JPH09138271A - Electronic scanning radar apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electronic scanning radar apparatus in which an undesired sideband level is low, whose efficiency is high and which is small, lightweight and low-cost. SOLUTION: A high-frequency signal which is generated by a high-frequency- signal generation circuit 20 is distributed into (n) pieces of signals by a distribution route 13, the signals are switched and output respectively by switching circuits 211 to 12n so as to be converted into pulse modulation waves, and the waves are adjusted to a desired phase and a desired amplitude by nonlinear amplifiers 171 to 17n so as to be radiated from antenna elements 161 to 16n. In the respective switching circuits 211 to 21n, their ON/OFF changeover is timing-controlled by a timing controller 22. In the timing controller 22, the switching circuits 211 to 21n are turned on one by one in definite order when a pulse transmission waveform rises. Inversely, they are turned off one by one when the waveform falls. Thereby, the number of transmitting elements is increased or decreased sequentially.

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 As is well known, in a radar device that transmits a pulse-modulated high-frequency signal (hereinafter referred to as a pulse-modulated wave), a sideband due to pulse modulation is generated outside the occupied band of the radar, and this side band is generated. May give interference to other communication devices. In order to avoid this interference, in the conventional radar device, measures are taken such as adding a filter for sideband suppression, and slowing the rising and falling speeds of the pulse modulated wave to lower the sideband generation level. .

By the way, in an active electronic scanning radar device using an array antenna, an amplifier for amplifying a transmission pulse modulated wave is provided for each antenna element. Generally, an amplifier having a non-linear characteristic is used as the amplifier in order to increase the power added efficiency.

In such an electronic scanning radar device, it is difficult to use the above-mentioned method in order to suppress the side band. On the other hand, as will be described later, inserting a filter after each amplifier has the effect of increasing the cost and weight, but there is also an embodiment. That is, provision is made such that a filter for sideband suppression is provided at a location after the pulse-modulated-wave generation circuit, or a measure is added to the pulse-modulated-wave generation circuit itself to slow the rising and falling speeds. , Even if the sideband level of the pulse-modulated wave that is input to the amplifier provided for each antenna element is suppressed, the waveform envelope of the pulse-modulated wave is deformed due to the nonlinear characteristics of the amplifier, so the sideband level increases again. Therefore, a sufficient suppression effect cannot be obtained.

Therefore, it is conceivable that the above-mentioned sideband suppression method can be used by configuring the amplifier provided for each antenna element by a linear amplifier. FIG. 7 shows an example.

In FIG. 7, reference numeral 11 denotes a high frequency signal generator having a pulse modulation function (hereinafter referred to as a pulse modulation wave generation circuit). The pulse modulation wave output from this circuit 11 is a side band suppressing filter 12 Removes the sideband frequency band. The output of the filter 12 is divided into n by the distribution path 13, and then the phase shifter 14
Phase control is performed by 1 to 14n, and linear amplifiers 151 to 15n
Is linearly amplified by and is radiated from the antenna elements 161 to 16n.

That is, in this configuration, the sideband frequency is suppressed by providing the filter 12 at one position behind the pulse-modulated wave generation circuit 11 to suppress the sideband frequency, and the linear amplifiers 151 to 15n linearly amplify the sideband. It is radiated from the antenna elements 161 to 16n as it is.

However, in the above-mentioned configuration, since the power addition efficiency of the linear amplifiers 151 to 15n is low, the efficiency as an antenna device is lowered and a new problem that the amount of heat generation is increased occurs.

From this, it is possible to use a non-linear amplifier and provide a side band suppressing function behind it. FIG. 8 shows an example. In FIG. 8, the same parts as those in FIG. 7 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 8, n phase shifters 141 to 14 are provided.
The pulse-modulated wave whose phase is controlled by n is amplified by nonlinear amplifiers 171 to 17n, sideband frequencies are removed by sideband suppression filters 181 to 18n, and transmitted from antenna elements 161 to 16n.

However, in such a method, the number of filters and circuits to be added becomes enormous, so that the antenna device becomes large in size, and problems such as an increase in weight and cost arise.

[0012]

As described above, the conventional electronic scanning radar device has no effective means for suppressing unnecessary sidebands. An object of the present invention is to provide an electronic scanning radar device that has a low unnecessary sideband level, high efficiency, and is small, lightweight and inexpensive.

[0013]

In order to solve the above-mentioned problems, the present invention forms an antenna array by arranging a plurality of antenna elements, and the phase and the phase of a pulse-modulated high-frequency signal supplied to each antenna element. In an electronic scanning radar device which forms a transmission beam by appropriately adjusting the amplitude, a plurality of pulse modulating means for pulse-modulating a high frequency signal supplied to the plurality of antenna elements, and a pulse for the plurality of pulse modulating means. And a timing control means for controlling the rising and falling timings by shifting between the antenna elements.

In particular, the pulse modulation means is provided for each of the plurality of antenna elements, and the timing control means is
The rising and falling timings of the pulse of the pulse-modulated high-frequency signal supplied to the antenna element are sequentially raised and lowered from one antenna element to the adjacent antenna element, and the antenna element in the transmission state is on the antenna array. It is characterized by making it continuous with.

Further, when the antenna array is divided into a plurality of sub-arrays, the pulse modulation means is provided for each sub-array, and the timing control means determines the rising and falling timings of the pulses of the pulse modulation means in the sub-array. The feature is that they are shifted for each.

The timing control means sequentially raises and lowers the rising and falling timings of the pulse from one subarray to the adjacent subarrays with respect to the pulse modulating means, and the antenna element in the transmitting state is the antenna array. It is characterized in that it is made continuous in the above.

Specifically, a high frequency signal generator for generating a high frequency signal for transmission, a distribution means for distributing the output of the high frequency signal generator into a plurality of systems, and an intervening route in the path distributed by the distribution means. A plurality of phase shifters and non-linear amplifiers that adjust the phase and amplitude of the transmission signal are arranged in an array, and high-frequency signals whose phases and amplitudes are adjusted by the plurality of phase shifters and non-linear amplifiers are radiated into space. A plurality of antenna elements, and a plurality of pulse modulation means for performing pulse modulation on the transmission high frequency signal in the distribution path by the distribution means,
A timing control means for driving the plurality of pulse modulation means by sequentially shifting the rising and falling timings of the pulse is provided.

In this case, each of the plurality of pulse modulation means is a switch circuit, and the timing control means performs pulse modulation by controlling ON / OFF of the switch circuit.

Alternatively, each of the plurality of pulse modulation means is provided with a switch circuit in a bias path of an amplification element in each of the plurality of nonlinear amplifiers, and the timing control means performs pulse modulation by performing on / off control. Is characterized by.

That is, the electronic scanning radar device according to the present invention is configured so as to shift the rising and falling timings of the pulse of the pulse modulated wave supplied to each antenna element or sub-array of the antenna array.

According to the above configuration, the rising and falling speeds of the pulse-transmitted waveform radiated into the space from the antenna element and beam-combined are higher than the rising and falling speeds of the pulse-modulated wave supplied to the antenna element or the sub-array. It is possible to equivalently slow down. Therefore, unnecessary sideband levels can be suppressed.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an electronic scanning radar device according to the present invention will be described in detail below with reference to FIGS. In FIGS. 1 and 4, the same parts as those in FIGS. 7 and 8 are designated by the same reference numerals, and a duplicate description will be omitted here.

FIG. 1 shows the configuration of the first embodiment. Here, after the high frequency signal generated by the high frequency generation circuit 20 is distributed through the distribution path 13 described above, the switching circuits 211 to 21n perform switching. The output is converted into a pulse-modulated wave, and the phase shifters 141 to
14n, the non-linear amplifiers 171 to 17n adjust the phase and amplitude to desired ones, and the antenna elements 161 to 16n radiate them. Each switch circuit 211
The timing controller 22 controls the ON / OFF switching of the timings 21n.

In the above structure, FIG. 2A shows a change in the number of transmitting elements with respect to time by the timing control of the timing controller 22, and FIG. 2B shows a transmitting waveform at that time.

That is, in the timing controller 22, the n switch circuits 211 to 21n are turned on one by one in a fixed order at the rising edge of the pulse transmission waveform to change the number of transmission elements from 0 to n. On the other hand, when the pulse transmission waveform falls, it is turned off one by one, and the number of transmission elements is changed from n to 0.

At this time, since the transmission power radiated in the air is proportional to the number of transmitting elements, the rising and falling speeds of the pulse transmission waveform become slow as shown in FIG. Can be suppressed.

For comparison, FIG. 3 shows a change in the number of transmitting elements with respect to time in a conventional electronic scanning radar device and a rise of a pulse-modulated wave supplied to an antenna element as a countermeasure against sideband suppression. And the transmission waveforms when no means such as slowing down the falling speed is applied.

In the conventional electronic scanning radar device, since the pulse-modulated wave is simultaneously supplied to all the antenna elements, the number of transmitting elements instantly increases from 0 to n as shown in FIG. It instantly decreases to 0, and as shown in FIG. 3 (b), the rising and falling speeds of the transmission waveform are fast, and unnecessary sideband levels are large.

As is clear from the above comparison, according to the configuration of the above embodiment, the individual antenna elements 161 to 16 are provided.
Even if the rising and falling speeds of the pulse-modulated wave supplied to n are high, the rising and falling speeds of the transmission waveform radiated in the air are equivalently low, so that unnecessary sideband levels can be suppressed. it can.

As a result, there is no need to take measures such as providing a filter for sideband suppression, or adding a function of slowing the rising and falling speeds to the pulse-modulated wave generation circuit itself. Further, even if an amplifier provided for each antenna element having a non-linear characteristic with good power addition efficiency is used, a filter is provided between each amplifier and the antenna element, and a rise of pulse-modulated wave and It is not necessary to add a function to slow down the falling speed.

In the above embodiment, the rising and falling timings of the pulse of the pulse-modulated high frequency signal supplied to the antenna elements 161 to 16n are sequentially set from one antenna element to the adjacent antenna elements. It is preferable to raise and sequentially lower the antenna elements so that the antenna elements in the transmitting state are arranged at consecutive positions on the antenna array.

As described above, if the antenna elements in the transmitting state are arranged at consecutive positions on the antenna array, the moment when only some of the elements are transmitting when they are not arranged continuously. It is effective in preventing the generation of grating lobes that occur in the.

FIG. 4 shows the configuration of the second embodiment. Here, pulse modulation switch circuits 231 to 23m (m = 4 in the figure) are interposed in the distribution path 13, and a timing controller 24 is used. Each switch circuit 231-23
By switching on / off m in a fixed order, transmission is switched in units of sub-arrays having a predetermined number of antenna elements.

In the above configuration, the switch circuits 231 to 23 of the timing controller 24 are shown in FIGS.
4 shows ON / OFF control timing, FIG. 4E shows a change in the number of transmitting antenna elements with respect to time by timing control, and FIG.

That is, in the timing controller 24, when the pulse transmission waveform rises, as shown in FIG.
As shown in (d), switch circuits 231 to 23
The sub-arrays SA1 to SA1 are turned on in the order of 4.
SA4 is sequentially set to the transmission state. As a result, the number of transmitting antenna elements gradually increases from 0 to n. On the other hand, when the pulse transmission waveform falls, each switch circuit is turned off in the order of 234 to 231 to bring the corresponding sub-arrays SA1 to SA4 into the transmission stop state in sequence.
As a result, the number of transmitting antenna elements gradually decreases between n and 0.

As described above, by gradually increasing and decreasing the number of transmitting elements, the rising and falling of the transmission waveform become stepwise, and the same effect as slowing down the rising and falling speeds can be more easily achieved. It can be obtained with various controls. This configuration is sufficient when controlling the timing of the pulse-modulated wave supplied to the antenna element for each antenna sub-array, and the number of pulse modulators can be saved.

Here, in the second embodiment, if the sub-arrays SA1 to SA4 of the antenna array are arranged as shown in FIG. 6, the antenna elements in the transmitting state are arranged at consecutive positions on the antenna array. And then
It is effective in preventing the generation of grating lobes.

In the above embodiment, the switch circuit is provided in the high frequency signal transmission line as a means for realizing the pulse modulation function. However, for example, the switch circuit is provided in the bias path of the amplification element inside the amplifier, and the switch circuit is provided. The pulse modulation function may be realized by controlling ON / OFF of the.

[0039]

As described above, according to the present invention, it is possible to provide an electronic scanning radar device which has a low unnecessary side band level, high efficiency, and is small in size, lightweight and inexpensive.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of an electronic scanning radar device according to the present invention.

FIG. 2 is a diagram showing changes in the number of transmission elements and transmission waveforms with respect to time according to the first embodiment.

FIG. 3 is a diagram for comparison with the first embodiment, in the case where no means such as adding a filter or slowing the rising and falling speeds of the pulse-modulated wave is provided as a countermeasure for sideband suppression. The figure which shows the change of the number of transmission elements with respect to time, and a transmission waveform.

FIG. 4 is a block diagram showing a configuration of a second embodiment according to the present invention.

FIG. 5 is a diagram showing a change in the number of antenna elements with respect to time and a transmission waveform according to the second embodiment.

FIG. 6 is a diagram showing a sub-array arrangement configuration in the antenna array of the second embodiment.

FIG. 7 shows an example of a conventional electronic scanning radar device in which a filter for sideband suppression is provided at one location behind a pulse-modulated wave generation circuit, and an amplifier provided for each antenna element is a linear amplifier. Block diagram of.

FIG. 8 illustrates another example of a conventional electronic scanning radar device, in which an amplifier provided for each antenna element has a non-linear characteristic and a filter is provided between each amplifier and the antenna element. FIG.

[Explanation of symbols]

11 ... Pulse modulated wave generation circuit 12 ... Sideband suppression filter 13 ... Distribution path 141-14n ... Phase shifter 151-15n ... Linear amplifier 161-16n ... Antenna element 171-17n ... Non-linear amplifier 181-18n ... Sideband suppression Filter 20 ... High frequency signal generation circuit 211-21n, 231-23m ... Pulse modulation switch circuit 22 ... Timing controller

Claims (7)

[Claims] 1. An electronic scanning radar apparatus for forming a transmission beam by appropriately arranging a phase and an amplitude of a pulse-modulated high frequency signal supplied to each antenna element, the antenna array being formed by arranging a plurality of antenna elements. A plurality of pulse modulation means for pulse-modulating a high-frequency signal supplied to the plurality of antenna elements, and timing control for shifting the rising and falling timings of the pulses with respect to the plurality of pulse modulation means between the antenna elements. An electronic scanning radar device comprising: 2. The pulse modulation means is provided for each of the plurality of antenna elements, and the timing control means sets the rising and falling timings of the pulse of the pulse-modulated high frequency signal supplied to the antenna elements to one. 2. The electronic scanning radar device according to claim 1, wherein the antenna elements are sequentially raised and lowered from an antenna element to an adjacent antenna element so that the antenna elements in a transmitting state are continuous on the antenna array. 3. When the antenna array is divided into a plurality of sub-arrays, the pulse modulation means is provided for each sub-array, and the timing control means determines the rising and falling timings of the pulses of the pulse modulation means in the sub-array. The electronic scanning radar device according to claim 1, wherein the electronic scanning radar device is shifted for each. 4. The timing control means sequentially raises and lowers the rising and falling timings of a pulse from one subarray to an adjacent subarray with respect to the pulse modulating means, and an antenna element in a transmitting state is The electronic scanning radar device according to claim 3, wherein the electronic scanning radar device is arranged so as to be continuous on the antenna array. 5. A high frequency signal generator for generating a high frequency signal for transmission, a distribution means for distributing the output of this high frequency signal generator into a plurality of systems, and a transmission means interposed in the path distributed by said distribution means. A plurality of phase shifters and non-linear amplifiers that adjust the phase and amplitude of signals, and a plurality of multi-phase amplifiers that are arranged in an array and emit high-frequency signals whose phases and amplitudes are adjusted by the plurality of phase shifters and non-linear amplifiers to space. An antenna element, a plurality of pulse modulation means for pulse-modulating the transmission high-frequency signal in a distribution path by the distribution means, and a pulse rising and falling timing for the plurality of pulse modulation means are sequentially shifted and driven. And an electronic scanning radar device. 6. The electronic scanning according to claim 5, wherein each of the plurality of pulse modulation means is a switch circuit, and the timing control means performs pulse modulation by controlling ON / OFF of the switch circuit. Radar equipment. 7. The plurality of pulse modulation means each include a switch circuit in a bias path of an amplification element inside the plurality of nonlinear amplifiers, and the timing control means performs on / off control to perform pulse modulation. The electronic scanning radar device according to claim 5, wherein