JPH03297207A - Plane antenna - Google Patents

Abstract

PURPOSE:To improve antenna efficiency by exciting paired unit radiation elements through an individual feeder line inserting a phase inverter circuit, which is composed of one folded line, between a pair radiation elements. CONSTITUTION:Circular patch elements 3, 7, 11 and 15 are equipped with individual feeder lines 6, 10, 14 and 18 composed of microstrip lines, and respectively arranged while being rotated at 180 deg. and including power feeding points. Between the pair of the individual feeder lines 6 and 10 and the pair of the lines 14 and 18, folded lines 25 and 26 having the 1/2 wavelength are respectively inserted and the end of the return lines 25 and 26, feeder lines 27 and 28 are connected from the inside. These feeder lines 27 and 28 are excited through a T branch 23. Thus, the antenna efficiency can be improved by uniformly exciting the radiation elements and reducing the number of feeder lines.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a planar antenna that uses a strip line as a feed line and excites a plurality of radiating elements.

[Conventional technology]

Generally, a flat antenna for receiving satellite broadcasting is required to have a high gain, has a large area, has a large number of radiating elements arranged on a flat surface, and each radiating element is coupled to a feed line.

Conventionally, a strip line, which is suitable for being lightweight and compact, has been used as a feed line for a planar antenna.

Further, as the strip line, a microstrip line consisting of a ground conductor and a strip conductor, or a triplate IJ tube line consisting of three conductor layers in which a strip conductor is arranged between upper and lower ground conductors is used.

Generally, when a microstrip line is used as a feed line, the radiating element is a half-wavelength microstrip line with both ends open, or a so-called patch antenna type that is a modified version of the microstrip line. and the feed line are directly coupled. In addition, in the case of triplate strip line feeding, a slot antenna type antenna with a half-wavelength slot y'pf provided on the upper ground conductor is used, and the slot antenna and the feeding line are often electromagnetically coupled. . Furthermore, as for the overall power feeding system, in the case of Str + 7x 7° line feeding, there is a parallel feeding method that combines two branch circuits, so that the line length from one feeding point to each radiating element is equal. used. The spacing between each radiating element is determined to suppress unnecessary side ropes and prevent deterioration of antenna radiation efficiency.
The interval must be reduced to about 0.5 wavelength to 0.9 wavelength.

However, in planar antennas using these strip lines, in order to excite the radiating element with a desired phase and uniform amplitude, the arrangement of the individual feed lines around the radiating element requires complicated and overcrowded wiring. There was a problem in that mutual interference between the lines occurred, impairing uniform excitation, and as a result, the radiation efficiency of the antenna decreased.

Furthermore, in conventional planar antennas, there is a problem that the matching circuit between the radiating element and the antenna element is not optimal due to restrictions on the arrangement of individual feed lines around the radiating element, resulting in a narrow band as a whole.

FIG. 4 shows a plan view of a planar antenna using the conventional IJ tube feed system. This antenna is.

The arrangement is such that the radiated power of each radiating element is combined in the front direction perpendicular to the surface.

Four circular patch radiating elements 3, 7, 11, 15 are spaced apart by a ground conductor 1 and an insulator 2, and are connected to individual feed lines 6, 10, 14, .
18, the in-phase power is fed in the same direction. Individual feed line 6
, 10.14, J8 is connected to one feeder line 2 by a T-branch 23 including a line section 20° 21 which becomes a quarter-wavelength impedance transformer with a different line width via a T-branch 19.22.
It is synthesized into 4.

Each circular patch has a cutout segment 4.5.8.9.12.13, J6 at a 45 degree angle from the feed point.
．． 17 gives a phase difference of 90 degrees to two resonance modes orthogonal to each other on the disc conductor, and excites them with equal amplitude to generate circularly polarized waves.

[Problem to be solved by the invention]

The problem with the above feed line arrangement is that the feed line 2 of the T branch 23
Since the vicinity of the 40T branch is not perpendicular to the line portion 20.2, there is asymmetrical magnetic field coupling, and there is no perfect two-branching, resulting in unequal power distribution on the left and right sides.

It has been experimentally known that the coupling to the line portion 20, which is the left branch, becomes stronger.

Further, the feed line 24 approaches the individual feed line No. 4 as well as the radiating element J5, causing unnecessary electromagnetic coupling with each other, resulting in non-uniform excitation of each radiating element.

There was a problem that the antenna efficiency was reduced.

The present invention has been made in view of the above problems, and its purpose is to provide a planar antenna that can be easily constructed and has high performance.

[Means and effects for solving the problem] The present invention consists of two radiating elements arranged facing each other at each feeding point, rotated 180 degrees, and a phase inversion circuit consisting of a bent line being inserted between the individual feeding lines. This simplifies the feed line near the radiating element, improves the symmetry of the feed, reduces unnecessary coupling in the feed line, and improves antenna efficiency by uniformizing the excitation of the radiating element. It is.

[First example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a plan view of a planar antenna according to a first embodiment of the present invention. Each of the radiating element types of this antenna is arranged to combine the main beams in the vertical front direction, as in the case of FIG. 4 above.

Four circular/mother-shaped radiating elements 3.7.11.15 are arranged at a predetermined interval by a ground conductor l and an insulator 2, and have cutout segments at 45 degree angles from each feed point. 4.5・8・9・12・13.16.17 By adding gold to the disk conductor, a 90 degree phase difference is given to two orthogonal resonance modes on the disk conductor, and circularly polarized waves are generated by exciting with equal amplitude. This is the format of the book that occurs.

Circular patch radiating elements 3, 7 and 1, 15fi micros? Equipped with individual feed lines 6.10 and 14.18 consisting of IJ tube lines, each including a feed point and 18
It is rotated 0 degrees. Between the individual feed lines 6 and 10 and between 14 and 18, return lines 25 and 26 each having a line length of 1/2 wavelength are inserted. More connected. The feed lines 27 and 28 are connected to one feed line 24 via a T-branch 23.

Next, excitation of the radiating element in the configuration of the present invention will be explained. The signal applied to the feed line 24 is divided into four equal parts, and at the same time, the signal applied to the feed line 24 is divided into four parts, and at the same time, the folded lines 25 and 26 act as a phase inversion circuit, so that the signal is divided into individual feed lines 6, 10 and 14.
The circular patch radiating elements 3 and 7 and 11 and 15, which are rotated 180 degrees from each other, are excited with a phase difference of 180 degrees at the connection point between the radiating elements and the 16 radiating elements, and in the end, all the radiating elements are in the same phase. It will excite.

As an effect of the present invention, the folding lines 25 and 26 are shaped so that the left and right distributions are exactly in a superior image relationship.

It has become possible to feed power with good symmetry from the center, and to uniformly excite the left and right radiating element pairs.

In addition, the IJ tube line width of the folded line (25, 26) may be made wider than other feed lines to widen the frequency characteristic of one phase inversion, or in some cases, the width may be narrowed and placed closely together. It is possible to improve the swiping efficiency and to select various shapes. In either case, the line length may be designed to have opposite phases at the center of the operating frequency.

[Second Embodiment] FIG. 2 is a plan view of a planar antenna showing a second embodiment of the present invention, in which the arrangement of the folded lines 25 and 26 is changed to the first embodiment.
In this embodiment, the configuration is almost the same, except that it has been rotated 90 degrees from the one shown in the figure.

The connection point of the individual feed line 6.10 for the return line 25.26 and the individual feed line 6.10 for the radiating element is set slightly inside the both ends of the return line 25.26, and the feed line length is is a little shortened. In this case, if the strip line width of the folded lines 25 and 26 is widened, the value of the load Q as a resonator becomes appropriately large, and the phase inversion function can be performed over a wide band.

[Third Embodiment] FIG. 3 is a structural diagram of a planar antenna showing a third embodiment of the present invention, in which it is applied to a triplate strip line feeding system. The arrangement of the feeder line is similar to the embodiment shown in FIG. 2, but an upper ground conductor 38 is laminated on the ground conductor and insulator 2 with an insulator 37 in between, and a tri-layer is placed between these two layers. A feeder line is formed using a plate strip line. The four radiating elements are the same as those in FIG. 1 or 2, but openings 39, 40, 41, and 42 are provided on the upper ground conductor 38 for passing radiated waves corresponding to each radiating element arrangement. It is set in.

In addition, in this embodiment, the turnback lines 29 and 30 have a wide U
The individual feed line 6.10.14.18 has a letter-shaped shape and is located at a point slightly away from both open ends of the folded line 29°30.
are connected, and the connection points of the feeder lines 31 and 32 to the pair of radiating elements are set further inside. The feeder lines 3 and 32 are connected to the T-branch 23 via line portions 33 and 34 that serve as quarter-wavelength impedance transformers. This converts the relatively high radiating element impedance seen from the individual feed line side to a low impedance. U
The shaped folded line has the highest amplitude distribution of high-frequency voltage at both open ends, and becomes a high-impedance feeding point, and the U
Because it has the property of becoming a low impedance feeding point towards the bottom of the letter.

In addition to its original purpose as a phase inversion circuit, it can also be used as a transformer. Depending on the feeding method of the individual feed lines, the feed point impedance may become low impedance. In this case, the positions of both feed points may be set opposite to the above, and impedance matching can be easily achieved. Furthermore, if the present invention is applied, there is a margin in the arrangement sweep of the feeder line, so the line width of the combined feeder line part can be made wider than in the conventional feeder method, thereby reducing the conductor resistance of the line and reducing the line loss. is possible. Further, in this third embodiment as well, the phase inversion function can be performed over a wide band, as in the second embodiment.

In each of the above embodiments, the case where the antenna is applied to a flat antenna in which the main beam is perpendicular to the surface has been explained. However, even when the main beam has a desired angle, if the power feeding method of the present invention is designed as a basis, the feeding method can be used. By using conventionally well-known methods such as inserting a phase difference load circuit into the line and adding rotation angle differences to the arrangement of radiating elements and feeding points, the wiring can be simplified compared to conventional methods, and the desired result can be achieved. This has the advantage that beam tilt can be easily achieved.

In addition, in the embodiments described so far, a single circular/square type radiating element was used as the radiating element, and a direct coupling method using individual feed lines was used as the feeding method, but as is well known, the upper ground conductor It is also possible to apply the present invention to a feeding system in which so-called electromagnetic coupling is performed using a slot-type radiating element provided above and a triplate strip line that crosses the slot of the radiating element.

〔Effect of the invention〕

As described above, according to the present invention, as a result of introducing a phase inversion circuit in the form of a folded line to the pair of radiating elements,
The symmetry and simplification of the feed line for each radiating element are further improved, and the antenna efficiency can be improved by making the excitation of the radiating element uniform and reducing the loss of the feed line.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a planar antenna according to one embodiment of the present invention, and FIGS. 2 and 3 are respectively other embodiments of the present invention. The configuration diagram shown in FIG. 4 is a configuration diagram of a conventional planar antenna. 1.38...Grounding conductor, 2,37...Insulator, 3゜7.11.15...Circular patch radiating element, 4.5゜1
1.9, 12.13.16.17... Notch segment, 6.10.14.18... Individual feed line, 7.
8.23...T branch, 25.26...Folding line (phase inversion circuit), 29.3o...U-shaped folding line, 20.21.33.34...4 minute 1 wavelength impedance transformer% 39.40.41.42...Aperture. 1 Figure 1

Claims (3)

[Claims] (1) In a planar antenna equipped with a plurality of radiating elements and a feed line branching from one signal terminal into a plurality of strip lines and exciting the plurality of radiating elements, the plurality of radiating elements are: It is composed of a combination of unit radiating element pairs, each unit radiating element pair has an individual feed line in which a phase inversion circuit consisting of one folded line is inserted between the pair of unit radiating elements, and the unit radiating element pair has A planar antenna characterized in that excitation is performed by direct coupling or electromagnetic coupling from a feed line connected to a phase inversion circuit. (2) In the planar antenna according to claim (1), the folded line constituting the phase inversion circuit is made of a 1/2 wavelength U-shaped strip line with both ends open and wider than the individual feed line. A planar antenna characterized in that a connection point is provided on the central groove side of the U-shaped strip line. (3) In the planar antenna according to claim (2), the connection points between the individual feed line and the feed line of each radiating element with respect to the U-shaped folded line for phase inversion are made different from the open end. A planar antenna characterized by combining an inverting circuit with an impedance transformation effect.