 3 shows another embodiment, in which a plurality of short-circuiting relays are used instead of the feeder shorting bar in the embodiment of Figure 1, and one of the relays is selectively operated according to the frequency. It is.

When the reception band of radio waves is wide (for example, 20MHz to 500MHz)
H11z) has doublet antenna 11 in Figure 2.
Since the impedance between the connection point a and a' of the feeder 12 and the feeder 12 changes depending on the frequency, it is necessary to set the impedance at an appropriate interval (Fig. 3) so that the feeder 12 is always short-circuited at the optimum position according to the frequency used. Multiple sets of feeder short-circuit relays 3
Place A as shown.

In FIG. 3, the contact terminals of relay A are fixed with screws between two feeders 2a and 2b at both ends via hollow vibrator 9. Each power line B, C of relay A is connected to feeder 2a, 2
This power line B leads to the metal conductor 1 through the hollow part of b.
, C are connected to a power supply device (not shown) that can select one of them according to the reception frequency and supply power.

When radio waves are received in this way, multiple short-circuit relays A
In order to select and operate the relay in the optimum position, the impedance of the junction point a-a between the doublet 7 antenna 11 and the feeder 12 in Fig. 2 is always kept in the optimum state for the operating frequency, as described above. can be used in,
This makes it possible to achieve a wideband antenna. Although an example has been described in which a relay is used instead of a shorting piece, a diode or a transistor may also be used. If the space between the feeders 2a and 2b is narrow, one relay may be used.

〔Effect of the invention〕

As explained above, in the present invention, the doublet antennas arranged in a ring are each grounded to the central casing of the antenna device by a feeder, so relatively low frequency signals such as static electricity and radio waves are completely eliminated. Since it is grounded and no induced voltage is generated, not only are accidents caused by static electricity and radio waves caused by electronic components of the device extremely reduced, but the impedance of the antenna can be optimally selected for signals in the frequency band used, increasing sensitivity. It is extremely effective as an antenna device for this type of purpose because it can construct an antenna device with good performance.

[Brief explanation of drawings]

1 and 3 are structural schematic diagrams showing one embodiment of a plurality of antenna elements having the same structure in the antenna device of the present invention, and FIG. 2 shows an embodiment of the antenna device of the present invention. FIG.

Claims (1)

[Claims] In Doppler direction finding equipment, multiple sets of tablet antennas are arranged in a ring, and the output of each antenna is electronically switched to amplify and detect changes in phase to determine the direction of arrival of radio waves. A plurality of sets of feeders each consisting of two parallel conductor rods that are grounded are arranged radially, and the bases of the plurality of sets of vertical dipole antennas are directly connected to the other ends of the feeders, respectively, and are movable to the middle part of the feeders. An antenna device for a direction finder, characterized in that a shorting piece is attached to adjust the impedance of a connection point between the dipole antenna and the feeder, and the connection point is used as a reception signal extraction point.