JPH0736485B2 - Planar array antenna - Google Patents

Description

The present invention relates to a planar array antenna suitable for use in, for example, receiving sanitary broadcasts.

[Outline of Invention]

According to the present invention, in a suspended line-fed planar antenna, a pair of excitation probes that are orthogonal to each other are formed on a common plane in correspondence with a large number of holes that form a part of a radiating element. To increase the antenna gain by reducing the transmission loss in the suspended line by widening the line width of the part where the suspended line is placed independently when the power supply signals are phase-combined in the suspended line. It was done.

[Conventional technology]

In a suspended line-fed planar antenna in which a substrate is sandwiched by metal or metallized plastic having a large number of holes that form part of a radiating element, a pair of excitation probes that are orthogonal to each other corresponding to a large number of holes are placed on a common plane. The present applicant has previously proposed a circularly polarized planar array antenna in which the feed signals to the pair of excitation probes are phase-combined in the suspended line.
60-162650).

According to this array antenna, it is possible to reduce the thickness, simplify the mechanical structure, and use an inexpensive microstrip line substrate even if an inexpensive and commonly available substrate is used for high frequencies. An antenna gain equal to or higher than that of the antenna is obtained.

Therefore, although not specifically stated, the radiation element spacing is 0.9 to 0.95 λo (λo: free space wavelength, 22.5 to 23.6 mm)
In addition, the line width of the suspended line, that is, the width of the cavity is 1.75 mm, and the diameter of the radiating element, that is, the diameter of the holes formed in the first and second metal plates is 16.35 mmφ.

Therefore, it is conceivable to further reduce the transmission loss of the suspended line. To do so, consider the line width for 12 GHz near the operating frequency (11.7 to 12.7 GHz for sanitary broadcasting, the allocation band differs depending on the country). It should be 2 mm or more. Then, it is necessary to reduce the diameter of the radiating element portion, and it is necessary to reduce the diameter from 16.35 mmφ to, for example, about 15.6 mmφ.

However, if the diameter of this radiating element is reduced to about 15.6 mmφ, the cutoff frequency of the waveguide main mode (TE ₁₁ mode) of this diameter will be about 11.263 MHz, so if the operating frequency is close, the excitation element (cavity ) And the excitation probe are difficult to match, and the band becomes narrow. As a result, the reflection loss characteristics change, and the reflection loss near the operating frequency (11.7 to 12.7 GHz) deteriorates.

Therefore, in the suspended line-fed planar antenna in which the substrate is sandwiched by metal or metallized plastic having a large number of holes forming part of the radiating element, the present applicant has a pair of excitations that are orthogonal to each other corresponding to the large number of holes. The probes are formed on a common plane, the feed signals to the pair of excitation probes are phase-combined in the suspended line, and metal pieces for matching adjustment are provided at the positions facing the pair of excitation probes. We proposed a planar array antenna to be constructed (Japanese Patent Application No. 61-63177).

[Problems to be solved by the invention]

By the way, in various planar array antennas used in the 12 GHz band or higher for satellite broadcasting reception, especially when a line (line) is used as a feeding system such as a strip line,
The loss due to the feeder line is the main factor that determines the antenna gain (operating gain). This becomes a problem especially when a gain of 30 dB or more is obtained.

Therefore, if a power supply line with lower loss can be realized, the above problem can be solved to some extent. However, when the feeding circuit network for circularly polarized wave reception is fed in the same phase as described above, if the array radiating element interval is set to 0.9 to 0.95λo to obtain the maximum gain, the sunspended line is formed. At 12 GHz, the width of the groove was only about 2 mm, and the transmission loss was large.

That is, conventionally, the line width is constant and thin due to the element spacing for obtaining a high gain, the circularly polarized wave combining portion, etc., and the feed loss (transmission loss) cannot be minimized to the optimum. In addition, the element spacing was fixed, and the diameter of the radiating element was reduced to widen the feeder line width as much as possible, but there was a limit.

The present invention has been made in view of the above circumstances, and provides a planar array antenna capable of reducing the transmission loss of a suspended line.

[Means for solving problems]

The planar array antenna according to the present invention has a first hole having a concave hole (4) and a through hole (5) which form a part of the radiating element.
And the second metal plate or the metallized plastic plate (1) and (2) and the metal plate or the metallized plastic plate (1) and (2) sandwiched between the hole (4) and the through hole (5). A pair of excitation probes (8) and (9) protruding by a predetermined length having an angle difference of approximately 90 ° in the center direction of the constituted circle, and the pair of excitation probes (8) and (9)
Metal pieces (12) and (13) for alignment adjustment, which are protruded by a predetermined length in the center direction of a circle composed of a hole (4) and a through hole (5), and a pair of excitation probes (8). ) And (9), a thin film substrate (3) consisting of conductor foils (7) and (7 ') and conductor foils (7) and (7') attached to the thin film substrate (3) are surrounded. A radiating element having a suspended line formed with a cavity (6) communicating with the hole (4) and the through hole (5) of the metal plate or metallized plastic plate (1) and (2). , A metal plate or a metallized plastic plate (1) and (2), and a thin film substrate (3) are provided with a large number of radiating elements arranged in parallel to form a suspended line-fed planar antenna. Suspend between the power supply (14) provided and each radiating element. Transmission loss is reduced by widening the horizontal length of the above-mentioned cavity (6) and / or the conductor foil (7) interconnected at equal intervals by the conductor foil (7 ') constituting the drain line. It is made up of.

[Action]

A pair of excitation probes (8) and (9) that are orthogonal to each other are formed on a common plane, corresponding to a large number of holes (4) and through holes (5). Then, the power supply signals to the pair of excitation probes are phase-synthesized within the suspended line. Further, metal pieces (12) and (13) for alignment adjustment are provided at positions facing the pair of excitation probes (8) and (9), respectively. Then, the line width of the portion where the suspended lines (6) and (7) are individually arranged is widened. By partially widening the line width, the transmission loss of the suspended line is reduced and the antenna gain is improved.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5, taking as an example the case where the invention is applied to a circularly polarized plane array antenna.

FIG. 3 shows the structure of a circularly polarized wave radiating element used in the present invention. FIG. 3A is its top view and FIG. 3B is FIG. 3A.
2 is a cross-sectional view taken along line I-I in FIG. In FIG. 3, (1) is the first metal plate (or metallized plastic plate), (2) is the second metal plate (or metallized plastic plate), and (3) is the first and second metal plates ( It is a thin film substrate (film-shaped flexible substrate) sandwiched between 1) and (2). The first metal plate (1) has a recessed hole (4), the second metal plate (2) penetrates vertically with the same diameter as the hole (4), and the upper side has a conical shape. It has a through hole (5). First and second metal plates (1), (2)
When the substrate (3) is clamped by, the hole (4) and the through hole (5) are positioned so as to coincide with each other. Also, a cavity (6) communicating with the hole (4) and the through hole (5) is formed when the substrate (3) is sandwiched between the first and second metal plates (1) and (2). Done

(7) is a conductor foil adhered to the substrate (3), and the conductor foil (7) is connected through the cavity (6) to form a suspended line. Further, the conductor foil (7) is provided on the common plane of the substrate (3) with holes (4) and through holes (5).
The pair of excitation probes (8) and (9) are formed by projecting a predetermined length so as to be orthogonal to the central direction of the. With such a configuration, since the circularly polarized waves are composed of linearly polarized waves that are orthogonal to each other with their phases shifted by π / 2, it means that the excitation probes corresponding to the respective linearly polarized wave components are arranged.

Further, (12) and (13) are a pair of excitation probes (8),
Metal pieces for matching adjustment, which are formed on the substrate (3) so as to face (9), respectively, and are capacitive. Further, one side of these metal pieces is in direct current contact with the metal plate (2). This makes it possible to lower the cutoff frequency equivalently and improve the reflection loss (VSWR) in the probe for converting (exciting) the suspended line into the waveguide mode. Of course, also in this configuration, the isolation between the two orthogonal excitation probes (8) and (9) is 20.
Since it is above dB, there is no problem for circular polarization reception (transmission).

FIG. 4 shows the configuration of the suspended line for feeding the planar array, and shows the state cut along the line II-II in FIG. 3B. Here, for example, a conductor foil (7) formed by etching a printed circuit board (3) having a thickness of about 25 to 100 μm is surrounded by the first and second metal plates (1) and (2) to form a hollow coaxial line. is doing. In this case, since the substrate (3) is thin and acts only as a supporting member, it is a feed line with little transmission loss even if it is not a low-loss substrate.

FIG. 5 shows a specific circuit for synthesizing circularly polarized waves. A pair of excitation probes (8) and (9) are connected by a conductor foil (7) forming a suspended line on the same plane of a substrate (3). However, at this time, λg / 4 (λ
The line (10) of (g: line wavelength at the center frequency) is inserted on one side where the phase is advanced so that it is in phase with the combining section (11). By changing the inserting direction of the λg / 4 line (10) in this way, right-handed or left-handed circularly polarized waves can be dealt with. By the way, Fig. 5 shows the case of receiving the right-handed circularly polarized wave, and assuming that the radio wave is going from the front to the back in the drawing, the electric field advances while rotating clockwise, so first the excitation probe (9) And the excitation probe (8) receives it after a delay of π / 2 (90 °). As a result, it can be seen that the synthesizing unit (11) is in phase.

FIG. 1 shows a circuit configuration in which a plurality of circularly polarized wave radiating elements as shown in FIG. 3 are co-phase-fed with a suspended line, whereby an array is constructed. Actually, as an example, at 12 GHz, the total of 16 vertical and 16 horizontal is 256.
It is an array of radiating elements, and its shape is about 40 cm.
It is a 40 cm square. At this time, the first and second metal plates (1) and (2) are provided with a plurality of holes (4) and through holes (5) corresponding to the radiating elements, respectively. (8) and (9) are interconnected by a conductor foil (7) forming a suspended line so as to be equidistant from the feeding point (14). In such a configuration, various directional characteristics can be obtained by changing the feeding phase and the power distribution ratio on the line. That is, the phase is changed by changing the distance from the feeding point (14) to the excitation probes (8) and (9), and the line is thinned or thickened at the branch point of the suspended line. Then, the amplitude is changed by changing the ratio of impedance, and the directional characteristic can be arbitrarily changed by this.

Moreover, here, one radiating element in the central part is removed, and a feeding waveguide converter (15) is provided in this, and this converter (15)
A waveguide (not shown) is connected to the feeding point (14) via.
Also, the end (16) left by removing the radiating element
Should be terminated with the same resistance as the characteristic impedance of the feeder. As a result, the length of the feeder line becomes shorter than in the conventional case, and the decrease in gain due to the loss of the feeder line is improved.

In addition, in the present embodiment, the line width of the portion where the suspended line is arranged independently is widened. That is, the suspended line is composed of the cavity portion (6) and the conductor foil (7), but when these are arranged alone between the radiating elements, the width thereof is widened. In FIG. 1, the conductor foil indicated by reference numeral (7 ') is arranged alone between the radiating elements, and thus has a width wider than other portions. Of course, although not shown, the width of the cavity (6) through which the conductor foil (7 ') passes may be widened accordingly.

In FIG. 4, the thickness of the substrate (3) is t, and the cavity (6) is
Is L, the height is d, and the width of the conductor foil (7) is W,
Conventionally, for example, t = 25 μm, d = 1.4 mm, L = 2 mm, W = 1 mm, and the transmission loss at frequency f = 12 GHz at this time is about 1 m per 1 m as shown by the broken line a in FIG. It was 3 dB. On the other hand, in the present embodiment, as an example, t and d are the same and L = 4 mm and W = 2 mm, but at this time, the frequency f = 12 GHz.
The transmission loss at was about 1.8 dB per meter as shown by the solid line b in FIG. Therefore, for example, if the line width expandable portion is 50 cm, the antenna gain is improved by about 0.6 dB as compared with the conventional example.

From this, it is understood that if the line width of the suspended line, that is, the width of the cavity (6) and the width of the conductor foil (7) are made wider than in the conventional case, the transmission loss is improved. Whether the width of the cavity (6) and the width of the conductor foil (7) are widened simultaneously or individually may be set arbitrarily in consideration of the characteristics shown in FIG.

Although the above-described embodiment is applied to the circularly polarized plane array antenna, the present invention is not limited to this and is similarly applicable to other plane array antennas. Further, it is applicable not only to the case of the suspended line but also to the case of the strip line.

〔The invention's effect〕

As described above, according to the present invention, since the line width (line width) of the feeder line such as the suspended line is partially widened, the feeder line loss (transmission loss) is reduced and the antenna gain is improved.

[Brief description of drawings]

FIG. 1 is a layout diagram showing an embodiment of the present invention, FIG. 2 is a characteristic diagram for explaining the present invention, FIG. 3 is a top view and a sectional view of a circularly polarized radiation element, and FIG. FIG. 5 is a cross-sectional view of the suspended line, and FIG. 5 is a configuration diagram of the circular polarization combiner. (1) is a first metal plate (or metallized plastic plate), (2) is a second metal plate (or metallized plastic plate), (3) is a substrate, (4) and (5) are holes and through holes. , (6) is a cavity, (7) is a conductor foil, (8), (9)
Is an excitation probe, and (20) and (21) are metal pieces for matching adjustment.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-59-207706 (JP, A) JP-A-54-75972 (JP, A) Konishi "Microwave integrated circuit" Industrial report (Sho 48.12.10) ) P. 21-42

Claims (1)

[Claims] 1. A metal plate or a metallized plastic plate having a recessed hole and a through hole forming a part of a radiating element, and a metal plate or a metallized plastic plate sandwiched between the metal plate or the metallized plastic plate, and comprising the hole and the through hole. A pair of excitation probes protruding by a predetermined length with an angle difference of approximately 90 ° in the center direction of the circle to be formed, and in the center direction of the circle formed by the hole and the through hole at a position facing the pair of excitation probes. A metal film for metallization or metallization so as to surround a metal piece for matching adjustment protruding by a predetermined length, a thin film substrate made of a conductive foil communicating with the pair of excitation probes, and a conductive foil adhered to the thin film substrate. A radiating element having a suspended line in which a cavity communicating with the hole and the through hole of the plastic plate is formed, and the metal plate or the metallized plastic plate and the thin film substrate as described above. A large number of radiating elements are arranged side by side to form a suspended line feeding type planar antenna, and a feeding portion provided on the back surface of a large number of radiating elements arranged side by side and a conductor foil forming the above suspended line between each radiating element, etc. A planar array antenna, characterized in that the cavities and / or lines serving as conductor foils interconnected at intervals are made wider in the lateral direction to reduce transmission loss.