JP2966690B2 - Antenna device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarization diversity type antenna apparatus for performing standby reception.

[0002]

2. Description of the Related Art There are two types of usages of an antenna device used by being built in a portable wireless device. The first mode of use is a mode in which a user separates from the body and holds the hand and enters a reception state only when the user wants to use it, such as a portable GPS receiver. The second mode of use is paging. Like a receiver, this is a mode in which the user always keeps the body in close contact with the body to maintain the standby reception state.

In the former case, since the user consciously holds the receiver and operates so as to obtain an optimum receiving state, there is no problem even if the antenna characteristics are constant. However, in the latter case, the user is passive and cannot perform any operation for optimal reception by the user. For this reason, it is necessary to change the antenna characteristic itself to obtain an optimum reception state.

FIG. 9 (a) shows a portable wireless device of this type which can receive circularly polarized waves with high sensitivity. In this type of portable wireless device, the space for arranging the antenna is limited, so that one circularly polarized antenna is switched between right-handed and left-handed to perform polarization diversity reception. FIG. 9 (a)
In this portable wireless device, a circularly polarized wave receiving antenna constituted by using a double-sided printed circuit board 2 is attached to a metal housing 1. In the circularly polarized wave receiving antenna, the radiation conductor 3 is formed on the front side of the double-sided printed circuit board 2 and the ground conductor 4 is formed on the rear side of the double-sided printed circuit board 2. The feed point 5 provided on the radiation conductor 3 and the circuit provided on the back side of the circularly polarized wave receiving antenna are connected through the ground conductor 4 with through-hole conductors.

FIG. 9B is a plan view of the double-sided printed circuit board 2. In this circularly polarized wave receiving antenna, feed points 5a and 5b are provided at the upper left corner and the upper right corner on the diagonal lines A and B of the rectangular radiation conductor 3, respectively, and 5a is selected as the feed point 5, and In addition to switching to the circularly polarized wave reception, 5b is selected as the feeding point 5 and switched to the left circularly polarized wave reception so that the polarization diversity reception can be performed by the single-point feeding type circularly polarized wave reception antenna. The length of the long side (upper and lower sides in FIG. 9B) a of the radiation conductor portion 3 and the length of the short side (left and right sides) b are illustrated as being extremely different from each other.
Actually, they differ only slightly (about several percent).

FIG. 10 shows a circuit configuration for performing polarization diversity reception. The respective feeding points 5a and 5b of the circularly polarized wave receiving antenna are selected by switching the switch section 6, and the received signal is input to a received signal processing section 7 as a reception level discriminating means. The switching control of the switch unit 6 includes:
The control unit 8 performs the processing according to the reception level determination result of the reception signal processing unit 7.

[0007] In this circularly polarized wave receiving antenna, normally, the switching state of the switch section 6 is fixed so that reception is performed while being fixed to one of the polarization planes. For example, the C / N (carrier-to-noise ratio) of the received signal is determined by the received signal processing unit 7 and the C / N
When N or the like becomes equal to or less than the determination reference, the switch unit 6 switches the feeding points 5a and 5b under the control of the control unit 8.
That is, polarization diversity reception is performed by switching the polarization plane. In addition, when C / N or the like becomes more than the reference value,
The operation is such that reception is performed with the polarization plane fixed.

If the circularly polarized wave receiving antenna for performing the polarization diversity reception is used for receiving an analog signal, the signal can be received with good intelligibility. For example, when the above-mentioned circularly polarized wave receiving antenna is used in a mobile communication device, even if the transmitting side transmits with right-handed circularly polarized light due to reflection in the middle of the signal propagation path, it may receive with left-handed circularly polarized wave. May have a good C / N ratio. In the above antenna device, regardless of the direct wave and the reflected wave, the one having the larger electric field strength is selected and received, so that the analog signal can be received with good intelligibility.

FIGS. 11A and 11B show another single-point feeding type circularly polarized receiving antenna having a different shape of the radiation conductor portion (patch) 3. FIG. FIG. 11A shows a circular radiation conductor 3.
FIG. 2B includes a rectangular radiation conductor portion 3, and each radiation conductor portion 3 has a notch 3 a for degenerate separation.
3b are formed respectively. Then, each of the notches 3a,
Feeding points 5a and 5b are provided on a substantially straight line passing through the center of the radiating conductor section 3 at an angle of ± 45 degrees with straight lines C and D connecting the center of 3b. Here, the feeding point 5a is for receiving right-handed circularly polarized waves, and the feeding point 5b is for receiving left-handed circularly polarized waves. Even with such a circularly polarized receiving antenna, FIG.
, It is possible to receive analog signals with good intelligibility.

[0010]

By the way, a signal emitted from a low-altitude satellite should be received at a substantially constant level everywhere on the earth where visibility is good.
Therefore, in the state where the average value of the reception level is high, the circularly polarized wave component (circularly polarized wave emitted from the satellite) is dominant, and
Conversely, when the average value of the reception level is low, it is considered that the reverse circularly polarized wave component (the circularly polarized wave having the opposite phase to the circularly polarized wave emitted from the satellite) is dominant.

FIG. 12 shows how the plane of polarization of a circularly polarized signal changes under the influence of a reflected wave. For the sake of simplicity, FIG. 12 shows the locus of the combined electric field vector when the amplitudes of the electric field vectors α and β of two spatially orthogonal linearly polarized components are equal. Here, the propagation direction of the radio wave is a direction toward the depth in a direction orthogonal to the paper surface. FIG.
2, the transmitted electric field vector locus (a) of the right-handed circularly polarized light is represented by a right-handed elliptically polarized wave (b), an oblique linearly polarized wave (c),
Left-handed elliptical polarization (d), left-handed circularly polarized light (e), left-handed elliptically polarized light (f), oblique linearly polarized light (g), right-handed elliptically polarized light (h), change sequentially and smoothly, right-handed again The process of returning to circularly polarized wave (a) is shown. Note that, of course, the reverse change process ((a)
→ (h) → (g) → (f) → (e) → (d) → (c) →
It is also conceivable to take (b) → (a)).

(A) and (e) in FIG. 12 show electric field vectors α and β of two linearly polarized components that are spatially orthogonal to each other.
Correspond to the trajectories of the combined electric field vectors when combined with a phase difference of +90 degrees and −90 degrees, respectively, and (b), (d),
(F) and (h) show that the electric field vectors α and β are +45 degrees, respectively.
(C), which corresponds to the locus of the combined electric field vector when combined with the phase differences of +135 degrees, -135 degrees, and -45 degrees.
(G) shows that the electric field vectors α and β are 0 degree (in-phase), 18
This corresponds to the locus of the combined electric field vector when combined at 0 degrees (opposite phase).

FIG. 12 illustrates the case where the amplitudes of the electric field vectors α and β of two spatially orthogonal linearly polarized components are equal, but if the amplitudes are not equal, FIG.
Does not change, except that the outer frame of the combined electric field vector locus indicated by the dotted line changes into a vertically long or horizontally long rectangle instead of a square. In the above description, the electric field vectors α and β of two linearly polarized components that are spatially orthogonal to each other are described.
The trajectory of the combined electric field vector is described above, but the trajectory of the combined electric field vector when the mixing ratio of the electric field vector of the normal circular polarization and the electric field vector of the reverse circular polarization generated by reflection or the like gradually changes. Can also be explained. That is, (a) shows the case where the right-handed circularly polarized component is 100% and the left-handed circularly polarized component is 0%, and (c) and (g) show the case where the right-handed circularly polarized component and the left-handed circularly polarized wave are used. (E) corresponds to a case where the right-handed circularly polarized wave component is 0%.
%, Which corresponds to the case where the left-hand circularly polarized wave component is 100%.

Considering the case where the received electric field is substantially constant in a certain area, such as a signal wave from a satellite, it can be classified into the following two cases. If the long section (average) reception electric field is equal to or more than a certain value, the view from the sky is good and the reflected wave (delayed wave) component is small. In FIG. 12, (a), (b), (c),
(G) and (h).

If the long-term (average) received electric field is equal to or less than a certain value, the visibility from the sky is poor, and the reflected wave (delayed wave) component is more than the direct wave component. FIG. 12 shows states (c), (d), (e), (f), and (g). In such a case, if the conventional polarization diversity reception is performed as it is, the switching between the states shown in FIGS. 12A and 12E, that is, the switching between the reception states of the signal waves having greatly different delay times. For example, when a digitally modulated signal is received by the above-mentioned circularly polarized wave receiving antenna, when a direct wave (for example, right-handed circularly polarized wave) receiving state and a reflected wave (for example, left-handed circularly polarized wave) receiving state are switched. Due to the delay time difference, each time switching is performed, reception data is overlapped or missing,
There is a disadvantage that it causes a fatal data error.

As a method for solving the above-mentioned problem, the number of options for switching the reception mode is increased, and FIG.
(C), (e), and (g), and it is conceivable to switch the reception mode according to the reception electric field. For example,
When the average received electric field is equal to or more than a certain value and the instantaneous received electric field is equal to or less than a certain value, one of (a), (c), and (g) is sequentially switched and selected (for example, (a) → (c) ) →
(Switching selection in the order of (a) → (g) → (a) →...), The switching is stopped when the instantaneous received electric field exceeds a certain value, and the average received electric field is below a certain value, and When the received electric field is below a certain value, (c), (e),
(G) is sequentially switched and selected (for example, (e) →
(D) → (e) → (g) → (e) →...), And the switching may be stopped when the instantaneous reception electric field exceeds a certain value.

[0017] In this case, extreme switching of the reception polarization plane, that is, switching of the reception state of the signal wave having a significantly different delay time is not performed, so that even when the digital modulation signal is received, the data overlaps. Alternatively, no data error occurs due to the lack. FIG. 13 shows a specific antenna device for realizing the above-described plurality of types of polarization plane reception. In this antenna apparatus, a two-point feeding type antenna is used as the circularly polarized wave receiving antenna, and two orthogonal feeding points obtained at two feeding points 5c and 5d are used.
The two linearly polarized components are +90 degrees, -90 degrees, 0 degrees and 18 degrees.
The signals are selectively combined at 0 degrees, and linearly polarized waves orthogonal to each other as well as right-handed and left-handed circularly polarized waves can be received.

The two-point feeding type circularly polarized wave receiving antenna shown in FIG. 13 is basically the same as the circularly polarized wave receiving antenna shown in FIG. 9 (b) except that the feeding points 5c and 5d are radiated. The difference lies in that it is provided at a position different from the center of the radiation conductor element portion 3 on each of the straight lines E and F connecting the midpoints of the opposite sides of the conductor element portion 3. Further, the reception outputs of the feeding points 5c and 5d are phase-shifted by +90 degrees, -90 degrees, 0 degrees or 180 degrees by the phase shift synthesizing unit 9 'and synthesized, so that the above-described stepwise polarization plane can be obtained. A switching operation can be achieved.

However, in the antenna device of FIG. 13, although the structure of the circularly polarized wave receiving antenna itself is simplified, the circuit configuration of the phase shift synthesizing unit 9 'is complicated, and the occupied area is increased. There was a problem. That is, the phase shift synthesizing unit 9 'requires a phase shift circuit for obtaining an output shifted by 90 degrees, which complicates the circuit configuration, and this type of phase shift circuit is usually a hybrid IC (for example, an inductance element). And an integrated circuit (IC) in which a capacitor and the like are integrally incorporated. Therefore, it becomes difficult to apply the present invention to a portable wireless device having a small component mounting area.

The present invention has been made in view of the above points, and an object of the present invention is to provide an antenna device which does not cause a data error even when receiving a digital signal and which can be downsized. Is to do.

[0021]

According to a first aspect of the present invention, there is provided a structure in which a radiation conductor and a ground conductor are opposed to each other with a dielectric or an air layer interposed therebetween to achieve the above object. The first feed point for circular polarization, the second feed point for left-hand circular polarization, and the third and fourth feed points for first and second linear polarizations orthogonal to each other are used as radiation conductors. An antenna main body is provided, and selection input means is provided for selectively receiving a received signal from each feeding point of the antenna main body.

For example, as a specific method of arranging the feeding point when the radiation conductor is rectangular, the radiation conductor is rectangular and a pair of substantially diagonal lines of the radiation conductor are arranged. The first and second feeding points may be respectively provided with the first feeding point on the counterclockwise diagonal, and the third and fourth feeding points may be provided substantially on a straight line connecting the centers of the opposite sides.

Further, as a specific method of arranging the feeding point when the radiating conductor is circular, a degenerate separation element having any of concave and convex is provided at a position symmetrical with respect to the center. A third feeding point is provided substantially on a first straight line connecting the degenerate separation elements, and a fourth feeding point is provided on a second straight line passing through the center and orthogonal to the first straight line. A first feed point is provided on a third straight line that crosses the first straight line at an angle of 45 degrees counterclockwise, and a fourth feed point that passes through the center and intersects the first straight line at an angle of 45 degrees clockwise. The second feeding point may be provided on the straight line.

Note that, depending on the shape of the radiation conductor, the third
And the tuning frequency of the antenna body having the fourth feeding point as the feeding point may be shifted. Therefore, in order to prevent this, as shown in claim 4, the equivalent radii of the power supply conductors for guiding the reception signals at the third and fourth power supply points to the selection input means through the ground conductor portion are made different. Then, the tuning frequency of the antenna body having the third and fourth feed points as feed points may be adjusted.

In order to further reduce the size of the antenna device, a radiation conductor and a ground conductor are formed by using copper foil on the front and back surfaces of the double-sided printed circuit board. It is preferable to provide a switching element of the selection input means between the power supply conductor and the radiation conductor, which guide the reception signal to the selection input means through the ground conductor. By the way, when the switching element is integrated into the antenna main body as described in claim 5, it is necessary to apply a DC bias to the switching element via the radiation conductor part in the conductor part. The antenna operation may be disturbed due to high frequency grounding. Therefore, in order to prevent this, a high-frequency choke circuit that separates the conductor portion and the radiation conductor portion from each other in high frequency may be provided.

As a specific polarization diversity receiving method for preventing a data error from occurring when a digital signal is received, a right-handed clock obtained from the first feeding point is described in claim 7. A first reception mode in which a circularly polarized reception signal is used as an antenna output, a second reception mode in which a left-hand circularly polarized reception signal obtained from a second feeding point is used as an antenna output, and third and fourth power supply A third reception mode in which the in-phase synthesized signal of the linearly polarized reception signals respectively obtained from the points is used as an antenna output, and an anti-phase synthesis signal of the linearly polarized reception signals obtained from the third and fourth feeding points, respectively, as an antenna. A receiving mode switching means for switching the receiving mode to one of a fourth receiving mode as an output, and the selection input means selectively receiving a received signal from each feeding point in accordance with the receiving mode. There.

According to another aspect of the present invention, there is provided a method for receiving a digital signal more satisfactorily without data errors, comprising a receiving level determining means for determining at least an average receiving level of the received signal, wherein the receiving mode switching means is provided. But,
When the average reception level is equal to or higher than a predetermined value, polarization diversity reception for switching the first, third, and fourth reception modes is performed. When the average reception level is equal to or lower than a predetermined value, the second, third, and fourth modes are used. The reception mode may be switched so as to perform polarization diversity reception in which the reception mode is switched.

[0028]

According to the first aspect of the present invention, as described above, the first feed point for right-hand circular polarization, the second feed point for left-hand circular polarization, and the first and second straight lines orthogonal to each other. Third and fourth polarization
The feed point is provided on the radiating conductor, and the received signal from each feed point of the antenna body is selectively taken in by the selection input means, so that the intermediate polarization between the right-handed circular polarization and the left-handed circular polarization is obtained. Receiving linearly polarized waves that are in a state is also possible, and a receiving mode for receiving linearly polarized waves is incorporated between the receiving modes of right-handed and left-handed polarized waves, and the polarization planes with extremely different phases are switched. Instead, the polarization plane is switched smoothly with a relatively small change in phase to reduce the occurrence of data errors even when receiving a digital signal. In other words, when receiving a circularly polarized wave (either clockwise or counterclockwise)
The phase changes under the influence of the reflected wave in the signal propagation path. In an extreme case, the circularly polarized wave is converted to the circularly polarized wave through the linearly polarized wave (the circularly polarized wave having the opposite phase to the circularly polarized wave). (Wave), and returns to a normal circularly polarized wave via a linearly polarized wave having an opposite phase. That is, when changing from normal circular polarization to reverse circular polarization, the light passes through linear polarization. Here, the phase of the linearly polarized wave and the normal circularly polarized wave or the reverse circularly polarized wave is an intermediate phase difference between the phase difference between the normal circularly polarized wave and the reverse circularly polarized wave. Therefore, if the receiving mode is switched between the receiving modes of the right-handed and left-handed circularly polarized waves and the receiving mode for receiving the linearly polarized wave is provided, the phase of the switching of the receiving mode becomes extremely different. Thus, switching can be performed smoothly, and data errors are less likely to occur even when digital signals are received. Also, clockwise,
By obtaining left-handed circular polarization directly from the antenna body,
A complicated and large-sized circuit such as a 90-degree phase synthesizing circuit is not required, and the configuration of a circuit unit that processes the output of the selection input means is simplified and downsized.

According to the fourth aspect of the present invention, the inductance component can be varied by changing the equivalent radius of the power supply conductor that guides the reception signals at the third and fourth power supply points to the selection input means through the ground conductor. Thus, the tuning frequency of the antenna body having the third and fourth feed points as feed points is adjusted. This prevents the tuning frequency of the antenna body having the third and fourth feeding points as the feeding points from being shifted due to the shape of the radiation conductor.

According to a fifth aspect of the present invention, a radiation conductor section and a ground conductor section are formed using copper foil on the front and back of a double-sided printed circuit board.
By providing the switching element of the selection input means between the power supply conductor and the radiation conductor part which guides the reception signal of each feed point through the ground conductor part to the selection input means, the number of circuit parts of the selection input means is reduced. Thus, the antenna device is further downsized.

According to a sixth aspect of the present invention, by providing a high-frequency choke circuit for separating a conductor portion and a radiation conductor portion at a high frequency, the antenna operation by applying a DC bias to the switching element via the radiation conductor portion is achieved. Prevent turbulence. In other words, when the switching element is integrated into the antenna main body as described in claim 5, it is necessary to apply a DC bias to the switching element via the radiation conductor at the conductor, and to radiate the radiation at the DC bias line. This is because the conductor may be grounded at a high frequency and the operation of the antenna may be disturbed.

[0032]

(Embodiment 1) FIG. 1 shows an embodiment of the present invention. The circularly polarized wave receiving antenna of the antenna device of the present embodiment includes:
Basically, it is the same as that described with reference to FIG. 9, and the same components are denoted by the same reference numerals and detailed description thereof will be omitted. In the case of the present embodiment, substantially diagonal lines A and B of the rectangular radiation conductor portion 3 are used.
Feeding points 5a and 5 provided at the upper left and upper right corners, respectively
In addition to b, feed points 5c and 5d provided at positions different from the center of the radiation conductor 3 on respective straight lines E and F connecting the midpoints of the opposite sides of the radiation conductor 3 described in FIG. Are provided. Here, the feeding point 5a is a feeding point for receiving right-handed circularly polarized waves, the feeding point 5b is a feeding point for receiving left-handed circularly polarized waves, and the feeding points 5c and 5d are feeding points for receiving orthogonally polarized linearly polarized waves. is there. The distances from the center of the radiating conductor element portion 3 to the respective feeding points 5a to 5d are substantially the same.

Incidentally, the radiation conductor portion 3 of the present embodiment is a rectangle (the lengths of the sides a and b are different). Therefore, the tuning frequency for the linearly polarized wave component at each of the feeding points 5c and 5d is different. Therefore, in order to correct this, in the present embodiment, the equivalent radius of a not-shown through-hole conductor (or may be a conductive pin) connecting the feeding points 5c and 5d to the circuit unit is adjusted, and tuning is performed at the same frequency. I have to do it. Note that adjusting the equivalent radius of the through-hole conductor results in adjusting the inductance component. In the case of FIG. 1, since the side a is longer than the side b, the radius of the through-hole conductor connected to the feeding point 5c is set slightly smaller than the radius of the through-hole conductor connected to the feeding point 5d. I have.

The output of the circularly polarized wave receiving antenna is subjected to phase shift combining in a phase shift combining section 9 and output to a received signal processing section 7. Here, in the case of the circularly polarized wave receiving antenna, the right-handed circularly polarized wave and the left-handed circularly polarized wave can be directly received.
Unlike the above case, a phase shift circuit for performing a 90-degree phase shift is not required, and only a 0-degree and a 180-degree phase shift circuit are required. here,
The 0-degree and 180-degree phase shift synthesizing circuits can be configured by using non-inverting and inverting type amplifying elements. I will not invite you.

FIG. 2A shows a specific circuit of the phase shift synthesizing section 9. The phase shift synthesizing section 9 basically includes an input terminal IN ₁
A right-handed circularly polarized wave signal received from the feed point 5a inputted (RHC) from the feeding point is input from the input terminal IN ₂ 5
Left-handed circularly polarized wave received signal and a (LHC) and the switch SW ₁ selectively capture from b, and whether capture linear polarization received signal from the feed point 5c inputted from the input terminal IN ₃ (LP1) Select switch SW ₄ and input terminal IN
Switch SW ₅ for selecting whether or not to take in the linearly polarized reception signal (LP2) from the feeding point 5d input from ₄
A phase-shift synthesizing circuit composed of MOSFETs Q ₁ and Q ₂ as an amplifying element and a switch SW ₂ for phase shifting one linearly polarized wave reception signal by 0 ° and 180 ° and synthesizing; whether to output either the composite linear polarization received signal to the reception signal processing unit 7 it is constituted by a switch SW ₃ for selecting. Here, in the case of the present embodiment, the switch SW
_1, in SW _4, SW _5, the feeding point of the receiving antenna 5a~
Selection input means for selectively receiving the received signal from 5d is constituted.

In the phase shift synthesizing circuit, a straight line from the feeding point 5c
The polarization reception signal is converted to a load resistance R₁, R _TwoAnd MOSFET
Q₁Amplification circuit consisting of
These linearly polarized reception signals are converted to load resistance R_Three, R_FourAnd MO
SFETQ_TwoAmplify with Where the resistance R_Two, R_ThreeContact
A DC voltage is applied to the connection point from the power supply terminal PS. What
Contact, capacitor C_FourIs a bypass capacitor.

[0037] In the amplifier circuit of the MOSFET Q ₁ side,
Coupling capacitor C ₁ from the s drain and source respectively of MOSFET Q _1, C ₂ the inverted output and non-inverting output through the are to be obtained. Then, the output of each of the amplification circuit to select via the switch SW _2, a MOSFET
It is combined with the output of the amplifier circuit of TQ ₂ side. Now, the non-inverted output is selected by the switch SW _2, when it is combined with the output of the amplifier circuit of the MOSFET Q ₂ side, phase (0 degrees) composite linear polarization reception signal. Conversely, the inverted output is the switch S
When selected by W ₂ and combined with the output of the amplifying circuit on the MOSFET Q ₂ side, an inverted-phase (180 °) combined linearly polarized reception signal is obtained.

The above switch SW₁~ SW_FiveIs a single pole double throw
And the control unit 8 controls the control terminal CNT.₁~ C
NT_ThreeThe switching is performed by the control voltage applied to the respective switches. S
Switch₁~ SW_FiveFIG. 2 (b) shows a specific configuration.
In the following description, the switch SW₁~ SW_FiveCollectively
And simply called a switch SW. The switch SW is a terminal
coupling capacitor C between a and b₆, C₇PIN via
Diode D₁, D_TwoAre connected in series. Where my husband
Each PIN diode D ₁, D_TwoConnects the anodes in common
And the commonly connected anode is the coupling capacitor C _FiveThrough
And connected to terminal c. Diode D₁, D_TwoNo
A bias voltage is applied to the node via the bias terminal BIAS.
Is applied. Also, PIN diode D₁, D_Twoof
The control voltage and the inverter are connected to the cathode from the control terminal CNT.
Data I₁Voltage is the control voltage inverted in
You. Note that the bias voltage, control voltage, and the inverted voltage
The pressure is choke coil L₁~ L_ThreeApply via
With the choke coil L₁~ L_ThreeThe voltage application end of
Pass capacitor C₈~ C_TenConnect to ground with
The high-frequency component is controlled by the control terminal CNT and the bias terminal BIA.
Output to the S side is prevented.

[0039] Now, when the control voltage applied from the control terminal CNT is at the high level, the PIN diode D ₁ becomes nonconductive, the output of the inverter I ₀ becomes low level, and the conductive state PIN diode D ₂ Become. At this time, the signal input from the terminal b is output from the terminal c. Conversely, when the control voltage is at a low level, the PIN diode D ₁ becomes conductive and the PIN diode D ₂
Are turned off, and the signal input from the terminal a is output from the terminal c.

The switching state (contact position) of each of the switches SW _{1 to} SW ₅ of the phase shift synthesizing unit 9 in the reception mode of right-hand circular polarization, left-hand circular polarization, in-phase combined linear polarization, and reverse-phase combined linear polarization. ) And the control voltage application state are shown in the following table.

[0041]

[Table 1]

The right-handed circularly polarized wave in the reception mode is shown in FIG.
(A), left-hand circularly polarized light corresponds to FIG. (E), in-phase combined linear polarization corresponds to FIG. (C), and anti-phase combined linear polarization corresponds to FIG. The contact position indicates which side of the terminals a and b has been switched, and-indicates that the terminal may be switched to either of the terminals a and b. Table 1 above
CNT _{1 to} CNT ₃ are control terminals CNT ₁ to CNT
Shows the control voltage applied to the NT _3, the control voltage indicates that it is a high level (H) and low level (L).

As shown in FIG. 2A, the control terminal CNT
₁, CNT_TwoThe control voltage applied to the switch SW₁,
SW_TwoAs shown in Table 1 above.
Switch SW₁, SW_TwoThe other switch off when
The switching state may be any of the terminals a and b. Therefore,
As shown by the broken line in FIG.₁, CNT _Two
May be connected in common.

Next, FIG. 3A shows the configuration of the control unit 8 which controls the switching of the reception mode in the phase shift synthesizing unit 9 in accordance with the result of the judgment such as the reception state of the reception signal processing unit 7. The control unit 8 includes a clock generator (CLK) 10, a clock signal generated by the clock generator 10, and a start / stop signal START /
AND gate 11 for calculating a logical product of STOP (taking AND), 2-bit binary counter 12 for counting output pulses output from AND gate 11, output of binary counter 12, and received signal processing unit 7 level judgment output
And a decoder 13 for generating a decode output corresponding to the LEVEL. That is, in the present embodiment, the reception mode switching means is constituted by the phase synthesis unit 9, the reception signal processing unit 7, and the control unit 8.

Level determination output LEVEL of received signal processing section 7
Is an output that goes high if the average received signal level is above a certain value. Also, start / stop signal
START / STOP is a signal that goes to a high level if the instantaneous value of the received signal is equal to or less than a certain value. In addition, 2 bits 2
Output X _1, X ₂ of the advance counter 12, respectively 2 ⁰ digit and 2 ¹
This is an output indicating whether the digit is 1/0. The output Y _{1 of the} decoder 13 is a signal applied to the commonly connected control terminals CNT ₁ and CNT ₂ indicated by a broken line in FIG. 2A, and the output Y ₂ is a signal applied to the control terminal CNT ₃ .

FIG. 3B shows one specific configuration of the decoder 13.
Show. The decoder 13 outputs the output X of the binary counter 12
₁, X_TwoAND gate AND₁And the output
X₁Inverter I for inverting₁And the gate
AND₁And inverter gate I₁The logical sum of the outputs of
OR (take OR) OR gate OR₁And the level judgment output
Inverter gate I for inverting power LEVEL_TwoAnd Andge
Auto AND₁Output and inverter gate I_TwoWith the output of
AND gate AND_TwoAnd OR gate OR
₁AND between level output and level judgment output LEVEL
Gate AND _ThreeAnd AND gate AND_Two, AND_Three
OR gate OR to OR the output of_TwoComposed of
You. In the decoder 13, the OR gate OR_TwoOutput
Output Y₁And the inverter gate I₁Output is output Y
_TwoBecomes

Here, the AND gate AND ₁ , the inverter gate I ₁ and the OR gate OR ₁ constitute a so-called decoding section which is the main part of the decoder 13, and the AND gates AND ₂ and AND ₃ , the OR gate OR ₂ and the inverter gate I ₂ Thus, a single-pole / double-throw switch circuit controlled by the level determination output LEVEL is formed. Now, it is assumed that the instantaneous value of the reception level fluctuates and becomes equal to or less than the predetermined value while the average reception level of the reception signal is higher than the predetermined value.
At this time, the level determination output LEVEL of the reception signal processing unit 7 is at a high level, and the start / stop signal START / STOP
Becomes high level. Therefore, a clock signal is supplied from the clock generator 10 to the binary counter 12 via the AND gate 11. At this time, the binary counter 12 starts counting and cyclically outputs its outputs X ₁ and X 2 as shown in Table 2.
₂ changes ((L, L) → (L, H) → (H, L) →
(H, H) → (L, L)).

[0048]

[Table 2]

In the above case, as shown in the upper half of Table 2, the receiving mode is changed from (a) to (c) in FIG.
(A) → (g) → (a)...
That is, the reception mode is repeatedly switched around the reception mode of right-hand circularly polarized wave. Then, on the way, the instantaneous value of the received signal exceeds a certain value, and the start / stop signal
When START / STOP goes low, the clock signal generated by the clock generator 10 is not supplied from the AND gate 11 to the binary counter 12, and the binary counter 12 stops counting. Thereby, the reception mode at that time is maintained. That is, when a good reception state is obtained, the reception mode is fixed.

Conversely, when the average received level of the received signal is lower than the fixed value and the instantaneous value of the received level is equal to or less than the fixed value, the receiving mode is changed from (e) in FIG.
(C) → (e) → (g) → (e)... That is, the reception mode is repeatedly switched around the reception mode of the left-hand circularly polarized wave. Then, when the instantaneous value of the received signal becomes a certain value or more on the way, the receiving mode is fixed at that time.

According to the present embodiment, a reception mode for receiving a linearly polarized wave is incorporated between the right-handed circularly polarized wave and the left-handed circularly polarized wave,
Without switching the polarization planes with extremely different phases, the polarization plane can be switched smoothly with relatively little change in phase, and data errors are less likely to occur even when receiving digital signals. can do. Further, by obtaining the right-handed and left-handed circularly polarized waves directly from the antenna main body, a complicated and large-sized circuit such as a 90-degree phase synthesizing circuit is not required, and the configuration of the circuit unit for processing the output of the selection input means is eliminated. Can be simplified, and the antenna device can be downsized.

(Embodiment 2) FIG. 4 shows another embodiment of the present invention. In the first embodiment described above, the radiation conductor 3 is rectangular, but this embodiment shows that the present invention can be applied even when the shape of the radiation conductor 3 is different. FIG. 4 (a)
FIG. 11A shows an example in which the present invention is applied to the radiation conductor 3 shown in FIG. In the following description, the same components as those in FIG. 11A are denoted by the same reference numerals, and description thereof will be omitted. FIG.
In the circularly polarized wave receiving antenna of (a), in addition to the feed point 5a for receiving the right-handed circularly polarized wave and the feed point 5b for receiving the left-handed circularly polarized wave, the feed points 5c and 5d for receiving the orthogonal linearly polarized wave are provided. Is provided. Here, the feeding point 5c is provided on a substantially straight line C connecting the centers of the notch portions 3a for degenerate separation of the radiation conductor portion 3, and a substantially straight line G orthogonal to the straight line C and passing through the center of the radiation conductor portion 3 is provided.
A feed point 5d is provided above.

FIG. 4B shows a circularly polarized wave receiving antenna provided with the radiation conductor 3 shown in FIG. 11B, and feed points 5c and 5d for receiving linearly polarized waves are degenerated by degenerating the radiation conductor 3. The feed point 5d is provided on a substantially straight line D connecting the center of the separation notch 3b, and substantially on a straight line H orthogonal to the straight line D and passing through the center of the radiation conductor 3. As described above, even in the case of the circularly polarized wave receiving antenna in which the shape of the radiation conductor portion 3 is different, the first embodiment
In the same manner as described above, the polarization plane can be switched smoothly with relatively little phase change, and the occurrence of data errors can be reduced even when a digital signal is received. Can be.

The feeding point 5 shown in FIGS.
In the case of c, the length of the radiation conductor along the straight lines C and D becomes shorter due to the cutouts 3a and 3b, and the tuning frequency becomes higher than that of the feed point 5d. Therefore, the radius of the through-hole conductor that guides the feeding point 5c to the circuit portion through the ground conductor portion 4 is smaller than that of the through-hole conductor on the feeding point 5d side. This makes the tuning frequency equal by adding an inductance component.

(Embodiment 3) FIG. 5 shows still another embodiment of the present invention. This embodiment is applied when the phase shift synthesizing unit 9 shown in FIG. 6 is used. Therefore, the phase shift synthesizing unit 9 in FIG. 6 will be described first. FIG. 6 shows only the switch unit on the receiving antenna side, and does not show a subsequent circuit such as a 0-degree and 180-degree phase shift circuit. Therefore, in the following description, the circuit unit in FIG. 6 is referred to as a switch unit 9a. In addition,
This switch section 9a functions as selection input means.

The switch section 9a selectively uses the PIN diodes D _{3 to} D ₆ connected to the feed points 5a to 5d of the radiation conductor section 3 to selectively shift the reception outputs from the feed points 5a to 5d. 9 to the subsequent circuit. Where P
The cathodes of the IN diodes D ₃ and D ₄ are connected to the feeding points 5 a and 5 b of the radiation conductor section 3, and are alternately turned on and off depending on whether the control voltage applied to the control terminal CNT ₁ is high or low. , And selectively output the right-handed and left-handed circularly polarized reception signals from the feeding points 5a and 5b.

PIN diode D_FiveIs at the feed point 5c.
Connected, and the PIN diode D₆Is at the feed point 5d
The cathode is connected to the control terminal CNT_ThreeApplied to
On and off at the same time with the control voltage
Output orthogonal linear polarization reception outputs from feed points 5c and 5d.
Power. Here, the radiating conductor 3 has a slot, which will be described in detail later.
From the bias terminal bias via the through hole conductor 3c
DC voltage is applied and PIN diode D_Three~ D₆
A voltage higher than the bias voltage by a fixed voltage at the anode
Is applied, the PIN diode D_Three~ D₆Is in order
Connected and conducting, lower than the anode bias voltage
Voltage (However, the bias voltage is
Voltage may be lower than the applied voltage).
When applied, the PIN diode D_Three~ D₆Is reverse biased
And become non-conductive. The PIN diode D_Three~ D
₆Voltage higher than the bias voltage by a certain voltage
When pressure is applied, the control voltage CNT ₁, CNT_ThreeControl
Assuming that the voltage is in the high level state,
Control voltage CNT when a voltage lower than the
₁, CNT_ThreeControl voltage is at a high level.
The following will be described.

In the case of FIG. 6, the function part as the single-pole / double-throw type switch SW ₁ of FIG. 2 is replaced by a PIN diode D ₃ ,
D ₄ , inverter gate I ₃ , choke coil L ₄ , L
₅ , L ₈ , coupling capacitors C ₁₂ and C ₁₃ and a bypass capacitor C ₁₁ . Also, the switch SW of FIG.
₄ with a PIN diode D ₅ , a choke coil L ₇ , L
_8, constituted by a coupling capacitor C ₁₄ and the bypass capacitor C _11, further the switch SW _5, PIN diode D
₆ , a choke coil L ₆ , L ₈ , a coupling capacitor C ₁₅ and a bypass capacitor C ₁₁ . The output of the circuit portions constituting the respective switches shown in out ₁ ~out _3.

FIG. 5A is a diagram showing the receiving antenna of this embodiment. In the receiving antenna of this embodiment, the PIN diodes D _{3 to} D ₆ of the switch section 9 a are integrated into the radiation conductor section 3. The feature is that it is incorporated. As shown in FIG. 6, in order to apply a bias voltage to the radiating conductor 3, a through-hole conductor 20e is provided at the center of the radiating conductor 3.
(See FIG. 5C). However, in the receiving antenna with a radiation conductor portion 3 of the rectangular embodiment, connecting directly to the radiation conductor portion 3 to a connection point between the choke coil L ₈ and the capacitor C ₁₁ of the switch portion 9a, the radiation conductor 3 It is grounded in alternating current, and the antenna operation is disturbed. Therefore, in order to prevent this, a high-frequency choke circuit 32 is provided at the center of the radiation conductor section 3 so that the switch section 9a and the receiving antenna are separated at a high frequency.

FIG. 5B shows feed points 5a to 5d (feed points 5a to 5d).
The power supply units 50a to 50d (collectively referred to as the power supply units 50) corresponding to the power supply points 5) are shown.
The power supply section 50 partially removes the copper foil of the radiation conductor section 3,
The through-hole conductor 20 (through-hole conductors 20a to 20a) for connection with the switch section 9a is provided in the copper foil removing section 30.
d), and a PIN diode D (general term for PIN diodes D _{3 to} D ₆ ) composed of a chip component is mounted between the through-hole conductor 20 and the radiation conductor portion 3. Therefore, the substantial feeding point 5 is the PIN diode D
Of the through-hole conductor 20 on the opposite side.

As shown in FIG. 5C, the high-frequency choke circuit 32 removes the copper foil from the center of the radiation conductor section 3 in a circular shape, and connects the copper foil removal section 31 to the switch section 9a at the center. A through-hole conductor 20e to be performed is formed, and the through-hole conductor 20e and the radiation conductor portion 3 are connected by an inductance element 32a made of a spiral copper foil pattern.

FIG. 7A shows the receiving antenna of FIG. 4A with the PIN diodes D ₃ -D ₃ of the switch section 9a of FIG.
D ₆ is integrated into the radiation conductor 3. FIG. 7B shows a specific structure of the power supply unit 50. By the way, in a reception antenna of this type in which the radiating conductor 3 is circular, a through-hole conductor 20 is formed at the center of the radiating conductor 3.
If e is provided, the antenna operation is not disturbed even if the radiation conductor section 3 is grounded in an AC manner. Therefore, in the case of FIG. 7, the high-frequency choke circuit 32 is not used, and the through-hole conductor 20e is directly connected to the switch section 9a. In this embodiment, as shown in FIG. 7C, the radiation conductor 3 is connected to the ground conductor 4 in an alternating manner.
In this case, in order to apply a DC bias to the radiation conductor portion 3, it is necessary to separate the radiation conductor portion 3 and the ground conductor portion 4 in terms of DC, so that the ground conductor portion 4 and the through-hole conductor 2 are separated.
Between 0e is coupled with capacitor C ₁₁ formed of chip components.

(Embodiment 4) The above description has been given of the case where the present invention is applied to a portable radio device or a satellite communication device mounted on a mobile body. However, the present invention is applied to an in-vehicle antenna device. Is also possible. In such an in-vehicle wireless device, the reception environment changes rapidly. For this reason, it is not possible to determine the reception state, particularly the distinction between right-handed and left-handed circularly polarized waves, from the average received electric field. Therefore, the reception state is determined from the instantaneous value of the reception level, and the reception mode is switched accordingly.

FIG. 8A shows a specific configuration of the control section 8 of the vehicle-mounted antenna device. The control unit 8 differs from FIG. 3 in that a level determination output corresponding to the average reception level of the reception signal is not input to the decoder 13 from the reception signal processing unit 7. That is, in the present embodiment, when the instantaneous value of the received signal is equal to or smaller than a certain value, the reception mode is changed to those shown in FIGS.
(E) and (g) are switched cyclically and stepwise smoothly (for example, (a) → (c) → (e) → (g) →
(A)), thereby ensuring a good reception state. Signal state of the output Y _1, Y ₂ output X _1, X ₂ and the decoder 13 of the binary counter 12 when switching to receive mode are shown in Table 3.

[0065]

[Table 3]

From Table 3, the output Y _{1 of the} decoder 13 is an output when the exclusive NOR (exclusive NOR) of the outputs X ₁ and X ₂ of the binary counter 12 is obtained, and the output Y ₂ is binary. because it is the inverted output of the output X ₁ of the counter,
In the case of Table 3, the decoder 13 can be composed of the exclusive NOR gate EXNOR and the inverter gate I shown in FIG.

In each of the above embodiments, the case where the antenna body, which is a so-called microstrip antenna, is constituted by the double-sided printed circuit board 2 has been described.
As long as the radiation conductor 3 and the ground conductor 4 are opposed to each other with a dielectric layer or an air layer interposed therebetween, the antenna conductor of the present invention can be applied. In this type of antenna main body, power is normally supplied from the back side of the ground conductor 4 via a power supply conductor. Further, it is desirable that the dielectric layer or the air layer is thinner than the wavelength corresponding to the resonance frequency of the antenna body.

[0068]

According to the first aspect of the present invention, as described above, the radiation conductor and the ground conductor are opposed to each other with a dielectric or an air layer interposed therebetween. An antenna body in which a feed point, a second feed point for left-hand circular polarization, and third and fourth feed points for first and second linear polarizations orthogonal to each other are provided on a radiation conductor; Since there is provided a selection input means for selectively receiving a reception signal from each feeding point, a reception mode for receiving a linearly polarized wave is incorporated between the reception modes for the right-handed circular polarization and the left-handed circular polarization. It is possible to switch the polarization plane smoothly with relatively little phase change without switching the polarization planes with extremely different phases, and a data error occurs even when receiving a digital signal. Can be reduced. Further, by obtaining the right-handed and left-handed circularly polarized waves directly from the antenna main body, a complicated and large-sized circuit such as a 90-degree phase synthesizing circuit is not required, and the configuration of the circuit unit for processing the output of the selection input means is eliminated. Can be simplified, and the antenna device can be downsized.

According to the fourth aspect of the present invention, the equivalent radii of the power supply conductors for guiding the reception signals at the third and fourth power supply points to the selection input means through the ground conductor portion are made different, so that the third and fourth power supply conductors are provided. The tuning frequency of the antenna body having the feeding points as the feeding points is adjusted, and the reception signals of the third and fourth feeding points pass through the ground conductor portion and are guided to the selection input means. By varying the equivalent radius, the inductance component can be varied to adjust the tuning frequency of the antenna body having the third and fourth feed points as the feed points, respectively. Therefore, depending on the shape of the radiation conductor, Third and fourth
It is possible to prevent the tuning frequency of the antenna main body having each of the feeding points as the feeding points from being shifted.

According to the fifth aspect of the present invention, the radiation conductor and the ground conductor are formed by using the copper foils on the front and back of the double-sided printed circuit board, and the reception signal at each feeding point passes through the ground conductor and is applied to the selection input means. Since the switching element of the selection input means is provided between the feeding conductor and the radiation conductor, the number of circuit components of the selection input means can be reduced, and the antenna device can be further downsized.

According to the sixth aspect of the present invention, since the high-frequency choke circuit for separating the conductor portion and the radiation conductor portion at a high frequency is provided, the antenna operation is disturbed when the switching element is integrated into the antenna body. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

2A is a specific circuit diagram of a phase shift synthesizing unit, and FIG. 2B is a specific circuit diagram of a switch used in the phase shift synthesizing unit.

FIG. 3A is a block diagram illustrating a specific configuration of a control unit;
(B) is a specific circuit diagram of a decoder of the control unit.

FIGS. 4A and 4B are plan views showing a receiving antenna structure according to another embodiment in which the shape of the radiation conductor is different.

FIG. 5A is a plan view of a receiving antenna of still another embodiment, FIG. 5B is a partial perspective view of a main part of the same, and FIG. 5C is an enlarged plan view of another main part.

FIG. 6 is a specific circuit diagram of a switch unit of the phase shift synthesizing unit applied to the above.

FIG. 7A is a plan view in which the shape of a radiation conductor in the above is changed, FIG. 7B is a partial perspective view of a main part of the same, and FIG. 7C is an enlarged sectional view of another main part. is there.

FIG. 8A is a block diagram illustrating a configuration of a control unit according to still another embodiment, and FIG. 8B is a specific circuit diagram of a decoder of the control unit.

9A is a perspective view of a conventional antenna device, and FIG.
Is a plan view of the receiving antenna.

FIG. 10 is a configuration diagram illustrating an overall configuration of the antenna device.

FIGS. 11A and 11B are plan views showing another conventional receiving antenna structure in which the shape of a radiation conductor portion is different.

FIG. 12 is an explanatory diagram showing a state in which the plane of polarization of a circularly polarized signal changes under the influence of a reflected wave.

FIG. 13 is a configuration diagram showing still another embodiment.

[Explanation of symbols]

2 double-sided printed circuit board 3 radiation conductor 4 grounding conductor 5a~5d feeding point 7 the reception signal processing unit 8 control unit 9 phase synthesis unit 20e through-hole conductors 32 high-frequency choke circuit SW _1, SW _4, SW ₅ switches D ₃ ~ D ₆ PIN diode

Claims (8)

(57) [Claims] 1. A structure in which a radiation conductor and a ground conductor are opposed to each other with a dielectric or an air layer interposed therebetween, wherein a first feed point for right-hand circular polarization and a second feed point for left-hand circular polarization are provided. Feed points, and third and fourth linearly polarized first and second linearly polarized
An antenna device comprising: an antenna body provided with a feed point of the above in a radiation conductor; and selection input means for selectively receiving a received signal from each feed point of the antenna body. 2. A radiating conductor portion is rectangular, and a first feeding point is provided on a pair of substantially diagonal lines of the radiating conductor portion, and a first feeding point and a second feeding point are provided on a counterclockwise diagonal line, respectively. The antenna device according to claim 1, wherein the third and fourth feeding points are provided on a substantially straight line connecting the centers of the antennas. 3. A radiating conductor portion having a circular shape, a degenerate separation element having any of concave and convex portions provided symmetrically with respect to the center, and a third feed point provided substantially on a first straight line connecting the degenerate separation elements. In addition, a fourth feed point is provided on a second straight line passing through the center and orthogonal to the first straight line, and on a third straight line passing through the center and intersecting at an angle of 45 degrees counterclockwise to the first straight line. first feed points provided, claims, characterized by comprising providing a second feed point for the first straight line passing through the center in the fourth straight line intersecting at an angle of 45 degrees clockwise 2. The antenna device according to 1. 4. The third and fourth feeding points are fed respectively by changing the equivalent radii of the feeding conductors for guiding the reception signals at the third and fourth feeding points through the ground conductor portion and leading to the selection input means. 2. The antenna device according to claim 1, wherein a tuning frequency of the antenna body as a point is adjusted. 5. A radiation conductor portion and a ground conductor portion are formed by using copper foil on the front and back surfaces of a double-sided printed circuit board, and a power supply conductor and a radiation lead a reception signal at each power supply point to the selection input means through the ground conductor portion. 2. The antenna device according to claim 1, wherein a switching element as a selection input means is provided between the antenna and the conductor. 6. A high-frequency choke circuit, comprising: a conductor for applying a DC bias to a switching element via a radiation conductor; and a high-frequency choke circuit for separating the conductor from the radiation conductor in a high-frequency manner. Item 6. The antenna device according to item 5. 7. A first reception mode in which a right-handed circularly polarized reception signal obtained from a first feeding point is used as an antenna output, and a second reception mode,
A second reception mode in which a left-handed circularly polarized wave reception signal obtained from the feeding point is used as an antenna output, and an in-phase composite signal of linearly polarized reception signals obtained from the third and fourth feeding points is used as the antenna output. A reception mode in which the reception mode is switched between a third reception mode and a fourth reception mode in which an inverted-phase combined signal of the linearly polarized reception signals obtained from the third and fourth feed points is used as an antenna output. 2. The antenna device according to claim 1, further comprising switching means, wherein the selection input means selectively receives a reception signal from each feeding point in accordance with a reception mode. 8. A receiving mode determining means for determining at least an average receiving level of a received signal, wherein said receiving mode switching means includes a first, a third, and a fourth receiving mode when the average receiving level is a predetermined value or more. , And when the average reception level is equal to or lower than a predetermined value, the reception mode is switched so as to perform the polarization diversity reception for switching the second, third, and fourth reception modes. The antenna device according to claim 7, wherein: