JP3452971B2 - Polarization variable antenna - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna suitable for a plane antenna for receiving satellite broadcasting by circular polarization, a plane antenna for mobile stations or a plane antenna for radars in mobile communications.

[0002]

2. Description of the Related Art In satellite broadcasting serviced in the 12 GHz band, the use allocation of right-handed circular polarization and left-handed circular polarization is internationally determined in order to prevent or reduce interference between channels. ing. Therefore, for example, when moving from the right circular polarization area to the left circular polarization area, in order to change the polarization from the right circular polarization to the left circular polarization,
Interference between channels is likely to occur when an antenna that can control the reception polarization is required, and when receiving near the boundary between the right-hand circular polarization area and the left-hand circular polarization area, for example. Therefore, it is necessary to use an antenna capable of controlling the reception polarization in order to reduce interference. Further, the radar antenna sometimes deteriorates in performance when it rains, and polarization control of the antenna may be required in order to reduce such performance deterioration. FIG. 12 is a perspective view showing a conventional polarization converter. Reference numerals 12 ₁ to 12 ₁₁ denote strip conductors arranged in parallel at appropriate intervals and formed by side edges of the strip conductors. Envelope is antenna (not shown)
Is provided on the front surface of the antenna so as to be perpendicular to the radiation center axis (shown by a chain line).

When the electric field component E of the radiated wave from the antenna is orthogonal to each surface of the strip conductors 12 ₁ to 12 ₁₁ , the electric field component of the radiated wave is hardly affected by the strip conductors 12 ₁ to 12 _11. , The polarization never changes. However, when the strip conductors 12 ₁ to 12 ₁₁ rotate about the radiation center axis of the antenna by a certain angle, the electric field component of the radiated wave from the antenna intersects the respective faces of the strip conductors 12 ₁ to 12 _{11 at} an angle. , the electric field component of the radiation field is to strip conductor 12 ₁
12 to ₁₁ components and strip conductors 12 ₁ perpendicular to each side of the decomposed into components parallel to each side of 12 _11, the propagation mode of the two separations - unlike de each other, after passing through the polarization converter The two components have different phases from each other. If the intersection angle between the radiation wave of the surfaces of the electric field component and strip conductor 12 ₁ to 12 ₁₁ of the antenna is 45 °, the to 12 ₁ perpendicular component and strip conductor on each side of the strip conductor 12 ₁ to 12 ₁₁ Since the magnitudes of the components parallel to the respective surfaces of 12 ₁₁ are equal to each other, the strip conductors 12 ₁ to
By appropriately selecting each width L and each interval S of 12 ₁₁ and forming so that the phase difference between both decomposition components after passing through the polarization converter is 90 °, The linearly polarized wave of can be converted into the circularly polarized wave. A specific numerical example of each part for converting the linearly polarized wave into the circularly polarized wave is shown. The interval S between the strip conductors 12 ₁ to 12 ₁₁ is 0.671λ _O
(Λ _O is a free space wavelength of the design frequency), and each width L of the strip conductors 12 ₁ to 12 ₁₁ is 3λ _o / 4.

[0004]

In the conventional polarization converter shown in FIG. 12, the area of the envelope surface formed by each side edge of the strip conductors 12 ₁ to 12 ₁₁ is relatively large, and the thickness of the converter is large. That is,
Since the width L of the strip conductors 12 ₁ to 12 ₁₁ is also relatively large, the polarization converter itself is large and heavy, and the entire antenna including such a polarization converter is also large, and its attitude is particularly high. Since it is unavoidable, when a planar shape is required for the entire antenna, an antenna provided with such a polarization converter cannot be used.
Further, if the conventional polarization converter is provided in the vicinity of the radiating element of the antenna, it may adversely affect the radiation characteristics of the radiating element.Therefore, it is necessary to provide it with a proper distance from the radiating element. From this point as well, it is inevitable that the posture of the entire antenna becomes high. As is apparent from the conversion operation, the conventional polarization converter requires that the incident wave be a plane wave.
If the radiating wavefront is spherical, as in the case of an array antenna consisting of a single radiating element or a small number of radiating elements, then a location at a relatively large distance from the radiating element, that is, a radiating spherical wave Since it is necessary to provide a polarization converter at a position where a part of the antenna can be approximately regarded as a plane wave, the posture of the entire antenna cannot avoid being extremely high. Furthermore, if the radiation wave that has passed through the conventional polarization converter is, for example, right-handed circular polarization, in order to change this to left-handed circular polarization, the polarization converter should be placed around the radiation center axis of the antenna. It is necessary to rotate 90 °, but as described above, it is not easy to rotate a polarization converter that is large and heavy.

[0005]

DISCLOSURE OF THE INVENTION Disclosed herein
Of the inventions, a brief description of typical ones will be made as follows.
It is as follows. That is, the present invention is directed to a variable polarization antenna.
A is a loop-shaped parasitic element that is provided on the front surface of the planar reflector, a feeding line connected to a portion of said loop-shaped parasitic element, the front surface of the loop-shaped radiation element, enough compared to the emission wavelength It is provided with a parasitic element which is provided at a narrow interval and has a gap that is sufficiently narrow compared to the emission wavelength.
To collect. Further, the present invention is a variable polarization antenna.
And a loop-shaped excitation element provided on the front surface of the planar reflector,
A feed line connected to a part of the loop-shaped excitation element;
The front of the loop-shaped excitation element is sufficiently narrow compared to the emission wavelength.
It is installed at two intervals and is released at two points symmetrical about the center.
Equipped with a parasitic element that has a sufficiently narrow gap compared to the wavelength of radiation
It is characterized by that. In a preferred embodiment of the invention
Indicates that the contour shape of the loop-shaped excitation element is circular or circular.
It is characterized by similar shapes. Preferred fruits of the invention
In the embodiment, the outline shape of the parasitic element is circular or circular.
It is characterized by a shape similar to. Preferred of the present invention
In another embodiment, the contour shape of the loop-shaped excitation element is
It is characterized by a shape similar to a square or a square.
In a preferred embodiment of the present invention, the contour shape of the parasitic element is
Characterized in that the shape is a square or a shape similar to a square
And

[0006]

When a high frequency power is applied to the exciting element via the feeder line, a high frequency current is distributed in the exciting element, and this current induces a high frequency current in the parasitic element. The angle between the line connecting the feeding point of the excitation element and the common center point of the excitation element and the parasitic element, and the line connecting the center of the gap of the parasitic element and the common center point of the excitation element and the parasitic element When is adjusted appropriately, a parasitic element having a gap acts as a perturbation element, a traveling wave current flows through the excitation element, and circularly polarized radiation is performed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A is a plan view showing an essential part of one embodiment of the present invention, and FIG. 1B is a plane from a plane including the X axis in FIG. It is sectional drawing which looked at the upper side toward. In addition, the excitation element 1 described later in FIG.
The origin is the center of X, the X axis is horizontal, the Y axis is perpendicular to the X axis, and the Z axis is perpendicular to the plane of the drawing. In FIG. 1, 1 is a circular loop-shaped excitation element made of a conductor such as a wire or strip, 2 is a reflector made of a conductor plate,
Reference numeral 3 denotes an input / output terminal, which is formed of, for example, a coaxial plug, and its outer conductor is connected to the reflector 2. Reference numeral 4 denotes a power supply line, one end of which is connected to the inner conductor of the coaxial connector 3 and the other end of which is connected to a power supply point at an arbitrary position of the excitation element 1. In the figure, the feed line 4 is formed so as to rise vertically along the extension direction of the inner conductor of the coaxial connector 3, bend at a right angle in the plane formed by the excitation element 1, and extend in the X-axis direction. In other words, that is, between the inner end of the inner conductor of the coaxial connector 3 and the feeding point of the excitation element 1, a reverse L
The case of connecting with a character-shaped power supply line is illustrated, but the coaxial plug 3
The inner end of the inner conductor of the above and the feed point of the excitation element 1 may be connected by an oblique feed line that linearly connects, and the coaxial plug 3 may be connected to the center point of the excitation element 1 (origin of the coordinate axis) as shown in the figure. Instead of being provided immediately below, the coaxial connector 3 is provided at an arbitrary position below the excitation element 1, for example, immediately below an arbitrary position of a line or a line forming the excitation element 1, and the inner end of the inner conductor of the coaxial connector 3 is provided. It may be formed such that a line or a line forming the excitation element 1 is connected to a feeding point at an arbitrary point by a linear feeding line extending vertically. Next, 5 is a parasitic element formed by bending a conductor such as a wire or a stripe and having a gap 6 in a part thereof. The parasitic element 5 shares the center with the excitation element 1 and the front surface of the excitation element 1 (radiation wave radiation direction) at a sufficiently small distance relative to the emission wavelength provided in parallel with the driven element 1, the length delta _P of the gap 6 is formed to be sufficiently small compared to the emission wavelength. In order to position the excitation element 1, the reflector 2, the feed line 4, the parasitic element 5 and the like at required positions and maintain a mechanical required relationship, for example, a solid dielectric is interposed between the excitation element 1 and the reflector 2. At the same time, a solid dielectric is interposed between the excitation element 1 and the parasitic element 5, and the solid dielectric, the excitation element 1, the reflector 2 and the parasitic element 5 are integrally coupled.

In the above, the case where the exciting element 1, the feeding line 4 and the parasitic element 5 are formed of conductors such as lines or stripes and the reflector 2 is formed of a conductor plate has been exemplified. A resin copper clad laminate is used to remove the unnecessary metal film by the same etching method as in the case of printed wiring, and the metal film left on the surface of the substrate is used for the excitation element 1 and the power supply line 4.
Of the first dielectric substrate on which a part of the first dielectric substrate is formed, and a second dielectric substrate on which a reflector 2 made of a metal film is provided on the front surface by the same method and a coaxial connector 3 is attached on the back surface, and the same method. And a third dielectric substrate having a parasitic element 5 formed of a metal film on the surface thereof are prepared, and the second dielectric substrate, the first dielectric substrate, and the third dielectric substrate are arranged in this order from the bottom. Overlapping, one end of a part of the power supply line 4 provided on the first dielectric substrate and the internal conductor of the coaxial connector 3 attached to the back surface of the second dielectric substrate are connected via a through hole. , 1st to 3rd
The dielectric substrates may be integrally bonded. First
Or, instead of providing the constituent elements of the antenna of the present invention on each surface of the third dielectric substrate, for example, when the excitation element 1 and a part of the feeder line 4 are provided on the back surface of the first dielectric substrate, In order to prevent a short circuit between the excitation element 1 and a part of the feed line 4 and the reflector 2 provided on the surface of the second dielectric substrate,
When it is necessary to take measures such as interposing an insulating plate between each of the first and second dielectric substrates and to provide an appropriate space between each of the first to third dielectric substrates. Also, the antenna of the present invention can be formed by interposing an insulating plate having an appropriate thickness. A normal dielectric plate is used instead of the glass cloth base material fluororesin copper-clad laminate, and a metal film having a required shape is attached to a required position on the front surface or the back surface by a method such as vapor deposition to form the antenna of the present invention. Is also possible. FIG. 2A is a plan view showing a main part of another embodiment of the present invention,
2B is a cross-sectional view including the X axis in FIG. 2A and seen from the plane perpendicular to the paper surface toward the paper surface.
The way of taking the rectangular coordinate axis in FIG. 2 is the same as that in FIG. In FIG. 2, 5 ₁ and 5 ₂ are parasitic elements, and 6 ₁ and 6 _{2 are}
Is a gap, and these parasitic elements 5 ₁ , 5 ₂ and gaps 6 ₁ , 6
₂ is disposed on a circle centered on the center of the driven element 1, the gap 6 ₁ and 6 ₂ are provided at two points symmetrical with respect to the center, a sufficiently narrow gap than the emission wavelength Has been formed.
Other reference numerals and configurations are exactly the same as those shown in FIG.

In any of the embodiments shown in FIGS. 1 and 2, the high frequency power applied to the coaxial plug 3 is supplied to the feeder line 4.
The high-frequency current is distributed to the excitation element 1 via the parasitic element 1, and the distributed current causes the parasitic element 5 (see FIG.
₂ ) or 5 ₁ and 5 ₂ (in the case of FIG. 2), an induced current occurs. FIG. 3 shows that the circumferential length of the excitation element 1 in each of the embodiments shown in FIGS. 1 and 2 is one wavelength of the radiated wave, the distance between the surface including the excitation element 1 and the reflector 2 is 0.0667 wavelength, and the gap is Circumferential length (in the case of FIG. 1) of the parasitic element 5 including the length of 6 or the gap 6 ₁
And the circumference of parasitic elements 5 ₁ and 5 ₂ (in the case of FIG. 2) including each length of 6 ₂ is set to 1.25 wavelength, the excitation element 1 and the parasitic element 5
Or, the outer diameter of the wire forming 5 ₁ , 5 ₂ is selected to be 0.025 wavelength, and the angle from the X axis to the center of the gap 6 of the parasitic element 5 measured counterclockwise (in the case of FIG. 1) or Parasitic element
Angle to the center of gap 6 ₂ between 5 ₁ and 5 ₂ (in case of Fig. 2) φ _P
While changing the, shows the measured values of polarization characteristics at the measurement point in the Z-axis direction in the axial ratio, the parasitic element horizontal axis measured from X-axis in a counterclockwise direction 5 (or 5 ₁ and 5 ₂ ) Gap 6
(Or 6 ₂ ) angle φ _P (deg) to the center, the vertical axis is the axial ratio (d
B), white circles are actual measurement values of the embodiment shown in FIG. 1, and black circles are actual measurement values of the embodiment shown in FIG. As is clear from the figure,
In any of the embodiments shown in FIGS. 1 and 2, the gap 6 (or 5) between the X-axis and the parasitic element 5 (or 5 ₁ and 5 ₂ )
6 ₂₎ when changing the angle phi _P and the center of the angle phi _P good axial ratio appears there, linearly polarized waves are converted into circular polarized waves.

FIG. 4 shows the circumferential length of the excitation element 1, the excitation element 1
Between the surface containing the and the reflector 2, the gap 6 (or 6 ₁ and 6 ₂ )
The dimensions of the circumference of the parasitic element 5 (or 5 ₁ and 5 ₂ ) including, and the outer diameter of the wire forming the excitation element 1 and the parasitic elements 5 or 5 ₁ and 5 ₂ are described with reference to FIG. with selected as in the case of the polarization measurement, the gain at the time of the angle phi _P and the center of the gap 6 or 6 a _second feed point and the parasitic element driven element 1, the axial ratio was adjusted to be optimal And the actual value of the axial ratio frequency characteristic, where the horizontal axis is the specific frequency with respect to the design frequency f _O , f _O is the frequency corresponding to the design wavelength λ _O , and the vertical axis is the axial ratio.
(dB) and gain (dB), white circles are the measured values of the embodiment shown in FIG. 1, black circles are the measured values of the embodiment shown in FIG. 2, and a substantially V-shaped curve shows the frequency characteristics of the axial ratio. A curve that is almost linear shows the frequency characteristic of gain. FIG. 5 is a circumferential length of the excitation element 1 in the embodiment shown in FIG. 1, a distance between a surface including the excitation element 1 and the reflector 2, a circumferential length of the parasitic element 5 including a gap 6,
The outer diameters of the wires forming the excitation element 1 and the parasitic element 5 are selected in the same manner as in the case of the polarization measurement described with reference to FIG. 3, and the excitation element 1 is adjusted so that the axial ratio is optimum. The horizontal axis represents the result of observing the phase transition of the current on the excitation element 1 when the angle φ _P between the feeding point and the center of the gap 6 of the parasitic element was adjusted. In the conductor length of the excitation element 1 measured counterclockwise from the point, that is, the feeding point, points a, b, c and d correspond to points a, b, c and d in FIG. The vertical axis represents the phase (deg), the solid line in the figure represents the phase transition on the excitation element 1, and the broken line represents the phase transition in free space. Excitation element 1 in the case where the parasitic element 5 is not provided in the antenna shown in FIG.
The phase transition of the current above is as follows for the change of the conductor length.
It consists of a region that hardly changes and a region that changes significantly, and has a stair-like form as a whole. This form is a characteristic that appears when the current distribution on the excitation element 1 is a standing wave distribution, and it is well known that linearly polarized waves are radiated. However, like the antenna of the present invention shown in FIG. 1, the parasitic element 5 having the gap 6 is arranged, and the angle φ between the feeding point a of the exciting element 1 and the center of the gap 6 of the parasitic element 5 is φ.
_{When P} is adjusted appropriately, the parasitic element 5 operates as a perturbation element, so that a traveling wave current flows through the excitation element 1 and the phase transition with respect to the change in conductor length has a characteristic of having a slope.
In particular, as shown in FIG. 5, the slope of the phase transition of the current in the excitation element 1 and the slope of the phase transition in the free space are
Good circularly polarized radiation is obtained when the two coincide substantially.

FIG. 6 shows the circumference length of the excitation element 1 in the embodiment shown in FIG. 2, the distance between the surface including the excitation element 1 and the reflector 2, and the parasitic element 5 ₁ including the gaps 6 ₁ and 6 _2. and 5 ₂ of the circumferential length,
The outer diameters of the wires forming the excitation element 1 and the parasitic elements 5 ₁ and 5 ₂ are selected in the same manner as in the polarization measurement described with reference to FIG. 3, and the axial ratio is optimized. shows the results of observing the phase shift of the current in the excitation element 1 at the time of adjusting the angle phi _P and the center of the gap 6 ₂ feed point and the parasitic element driven element 1, the horizontal axis in FIG. 2 The point a of the excitation element 1, that is, the conductor length of the excitation element 1 measured counterclockwise starting from the feeding point, points a, b, c and d are points a, b, c and d in FIG. Correspond. or,
The vertical axis represents the phase (deg), the solid line in the figure indicates the phase transition on the excitation element 1, and the broken line indicates the phase transition in free space. As with the antenna shown in FIG. 1, also parasitic element 5 ₁ and the antenna shown in FIG. 2
Excitation element 1 assuming that 5 ₂ is not installed
The phase transition of the current above is as follows for the change of the conductor length.
It consists of a region that hardly changes and a region that changes relatively greatly, and has a staircase-like form as a whole. This form is a characteristic that appears when the current distribution on the excitation element 1 is a standing wave distribution. Is emitted as described above. As the illustrated case of the present invention antenna shown in FIG. 2, disposed parasitic elements 5 ₁ and 5 ₂ with a gap 6 ₁ and 6 _2, the feed point a and the parasitic elements of the driven element 1 5 When properly adjusted the angle phi _P between ₁ and 5 ₂ in the center of the gap 6 _2, parasitic element 5 ₁ and 5 ₂ operates as a perturbation element, the change in conductor length traveling wave current flows through the excitation element 1 Has a characteristic that the phase transition has a slope, and in particular, as shown in FIG. 6, it is preferable when the slope of the phase shift of the current in the excitation element 1 and the slope of the phase transition in the free space substantially match. Circularly polarized radiation is produced. When the angle φ _P between the feeding point a of the excitation element 1 and the center of the gap 6 in the parasitic element 5 in FIG. 1 is approximately + 45 ° (or approximately −135 °),
As shown in FIG. 5, the phase of the current on the excitation element 1 is
Left-handed circularly polarized waves are radiated with a delay in the order of points d, c, b and a on the excitation element 1. When the angle φ _P is approximately −45 ° (or approximately + 135 °), the d point in FIG. 1 is replaced with the b point, and the b point is replaced with the d point, and the length of the excitation element 1 is replaced with the feeding point a. Assuming that the starting point is measured clockwise, the phases of the currents on the excitation element 1 are the d point (b point in FIG. 1) replaced, the c point, and the b point replaced (d point in FIG. 1).
The right-handed circularly polarized wave is radiated with a delay in the order of point) and point a. Also in the embodiment shown in FIG. 2, the above relationship, that is, the angle φ
The relationship between _P and the rotation direction of the radial circularly polarized wave is almost the same as in the case of the embodiment shown in FIG.

FIG. 7 shows the circumferential length of the excitation element 1 in the embodiment shown in FIG. 1, the distance between the surface containing the excitation element 1 and the reflector 2, the circumferential length of the parasitic element 5 including the gap 6, The outer diameters of the wires forming the excitation element 1 and the parasitic element 5 are selected in the same manner as in the case of the polarization measurement described with reference to FIG. 3, and the excitation element 1 is adjusted so that the axial ratio is optimum. Adjusting the angle φ _P between the feeding point a and the center of the gap 6 of the parasitic element 5,
FIG. 7A shows the directivity when the phase transition on the excitation element 1 is in the state shown in FIG.
7B shows the directivity of the −Z plane, and FIG. 7B shows the directivity of the YZ plane, where θ is the inclination angle from the Z axis. FIG. 8 shows the circumferential length of the excitation element 1 in the embodiment shown in FIG. 2, the distance between the surface including the excitation element 1 and the reflector 2, and the gap.
The circumference lengths of the parasitic elements 5 ₁ and 5 ₂ including 6 ₁ and 6 ₂ and the outer diameters of the wires forming the exciting element 1 and the parasitic elements 5 ₁ and 5 ₂ are the same as those described with reference to FIG. The angle φ between the feeding point a of the excitation element ₁ and the center of the gap 6 ₂ between the parasitic elements 5 ₁ and 5 ₂ should be selected in the same manner as in the case of wave measurement, and the axial ratio should be optimized.
FIG. 8A shows the directivity when _P is adjusted to bring the phase transition on the excitation element 1 into the state shown in FIG. 6. FIG. 8A shows the directivity of the XZ plane as shown in FIG. b) is Y-
The directivity of the Z plane is shown, and θ is the inclination angle from the Z axis. In each of the directivities shown in FIGS. 7 and 8, the maximum radiation in the Z-axis direction is obtained, and
Since the beam widths in FIG. 8B are substantially equal, and the beam widths in FIGS. 8A and 8B are also approximately equal,
Each of the antennas shown in FIGS. 1 and 2 is excellent when used alone, and can be said to be an excellent antenna as a constituent element of a planar array antenna. The present invention antenna, so exhibits the same directional and directional shown in FIG. 7 or 8 even when omitting the parasitic element 5 or 5 ₁ and 5 _2, without affecting the directivity, polarization It is suitable when controlling only waves. For example, in a radar, a method of radiating a circularly polarized wave is used as the most effective method for distinguishing a reflected interference wave from a raindrop in the atmosphere and a reflected wave from a target at the time of rainfall. ing. The principle of identification in this method is that the circular polarization direction reflected from a spherical body such as a raindrop is opposite to the radial polarization polarization direction, but it has a complicated shape and is made of various materials. The reflected wave from the target object is an elliptically polarized wave and is used to distinguish the reflected interference wave from the reflected wave from the target object. When a radar antenna is formed by the excitation element 1 in the antenna of the present invention, linear polarized waves are always radiated, and parasitic elements 5 or 5 ₁ , 5 ₂ are attached to radiate circular polarized waves when it rains. Advantages of linearly polarized waves, that is, the level of reflected waves from the target is high and it is possible to search for a long distance, and advantages of circularly polarized waves, that is, reflected interference waves at the time of rain and reflected waves from the target It is possible to provide both advantages of being able to identify

FIG. 9 (a) is a plan view showing the main part of another embodiment of the present invention, and FIG. 9 (b) is a plane including the X axis in FIG. 9 (a) and perpendicular to the plane of the paper. It is sectional drawing which looked at the upper side toward. Note that the method of setting the rectangular coordinate axes in FIG. 9 is the same as in FIG. This example is different from the example shown in FIG. 1 in that the contour shapes of the excitation element 1 and the parasitic element 5 are formed in a square shape, and other reference numerals, configurations and operations are the same as those of the example shown in FIG. Is almost the same as. 10A is also a plan view showing the main part of another embodiment of the present invention.
FIG. 10B is a cross-sectional view including the X axis in FIG. 10A and looking upward from a plane perpendicular to the paper surface toward the paper surface.
The way of taking the rectangular coordinate axis in FIG. 10 is the same as that in FIG. In this embodiment, the excitation element 1 and the parasitic element 5 ₁
In the 5 _second contour point that is formed in a square only differs from the embodiment shown in FIG. 2, other symbols, the configuration and operation is substantially similar to the embodiment shown in FIG. In each of the embodiments shown in FIGS. 1, 2, 9 and 10, the parasitic element 5 or
In the case where 5 ₁ and 5 ₂ are provided on the dielectric plate, in order to adjust the axial ratio, the feeding point of the excitation element 1 and the parasitic element 5
Or when changing the angle phi _P between the center of the gap 6 or 6 ₂ in 5 ₁ and 5 _2, parasitic element 5 or 5 ₁ and
5 ₂ provided the dielectric plate, with the structure described may be rotated around the passive element 5 or 5 ₁ and 5 ₂ center,
You can easily reach the goal.

FIGS. 11A and 11B are front views showing an example in which a rectangular planar array antenna is formed by using the antenna of the present invention shown in FIG. 1 as an element antenna. The exciting elements are arranged on the same plane, and each parasitic element is arranged on the same plane in front of the arrangement plane of the exciting element, and the position spacing of the common center of the exciting element and the parasitic element in each element antenna is set. It is formed so as to be equal in the vertical and horizontal directions, and the positions of the feeding points of the element antennas and the positions of the gaps in the parasitic elements are all at the same position. The array antenna shown in FIG. 11A radiates a right-handed circularly polarized wave from the plane of the drawing to the front, and FIG.
The array antenna shown in (1) radiates a left-handed circularly polarized wave toward the front from the paper surface. FIG. 11 exemplifies a case where an array antenna is formed by using the antenna of the present invention shown in FIG. 1 as an element antenna. However, any one of the antennas of the present invention shown in FIGS. 2, 9 and 10 is an element antenna. FIG. 11 shows the mutual relationship between the element antennas and the arrangement relationship between the excitation element and the parasitic element.
A rectangular planar array antenna can be formed in the same manner as the relationship described for. The antenna of the present invention shown in each of FIGS. 1, 2, 9 and 10 is used as an element antenna, and the arrangement relationship of each element antenna and the arrangement relationship of the excitation element and the parasitic element in each element antenna are as described above. The center axis of the dielectric plate on which each excitation element is arranged is aligned with the center axis of the dielectric plate on which each parasitic element is arranged, and the center axis of the dielectric plate on which each excitation element is arranged When the dielectric plate with each parasitic element is rotatably and removably attached around, the dielectric plate with each parasitic element is rotated by 90 °, and the feeding point of each exciting element is rotated. Figure 11 shows the interrelationship between the gap between
From the state of FIG. 11A to the state of FIG.
By changing the state of (b) to the state of FIG. 11 (a), conversion of right-handed circularly polarized wave and left-handed circularly polarized wave can be easily and quickly performed, and a dielectric having each parasitic element disposed. By removing the body plate, the polarization of each element antenna can be changed to linear polarization. If each parasitic element is provided on the inner surface of the reddom of the antenna, the redom can be attached without raising the posture of the antenna.

In the above description, the case where the exciting element and the parasitic element are formed in a circular shape or a square shape has been described. A similar shape, i.e.
The present invention can be implemented by forming it into any polygonal shape or the like. Further, for convenience of explanation of the operation of the antenna of the present invention,
It has been explained that the contour shapes of the excitation element and the parasitic element are similar, the centers of both elements are the same, and the plane including the excitation element and the plane including the parasitic element are parallel to each other. When the contour shapes of the parasitic element and the parasitic element are not similar, the centers of both elements do not match, or the plane containing the excitation element and the plane containing the parasitic element are not parallel, etc. The present invention can also be implemented.

[0016]

The antenna of the present invention has a very simple structure, is extremely light in weight, and can be constructed in a low attitude, and is therefore suitable as an antenna whose attitude height is limited like a mobile station antenna in mobile communications. In addition to controlling the circularly polarized wave by rotating a large and heavy polarization converter as in the conventional case, the circularly polarized wave can also be controlled by rotating the antenna of the present invention. Is the same as the conventional one, but the parasitic element that is the object of rotation is relatively small and light in weight, so it is extremely easy to control circular polarization, and the cost can be significantly reduced by using common components. Therefore, it can be used as a receiving antenna for satellite broadcasting having different polarizations such as right-hand circular polarization and left-hand circular polarization depending on the region, and is also suitable as a radar antenna.

[Brief description of drawings]

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

FIG. 2 is a diagram showing another embodiment of the present invention.

FIG. 3 is a diagram for explaining the operation of the antenna of the present invention.

FIG. 4 is a diagram for explaining the operation of the antenna of the present invention.

FIG. 5 is a diagram for explaining the operation of the antenna of the present invention.

FIG. 6 is a diagram for explaining the operation of the antenna of the present invention.

FIG. 7 is a diagram showing the directivity of the antenna of the present invention.

FIG. 8 is a diagram showing the directivity of the antenna of the present invention.

FIG. 9 is a diagram showing another embodiment of the present invention.

FIG. 10 is a diagram showing another embodiment of the present invention.

FIG. 11 is a diagram showing an array antenna configured by using the antenna of the present invention.

FIG. 12 is a perspective view showing a conventional polarization converter.

[Explanation of symbols]

1 Excitation element 2 Reflector 3 Input / output terminal 4 Feed line 5 Parasitic element 6 Gap 5 ₁ , 5 ₂ Parasitic element 6 ₁ , 6 ₂ Gap 12 _{1 to} 12 ₁₁ Band conductor

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-268432 (JP, A) JP-A-63-240104 (JP, A) Actual Kaihei 4-91408 (JP, U) JP-B-35- 10268 (JP, B1) Special table Sho 62-581501 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01Q 7/00 G01S 7/03 H01Q 15/24 H01Q 19/10 H01Q 21/06

Claims (2)

(57) [Claims] 1. A loop-shaped excitation element provided on the front surface of a planar reflector, a power supply line connected to a part of the loop-shaped excitation element, and a front surface of the loop-shaped excitation element with respect to a radiation wavelength. A loop-shaped parasitic element which is provided with a sufficiently narrow interval and has one gap that is sufficiently narrow compared to the radiation wavelength, and the center of the loop-shaped excitation element and the feeding point of the loop-shaped excitation element A straight line passing through and a straight line passing through the center of the loop-shaped parasitic element and the center of the gap of the loop-shaped parasitic element are polarization variable antennas that intersect at a predetermined crossing angle, and the predetermined crossing The angle is an angle at which an axial ratio of a circularly polarized radiation wave radiated from the polarization variable antenna is 3 dB or less. 2. A loop-shaped excitation element provided on the front surface of a planar reflector, a power supply line connected to a part of the loop-shaped excitation element, and a front surface of the loop-shaped excitation element in comparison with a radiation wavelength. A loop-shaped parasitic element provided with a sufficiently narrow interval, the parasitic element having two spaces symmetrical with respect to the center of the loop-shaped parasitic element and having a sufficiently narrow gap as compared with a radiation wavelength, A straight line passing through the loop-shaped excitation element and the feeding point of the loop-shaped excitation element and a straight line passing through the center of the two gaps of the loop-shaped parasitic element cross at a predetermined crossing angle. The variable antenna according to claim 1, wherein the predetermined crossing angle is an angle at which an axial ratio of a circularly polarized radiation wave radiated from the polarization variable antenna is 3 dB or less.