JPH11142505A - Electronic scanning radar equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable control for increasing the receiving antenna gain in accordance with passage of time, with simple constitution, by shifting the timing for connecting switches, between a plurality of switches, and gradually increasing the number of antenna elements for synthesizing receiving signals, in accordance with time passage. SOLUTION: A high frequency signal is distributed to antenna elements by a distributer 11, and inputted in transmitting and receiving modules 131-13n connected with antenna elements 121-12n. In the modules, the signals are adjusted to have desired phases and amplitudes by phase shifters 141-14n and power amplifiers 151-15n, and fed to the antenna elements through circulators 161-16n. As to high frequency signals received by the antenna elements, the amplitudes and the phases are suitably adjusted by low noise amplifiers 171-17n and phase shifters 181-18n through the circulator. After the connection timing is shifted by switches 191-19n controlled by a receiving timing controller 22, the signals are synthesized by a synthesizer 20, and supplied to a receiver 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic scanning radar device used for an air traffic control device or the like.

[0002]

2. Description of the Related Art In a radar apparatus for transmitting a pulse-modulated high-frequency signal (hereinafter referred to as a pulse-modulated wave) and detecting a signal reflected from a target, a received power _Pr is represented by the following equation.

[0003] _{P r = P t G t G} r λ 2 (4π) -2 R -4 ··········· (1) P r: received power P _t: transmission power G _t: transmitting Antenna gain _Gr : receiving antenna gain λ: wavelength R: distance to target That is, when the distance to the target is large, the received power is small, and when the distance to the target is small, the received power is large.

On the other hand, in order to keep the target reception power constant,
When the distance is large, the receiving sensitivity must be large, and when the distance is small, the receiving sensitivity needs to be small. Therefore, since the time until the reflected signal returns after transmission is proportional to the distance, the reception sensitivity may be controlled immediately after transmission by decreasing the sensitivity and increasing the sensitivity over time. This is generally called STC (Sensitivity Time Control).

[0005] As a method of realizing the STC, conventionally, an RFSTC (Radiation Control) for controlling the gain of a high-frequency amplification stage of a receiver is known.
o Frequency STC) and IF that controls the gain of the intermediate frequency stage
There is an STC (Intermediate Frequency STC), in which a variable attenuator is provided in the path of a high-frequency signal or an intermediate frequency signal, and the amount of attenuation of the variable attenuator is controlled over time.

FIG. 7 is a block diagram showing an example of a conventional electronic scanning radar apparatus.

[0007] In FIG. 7, reference numeral 10 denotes a high-frequency signal generator.
Are distributed to the number of antenna elements, and the antenna elements 121 to 1
Input to the transmission / reception modules 131 to 13n connected to 2n. The phase and the amplitude are adjusted by the phase shifters 141 to 14n and the power amplifiers 151 to 15n inside the module, and supplied to the antenna elements via the circulators 161 to 16n.

On the other hand, the high-frequency signal received by the antenna element is transmitted to low-noise amplifiers 171-1 through circulators.
7n and the phase shifters 181 to 18n appropriately adjust the amplitude and phase, and the signals are combined by the combiner 20 and supplied to the receiver 21. At this time, a variable attenuator 26 is provided between the combiner 20 and the receiver 21 to realize RFSTC. 27 is an attenuation controller for controlling the variable attenuator.

However, a variable attenuator is difficult to obtain a large amount of attenuation. In particular, when the amount of attenuation is large, it is difficult to control the amount of attenuation accurately. Further, the attenuation controller 27 for controlling the variable attenuator needs to generate an accurate control voltage in synchronization with the radar transmission / reception timing.
A converter was needed and costly.

[0010]

As described above, in the conventional electronic scanning radar device, a variable attenuator is used to realize the STC, so that accurate control is difficult and costly.

[0011]

According to the present invention, there is provided an antenna array comprising a plurality of antenna elements arranged side by side, and the phase and amplitude of a pulse-modulated high-frequency signal supplied to the plurality of antenna elements are determined. In an electronic scanning radar device that forms a transmission beam by appropriately adjusting the phase and amplitude of a high-frequency signal received from a plurality of antenna elements and then combining them to form a reception beam. A plurality of switch means for connecting / cutting off the received high-frequency signal are provided in parallel, and the switch is cut off during a period in which a transmission pulse is supplied. And gradually increasing the number of antenna elements for synthesizing the received signal over time.

Further, the number of antenna elements for synthesizing a received signal is sequentially increased from one antenna element to an adjacent antenna element, and the antenna elements for synthesizing the received signal are arranged at continuous positions on the antenna array. It is characterized by having.

Further, the antenna array is divided into two or more antenna sub-arrays having less than the number of antenna elements, and the timing for synthesizing the received signal is shifted for each antenna sub-array.

Further, the antenna array is divided into two or more antenna sub-arrays having less than the number of antenna elements, and the number of antenna sub-arrays for synthesizing the received signal is sequentially increased from one antenna sub-array to an adjacent antenna sub-array. Are arranged at continuous positions on the antenna array.

Further, the antenna array is divided into two or more antenna sub-arrays having less than the number of antenna elements, and each antenna sub-array is arranged substantially concentrically from the center of the antenna surface, and the antenna sub-array for synthesizing the received signal is arranged on the antenna surface. It is characterized in that the number is sequentially increased from the central antenna sub-array toward the peripheral antenna sub-array.

Further, a switch means for connecting / disconnecting the received high-frequency signal is provided for each antenna element.

Further, a switch means for connecting / disconnecting the received high-frequency signal is provided for each antenna sub-array.

Further, the switch means for connecting / disconnecting the received high-frequency signal is realized by turning on / off a bias voltage of a receiving amplifier provided for each antenna element.

Further, the present invention is characterized in that the receiving sensitivity is controlled in proportion to the fourth power of the elapsed time after signal transmission.

The antenna gain of an array antenna is approximately proportional to the number of antenna elements to be combined. Therefore, according to the above configuration, the receiving antenna gain increases as time elapses, and STC can be realized.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electronic scanning radar apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of an electronic scanning radar apparatus according to the present invention. High frequency signal generator 1
The high-frequency signal generated at 0 and pulse-modulated
Are distributed to the number of antenna elements, and the antenna elements 121 to 1
Input to the transmission / reception modules 131 to 13n connected to 2n. Inside the module, the phase and the amplitude are adjusted to desired phases by phase shifters 141 to 14n and power amplifiers 151 to 15n, and supplied to the antenna elements via circulators 161 to 16n. On the other hand, the high-frequency signal received by the antenna element is appropriately adjusted in amplitude and phase by low-noise amplifiers 171 to 17n and phase shifters 181 to 18n via a circulator, and a switch 191 controlled by a reception timing controller 22 After the connection timing is shifted by .about.19n, they are combined by the combiner 20 and supplied to the receiver 21.

FIG. 2 is a graph showing a change in the number of reception combining elements and a change in the reception antenna gain with respect to time in the electronic scanning radar apparatus according to the present invention. The horizontal axis in FIG. 2 is time,
The vertical axis represents the number n of reception combining elements and the reception antenna gain _Gr . After the end of the transmission timing, when the number of reception combining elements is gradually increased, the reception antenna gain is gradually increased accordingly. At this time, if the number of receiving synthesis elements is made proportional to the fourth power of the time elapsed after the end of the transmission timing, the elapsed time is proportional to the distance to the target, and the receiving antenna gain increases in proportion to the fourth power of the distance to the target. However, during this time, the received power shown in equation (1) can be kept constant.

In the above embodiment, the number of antenna elements for synthesizing the received signal is sequentially increased from one antenna element to the adjacent antenna element, and the antenna element for synthesizing the received signal is located on the antenna array. It is good to arrange in a continuous position.

As described above, if the antenna elements for synthesizing the received signals are arranged at continuous positions on the antenna array, only some of the elements will be received if they are not arranged continuously. Has the effect of preventing the generation of grating lobes that occur when the signals are combined.

FIG. 3 is a block diagram showing another embodiment of the present invention. In the present embodiment, a distributor and a combiner are shared to form a distributor / synthesizer 23, and transmission / reception switches 241 to 24n are provided in the transmission / reception module. The timing controller 22 controls the transmission / reception changeover switches 241 to 24n in each module by shifting the timing of connecting the switches to the reception path side,
Similar effects can be obtained.

FIG. 4 shows an embodiment of a sub-array arrangement of the electronic scanning radar apparatus according to the present invention.

In the beam combining of the phased array, in order to keep the side lobes low, it is common practice to make the combined gain distribution of the antenna elements high at the center of the antenna array and low at the periphery. Therefore, if the antenna sub-arrays are arranged substantially concentrically from the center of the antenna surface and the number of antenna sub-arrays for synthesizing the received signals is sequentially increased from the antenna sub-array at the center of the antenna surface to the peripheral antenna sub-array, some sub-arrays Can maintain the above-mentioned combined gain distribution even when combining received signals, and can suppress the occurrence of side lobes.

In the above-described embodiment, the switch circuit is provided in the reception signal transmission path as means for connecting / cutting the reception signal. For example, the switch circuit is provided in the bias path of the amplifying element inside the low noise amplifier. It is also possible to realize a connection / shut-off function of a received signal by controlling on / off of this switch circuit.

FIG. 5 is a block diagram showing another embodiment of the present invention. Connect the received signal in the middle of the reception synthesis circuit /
By switching the switch circuits 251 to 254 to intervene and sequentially controlling the connection of the switch circuits by the timing controller 28, the number of received signals is switched in units of subarrays having a predetermined number of antenna elements. In the above configuration, FIG.
(A) to (d) show ON / OFF control timings of the timing controller 28 for the switch circuits 251 to 254, and (e) shows the reception antenna gain at that time. By thus increasing the number of reception combining elements in a stepwise manner, the reception antenna gain can be increased in a stepwise manner, and the STC can be realized with simpler control. This configuration is sufficient when controlling the number of reception combining elements for each subarray, and the number of switch circuits can be saved.

In the above embodiment, the number of antenna sub-arrays for synthesizing received signals is sequentially increased from one antenna sub-array to an adjacent antenna sub-array. It is good to be arranged in the position where it did.

With this configuration, the antenna elements that combine the received signals are arranged at continuous positions on the antenna array, which has the effect of preventing the occurrence of grating lobes.

[0033]

According to the present invention, it is possible to control the reception antenna gain to increase with time with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating the present invention.

FIG. 2 is a graph illustrating the present invention.

FIG. 3 is a block diagram illustrating the present invention.

FIG. 4 is a schematic plan view illustrating the present invention.

FIG. 5 is a block diagram illustrating the present invention.

FIG. 6 is a graph illustrating the present invention.

FIG. 7 is a block diagram illustrating a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... High frequency signal generator 11 ... Distributor 121-12n ... Antenna element 131-13n ... Transceiving module 141-14n ... Phase shifter 151-15n ... Power amplifier 161-16n ... Circulator 171-17n ... Low noise amplifier 181-18n ... Phase shifters 191-19n ... Switch circuit 20 ... Synthesizer 21 ... Receiver 22 ... Timing controller 23 ... Distribution / synthesizer 241-24n ... Transmission / reception switch 251-254 ... Switch circuit 26 ... Variable attenuator 27 ... Attenuation Controller 28 ... Timing controller

Claims (9)

[Claims] An antenna array is formed by arranging a plurality of antenna elements, and a transmission beam is formed by appropriately adjusting the phase and amplitude of a pulse-modulated high-frequency signal supplied to the plurality of antenna elements. In an electronic scanning radar device which forms a reception beam by appropriately adjusting the phase and amplitude of a high-frequency signal received from an antenna element, a switch means for connecting / cutting a high-frequency signal received from the antenna element is provided in parallel. , And this switch is turned off during the period when the transmission pulse is supplied,
An electronic scanning radar device wherein after the transmission period ends, the timing of connecting the switches is shifted among a plurality of switches, and the number of antenna elements for synthesizing the received signal is gradually increased as time elapses. 2. An antenna element for synthesizing a received signal is sequentially increased from one antenna element to an adjacent antenna element, and the antenna elements for synthesizing the received signal are arranged at continuous positions on the antenna array. 2. The electronic scanning radar device according to claim 1, wherein: 3. The electronic scanning radar device according to claim 1, wherein the antenna array is divided into two or more antenna sub-arrays having less than the number of antenna elements, and a timing of synthesizing a received signal is shifted for each antenna sub-array. . 4. An antenna array is divided into two or more antenna sub-arrays having less than the number of antenna elements, and the number of antenna sub-arrays for synthesizing received signals is sequentially increased from one antenna sub-array to an adjacent antenna sub-array. 4. The electronic scanning radar device according to claim 3, wherein the antenna elements that combine are arranged at continuous positions on the antenna array. 5. The antenna array is divided into two or more antenna sub-arrays having less than the number of antenna elements, each antenna sub-array is arranged substantially concentrically from the center of the antenna surface, and an antenna sub-array for synthesizing a received signal is arranged on the antenna surface. 5. The electronic scanning radar apparatus according to claim 4, wherein the number of the sub-arrays is sequentially increased from the central antenna sub-array toward the peripheral antenna sub-array. 6. The electronic scanning radar device according to claim 1, wherein switch means for connecting / disconnecting the received high-frequency signal is provided for each antenna element. 7. The electronic scanning radar device according to claim 3, wherein switch means for connecting / disconnecting the received high-frequency signal is provided for each antenna sub-array. 8. A switching device for connecting / disconnecting a received high-frequency signal is realized by turning on / off a bias voltage of a receiving amplifier provided for each antenna element. 7. The electronic scanning radar device according to 6. 9. The electronic scanning radar device according to claim 1, wherein the receiving sensitivity is controlled in proportion to the fourth power of an elapsed time after signal transmission.