JPH04183003A - Triplet antenna - Google Patents

Abstract

PURPOSE:To obtain the triplet antenna having the low characteristic of coupling elements even when being arrayed while stablizing the resonance frequency by providing a conductor between ground conductor boards. CONSTITUTION:Between a ground conductor board 11 and another ground conductor board 12 faced to this conductor board 11, a microwave plane line 20 is close connected through dielectric substrates 13 and 14 abutted to the ground conductor boards 11 and 12. On the ground conductor board 12, a circular slot 15 is formed so as to be faced to the microwave plane line 20. Then, the ground conductor boards 11 and 12 are short-circuited by conductors 21a-21d. Thus, the triplet antenna is obtained with the stable resonance frequency and the low characteristic of coupling elements even when it is arrayed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a triplate antenna mounted on a moving object.

[Prior Art: A mobile satellite communication system has been proposed in which communication is performed between an fco mobile station installed in a mobile body such as a car and a fixed station via a communication satellite. As an antenna to be installed on a moving object in this system, there is a demand for an antenna that is small, lightweight, thin, and uses high-performance antenna elements without back radiation and has low inter-element coupling.

FIGS. 5A, 5B, and 5C show conventional triplate antennas used in this mobile satellite communication system.

5A, 5B, and 5C, an opening 55a is formed in an annular manner on the entire surface 53a of a rectangular dielectric substrate 53, and a two-ring slot 55 is formed in the center of the substrate. A ground conductor plate 52 is provided. On the other hand, on the lower surface 53b of the dielectric substrate 53, as shown in FIG.
A dielectric substrate 54 is provided with a microphone C strip conductor 60 formed on the surface 54a, and a ground conductor plate 51 is provided on the lower surface 54b of the dielectric substrate 54. In the conventional triplate antenna configured in this way, the dielectric substrates 53, 54
and microstrip conductor 60 and ground conductor plate 51.52
forms a triplate line 61, and when a microwave signal is input to this triplate line 61, the opening 55a of the annular slot 55 is excited, so that a linearly polarized radio wave is transmitted through the annular slot. It is radiated into the space in the surface direction of the ground conductor plate 52 where 55 is formed.

Therefore, this triplate antenna can be used as a linearly polarized antenna that suppresses radiation to the back side.

Problems to be Solved by the Invention] However, when the above-described conventional triplate antenna is used as a linearly polarized antenna, the ground conductor plate 1
Since the opening 55a of the annular slot 55 is formed in 2 and the ground conductor plates 11 and 12 are different, the structure of the triplate line 6I will be unbalanced. A large number of unwanted propagating waves are generated.

As a result, if a propagating wave having a frequency close to the resonance of the opening 55a of the annular slot 55 is generated, the resonance of the opening 55a of the annular slot 55 and the propagating wave are coupled, and the annular slot There is a problem that the resonance frequency of the opening 55a of the opening 55 is shifted.

When the opening 55a of the annular slot 55 is used as an element of an array antenna, this propagating wave causes a large coupling between the lines of the triplate structure, which increases the inter-element coupling. The problem is that the radiation characteristics of the antenna deteriorate.

The present invention has been made to solve these problems, and provides a triplate antenna that has a more stable resonance frequency than conventional antennas and has low inter-element coupling characteristics even when arrayed. The purpose is to

[Means for Solving the Problems] The present invention provides a first grounding conductor plate and a second grounding conductor plate opposing thereto. A microwave plane line is sandwiched between dielectric substrates, a slot is formed in the first or second ground conductor plate so as to face the microwave plane line, and the first and second ground conductor plates are connected to the conductor. It is characterized by the fact that it prevents short circuits.

[Function] For example, by providing one microwave plane line as described above and inputting a microwave signal to this microwave plane line, the annular slot opening formed in the first or second ground conductor plate is excited. do. As a result, the linearly polarized electromagnetic wave of the input microwave signal is radiated to the outside from the annular slot opening of the triplate antenna.

At this time, the first and second ground conductor plates are short-circuited, and the f-co conductor acts to suppress the generation of unnecessary propagation waves between the ground conductor plates, which conventionally occurs, and as a result, the triplate antenna is Only the annular slot portion will be excited.

Therefore, the resonant frequency matches the value derived from the structure of the annular slot opening, and inter-element coupling in a one-piece array structure without unnecessary propagation waves of the ground conductor plate can also be suppressed.

[Embodiment (First Embodiment) FIGS. 1A, 1B, and 1C show the linearly polarized wave triangulation of the first embodiment of the present invention, which is applicable to the above-mentioned mobile satellite communication system. A plate-type antenna is shown.

This linearly polarized triplate antenna has a ground conductor plate 1
1 and another ground conductor plate 12 opposite thereto, a dielectric substrate 13.1 is placed in contact with the ground conductor plate 11.12.
4, sandwich the microwave plane line 20 between them, and insert an annular slot 15 in the ground conductor plate 12.
The ground conductor plate 11 and the ground conductor plate 12 are short-circuited by conductors 2+a to 21d.

1A, 1B, and 1C, a ground conductor plate 11 is provided on the entire surface of the side surface 14b, and a microwave plane line having a width W as shown in FIG. 1B is provided on the side surface 14a opposite to the side surface 14b. 20 is formed on the dielectric substrate 14;
A ground conductor plate 12 is formed on the entire surface of the side surface 13a, and a dielectric substrate 13 is formed so as to sandwich the microstrip conductor 20 therebetween. Here, a triplate line 22 is formed by the dielectric substrates 13 and 14, the microstrip conductor 20 sandwiched therebetween, and the ground conductor plates 11 and 12. Incidentally, in the center part of the ground conductor plate 12, the first B
As shown in the figure, the inner radius is rs.

An annular slot I5 having a slot width Ws is formed so that its arc is perpendicular to the microstrip conductor 20, and the microstrip conductor 20 is an annular slot]
It is formed to extend by a length S from the intersection 15a with the annular slot 15 toward the center point of the annular slot 15. Further, in the ground conductor plates 11 and 12 and the dielectric substrates 13 and 14, there are small-diameter through holes 26a to 26 that pass through each substrate at the same position between the respective substrates, for example near the four corners of each substrate.
d, 25a to 25d, 27a to 27d128a
28d are formed, respectively. These ground conductor plates 11. +2, the dielectric substrate 13.14 is the 1st C
After being laminated as shown in the figure, the ground conductor plates 11 and 1
The above-mentioned through holes 25a to 25d, 26a to 26d are provided in the respective substrates so that the two are short-circuited.
, 27a to 27d, and 28a to 28d have conductors 2
1a to 21d are buried.

The operation of the f-nitri plate type antenna constructed in this way will be described below.

By inputting a microwave signal to the triplate line 22, the annular slot 15 formed in the ground conductor plate 12
can be excited. At this time, at this position between the ground conductor plate +1°12 by the conductors 21a to 21d,
Forced ground conductor plate II.

The electric field between 12 becomes zero. Therefore, a propagating wave with an electric field amplitude at this position cannot exist between the ground conductor plates 11,12. Therefore, by appropriately selecting the installation positions of the conductors 21a to 21d, it is possible to suppress the generation of propagating waves between the ground conductor plates having a frequency near the resonance frequency of the opening of the annular slot I5 determined by the center radius rs and width Ws. becomes possible. This allows the triplate antenna to be used as a linearly polarized antenna.

As is well known, by changing the length S of the microstrive conductor 20, the actance component of the antenna impedance at the resonant frequency of the linearly polarized triplate antenna changes. Therefore, the length S is set so that the characteristic impedance of the triplate line 22 matches the antenna impedance of the triplate antenna.

In the above embodiment, the ground conductor plate II and the ground conductor plate 1
Although conductors 21a to 21d are used to short-circuit 2, the present invention is not limited to this, and small-diameter through holes 25a to 25d,
Through hole processing may be performed on 26a to 26d, 27a to 27d, and 28a to 28d.

Further, in this embodiment, the shape of the slot formed in the ground conductor plate I2 is not limited to a circular ring, but a straight slot may also be used.

In addition, in this embodiment, the triplate antenna is used as a linearly polarized antenna, or is not limited to this.
It may be used as a circularly polarized antenna by point feeding or by adding a degenerate separation element.

As shown in FIG.
using, the center radius rs is 35 mm and the slot width W
Two annular slots 15 with s of 1.5 mm are formed on the ground conductor plate 12 with a distance between adjacent circular arcs of 30 mm, and the width W of the microstrip conductor 20 is set such that its characteristic impedance is 50 Ω. Two microstrip conductors 20 are formed in parallel with an interval of 100 mm so that the length S of the conductor 20 is 45 mm. Conductor 2+a to 21 short-circuiting ground conductor plate 11.12
A triplate type antenna with a structure in which d is added, and the 5th A
We fabricated triplate antennas with a structure in which no conductor was added to short-circuit the upper and lower ground conductor plates 51 and 52 as shown in Figures 5B and 5C, and conducted experiments on these triplate antennas as follows. Conductors 21ar and 21d8 are connected to one of the ends 20a of the two microstrip conductors 20 formed on the triplate antenna at a frequency of 1.3.
A microwave signal from GHz to 1.7 GHz is input, and the end 2 of the microstrip conductor 20 on the substrate edge side is
By outputting a microwave signal of the same frequency from the other 20b of 0a, the frequency characteristics of the input end reflection coefficient Sll and the input end passing coupling coefficient S21 are measured. Figures 2 and 3
The figure shows the frequency characteristics of the input end reflection coefficient Sll and the input end transmission coupling coefficient 821 in a structure in which shorting conductors 21a to 21d are added, and FIGS. 6 and 7 show the input end reflection coefficient 811 in a structure in which shorting conductors are not added. , input end transmission coupling coefficient S12
shows the frequency characteristics of As shown in these figures, the structure with the short-circuit conductor added has a measurement frequency band of 1.56G.
While a single resonance was obtained at Hz due to the excitation of only the annular slot opening, in the structure without adding a shorting conductor, in addition to this, a single resonance was obtained near this at 1.6 GHz and at 1.4 GHz further away. It can be seen that resonance occurs due to propagating waves between the ground conductor plates. Second, the transmission coupling characteristic of S21 is that in the structure with a short-circuit conductor added, coupling occurs only at the resonance frequency of the annular slot opening, whereas in the structure without the short-circuit conductor, the coupling occurs at the resonance frequency of the annular slot opening. It can be seen that in addition to resonance, large coupling is caused by propagating waves between the ground conductor plates.

As explained above, between the ground conductor plate 11 and another ground conductor plate 12 opposite thereto, the ground conductor plates I+, 1
A microwave plane line 20 is sandwiched between the two dielectric substrates 13 and 14, and an annular slot 15 is formed in the ground conductor plate 12 so as to face the microwave plane line 20. By short-circuiting the ground conductor plate 11 and the ground conductor plate I2 using conductors 21a to 2]d, a triplate antenna with stable resonance frequency and small inter-element coupling characteristics even when arrayed is realized. can.

(Second Embodiment) FIGS. 4A, 4B, and 4C show a linearly polarized triplate antenna according to a second embodiment of the present invention, which is applicable to the above-mentioned mobile satellite communication system. show. Fourth
In Figure A, Figure 4B, and Figure 4c, Figure 1A, Figure 1
Components similar to those shown in FIG. B and FIG. 1C are designated by the same reference numerals.

This linearly polarized triplate antenna differs from the linearly polarized triplate antenna of the first embodiment in that a circular microstrip patch 31 is formed concentrically with the annular slot 15 and is larger than the outer diameter of the annular slot j5. A dielectric substrate 32 having a structure formed thereon is provided on the surface 12a of the ground conductor plate 12 of the triplate line 22. That is, the antenna of the second embodiment is a microstrip antenna in which the triplate antenna of the first embodiment serves as a feed line and the annular slot opening serves as an electromagnetic coupling port.

The microstrip antenna of the second embodiment configured as described above has a two-frequency resonance characteristic due to electromagnetic coupling between the opening of the annular slot 15 and the circular microstrip patch 31, and has a two-frequency resonance characteristic at two frequencies. Shows linearly polarized radiation characteristics. By using the structure of the first embodiment as a feed line, this dual-frequency antenna works as a dual-frequency linearly polarized antenna having the same function and effect as the first embodiment.

In this embodiment, the shape of the slot formed in the ground conductor plate I2 is an annular ring, but the shape is not limited to this, and a straight slot may also be used.

Further, in this embodiment, the microstrip antenna is used as a linearly polarized antenna, but the microstrip antenna is not limited to this, and may be used as a circularly polarized antenna by adding two-point feeding or a degenerate M element.

[Effects of the Invention] As detailed above, according to the present invention, by providing a conductor between the ground conductor plates, the generation of propagation waves between the ground conductor plates can be suppressed, and the generation of unnecessary propagation waves can be suppressed. Excitation of only the annular slot opening can be obtained, the resonance frequency is stable, and the resonance frequency can be easily set. In addition, the existence of propagating waves between the ground conductor plates is a major factor in coupling between elements when forming a triplate antenna into an array. Figure 1A is an exploded perspective view of the triplate type planar antenna of the first embodiment according to the present invention, and Figure 1B is the triplate type planar antenna of Figure 1A. The plan view of FIG. 1C is A- in FIG. 1B.
A vertical cross-sectional view along line A', FIG. 1D is a plan view of the triplate antenna used in the experimental example using the triplate antenna of the present invention, and FIG. 2 is the input of the triplate planar antenna of the example. FIG. 3 is a graph showing the frequency characteristics of the input end transmission coupling coefficient 821 of the triplate type planar antenna of the embodiment, and FIG. 4A is a graph showing the frequency characteristics of the end reflection coefficient Sll. FIG. 4B is an exploded perspective view of the triplate type planar antenna of the embodiment of FIG. 4A, and FIG.
The figure is a longitudinal sectional view taken along the line A-A' in Figure 4B,
Fig. 5A is an exploded perspective view of a conventional triplate type planar antenna, Fig. 5B is a plan view of the triplate type planar antenna of Fig. 5A, and Fig. 5C is an exploded perspective view of a conventional triplate type planar antenna.
6 is a graph showing the frequency characteristics of the input end reflection coefficient Sll of the conventional triplate type planar antenna, and FIG. 7 is a graph showing the input end transmission coupling coefficient S21 of the conventional triplate type planar antenna. It is a graph showing frequency characteristics.

II, +2 Ground conductor plate, 13.14.32...Dielectric substrate, 15 Circular slot, 20...Microstrip line, 21a to 21d Conductor, 31--Circular microstrip batch, 41a to 41d...Conductor.

Patent Applicant A.T.R. Optical Radio Communication Laboratory Co., Ltd. Fig. 1A Fig. 1B Fig. 0a Fig. 1C Fig. 221 Fig. 3 Happy 4A Fig. 4B Fig. 20a Fig. 4C Fig. 5A Fig. 5B Fig. 0a Fig. 50 Figure 6

Claims (2)

[Claims] (1) A microwave plane line is connected between the first ground conductor plate and the second ground conductor plate opposite thereto using the respective dielectric substrates that are in contact with the first and second ground conductor plates. sandwiched,
A triplate antenna characterized in that a slot is formed in the first or second ground conductor plate so as to face the microwave plane line, and the first and second ground conductor plates are short-circuited by a conductor. (2) The triplate antenna according to claim 1, further comprising a dielectric substrate having a microstrip patch conductor formed on the surface of the first or second ground conductor plate in which the slot is formed.