JPH08181531A - Slot coupling microstrip antenna with radome - Google Patents

Abstract

PURPOSE: To reduce manufacture man-hours of a microstrip antenna with a radome and to prevent degradation of reliability due to vibration or deformation of the radome. CONSTITUTION: This antenna is provided with a microstrip line 13 formed by using an earth conductor 2 and a center conductor (strip conductor) 13a to have a dielectric board 12 in between, a radiation conductor 4 arranged toward the earth conductor 2 of the microstrip line 13 with an air gap 5, and a radome 6 having a recessed part 6a with the radiation conductor 4 imbeded at its inner face, a slot 11 used to electromagnetically couple the microstrip line 13 to the radiation conductor 4 is formed to the earth conductor 2. A high frequency signal fed to the microstrip line 13 is fed to the radiation conductor 4 via the slot 11 and the air gap 5. The microstrip line 13 being a feeder and the radiation conductor 4 are not connected to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a microstrip antenna having a radiation conductor arranged in a radome, and more particularly to simplification of a feeding structure.

[0002]

2. Description of the Related Art Generally, antennas are required to have high environmental resistance. Therefore, the antenna often has a structure in which the radiating element is housed in the radome. As an antenna used in a mobile body, especially in an aircraft, a microstrip antenna is advantageous from the requirements of thinness, light weight, low profile and the like. In view of such a situation, the inventor of the present application has proposed a structure of a microstrip antenna in which the antenna configuration is simplified, the number of parts is reduced, and the weight and thickness are reduced (Actual Publication No. 3-9511). The structure is shown in Figure 1.
0 is shown in a sectional view.

The conventional microstrip antenna shown in FIG. 10 has a base 1 which also functions as a ground conductor, a radome 6 which covers the upper surface of the base 1 and forms a predetermined space 5 between the upper surface and the base 1, and a concave portion of the radome 6. The radiation conductor 4 embedded in 6a and the central conductor 10a are connected to the radiation conductor 4,
The coaxial cable 10 is fixed to the base 1 in a state of penetrating the base 1 and supplies power to the radiation conductor 4.

With this configuration, the number of parts can be reduced,
In addition, the air existing in the gap 5 between the radiation conductor 4 and the base 1 is used as a dielectric, and the radiation conductor 4 is embedded in the recess 6a on the inner surface of the radome 6, so that weight reduction and thinning are realized. ing.

[0005]

However, as shown in FIG.
In the structure of the conventional microstrip antenna shown in FIG. 1, a lot of time is required for the soldering of the coaxial cable 10 and the base 1 and the soldering of the central conductor 10a and the radiating conductor 4 at the time of assembly, and as a result, the antenna is It was causing an increase in manufacturing costs. Further, stress due to vibration and deformation of the radome 6 is likely to be concentrated on the soldered portion between the central conductor 10a and the radiation conductor 4, and skill is required for soldering work for sufficiently improving the reliability of the soldered portion. did. Thus, the conventional microstrip antenna with a radome has problems to be solved in terms of manufacturing cost and reliability.

[0006]

The present invention provides the following means for solving the above-mentioned problems.

A parallel conductor plate transmission line including at least a structure in which a ground conductor is closely attached to one surface of a dielectric substrate and a strip conductor is closely attached to the other surface of the dielectric substrate, and the ground of the parallel conductor plate transmission line. A radiation conductor disposed on the conductor side with a gap from the ground conductor, and a radome that covers a large area of the ground conductor to form a closed space with the ground conductor. A slot for electromagnetically coupling the parallel conductor plate transmission line to the radiation conductor is formed in the ground conductor, the slot is in the ground conductor in a region covered by the radome, and the radiation conductor is provided in the radome. The area occupied by the radiation conductor in the radome is obtained by projecting the slot onto the inner surface of the radome from a direction orthogonal to the ground conductor. Radome slotted coupled microstrip antenna which comprises at least a portion of the slot projection area in which the slot is photographed.

The radiation conductor is attached to the inside of the radome, is embedded in a recess having an opening on the inner surface of the radome, or is embedded in the thickness of the radome. A slot-coupled microstrip antenna with a radome according to.

A parallel conductor plate transmission line including at least a structure in which a ground conductor is closely attached to one surface of a dielectric substrate and a strip conductor is closely attached to the other surface of the dielectric substrate, and the ground of the parallel conductor plate transmission line. The parallel conductor includes a radiation conductor disposed on the conductor side with a gap from the ground conductor, and a radome embedded in the recess or the thickness of the radiation conductor which is open to the ground conductor side. A slot-coupled microstrip antenna with a radome, wherein a slot for electromagnetically coupling a plate transmission line to the radiation conductor is formed in the ground conductor, and the radome covers a region including the slot in the ground conductor. .

A slot-coupled microstrip antenna with a radome as described above, characterized in that a space surrounded by the ground conductor and the radome is filled with a paper honeycomb material.

A microstrip line formed by sandwiching a dielectric substrate with a ground conductor and a strip conductor, a radiation conductor disposed on the ground conductor side of the microstrip line with a gap from the ground conductor, and the radiation conductor. And a radome having a recess on the inner surface of which is embedded,
A slot-coupled microstrip antenna with a radome, wherein a slot for electromagnetically coupling the microstrip line to the radiation conductor is formed in the ground conductor.

A strip line formed by further sandwiching a structure in which a strip conductor is sandwiched between first and second dielectric substrates parallel to each other, and further sandwiched between first and second ground conductors parallel to the first dielectric substrate. A radiation conductor disposed on the first ground conductor side of the strip line with a gap from the first ground conductor; and a radome having a recess on the inner surface in which the radiation conductor is embedded. A slot-coupled microstrip antenna with a radome, wherein a slot for electromagnetically coupling the strip line to the radiation conductor is formed in the first ground conductor.

[0013]

In the slot-coupled microstrip antenna with a radome of the present invention, the radiation conductor and the feed line are electromagnetically coupled to each other through the air gap by adopting the above-described configuration, so that the radiation conductor and the feed line are not required to be soldered. Become. Further, by using a parallel conductor plate transmission line such as a microstrip line or a strip line as the feed line, a parallel conductor plate transmission line also serves as the base 1 in the conventional microstrip antenna with a radome shown in FIG. Consequently, soldering between the base and the power supply line is also unnecessary. Therefore, the present invention can solve the problems left over in the prior art that the manufacturing cost is increased and the reliability is lowered due to the soldering of the feeding line and the radiation conductor and the soldering of the feeding line and the base.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the accompanying drawings.

FIG. 1 is a sectional view showing the structure of an embodiment of the present invention, FIG. 2 is a perspective view of a microstrip line 13 used in the embodiment of FIG. 1, and FIG. 3 is a plan view of the embodiment of FIG. 4 is a bottom view of the embodiment shown in FIG. This microstrip antenna includes a ground conductor 2 and a dielectric substrate 12.
A radome 6 shaped so that a predetermined gap 5 is formed between the microstrip line 13 including the center conductor (also referred to as a strip conductor) 13a and the upper surface of the ground conductor 2, and the inner surface of the radome 6. Recess 6a provided in
And the radiation conductor 4 embedded in the. The microstrip line 13 is a type of unbalanced parallel conductor plate transmission line. A slot 11 is provided in the ground conductor 2 immediately below the radiation conductor 4.

The microstrip antenna of this embodiment is mounted on an aircraft and mounted on the surface of the aircraft body through a frame 14 made of a metal or a dielectric material. The frame 14 separates the microstrip line 13 from the machine body, and maintains a constant separation distance from the surface of the machine body to the microstrip line 13.

Microstrip line 13 and radome 6
The peripheral portion of the frame and the frame 14 are fixed by the screw 8, and air exists in the space 5 formed between the ground conductor 2 and the radiation conductor 4, and this air functions as a dielectric. Further, the radiation conductor 4 is provided on the inner surface of the radome 6 and is embedded in the recess 6 a opened to the side of the ground conductor 2. The lower surface is exposed in the void 5 and is fixed to the radome 6, so that the radiation conductor 4 is predetermined from the slot 11. Supported by the distance.

Since the slot 11 is provided in the ground conductor 2 of the microstrip line 13, a high frequency signal input to the microstrip line 13 is transmitted to the slot 1.
Power is supplied to the radiation conductor 4 via 1. That is, the microstrip line 13 and the radiation conductor 4 are electromagnetically coupled via the slot 11 and the gap 5. It is an important feature of the present invention that the microstrip line 13, which is a power feeding path for high frequency signals, is electromagnetically coupled to the radiation conductor 4 in a non-contact manner.

The positional relationship among the slot 11, the central conductor 13a and the radiation conductor 4 is shown in the plan view of FIG. Center conductor 13a
Has a predetermined line length that intersects with the slot 11 at a position (offset position) displaced from the center of the slot 11 and exceeds the slot 11. When the length from the position of the slot 11 to the tip of the center conductor 13a is defined as the stub length, by adjusting parameters such as the stub length L, the offset position, the slot size, the thickness of the gap 5, and the area of the radiation conductor 4, A desired resonance frequency, band characteristic, etc. can be obtained.

FIG. 6 shows the dielectric substrate 12 with a relative permittivity ε _r =
2.6, Teflon substrate with thickness t = 0.8mm, radiation conductor 4
Is a copper foil embedded in a Teflon radome 6 having a relative permittivity ε _r = 2.6 and a thickness t = 1.6 mm, and the wavelength in the microstrip line 13 is λ _g, and the stub length L is 0.1 λ. _g , 0.14λ _g , 0.15λ _g , 0.2λ _g , the thickness of the void 5 (from the ground conductor 5 to the radiation conductor 4
Is a characteristic diagram when the horizontal axis is the distance to (mm) and the vertical axis is the relative bandwidth (%) of VSWR = 2.

As the dielectric substrate 12, unnecessary radiation (back lobe) to the rear of the antenna is suppressed and the slot 1
In order to reduce the dimensions of 1 and the microstrip line 13, a substrate having a relative permittivity ε _r = 10 is used. ε _r =
Examples of the substrate 10 include a PPO substrate manufactured by Matsushita Electric Works, Ltd.

Next, FIG. 7 is a sectional view showing a second embodiment of the present invention. In this embodiment, a strip line 1 is used instead of the microstrip line 13 in the embodiment of FIG.
7 is provided. The strip line 17 is formed by stacking a second dielectric substrate 15 and a second ground conductor 16 below the microstrip line 13, and a center conductor 13a is sandwiched between the ground conductor 2 and the ground conductor 16 in a balanced manner. Parallel conductor plate transmission line, which is called a triplate strip line or a shield strip line. In the embodiment of FIG. 7, the earth conductor 16 serves as the bottom of the antenna, so that the frame 14 of FIG.
It can be directly mounted on the body of an aircraft, which is effective for lowering the antenna attitude.

The structure of FIG. 7 (a structure in which the radiation conductor 4 and the slot 11 are paired) is used as one antenna element.
For example, a plurality of the antenna elements can be arranged in the longitudinal direction of the central conductor 13a to form an array antenna. When configuring the array antenna, the parallel plate mode propagating between the ground conductors 2 and 16 causes unnecessary inter-element interference and radiation, so that the ground conductor 2 and the ground conductor 16 are short-circuited around the slot 11. Provide pins, through holes, etc.

FIG. 8 is a sectional view showing a third embodiment of the present invention. This embodiment differs from the first embodiment shown in FIG. 1 and the second embodiment shown in FIG. 7 in that the radiation conductor 4 is completely embedded inside the thick wall of the radome 6. Note that FIG. 8 is a modification of the first embodiment, and the modification of the second embodiment can be similarly configured.

In order to increase the support strength of the radome 6, it is preferable to fill the space 5 with a paper honeycomb material. In this case, since the paper honeycomb material has a structure in which it makes surface contact with and supports the inner wall surface of the radome 6, it is possible to significantly improve the support strength and the vibration resistance, and at the same time, to reduce wind pressure and atmospheric pressure difference. Radome 6
The deformation of can be greatly reduced. When the deformation of the radome 6 is reduced, the electromagnetic coupling between the microstrip line 13 and the radiation conductor 4 is stabilized, which in turn can stabilize the antenna characteristics.

The slot 11 shown in the above embodiment is used.
Is linear, which causes the antenna to excite linearly polarized waves. Circular polarized wave excitation may be required depending on the application. In that case, if the 3 dB hybrid circuit is added by changing the shape of the slot to the cross shape (cross slot 21) shown in the plan view of FIG. It can be configured as a circularly polarized antenna.

In the embodiment of FIGS. 1 and 7, the radiation conductor 4 is buried in the recess 6a of the radome 6, and in the embodiment of FIG. 8, the radiation conductor 4 is completely buried inside the wall thickness of the radome 6. . However, the present invention is not limited to the configuration of FIG. 1, FIG. 7 or FIG. 8 as long as the radiation conductor 4 faces the slot 11 via the gap 5, and for example, a gold thin film deposited on a dielectric substrate. Alternatively, the radiation conductor 4 may be configured with the dielectric substrate and the dielectric substrate may be attached to the inner surface of the radome 6 directly above the slot 11. Alternatively, the radiation conductor 4 made of metal foil may be directly attached to the inner surface of the radome 6.

In the above-mentioned embodiments, the feeding path for the high frequency signal is the microstrip line 13 or the strip line 1.
Composed of 7. These feed lines are called by various names such as parallel conductor plate transmission lines or simply strip lines. In the present invention, regardless of its name, the parallel conductor plate transmission line is such that the ground conductor is closely attached to one surface of the dielectric substrate,
It refers to various high-frequency transmission lines including at least a structure in which a strip conductor (referred to as the central conductor 13a in the above embodiments) is closely attached to the other surface of the dielectric substrate.

[0029]

As described above in detail with reference to the embodiments, according to the present invention, the radiation conductor and the feeding line can be coupled in a non-contact manner, and the radiation conductor and the feeding line are not required to be soldered. , The parallel conductor plate transmission line which is the power feeding line is shown in FIG.
Since it also serves as the base 1 of 0, there is no need to solder the feed line to the base, and the structure is simplified, so the assembly man-hours can be greatly reduced, and the manufacturing cost can be improved, and the radome can be vibrated and deformed. As a result, there is no fear that the coupling between the power supply line and the radiation conductor will be broken, and the reliability can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a microstrip antenna according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a microstrip line used in the embodiment of FIG.

FIG. 3 is a plan view of the embodiment of FIG.

FIG. 4 is a bottom view of the embodiment of FIG.

5 is a plan view showing the positional relationship between the slot 11, the center conductor 13a, and the radiation conductor 4 in the embodiment of FIG.

6 is a characteristic diagram showing the relationship between the thickness of the void 5 (thickness of the air layer) and the relative band of VSWR = 2 in the embodiment of FIG.

FIG. 7 is a sectional view showing a second embodiment of the present invention.

FIG. 8 is a sectional view showing a third embodiment of the present invention.

FIG. 9 is a plan view illustrating a black slot.

FIG. 10 is a sectional view showing a conventional microstrip antenna with a radome.

[Explanation of symbols]

 1 ... Base 2 ... Ground conductor 4 ... Radiation conductor 5 ... Void 6 ... Radome 6a ... Recess 8 ... Screw 10 ... Coaxial cable 10a ..Center conductor 11 ... Slot 12 ... Dielectric substrate 13 ... Microstrip line 13a ... Center conductor (strip conductor) 14 ... Frame 15 ... Second dielectric substrate 16 ...・ Second ground conductor 17 ・ ・ ・ Strip line 21 ・ ・ ・ Black slot

Claims (6)

[Claims] 1. A parallel conductor plate transmission line including at least a structure in which a ground conductor is closely attached to one surface of a dielectric substrate and a strip conductor is closely attached to the other surface of the dielectric substrate, and a parallel conductor plate transmission line. A radiation conductor disposed on the side of the ground conductor with a gap from the ground conductor; and a radome that covers a large area of the ground conductor to form a closed space between the ground conductor and the radome. A slot for electromagnetically coupling the parallel conductor plate transmission line to the radiation conductor is formed in the ground conductor, the slot being in the ground conductor in a region covered by the radome, and the radiation conductor being the radome. The area occupied by the radiation conductor in the radome is obtained by projecting the slot onto the inner surface of the radome from a direction orthogonal to the ground conductor. A slot-coupled microstrip antenna with a radome, wherein the slot includes at least a part of a slot projection area in which the slot is imaged. 2. The radiation conductor is attached to the inside of the radome, is embedded in a recess having an opening on the inner surface of the radome, or is embedded in the thickness of the radome. A slot-coupled microstrip antenna with a radome according to claim 1. 3. A parallel conductor plate transmission line including at least a structure in which a ground conductor is adhered to one surface of a dielectric substrate and a strip conductor is adhered to the other surface of the dielectric substrate, and the parallel conductor plate transmission line. A radiation conductor disposed on the side of the ground conductor with a gap from the ground conductor; and a radome embedded in the recess or the wall thickness of the radiation conductor which is open to the side of the ground conductor, A slot coupling micro with a radome, wherein a slot for electromagnetically coupling a parallel conductor plate transmission line to the radiation conductor is formed in the ground conductor, and the radome covers a region including the slot in the ground conductor. Strip antenna. 4. A slot-coupled microstrip antenna with a radome according to claim 3, wherein a space surrounded by the ground conductor and the radome is filled with a paper honeycomb material. 5. A microstrip line in which a dielectric substrate is sandwiched between a ground conductor and a strip conductor, a radiation conductor disposed on the ground conductor side of the microstrip line with a gap from the ground conductor, And a radome having a recess on the inner surface in which a radiation conductor is embedded, wherein a slot for electromagnetically coupling the microstrip line to the radiation conductor is formed in the ground conductor. Strip antenna. 6. A structure in which a strip conductor is sandwiched between first and second dielectric substrates that are parallel to each other, and is further sandwiched between first and second ground conductors that are parallel to the first dielectric substrate. A strip line, a radiation conductor disposed on the first ground conductor side of the strip line with a gap from the first ground conductor, and a radome having a recess in which the radiation conductor is embedded on the inner surface. A slot-coupled microstrip antenna with a radome, characterized in that a slot for electromagnetically coupling the strip line to the radiation conductor is formed in the first ground conductor.