JP2001298317A - Electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the directivity of an array antenna over a wide band and to enable miniaturization by narrowing an antenna element interval at the same time. SOLUTION: When the phases of received signals from the respective antenna elements of the array antenna are equal, the array antenna becomes a high- efficiency antenna and when the phases are reverse, the received signals are canceled. In order to provide such a phase difference, a phase shifter is inserted for providing a phase ϕ(ω) defined from an antenna element interval (d) and a feeder line length (1). Thus, the desired directivity is provided over the wide band and the miniaturization is enabled by narrowing the antenna element interval (d).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device having an array antenna having a phase circuit.

[0002]

2. Description of the Related Art An array antenna used in a conventional electronic device is a linear array having, for example, an array antenna element (hereinafter referred to as an element) having a spacing of λ / 2, an excitation phase difference of 0, a broadside array having no excitation phase difference, and an element spacing. Is an endfire array or the like having a wavelength of λ / 4 and an excitation phase difference of π / 2. A phase shifter is connected to each element in order to control a phase difference generated in each element with respect to an electromagnetic wave having a predetermined frequency. A method for eliminating the phase shift has been adopted.

[0003]

However, in a conventional array antenna having a phase shifter for each element, the element spacing relatively changes due to a wavelength change accompanying a frequency change of a received or transmitted electromagnetic wave, Since the phase difference between the antenna elements changes, the directivity of the antenna changes, and the main lobe gain decreases.

Therefore, in an electronic device using a conventional antenna as a receiver or a transmitter, there is a problem that a frequency band of an electromagnetic wave to be received or transmitted is narrow.

In other words, in order to make the directivity of the antenna constant, there has been a problem that the phase shift amount must be reset in the phase shifter for each frequency of the electromagnetic wave to be received or transmitted.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is intended to reduce the phase difference caused by the antenna element interval, the antenna feed wiring distance difference, and the feed phase difference with respect to a change in the frequency of an electromagnetic wave to be received or transmitted. An object of the present invention is to provide an antenna capable of obtaining a desired directivity over a wide band, and an electronic device using the same.

[0007]

According to the research conducted so far, we have found that in order to improve the directivity of an array antenna and broaden the frequency band, the phase of an antenna element or an electronic device is changed according to the frequency. It became clear that providing a circuit was important.

[0008] The above object is achieved by providing an antenna and an electronic device using the same with a phase circuit that produces a phase change corresponding to the frequency of a received or transmitted electromagnetic wave.

More specifically, in an array antenna for transmitting or receiving an electromagnetic wave, a phase circuit whose phase changes in accordance with the frequency of the electromagnetic wave to be transmitted or received is connected to an antenna element.

In the above-described array antenna, the side lobe or the back lobe is smaller than the main beam by 6 dB or more in the entire desired frequency range.

An electronic device having the above-described array antenna.

An electronic device that receives or transmits an electromagnetic wave includes a phase circuit that changes a phase according to the frequency of the electromagnetic wave that is received or transmitted by a receiver or a transmitter of the electronic device.

Also, in an electronic device having a receiver for receiving an electromagnetic wave radiated from an object to be measured and an electromagnetic field processor for processing information of the electromagnetic wave detected by the receiver, the electronic device includes: It has a phase circuit that changes the phase according to the frequency.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment showing an array antenna according to the present invention will be described below with reference to FIG.

FIG. 1 shows a configuration of an array antenna and a radio wave propagation path of a magnetic field measuring apparatus of the present invention. As shown, antenna # 1 (101) and antenna # 2 (10
2) is separated by a distance d (108), and the lengths of the feed lines are set to l1 (109) and l2 (110), and a phase shifter such as an all-pass filter (APF, all-pass circuit) is inserted between them. Path 111 and path 11 from the wave direction
2 are made to have the same phase, and the phases of the signals that have propagated through the path 113 and the path 114 from the noise direction are made to have opposite phases. In the case of reception, this is combined with a synthesizer (10
3) to obtain an output 104. In the case of transmission, a distributor may be provided instead of the synthesizer (103), and a feeder circuit may be provided instead of the output.

First, the case where the desired wave Es (106) is received will be considered. The desired wave Es (106) arriving from the direction of the antenna # 1 (101) is transmitted to the antenna # 1 (101).
, The electric field E1 is obtained, and the antenna # 2 (102) further separated by the distance d (108) becomes the electric field E2. Here, E1 and E2 when the distance from the wave source is r are shown in (Equation 1).

[0017]

(Equation 1)

Here, it is assumed that the phase of the antenna reception voltage changes by θ with respect to the electric field. From this, antenna # 1
The receiving end voltages V1 and V2 of (101) and # 2 (102) are represented by (Equation 2).

[0019]

(Equation 2)

The received voltage that reaches the combiner (103) through the paths 111 and 112 is the feed line length l1 (10
9), the phase changes by propagating through l2 (110).
Here, assuming that there is no attenuation when propagating through the feed line lengths l1 (109) and l2 (110), antenna # 1
Assuming that the phase shift by the phase shifter (105) connected to the feed line l1 (109) of (101) is φ (ω), the combiner (1
The reception voltages V1 'and V2' reaching the signal 03) are expressed by (Equation 3).

[0021]

(Equation 3)

Assuming that the phase of V1 'is φ1' and the phase of V2 'is φ2' when the voltages received by the two antennas reach the combiner (103), the phases are expressed by (Equation 4). expressed.

[0023]

(Equation 4)

The condition that the phase becomes the same is as shown in (Equation 5), and the received voltage at this time is as shown in (Equation 6).

[0025]

(Equation 5)

[0026]

(Equation 6)

The phase circuit (105) for realizing φ (ω) shown in (Equation 5) is connected to the feed line (10) of the antenna # 1 (101).
By connecting to (9), an array antenna having the maximum sensitivity in the direction of antenna # 1 (101) can be realized regardless of the frequency as shown in (Equation 6).

In the antenna according to the present invention,
Since the characteristic of the endfire array changes to the characteristic of the broadside array at a high frequency at which the distance d between the antennas reaches half a wavelength, the antenna has no maximum sensitivity in the direction of the antenna # 1 (101). This places an upper limit on the frequency that can be recognized by the electronic device having the antenna according to the present invention.

Further, a limit on the low frequency side arises from the characteristics of the antenna # 1 (101) or the antenna # 2 (102) alone. Therefore, in the electronic device having the antenna of the present invention, by providing a desired frequency range within the upper and lower limits, the antenna # 1 (10
An electronic device having an array antenna having the maximum sensitivity in the direction of 1) can be realized.

Next, the case where the array antenna according to the present invention cancels the noise En (107) will be described.

Here, the noise is caused by antenna # 2 (102)
From the direction of. Antenna # 2 (10
The noise En (107) arriving from the direction 2) becomes an electric field E2 at the point of the antenna # 2 (102), and further has a distance d (1).
08) In the remote antenna # 1 (101), the electric field E1 is generated. Here, E1 and E2 when the distance from the wave source is r are shown in (Equation 7).

[0032]

(Equation 7)

Here, it is assumed that the phase of the antenna reception voltage changes by θ with respect to the electric field. From this, antenna # 1
The receiving end voltages V1 and V2 of (101) and # 2 (102) are represented by (Equation 8).

[0034]

(Equation 8)

The received voltage that reaches the combiner (103) through the paths 111 and 112 is equal to the feed line length l1 (10
9), the phase changes by propagating through l2 (110).
Here, assuming that there is no attenuation when propagating through the feed line lengths l1 (109) and l2 (110), antenna # 1
Assuming that the phase shift by the phase shifter (105) connected to the feed line l1 (109) of (101) is φ (ω), the combiner (1
The received voltages V1 'and V2' reaching the signal 03) are respectively expressed by (Equation 9).

[0036]

(Equation 9)

Assuming that the phase of V1 ′ is φ1 ′ and the phase of V2 ′ is φ2 ′ when the voltages received by these two antennas reach the combiner (103), the phases are expressed by (Equation 10). expressed.

[0038]

(Equation 10)

The condition that this phase becomes the opposite phase is (Equation 11)
The received voltage at this time is as shown in (Equation 12).

[0040]

[Equation 11]

[0041]

(Equation 12)

A phase shifter (105) having a phase circuit for realizing φ (ω) shown in (Expression 11) is connected to antenna # 1 (101).
(109), it is possible to realize an array antenna having the lowest sensitivity (null point) in the direction of antenna # 2 (102) irrespective of the frequency as shown in (Equation 12).

Next, FIG. 2 shows a case where a dipole antenna which receives the desired wave with high sensitivity or cancels noise is used as an array antenna according to the present invention. FIG. 2 shows a case where the directions of the currents of the antennas are set to be equal.

FIG. 3 shows a case where power is supplied so that the direction of the current of each antenna is opposite. In this case, the condition of the phase shown in (Equation 11) is changed to the condition of in-phase as shown in (Equation 13).

[0045]

(Equation 13)

However, even in this case, the synthesized output is (Equation 1)
As shown in 4), it is possible to cancel noise.

[0047]

[Equation 14]

Next, the directivity when the dipole antenna shown in FIG. 2 is used is shown in FIG. From FIG. 4, antenna # 1
It can be understood that the maximum sensitivity is obtained in the direction of, and by adjusting the direction of the electromagnetic wave to be received or transmitted in this direction, the electromagnetic wave can be received or transmitted with high sensitivity. Also, it can be seen that the antenna has the lowest sensitivity in the direction of antenna # 2, and that the noise can be canceled by setting the direction of arrival of the noise to this direction.

Although the case where the number of antenna elements is two has been described as an example, the present invention can be realized even when the number of elements is two or more as shown in FIG. By using multiple elements in this way, it is possible to further narrow the main beam width of directivity.

Next, FIG. 6 shows an embodiment of an APF (all-pass circuit), and FIG. 7 shows calculation results of a change in phase and a change in amplitude with respect to the frequency of the APF.

Actually, when the array antenna according to the present invention is used as a transmitter or a receiver, the antenna element is located at RL in FIG.

In FIG. 7, when a voltage is applied to the AFP shown in FIG. 6, for each frequency, the current amplitude (701) and phase change (70
2) occurs. That is, it shows the characteristics when an antenna having an APF is used as a transmitter.

The value of the parameter used in FIG.
1.50 Ω, R2 = 1.50 Ω, L1 = 0.16 nH, L2 = 0.16 n
H, C1 = 0.16 nF, C2 = 0.16 nF, RL = 50.0 Ω, RL2 =
50.0Ω.

The change of the phase with respect to the frequency shown in FIG.
As can be seen from 2), the APF can change the phase with respect to a predetermined frequency. It goes without saying that a similar circuit configuration may be used when an antenna having an APF is used as a receiver.

It is needless to say that the APF is not limited to the circuit shown in FIG. 6, but may be any circuit configuration that can produce a phase change corresponding to the frequency of the electromagnetic wave to be received or transmitted. Absent.

FIG. 8 shows a circuit to which the first antenna element is connected and a circuit to which the second antenna element is connected and to which the APF is connected. The circuit to which the AFP is connected has the same configuration as that of FIG.

An antenna element is connected to the positions of RL and RL2 in FIG.

As described above, in the array antenna and the electronic device, when an electromagnetic wave is received or transmitted, a phase difference occurs due to an antenna element interval, an antenna feed wiring distance difference, and a feed phase difference. Therefore, the calculation is performed by providing a transmission line corresponding to the phase difference in one circuit. That is, a transmission line corresponding to a phase difference is provided in order to reproduce in a simulation a phase shift that occurs when a plurality of antenna elements are arranged.

Next, FIG. 9 shows a simulation result of a phase shift occurring in the transmission line corresponding to the phase difference of FIG. 8 and a phase shift caused by the APF.

As shown in FIG. 9, from 10 MHz to 100
Up to 0 MHz (1 GHz), the shift due to the transmission line and the AP
It can be seen that the phase shifts due to F match. This indicates that since the phase shift caused by the transmission line represents the phase shift caused by the antenna element interval, the antenna feed wiring distance difference, and the feed phase difference, the APF can correct the phase shift at the antenna element interval and the like. ing.

On the other hand, at 2000 MHz, the phase shift caused by the antenna element interval, the antenna feed wiring distance difference and the feed phase difference does not match the phase shift due to the APF, and the phase is shifted by 90 °.

In this simulation, 10M was used.
Although the parameters of the APF are set so as to match the phase shift from Hz to 1 GHz, it goes without saying that the APF can be designed to match the phase shift at a desired frequency.

Next, FIGS. 10 to 12 show current amplitude values of a circuit to which the antenna element shown in FIG. 8 is connected, a circuit to which the antenna is connected and the APF is connected, and an amplitude obtained by synthesizing the respective currents. Indicates a value.

FIG. 10 shows the current amplitude of the circuit having the APF, FIG. 11 shows the current amplitude of the circuit having no APF, and FIG. 12 shows the amplitude when the currents are combined.

As described with reference to FIG. 9, at 1 GHz and 500 MHz which is less than 1 GHz, the phase shift caused by the antenna element interval, the antenna feed wiring distance difference, and the feed phase difference is equal to the phase shift due to the APF, so the combined current Are also in a mutually reinforcing relationship.

On the other hand, at 2 GHz, the relationship between the respective phases is 9
Since they are shifted by 0 °, the combined amplitudes do not have a constructive relationship. In the case of 2 GHz, as can be seen from the directivity diagram of FIG. 4, the value becomes 0 in the positive direction, but the sensitivity in the horizontal direction is several dB lower than that in the case of 1 GHz. Therefore, the 2 GHz amplitude shown in FIG. 12 relates to the horizontal direction.

That is, the above simulation result is as follows:
By providing a predetermined APF in the antenna or the electronic device, the antenna element interval, the antenna power supply wiring distance difference, and the power supply for a desired frequency band of the electromagnetic wave to be received or transmitted (set at 1 GHz or less in FIGS. 9 to 12). This shows that a desired directivity can be obtained by making the phase difference caused by the phase difference uniform with respect to the change in the frequency of the electromagnetic wave to be received or transmitted.

In this embodiment, only one of the A
Although the PF is provided, it goes without saying that the same effect can be obtained by connecting the APF to each of the plurality of antenna elements.

The array antenna according to the present invention can be used for, for example, a multi-wave transmission or reception antenna and an antenna for wide band communication such as spread spectrum communication, taking advantage of the narrow directivity and wide band. In addition,
Spread-spectrum communication means "Next-generation digital modulation and demodulation technology" (edited by Trikkeps, published on June 1, 1996)
As described in (1), a spectrum of an information signal limited to a certain band is not divided by time and frequency, but is spread over a wide band by a spreading code capable of identifying each user. This is a communication method that is resistant to interference and disturbance and that enables random access.

Next, a description will be given of a magnetic field measuring apparatus which is an embodiment using an antenna according to the present invention in a receiver.

FIG. 13 shows a part of a magnetic field measuring apparatus using the antenna according to the present invention as a probe of the magnetic field measuring apparatus, and FIG. 14 shows a magnetic field measuring apparatus and its system.

Hereinafter, a method for measuring unnecessary radiation from the measured object 240 with the probe 242 which is an array antenna according to the present invention will be described.

The probe is an X-direction probe drive mechanism 25.
1. The Y-direction probe driving mechanism 252, the Z-direction probe driving mechanism 253, and the θ-direction probe rotating mechanism 254 are arranged at desired positions. Thereafter, the detected magnetic field signal 249 detected by the magnetic field probe 242 is processed by the electromagnetic field detector 243 as a voltage value, and is processed by the memory 246 and the computer 245 into the magnetic field intensity at the measurement position, and the processing result is displayed on the display device. 247. Also, for example, the measurement start position, the measurement end position, and the like are input to the input device 248, and the unnecessary radiation from the object is measured while controlling the measurement position of the probe by the computer 245 and the motor controller 244.

When the array antenna according to the present invention is used as a probe, the directivity is narrow, so that the main beam is directed to the object to be measured, thereby eliminating the need for an electronic device having high-density and miniaturized electronic components. It is possible to measure radiation over a wide band with high resolution. Actually, by using the antenna according to the present invention, unnecessary radiation radiated from a 0.5 mm square (0.25 mm 2) can be specified.

Next, an automatic toll system as another embodiment using the array antenna according to the present invention will be described.

The automatic toll system reads radio waves emitted from an entrance or an exit or a traveling lane or the like when a car passes through an entrance or an exit of a highway or the like on a toll road, and reads the radio waves with, for example, an on-vehicle radio transmission / reception device. Is a system for automatically charging a fee by sending back the information of

In this system, the directivity of the antenna can be enhanced by using the antenna according to the present invention for the radio transceiver installed at the entrance of the expressway or the like and the radio transceiver installed in the car. Information can be appropriately exchanged with a desired vehicle.

The above embodiment is one of the embodiments in which the array antenna connected to the APF is used for the receiver or the transmitter, and the array antenna connected to the APF is used for another electronic device or device. Needless to say, this is possible.

[0079]

As described above, in the array antenna according to the present invention, the phase difference caused by the antenna element spacing, the antenna feed wiring distance difference, and the feed phase difference is reduced by one with respect to the frequency of the received or transmitted electromagnetic wave. As a result, desired directivity can be obtained over a wide band.

Further, miniaturization can be realized by maintaining the directivity of the array antenna over a wide band and narrowing the interval between antenna elements.

Further, it is possible to provide a receiver or a transmitter using an array antenna capable of obtaining desired directivity over a wide band and an electronic device using the same.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an array antenna according to the present invention.

FIG. 2 shows an example in which the present invention is configured using a dipole antenna.

FIG. 3 shows an example in which the present invention is configured using a dipole antenna.

FIG. 4 is a diagram showing the directivity of the antenna according to the present invention.

FIG. 5 is a configuration diagram of an array antenna according to the present invention having a plurality of antenna elements.

FIG. 6 is an example of a circuit diagram of an APF;

FIG. 7 is a diagram showing frequency characteristics of an APF.

FIG. 8 is an example of a circuit to which an antenna element is connected and a circuit to which an AFP is connected;

FIG. 9 shows a phase shift and APF between antenna elements and the like.
Showing calculation results showing the phase shift due to

FIG. 10 is a diagram showing the amplitude of a current in the circuit shown in FIG. 8;

FIG. 11 is a diagram showing a current amplitude in the circuit shown in FIG. 8;

12 is a diagram in which the amplitudes of currents in the circuit shown in FIG. 8 are combined.

FIG. 13 is a diagram in which the antenna according to the present invention is used in a magnetic field measuring device.

FIG. 14 is a diagram in which the antenna according to the present invention is used in a magnetic field measuring device.

[Explanation of symbols]

 Reference Signs List 101 antenna # 1 102 antenna # 2 103 combiner / distributor 104 reception output / transmission feed circuit 105 phase shifter 106 desired wave 107 noise 108 distance between antenna elements 109 feed line length of antenna # 1 110 feed of antenna # 2 Line length l2 111 Path through desired antenna # 1 112 Path through desired antenna # 2 113 Path through noise antenna # 2 114 Path through noise antenna # 1 230 Coaxial cable 239 Pedestal 240 DUT 241 Probe movable stage 242 Magnetic field probe 243 Magnetic field detector 244 Motor controller 245 Control computer 246 Memory 247 Display device 248 Input device 249 Detected magnetic field signal 250 Stage control signal 251 X direction probe drive mechanism 252 Y direction probe Drive mechanism 253 Z-direction probe drive mechanism 254 θ-direction probe rotation mechanism 255 Probe mounting part 256 Stage control cable 301 Dipole antenna (element) 302 Dipole antenna (element) 303 Dipole antenna (element) 701 Current amplitude characteristic 702 Phase change

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04B 7/10 H04B 7/10 A (72) Inventor Makoto Torigoe 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Japan Stock F-term in Hitachi, Ltd. Production Technology Laboratory (reference) 5J021 AA02 AA05 AA06 AB03 CA01 DB03 FA05 FA23 FA32 GA02 GA05 GA08 JA02 JA07 5K059 CC04 DD32 DD37

Claims (4)

[Claims] 1. An electronic device for receiving or transmitting an electromagnetic wave, wherein the electronic device has a phase circuit for changing a phase according to a frequency of the electromagnetic wave received or transmitted by a receiver or a transmitter of the electronic device. Electronic devices. 2. An electronic device for receiving or transmitting an electromagnetic wave, wherein a phase circuit for changing a phase according to a frequency of the electromagnetic wave transmitted or received by an array antenna of the electronic device is connected to an antenna element of the array antenna. Electronic device. 3. The electronic device according to claim 1, wherein a side lobe or a back lobe is smaller than the main beam by 6 dB or more over a desired frequency range. 4. An electronic device for measuring an electromagnetic wave radiated from an object to be measured, wherein the electronic device has a phase circuit for changing a phase according to a frequency of the received electromagnetic wave.