JPS607546Y2 - Antenna device for secondary surveillance radar - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an antenna device for a secondary surveillance radar.

Conventionally, an antenna device for a secondary surveillance radar (hereinafter referred to as SSR) consists of a directional antenna and an omnidirectional antenna.The directional antenna is installed above the parabolic reflector in the primary radar, and the omnidirectional antenna is is placed apart from this reflector.

In such a secondary surveillance radar antenna device, a directional antenna rotates together with a reflector to directly radiate an interrogation signal to the aircraft, and a predetermined period of time (2 μs) is emitted from this signal.
A control signal is radiated from the omnidirectional antenna with a delay.

A response signal from the aircraft is received by a directional antenna and displayed on an indicator.

However, the beam-shaped electric field formed by the directional antenna is affected by the ground surface and has a drawback of poor roving characteristics.

The present invention eliminates such drawbacks, improves roving characteristics, and provides an antenna device that can improve SSR performance.

An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a parabolic reflector 2 in a primary radar such as an airport surveillance radar (ASR) is mounted on a rotating table 6 rotatably installed on a pedestal 4.

A horn 8 is installed in front of this reflector 2, and a primary radar signal is supplied from inside the pedestal 4 via a rotary joint and a waveguide 10.

Such a signal is radiated from the horn 8 to the reflector 2, and as the reflector 2 rotates, horizontal scanning is performed and the function of the primary radar is distantly related.

Further, a directional antenna 12 such as a Yagi antenna element is installed on the horn 8.

As shown in FIG. 2, this antenna 12 receives the output from the transmitter 20 through a circulator 22, a rotary joint 24,
An interrogation signal of the SSR is supplied via an electronic distribution switch 26 and a 180° coupler 27.

This directional antenna 12 is composed of two Yagi antennas, and these Yagi antennas are arranged facing the reflector 2 and spaced apart from each other by a predetermined distance with respect to the position of the horn 8.

The interrogation signal supplied to the directional antenna 12 is radiated via the parabolic reflector 2.

In addition, first and second antennas 14 and 16 made of a plurality of dipole elements and the like are provided in front and behind the reflector 2.

These antennas 14 and 16 have dipole elements arranged in a row in the vertical direction perpendicular to the directivity direction of the parabolic reflector 2, and a control signal separated from a switch 26 shown in FIG. 2 is distributed by a directional coupler 28, respectively. Supplied.

The electric field pattern shown in FIG. 3 is generated by the first and second antennas 14, 16 and the directional antenna 12.

FIG. 3a shows a horizontal electric field pattern, and FIG. 3 shows a vertical electric field pattern. Therefore, the electric field 30 of the interrogation signal from the directional antenna 12 has a directional pattern shape, and the first and second antennas Electric field 32 of the control signal by 14, 16
is formed as a bidirectional pattern in front and behind the parabolic reflector 2.

Directional antenna 12 and first and second antennas 14.
16 is rotated together with the parabolic reflector 2, and a response signal from the aircraft is received by the directional antenna 12 via the reflector 2.

As explained above, according to the present invention, since the interrogation signal is radiated via the parabolic reflector 2, the electric field pattern 3
The roving characteristics at zero can be made good, and the vertical angle electric field distribution state of the interrogation signal and control signal can be approximated by the reflector 2, making it possible to match the roving notches, which improves the performance of SSR. can be done.

The directional antenna 12 is configured by two Yagi antennas arranged apart from each other as in the illustrated embodiment, and a 180° coupler 27 is used.
By receiving response signals from the aircraft in the same phase and opposite phase, the electric field direction pattern forms a sum pattern and a difference pattern, and the position (angle) of the aircraft is
The accuracy of information can be increased.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment of the antenna device of the secondary surveillance radar according to the present invention, Fig. 2 is a connection diagram showing the signal circuit of Fig. 1, and Fig. 3 a and b are horizontal views of Fig. 1. and a vertical electric field pattern diagram. 2... Parabolic reflector, 8... Horn, 12... Directional antenna, 14, 16...
...Omnidirectional antenna.

Claims (1)

[Scope of utility model registration request] a primary radar antenna having a parabolic reflector and a horn that feeds power to the parabolic reflector; a directional antenna that is provided on the horn portion of this antenna and feeds an interrogation signal to the reflector; An antenna device for a secondary surveillance radar, comprising first and second antennas arranged at the front and rear of the reflector and radiating a control signal forward and backward in the pointing direction of the reflector.