JP2017055166A - Antenna device and phase-shift control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve an antenna device with a hybrid type phase shifter which can adapt to a wider band in phase control and enables downsizing of a device.SOLUTION: An antenna device according to an embodiment has a hybrid type phase shifter configuration, and has a configuration having an antenna element for receiving a radio wave, analog type phase correction means, A/D conversion means, and digital type phase control means. The analog type phase correction means performs phase correction of a radio wave signal received by the antenna element. The A/D conversion means converts the phase-corrected radio wave signal into a digital signal. The digital type phase control means executes phase shift in a time domain to the digital signal to control a phase.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an antenna device having a hybrid phase shifter and a phase shift control method.

  Conventionally, for example, an array antenna apparatus is provided with a phase shifter for controlling the phase of a radio wave (radio wave signal) received by an antenna element. Here, the phase control may be referred to as phase control or phase shift control. Further, correcting the phase shift in the phase control may be referred to as phase correction.

  The phase shifters are roughly classified into an analog phase shifter that performs analog phase control (phase shift control) and a digital phase shifter that performs digital phase control. The analog phase shifter has a configuration in which, for example, a semi-rigid cable is used and the cable length is switched by a switch. That is, the analog type phase shifter performs phase control by changing the length of the path through which the analog radio signal is transmitted.

  The digital phase shifter is configured to perform phase control by converting an analog radio wave signal into a digital signal by an A / D converter and executing an operation (multiplication, etc.) on the digital signal.

Japanese Patent No. 3292553

  The analog phase shifter is configured to perform phase control by switching the cable length. For this reason, when the required cable length increases, the equipment for realizing the analog type phase shifter is increased in size and becomes a factor that hinders downsizing of the antenna device. On the other hand, since the frequency dependence of radio waves is low, it can be applied to broadband radio waves.

  On the other hand, since the digital phase shifter is configured to perform phase control by computing digital signals, the antenna device can be downsized. On the other hand, when a digital phase shifter widens the frequency bandwidth of a radio wave, a situation may occur in which the directivity directions of the upper limit and lower limit frequencies of the band are shifted. This is because the phase control calculation is performed on the basis of the tuning frequency, and therefore an error occurs in the phase control when the tuning frequency and the frequency of the input signal (radio signal) are shifted (see FIG. 3).

  Therefore, there is a problem of realizing an antenna device having a hybrid phase shifter that can be applied to a wide band of phase control and can be downsized.

  The antenna device of the present embodiment is configured to include an antenna element that receives radio waves, an analog phase correction unit, an A / D conversion unit, and a digital phase control unit. The analog type phase correction means corrects the phase of the radio signal received by the antenna element. The A / D conversion means converts the phase-corrected radio wave signal into a digital signal. The digital phase control means controls the phase by executing a phase shift in the time domain with respect to the digital signal.

The block diagram for demonstrating the structure of the antenna apparatus regarding embodiment. The figure for demonstrating the specific example of the delay line regarding embodiment. The figure for demonstrating the effect of embodiment. The flowchart for demonstrating operation | movement of the antenna apparatus of embodiment.

Embodiments will be described below with reference to the drawings.
[Configuration of antenna device]
FIG. 1 is a block diagram illustrating a configuration of an antenna device according to the present embodiment. As shown in FIG. 1, the antenna device of this embodiment includes an array antenna 1 composed of a plurality (for example, 64 elements) of antenna elements (aerial lines) 10, and delay lines ( A delay line 2, an A / D (analog to digital) converter 3, and a digital phase control circuit 4. Further, the antenna device has a beam combiner 5 that combines the outputs of the digital phase control circuits 4.

  The antenna device of the present embodiment has a configuration including a so-called hybrid phase shifter that includes a delay line 2 and a digital phase control circuit 4. As shown in FIG. 2, the delay line 2 corresponds to an analog phase shifter, and functions as a phase corrector that corrects a phase shift in phase control. Specifically, the delay line 2 configures, for example, a 4-bit phase shifter, and switches a path through which an analog radio signal is transmitted by the switch 20. For example, a semi-rigid cable or the like is used for the route, and the route is configured by cables 21A-21E having different cable lengths.

  The digital phase control circuit 4 corresponds to a digital phase shifter and includes a buffer memory 14 and a phase shifter 15 as shown in FIG. The buffer memory 14 temporarily stores the digital signal (data) output from the A / D converter 3. The phase shifter 15 is a phase shift circuit that performs a bit phase shift in the time domain of the digital signal stored in the buffer memory 14. That is, the digital phase control circuit 4 of the present embodiment performs phase control of the radio signal by the bit phase shift of the digital signal sampled by the A / D converter 3.

[Operational effects of this embodiment]
FIG. 4 is a flowchart for explaining the operation of the antenna device of this embodiment. As shown in FIG. 4, the antenna apparatus receives radio waves (analog radio wave signals) by each antenna element 10 of the array antenna 1 (block 40). As will be described later, each delay line 2 performs phase correction (analog phase correction) for correcting a phase shift in phase control by the digital phase control circuit 4 (block 41).

  Each A / D converter 3 converts the analog radio wave signal phase-corrected by each delay line 2 into a digital signal (data) (block 42). Each digital phase control circuit 4 performs phase control on the digital signal sampled by the A / D converter 3 by executing a bit phase shift (digital phase shift) in the time domain (block 43).

  The beam combiner 5 combines the outputs from the digital phase control circuits 4 (block 44). The beam combiner 5 takes out the radio signal having the maximum amplitude because the phase difference between the radio signals received by the antenna elements 10 is eliminated by the phase control of each digital phase control circuit 4.

  In the antenna device of the present embodiment as described above, the following remarkable effects can be obtained.

  The digital phase control circuit 4 of the present embodiment performs a bit phase shift (digital phase shift) in the time domain as phase control for the sampled digital signal. Therefore, since it does not depend on the frequency of the radio signal received by each antenna element 10, it is also effective for a broadband radio signal. In other words, the present invention can be applied to a wide band of phase control.

  FIG. 3 is a diagram illustrating a state in which the shift of the center direction is simulated when the bandwidth is increased in the digital phase shifter that performs phase control by the above-described calculation. FIG. 3 shows that the deviation of the center orientation is 6.1 deg at the frequency (550 MHz) 31 of the input signal with respect to the reference tuning frequency (500 MHz) 30, and the deviation of the center orientation is 5.5 deg at the frequency (450 MHz) 32 of the input signal. It shows that it becomes. That is, in a digital phase shifter that performs phase control by conventional calculation, the phase control calculation is performed with reference to the tuning frequency, so if the tuning frequency deviates from the frequency of the input signal (radio signal), there is an error in the phase control. Occurs.

  On the other hand, the digital phase control circuit 4 of the present embodiment does not cause an error in the phase control in the wide band and can be adapted to the wide band of the phase control. Here, the digital phase control circuit 4 of the present embodiment performs phase control on the digital signal sampled by the A / D converter 3. For this reason, the phase shift of the time shorter than one sample time cannot be controlled by the phase shift of the sampled digital signal.

  Therefore, in the present embodiment, a phase shift in the phase control of the digital phase control circuit 4 is corrected by a hybrid configuration including the delay line 2 corresponding to an analog phase shifter. That is, the delay line 2 is caused to function as a phase corrector to correct a phase shift for a time less than one sample time. Specifically, as shown in FIG. 2, the cable 21A-21E is switched by the switch 20, and the phase shift is corrected by adjusting the cable length.

  As described above, according to the present embodiment, the phase control by the digital phase control circuit 4 is performed by the so-called hybrid phase shifter configuration, so that compared with the case where the analog phase shifter configuration is adopted. The antenna device can be downsized. Further, the phase control by the digital phase control circuit 4 of the present embodiment does not depend on the frequency of the received radio wave signal, and therefore can be applied to a wide band.

  Here, referring to a specific example, when the hybrid phase shifter configuration of the present embodiment is compared with the conventional analog phase shifter configuration, the analog phase shifter of the present embodiment The equipment scale of the corresponding delay line 2 will be described.

  As the specifications of the array antenna device, the frequency is 500 MHz, the wavelength is 0.6 m, the number of antenna elements is 64 (ch), the arrangement interval of each antenna element is 0.3 m, the arrangement length is 18.9 m, and the maximum path difference is 13.4 m. Assume a case. When a conventional analog phase shifter configuration is adopted, the cable length required for the transfer device is determined by the maximum path difference, so a 13.4 m cable is required. That is, if the array antenna is directed to 45 degrees, phase control is performed using a cable of about 13.4 m.

  On the other hand, when the hybrid phase shifter configuration of this embodiment is adopted, the A / D converter 3 has a sampling frequency of 1000 Msa / s (megasamples / second), a cycle of 0.001 μsec, and a length of one sample. Assume that the length is 0.3 m. In this case, since the path length of one sample is 0.3 m in the A / D conversion process of the A / D converter 3, after converting an analog radio wave signal to a digital signal, the required number of samples with 0.3 m as a unit length Phase control can be performed by shifting the phase of the digital signal by the amount. That is, in this embodiment, phase control for 13.2 m can be performed by phase shift for 44 samples. Accordingly, the cable length necessary for the delay line 2 functioning as a phase corrector is a remainder obtained by dividing the maximum phase difference by the length per sample, for example, 0.16 m.

As described above, when performing phase control using the A / D converter 3 having a sampling frequency of 1 GHz, the cable length required for phase correction by the delay line 2 is the maximum phase difference per sample. For example, the maximum is 0.3 m. Therefore, for the cable length of 13.4m required when the conventional analog phase shifter configuration is adopted,
The cable length necessary for the delay line 2 of the present embodiment is greatly shortened.

  In short, according to the present embodiment, a hybrid type shift is performed in which analog phase correction using a cable by the delay line 2 and digital phase control using the A / D converter 3 and the digital phase control circuit 4 are performed. With the phaser configuration, it is possible to realize downsizing of equipment corresponding to an analog type phase shifter and widening of phase control. Therefore, it is possible to realize an antenna device that can be adapted to a wide band of phase control and can be downsized.

  Although this embodiment has been described as applied to an array antenna device, it is particularly effective for a receive-only array antenna device for receiving a radio wave having an indefinite input frequency and a wide band. Further, it is effective for an array antenna device applied to a sensor for detecting radio waves.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Array antenna, 2 ... Delay line (delay line), 3 ... A / D converter,
4 ... Digital phase control circuit, 5 ... Beam combiner, 10 ... Antenna element (aerial),
20 ... switch, 21A-21E ... cable.

Claims (6)

An antenna element for receiving radio waves;
Analog type phase correction means for correcting the phase of the radio signal received by the antenna element;
A / D conversion means for converting the phase-corrected radio wave signal into a digital signal;
An antenna device comprising: digital phase control means for controlling a phase by executing a phase shift in a time domain with respect to the digital signal.   The antenna apparatus according to claim 1, wherein the analog phase correction unit includes a delay line for performing phase correction according to a cable length.   The digital phase control means is configured to perform a bit phase shift in the time domain on the digital signal sampled by the A / D conversion means from the phase-corrected broadband radio wave signal. The antenna device according to claim 1 or 2.   The antenna device according to claim 1, wherein the antenna element constitutes a reception-only antenna that receives a broadband radio wave. An array antenna in which a plurality of antenna elements are arranged;
Each of the antenna elements is connected to a phase shift means composed of the analog phase correction means, the A / D conversion means, and the digital phase control means, and outputs from each of the phase shift means. The antenna device according to any one of claims 1 to 4, further comprising beam combining means for combining. A phase shift control method applied to an array antenna apparatus,
Processing to perform analog phase correction on radio signals received from a plurality of antenna elements;
Processing to convert each phase-corrected radio signal into a digital signal;
And a phase shift control method for performing digital phase control for performing phase shift in the time domain on each digital signal.