JP3176326B2 - Crankline antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar crankline antenna formed of a microstrip conductor.

[0002]

2. Description of the Related Art A crankline antenna is known as a planar antenna capable of radiating circularly polarized waves. This crankline antenna is generally formed by connecting a plurality of basic crankline elements that are shifted from each other by 周期 cycle on the surface of a dielectric substrate having a ground plane formed on the back surface. Then, by propagating the traveling wave from one end to the other end of the plurality of connected crankline basic elements, a circularly polarized wave is emitted in a direction perpendicular to the surface of the dielectric substrate. Such a crankline antenna is constituted by a microstrip conductor.

[0003]

Incidentally, there has also been proposed a crankline antenna comprising only one cell of the basic element of the crankline. Even if the crankline antenna is constituted by only one cell of the basic crankline element, the circularly polarized wave can be radiated in the direction perpendicular to the plane of the basic crankline element. However, in a crankline antenna including only one cell of the basic element of the crankline, a desired beam tilt angle can be obtained even if the length of the element of the basic element of the crankline is adjusted in order to tilt the beam of the circularly polarized beam. There was a problem that can not be.

In a crankline antenna consisting of only one basic cell element, it is difficult to suppress cross-polarization components, and only narrow-angle circular polarization can be obtained. . Further, as an auxiliary means for obtaining a desired beam tilt, there is a means for mechanically tilting the basic crankline element, not in parallel with the ground plane. However, this method has the disadvantage that the height of the crankline antenna is higher than in the case where no inclination is provided, and the positional relationship between the basic crankline element and the ground plane becomes non-uniform. There was a problem that it became difficult.

Further, as another method, it is conceivable to mechanically incline the entire crankline antenna including the ground plane. However, in this method, a height is required when installing the crankline antenna. There is a problem that the mounting structure is complicated.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a thin crankline antenna that can easily adjust a beam tilt angle without using mechanical means and suppresses cross-polarization components.

[0006]

In order to achieve the above object, a planar crankline antenna according to the present invention has a circular polarization.
Are displaced by about 1/2 cycle so that
Between the first crankline and the second crankline
The starting and ending ends of the connected crank line
And down the base element, said crank line basic element and the ground plane being spaced apart from a predetermined distance, said being connected to the end of the crank line basic element, substantially perpendicular to the arrangement surface of the crank line basic element and a vertical conductor is a length <br/> is capable of suppressing the cross-polarization component which is bent in a direction, by supplying power to the starting end of said crank line basic element, said crank line basic element Chill in the direction perpendicular to the placement plane
To radiate circularly polarized waves in the direction of

In the above crankline antenna, the basic crankline element is formed on a front surface of a dielectric substrate, and the vertical conductor is formed on a side surface thereof. The ground plane may be formed at the same time.

In such a crankline antenna of the present invention, a predetermined length of vertical conductor is provided at the end, and the cross polarization component is reliably suppressed by adjusting the length of this vertical conductor. Therefore, the crankline antenna according to the present invention can radiate a wide-angle circularly polarized beam in which the cross polarization component is suppressed. At this time, according to the present invention, since only the vertical conductor is added to the end of the basic crankline element, the low-profile crankline antenna can be maintained without increasing the height of the antenna. Become like In addition, a beam having a desired beam tilt angle can be obtained by adjusting the length of each element of the crankline basic element.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a top view, FIG. 2 is a side view, and FIG. 3 is a perspective view showing the configuration of an embodiment of a crankline antenna according to the present invention. The crankline antenna shown in FIG. 1 includes a crankline basic element (hereinafter, referred to as “crankline”) 1, which includes a first crankline, a second crankline, and a vertical conductor 2 (not shown). It is composed of The first crankline includes a crankline 1-2 having a length a, a crankline 1-3 having a length b bent from the crankline 1-2, and a crankline 1-.
3 has a length c that is bent so as to be parallel to the crankline 1-2, and a length b that has been bent so as to be parallel to the crankline 1-3 from the crankline 1-4. It is composed of a crankline 1-5 and a crankline 1-6 bent from the crankline 1-5 to be located on an extension axis of the crankline 1-2.

The second crankline has a length c /
2 and a crank line 1-1 having a length b bent from the crank line 1-12.
1 and crankline 1-
12 and a length b bent from the crankline 1-10 to be parallel to the crankline 1-11.
And a crankline 1-8 having a length c / 2 bent so as to be located on the extension axis of the crankline 1-9 from the crankline 1-9. The first crankline and the second crankline are connected by a crankline 1-1 at an end thereof, and are connected by a crankline 1-1 at a start end.
7. It should be noted that the first crank line and the second crank line are arranged such that the crank lines of the same pattern are shifted by 周期 cycle.

As shown in FIG. 2 and FIG. 3 at a T point at the terminal end, a length Lv
The vertical conductor 2 is connected to the crankline 1-1, and the power supply conductor 3 is connected to the crankline 1-7 at a point F at the start end as shown in FIGS. Note that the power supply conducting wire 3 does not need to be provided as shown in FIG. 3, and the core wire of the coaxial cable 10 may be exposed and connected to the point F as shown in FIG. Further, the crankline 1 configured as described above is arranged at a predetermined height h from the ground plane 4 as shown in FIG. 2, and the vertical conductor 2 is bent toward the ground plane 4. It is formed on the crankline 1. The height h is, for example, approximately λ / 4 (λ: wavelength of the center frequency of the used band). Note that the vertical conductor 2 does not need to be bent in the direction toward the ground plane 4, and the electrical characteristics do not change even if the vertical conductor 2 is bent in the opposite direction or not.

Power is supplied from the power supply conductor 3 to the start point F of the crank line 1 constituted by the microstrip conductor. The first and second crank lines have the same pattern that is shifted from each other by 周期 period, and therefore, the first and second crank lines are combined with a circularly polarized wave synthesized from the first and second crank lines. Will be emitted. The characteristics of the radiated circularly polarized wave are determined by the lengths a, b, and c of the crankline segments. in this case,
The lengths a, b, and c of the crankline segments are determined so that good circular polarization can be obtained. For example, the segment length b is approximately λ / 2 (λ: wavelength at the center frequency of the used band). And
The segment length a is, for example, approximately 0.24λ, and the segment length c is, for example, approximately 0.30λ.

The length Lv of the vertical conductor 2 is approximately 0.25.
λ, but not so long as to contact the ground plane 4. The vertical conductor 2 is provided to cancel a current component returning from the terminal T to the power supply side by a current component flowing through the vertical conductor 2. That is, the cross polarization component, which is an unnecessary wave component radiated by the current component returning from the terminal end T to the power supply side, can be suppressed by providing the vertical conductor 2. This is an operational effect that cannot be obtained with the conventional one-cell crankline antenna.

Incidentally, the crank line 1 in the crank line antenna of the present invention has a shape shown in FIG. 3, and can be manufactured by processing a sheet metal. As shown in FIG. 2, the crankline 1 manufactured in such a shape is mounted on a ground plane 4 made of a metal plate so as to maintain the height h (for example, λ / 4). Can be manufactured. However, instead of the power supply conductor 3, the core of the coaxial cable may be exposed and electrically connected to the point F.

In the above description, as described above, the crankline antenna of the present invention is constituted by the ground plane 4 made of a metal plate and the crankline 1 formed by processing a metal plate. A configuration may be adopted in which a ground plane is formed and a crankline is formed on the other surface. This configuration example will be described with reference to FIG. The relative dielectric constant ε of the dielectric substrate 5 shown in FIG.
_The dielectric substrate 5 is made of foamed resin or has a honeycomb core shape so that _r becomes approximately 1.0, which is substantially equal to air. The conductive ground plane 4 is formed by attaching or printing a conductive ground plane 4 on the back surface of the dielectric substrate 5 having such a low dielectric constant. Then, the crankline 1 formed by processing the metal plate is placed on the dielectric substrate 5.

Alternatively, it is formed by printing the crank line 1, the vertical conductor 2, and the power supply conductor 3 on a thin film. Then, the film on which the crankline 1 is formed is placed on the front surface of the dielectric substrate 5, and the vertical conductor 2 or the power supply conductor 3 is in contact with the side surface of the dielectric substrate 5, and By covering with a cover from above, the dielectric substrate 5 and the film are integrated. Thus, a crankline antenna made of a microstrip conductor can be manufactured. It should be noted that a core wire of a coaxial cable may be used instead of the power supply conductor 3.

The electrical characteristics of the above-described crankline antenna will be described with reference to FIGS. The center frequency of the used band in this case is 1.5 GHz. FIG. 5A shows the Z axis of the crankline antenna of the circularly polarized beam emitted when the length a or c of the segment of the crankline 1 is changed (see FIG. 1).
5 is a graph showing a tilt angle θt with respect to. A graph showing the axial ratio in the direction of the beam tilt angle θt at this time is shown in FIG.
Shown in In this case, the length Lv of the vertical conductor 2 is set to approximately 0.25λ.

Referring to FIG. 5A, the beam tilt angle θ is reduced by shortening the element length a or the element length c.
t can be increased. Then, the axial ratio (axial rati) when 45 ° is obtained as the tilt angle θt
As o), a good value of 3 dB or less is obtained.

FIG. 6 is a view showing a radiation pattern when the tilt angles θt are set to approximately 45 ° by adjusting the lengths of the element lengths a and c. E _R shown by a solid line is a main radiation pattern of a circularly polarized beam, and E _L shown by a broken line is a radiation pattern of a cross polarization component which is an unnecessary wave component. The length Lv of the vertical conductor 2 in this case is Lv = 0.25λ.
A radiation pattern indicated by a dashed line is a radiation pattern in a cross polarization component of a conventional crankline antenna having no vertical conductor 2. As shown in FIG. 6, in the crankline antenna of the present invention, a wide-angle circularly polarized beam is obtained. The half width of the beam at this time is a wide angle of about 60 °. Further, in the crankline antenna of the present invention, a cross-polarization component, which is an unnecessary wave component in the conventional crankline antenna,
It turns out that it is sufficiently suppressed.

Further, the size of the radiation beam of the cross polarization component in the direction near θ = −50 ° in FIG. 6 can be further suppressed by adjusting the length Lv of the vertical conductor 2. Therefore, the length Lv of the vertical conductor 2 is represented by L
FIG. 7 shows a radiation pattern when v = 0.23λ. As shown in FIG. 7, the cross polarization component in the direction near θ = −50 ° can be improved from approximately −6 dB to approximately −11 dB by setting Lv = 0.23λ.

[0021]

As described above, in the crankline antenna of the present invention, a predetermined length of vertical conductor is provided at the end, and the cross polarization component is suppressed by adjusting the length of this vertical conductor. ing. Therefore, the crankline antenna according to the present invention can radiate a wide-angle circularly polarized beam in which the cross polarization component is suppressed. At this time, according to the present invention, since only the vertical conductor is added to the end of the basic crankline element, it is possible to maintain a low-profile crankline antenna without increasing the antenna height. . In addition, a beam having a desired beam tilt angle can be obtained by adjusting the length of each element of the crankline basic element. As described above, the crankline antenna of the present invention can provide a special operation and effect that cannot be achieved by the conventional crankline antenna only by adding a simple configuration.

[Brief description of the drawings]

FIG. 1 is a top view illustrating an example of a configuration of an embodiment of a crankline antenna according to the present invention.

FIG. 2 is a side view showing an example of the configuration of the embodiment of the crankline antenna of the present invention.

FIG. 3 is a perspective view showing an example of the configuration of the embodiment of the crankline antenna of the present invention.

FIG. 4 is a diagram showing an example of another configuration of the crankline antenna of the present invention.

FIG. 5 is a diagram showing changes in a beam tilt angle and an axial ratio in the crankline antenna of the present invention when the length of the crankline segment is changed.

FIG. 6 is a diagram showing a main radiation pattern and a cross-polarization component radiation pattern of the crankline antenna of the present invention, and a cross-polarization component radiation pattern of a conventional crankline antenna.

FIG. 7 is a diagram showing a main radiation pattern and a radiation pattern of cross-polarized components when the length of the vertical conductor is changed in the crankline antenna of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crank line 2 Vertical conductor 3 Power supply conductor 4 Ground plane 5 Dielectric substrate 10 Coaxial cable

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01Q 13/20

Claims (2)

(57) [Claims] 1. A half cycle so that a circularly polarized wave is radiated.
A first crankline and a second
The start and end of the crank line are connected
A crank lines basic elements being, and the ground plane to which the crankshaft line basic elements are spaced apart from a predetermined distance, you are connected to said end of said crank line basic element
Ri, of suppressing the cross-polarization components which are bent in a direction substantially perpendicular to the arrangement surface of the crank line basic element
Includes a vertical conductor has a length which can, of said crank by a line that supplies power to the starting end of the basic element, the crank line circularly polarized in a direction tilted with respect to the direction orthogonal to the arrangement surface of the base element A crankline antenna characterized by radiating light. 2. The crankline basic element is formed on a front surface of a dielectric substrate, the vertical conductor is formed on a side surface thereof, and the ground plane is formed on a back surface of the dielectric substrate. The crankline antenna according to claim 1, wherein: