JP3569078B2 - Frequency converter for phased array antenna - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a phased array antenna that converts received signals from a plurality of antenna elements or sub-array elements into an intermediate frequency signal and then combines the signals, and more particularly to a frequency converter that converts a received signal into an intermediate frequency signal.
[0002]
[Prior art]
Some conventional phased array antennas include a plurality of antenna elements or sub-array elements and a low-noise block converter corresponding to each of them. In this phased array antenna, received signals of a plurality of antenna elements or sub-array elements are supplied to corresponding low-noise block converters. In these block converters, each of the received signals is frequency-converted into an intermediate frequency signal. The phases of these intermediate frequency signals are adjusted by correspondingly provided phase shifters. The phase-adjusted intermediate frequency signals are combined by a combiner. FIG. 10 shows an example of the low noise block converter.
[0003]
In the low-noise block converter, a reception signal from the corresponding antenna element or sub-array element, for example, a satellite broadcast or satellite communication signal in the 11 GHz band is supplied to the mixer 106 via the input probe 100, the high-frequency amplifier 102, and the band-pass filter 104. Is done. The mixer 106 is also supplied with a local oscillation signal from a local oscillation circuit 108 provided for each low noise block converter. The mixer 106 converts the frequency of the received signal into an intermediate frequency signal of, for example, a 1 GHz band by using the local oscillation signal. This intermediate frequency signal is supplied to the intermediate frequency amplifier 112 via the low pass filter 110. The amplified intermediate frequency signal is supplied from an output terminal 114 to a phase shifter (not shown).
[0004]
In order to operate the high frequency amplifier 102, the intermediate frequency amplifier 112, and the local oscillation circuit 108, a DC power supply superimposed on the coaxial cable connected to the output terminal 114 is extracted by the DC power supply separation circuit 116, and the power supply circuit 118 After performing processing such as stabilization, the signal is supplied to the high-frequency amplifier 102, the intermediate frequency amplifier 112, and the local oscillation circuit 108. These low-noise block converters are housed in the chassis one by one. As is clear from FIG. 10, the high-frequency amplifier 102 and the intermediate-frequency amplifier 112 each include a plurality of amplification stages.
[0005]
[Problems to be solved by the invention]
Such low noise block converters each include a local oscillation circuit 108. It is difficult to completely match the frequencies of the local oscillation signals of these local oscillation circuits 108. The frequency of each local oscillation signal varies, for example, about ± 500 KHz. Due to the variation in the frequency of each local oscillation signal, the frequency of the intermediate frequency signal from each low noise block converter also varies. Therefore, when the phases of these intermediate frequency signals are adjusted and then combined, loss occurs due to the variation in the frequency.
[0006]
Each low noise block converter is individually housed in the chassis. When configuring a phased array antenna using a large number of antenna elements, a number of low noise block converters equal to the number of antenna elements is required. Therefore, the volume occupied by the low-noise block converter in the phased array antenna increases, and the phased array antenna also increases in size.
[0007]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a phased array antenna in which a combined loss due to a frequency variation of each intermediate frequency signal is reduced. Another object of the present invention is to provide a phased array antenna that can be reduced in size.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a signal received by a plurality of antenna elements or sub-array elements, by frequency conversion means corresponding to these antenna elements or sub-array elements, respectively, using a local oscillation signal, A phased array antenna that converts the signals into first intermediate frequency signals, adjusts the phases of these first intermediate frequency signals, and combines the signals. The means are respectively housed in a plurality of recesses provided corresponding to the respective frequency conversion means on one surface side of one chassis, and the local oscillation means is provided on the other surface of the chassis. An oscillating means housed in the first recess, and a second recess provided at each vertex position of a rectangle drawn around the first recess on the other surface of the front chassis. And a distribution amplifier which has the same gain connected to the oscillating means via a cable of the same length and which distributes the output of the amplifier in the same number. And a container.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
The embodiment of the phased array antenna provided with the frequency converter according to the present invention includes a plurality of, for example, 16 antenna elements 2 as shown in FIG. These antenna elements 2 are for receiving satellite broadcast or satellite communication signals transmitted from a geostationary satellite such as a broadcast satellite or a communication satellite. Note that a sub-array antenna can be used instead of each antenna element 2.
[0021]
The signals received by these antenna elements 2 are supplied to low noise block converters 4 corresponding to these antenna elements 2 respectively. These low-noise block converters 4 use the local oscillation signal to frequency-convert the input received signals into first intermediate frequency signals. The local oscillation signal is supplied from one local oscillation circuit 6 to each low noise block converter 4.
[0022]
The first intermediate frequency signals from each of the low noise block converters 4 are supplied to a phase shifter 8 provided so as to correspond thereto, and the phase is adjusted so that the beam direction of each antenna element 2 becomes a specific direction. You. Each phase-adjusted first intermediate frequency signal is supplied to the synthesizer 10 and output as a synthesized first intermediate frequency signal. This synthesized first intermediate frequency signal is split into two by the splitter 12. The level of one distribution output is detected by the detector 14. This detection level is supplied to the CPU 16, and the CPU 16 adjusts the phase of each phase shifter 8 according to the detection level, and adjusts the beam of each antenna element 2 in the direction in which the reception level becomes maximum.
[0023]
As shown in FIG. 1, each antenna element 2, low noise block converter 4, and local oscillation circuit 6 are provided in one chassis 20.
[0024]
Each antenna element 2 is arranged in a 4 × 4 matrix on one surface of an antenna substrate 22 formed, for example, in a square shape. A ground plane 24 as a ground conductor is formed on the entire area of the other surface of the substrate 22. The ground surface 24 is attached to the chassis 20 so as to contact one surface, for example, the upper surface of the chassis 20. The chassis 20 is formed of a conductive material, for example, a metal.
[0025]
The local oscillation circuit 6 is provided on one surface of the chassis 20. As shown in FIG. 3, the local oscillation circuit 6 has a unit, for example, a local oscillation signal four distribution amplifier 6a. The local oscillation signal four distribution amplifier 6a includes an oscillator 18 that oscillates a local oscillation signal. The local oscillation signal from the oscillator 18 is amplified by the amplifiers 20 and 22 and then divided into four by the four divider 24. These four distribution outputs are further divided into four by units, for example, four distribution amplifiers 6b to 6e. That is, the local oscillation signal of the oscillator 18 is divided into 16 parts. The four distribution amplifiers 6b to 6e amplify one of the four divided outputs by the amplifiers 26 and 28, and further distribute the four divided outputs by the four distribution amplifier 30. The gains of these amplifiers 26 and 28 are the same in any of the four distribution amplifiers 6b to 6e. Therefore, the local oscillation signals supplied to each low noise block converter 4 have the same frequency and the same amplitude.
[0026]
As shown in FIG. 1, the local oscillation signal four-distribution amplifier 6a is housed in a recess 32 formed in the center of one surface of the chassis 20. In addition, as is apparent from FIG. 1, the four distribution amplifier 6a is formed on a printed circuit board. Further, on one surface of the chassis 20, a concave portion 34 is also formed at a position of each vertex of a rectangle drawn around the concave portion 32. The four distribution amplifiers 6b to 6e are arranged in these concave portions 34, respectively. These four distribution amplifiers 6b to 6e are also formed on a printed circuit board.
[0027]
The quadrant output from the local oscillation signal quadrant amplifier 6a is supplied to each quadrant amplifier 6b to 6e via four semi-rigid cables 36 of the same length. In order to allow these semi-rigid cables 36 to pass through, two grooves 38 having a T-shaped planar shape are formed from the edges on both sides of the recess 32 toward the recess 34. Each of the concave portions 32 and 34 has a square planar shape, and completely accommodates the local oscillation signal four distribution amplifier 6a and the four distribution amplifiers 6b to 6e. Since the local oscillation signal four distribution amplifier 6a and the four distribution amplifiers 6b to 6e are accommodated in the concave portions 32 and 34 provided in the conductive chassis 20, these local oscillation signal four distribution amplifiers 6a and four distribution amplifiers are provided. The leakage of the local oscillation signal from 6b to 6e is shielded. Further, the ground surface 24 of the antenna substrate 22 contacts one surface of the chassis 20 and closes the upper openings of the concave portions 32 and 34, so that the shielding effect is further enhanced.
[0028]
Each low noise block converter 4 is provided on the other surface side of the chassis 20. The low-noise block converter 4 includes an input probe 40, a high-frequency amplifier 42, a band-pass filter 44, a mixer 46, a low-pass filter 48, a first intermediate frequency amplifier 50, and a power supply circuit 52, similarly to the conventional low-noise block converter shown in FIG. And a power supply separation circuit 54.
[0029]
However, each low noise block converter 4 does not include a local oscillation circuit. A local oscillation signal is supplied from an external local oscillation circuit 6 to a mixer 46. Therefore, the local oscillation signal input unit 56 is provided in the low noise block converter 4. The intermediate frequency amplifier 50 does not have a large gain, but has such a gain as to compensate for a combined loss described later. This low noise block converter 4 is configured on a printed circuit board as shown in FIG.
[0030]
These low noise block converters 4 are housed in recesses 58 provided on the other surface of the chassis 20. These concave portions 58 are provided, for example, in a matrix of 16 corresponding to each low noise block converter 4. As shown in FIG. 5, these concave portions 58 have a rectangular planar shape, for example, a square shape. A total of four sets of these recesses 58 are formed with four sets as one set. In each set, four recesses 58 are arranged around the recess 34. One corner of each recess 54 overlaps a corner of the recess 34. However, the center of each recess 58 does not overlap with each recess 34.
[0031]
The low-noise block converter 4 is housed in these recesses 58 so as not to protrude therefrom. Therefore, these recesses 58 function as shield cases, and it is possible to prevent the first intermediate frequency signal generated by the mixer 46 from leaking. The other surface of the chassis 20 is covered and shielded by a shield plate 59 as shown in FIG. Therefore, leakage can be further prevented.
[0032]
As shown in FIG. 1, in each low noise block converter 4, an input probe 40 is formed at the center. These input probes 40 are inserted into the input probe holes 60 penetrating from the center of the inner deep portion of each concave portion 58 to one surface side of the chassis 20, and as shown in FIG. Also project upward. Although not shown, the protruding ends of the input probes 40 are connected to feed points of the respective antenna elements 2. That is, each input probe hole 60 is provided so as to correspond to the feeding point of each antenna element 2.
[0033]
A local oscillation signal input section 56 is provided at one corner of each low noise block converter 4. These local oscillation signal input sections 56 are connected to any of the four distribution amplifiers 6b to 6e. Therefore, as shown in FIG. 6, a local oscillation signal input hole 62 is formed from a portion of each recess 58 overlapping the recess 34 toward the recess 34. As shown in FIG. 7, a local oscillation signal input portion 56 is inserted into these local oscillation signal input holes 62, and the distal end is provided at one of the four distribution amplifiers 6b to 6e housed in the concave portion 34. Connected to terminal.
[0034]
The output of each low noise block converter 4 is supplied from the power supply separation circuit 54 to, for example, the phase shifter 8 via the coaxial cable 64. At this time, the coaxial cable 64 is supplied to the phase shifter 8 through a coaxial cable passage hole 66 formed in the shield plate 59. That is, in the frequency converter, as shown in FIG. 8, the input probe 40 connected to the feeding point of the antenna element 2 protrudes from one surface side of the chassis 20, and the coaxial cable 64 connected to the phase shifter 8 from the other surface side. The low noise block converter 4 and the local oscillation circuit 6 are housed in the chassis 20.
[0035]
In the frequency converter configured as described above, since each low-noise block converter 4 and local oscillation circuit 6 are provided in one chassis 20, a phased array antenna can be installed in a small installation space. Since the local oscillation signal having the same frequency and the same amplitude is supplied from the local oscillation circuit 6 to each low noise block converter 4, the first intermediate frequency signal generated by each low noise block converter 4 has the same frequency and the same amplitude. . Therefore, even when the signals are combined by the combiner 10, no large loss occurs. The chassis 20 provided with the low noise block converter 4 and the local oscillation circuit 6 is covered with a radome (not shown). Since many low-noise block converters 4 are used, the amount of heat generated is large, the temperature inside the radome increases, and thermal stress occurs in the block converters 4 and the like, which may cause performance degradation. Therefore, in each of the low noise block converters 4, the first intermediate frequency amplifier 50 has a gain enough to compensate for the combined loss in the phase shifter 8, thereby suppressing heat generation and saving power.
[0036]
The above embodiment is merely an example of the present invention, and various modifications are possible. For example, the local oscillation circuit 6 divides the local oscillation signal into four, and further divides each four-divided output into four. For example, as shown in FIG. 9, after the oscillation signal from the oscillator 18 is amplified by the amplifier 70, the local oscillation signal is supplied to n (n is an arbitrary integer of 2 or more) low noise block converters 401 to 40n. The local oscillation signal may be distributed to n by the n distributor 72. In the above-described embodiment, the input portion of each low noise block converter 4 is the input probe 40. Alternatively, for example, a waveguide may be used.
[0042]
【The invention's effect】
According to the present invention, since each frequency conversion means is provided on one surface side of the chassis and the local oscillation means is provided on the other surface side, the installation space can be further reduced. In addition, since the frequency conversion unit and the local oscillation unit are provided on the opposite surfaces of one chassis, the signals do not interfere with each other. Furthermore, since each of the frequency conversion means and the local oscillation means are provided in each of the recesses provided corresponding to them, it is possible to reliably prevent the first intermediate frequency signal and the local oscillation signal from leaking, and The ground can be shared.
[Brief description of the drawings]
FIG. 1 is a partially assembled view of an embodiment of a phased array antenna using a frequency conversion device according to the present invention.
FIG. 2 is a block diagram of the embodiment.
FIG. 3 is a block diagram of a local oscillation circuit used in the embodiment.
FIG. 4 is a block diagram of a low noise block converter used in the embodiment.
FIG. 5 is a bottom view of the chassis of the embodiment.
FIG. 6 is a sectional view taken along line AA of FIG.
FIG. 7 is a sectional view taken along line BB of FIG. 5;
FIG. 8 is a front view of this embodiment.
FIG. 9 is a block diagram of a modification of the local oscillation circuit used in this embodiment.
FIG. 10 is a block diagram of a low noise block converter used for a conventional phased array antenna or parabolic antenna.
[Explanation of symbols]
2 antenna element 4 low noise block converter 6 local oscillation circuit 8 phase shifter 10 combiner 20 chassis 32 34 58 recess

Claims (1)

Signals received by the plurality of antenna elements or sub-array elements are respectively converted into first intermediate frequency signals using local oscillation signals by frequency conversion means corresponding to these antenna elements or sub-array elements, respectively. After adjusting the phase of the frequency signal, in the phased array antenna to be synthesized,
A common local oscillation means is provided for each of the frequency conversion means,
Each of the frequency converters is housed in a plurality of recesses provided corresponding to the respective frequency converters on one surface side of one chassis,
The local oscillating means is provided at an oscillating means housed in a first recess provided on the other surface of the chassis and at each vertex position of a rectangle centered on the first recess on the other surface of the front chassis. A distributing amplifier housed in the second recess, each distributing amplifier having the same number of outputs as the amplifier having the same gain connected to the oscillating means via a cable of the same length. A frequency converter for a phased array antenna.

Images