JPH09130136A - Double frequency shared microstrip antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the desired band width without increasing the antenna thickness nor causing any rupture due to the thermal expansion, etc., by forming an air layer in a conductor barrel. SOLUTION: The microstrip antenna includes a sheet type ground conductor 32 of a conductive metal unified on almost entire lower surface of a dielectric substrate 31 and an annular patch antenna 33 of a sheet type conductive metal unified on the upper surface of the substrate 31, respectively. The inner circumference of a radiant conductor 33 is electrically connected to the conductor 32 via a conductor barrel 34 having its diameter equal to the inner diameter of the antenna 33. The barrel 34 contains a hollow part (air layer) 34a where the conductor is eliminated. At the same time, a dielectric substrate 35 is laminated on the substrate 31. Furthermore, a circular patch antenna 36 of a sheet type conductive metal is formed concentrically with the antenna 33 on the upper surface of the substrate 35. In such a constitution, the band width can be increased without the increase of the antenna thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microstrip antenna, and more particularly, to a structure of a dual frequency microstrip antenna suitable for a mobile satellite communication antenna mounted on an airplane or the like.

[0002]

2. Description of the Related Art Conventionally, for example, as a satellite communication antenna mounted on an aircraft, a lightweight and thin microstrip antenna is generally used. As the microstrip antenna, for example, a dual frequency common microstrip antenna disclosed in Japanese Utility Model Laid-Open No. 2-35514 as shown in FIGS. 9 and 10 is known. That is,
FIG. 9 shows a cross-sectional view of a conventional circularly polarized dual-frequency dual-use microstrip antenna, and FIG. 10 shows a top view thereof. As shown in FIGS. 9 and 10, the ground conductor 2 is formed on almost the entire lower surface of the dielectric substrate 1, and the ring-shaped radiating conductor (ring patch antenna) 3 is formed at the center of the upper surface. Here, the inner circumference of the radiation conductor 3 and the ground conductor 2 are electrically connected by a cylindrical conductor 4 having a diameter equal to the inner diameter of the ring-shaped radiation conductor 3. In addition, the dielectric substrate 5 is placed on the dielectric substrate 1.
Are laminated, and a circular radiation conductor (circular patch antenna) 6 is formed on the upper surface thereof in a concentric shape with the radiation conductor 3.

Further, the center conductor 8 of the power feeding coaxial cable 7 passes through the inside of the inner diameter of the radiation conductor 3 and penetrates the dielectric substrate 1 and the dielectric substrate 5, and a required position in the circumferential direction from the center 10 of the radiation conductor 6. , The ground conductor 11 of the coaxial cable 7 is electrically connected to the ground conductor 2, and the ground conductor 11 of the coaxial cable 7 is electrically connected to the ground conductor 2. Further, the power feeding coaxial cable 12 is provided at the outer diameter side position of the power feeding coaxial cable 7 located at the center.
The center conductor 13 of the radiating conductor 3 penetrates the dielectric substrate 1 and
Of the coaxial cable 12 is electrically connected to the ground conductor 2, and the ground conductor 15 of the coaxial cable 12 is electrically connected to the ground conductor 2. Also,
Similarly, the radiation conductor 3 serving as a circular patch antenna is fed with another coaxial cable 9 and the radiation conductor 6 serving as a circular patch antenna is fed with a coaxial cable 14 at respective required positions. ing. That is, the circular patch antenna 3 and the circular patch antenna 6 are respectively connected to feeding coaxial cables 9 and 14 at two points.

By forming the antenna as described above, the circular patch antenna 6 can be excited through the feeding coaxial cable 7, and the resonance frequency of the circular patch antenna 6 and the resonance frequency of the circular patch antenna 3 can be changed. By making them different, the above antenna can be used as a dual frequency microstrip antenna. For example, here
The above two resonance frequencies can be used as a transmission frequency and a reception frequency. Further, in this dual-frequency transmitting / receiving microstrip antenna, circularly polarized waves can be generated by shifting the phases of the inputs of the feeding coaxial cable 7 and the feeding coaxial cable 9 to the feeding lines by 90 °. By setting the circular polarized waves of the transmitting antenna and the receiving antenna in the same direction, for example, right-handed polarized wave or left-handed polarized wave, it is possible to establish isolation of about 30 dB between the transmitting antenna and the receiving antenna. It is well known that circularly polarized waves can be generated by providing a notch in the patch portion even if there is only one feeder line.

The dual-frequency dual-use microstrip antenna can be used, for example, as a mobile satellite communication antenna as shown in FIG. Here, the duplexer is for preventing sneaking from the transmitting side to the receiving side. For example, when a total isolation amount of about 90 dB is required, the dual frequency shared antenna is 30 d.
If the B isolation can be secured, the duplexer may have an isolation of about 60 dB. In order to increase the amount of attenuation of the duplexer, not only the cost increases but also the size increases. However, a method for increasing the isolation in the above dual frequency microstrip antenna to reduce the load on the duplexer is Kaihei 5 -175727. In this method, the nine feed lines as the radiation conductors are formed by being rotated counterclockwise by a relative angle θr relative to the circular patch antenna. By changing the θr here, the isolation between the circular patch and the circular patch can be changed, and the maximum isolation of about 55 dB can be obtained, and it is sufficient for the duplexer to obtain about 35 dB of isolation. Therefore, the load on the duplexer is reduced, and the size and cost are reduced.

By the way, in order to adjust the bandwidth of the upper antenna of the dual frequency antenna, that is, the circular patch antenna 6 as a radiation conductor, the substrate thickness of the dielectric substrate 5 is adjusted or the dielectric constant is adjusted. There is a way. As the substrate thickness increases, the bandwidth increases, and when it decreases, the bandwidth decreases. Moreover, the bandwidth becomes narrower as the permittivity becomes higher, and becomes wider as the permittivity becomes lower. Therefore, it can be seen that in order to widen the bandwidth, it is sufficient to increase the substrate thickness and reduce the dielectric constant. However, when mounted on an aircraft, for example,
Since the mobile satellite communication antenna is usually mounted outside the machine body, increasing the thickness of the substrate increases the thickness of the entire antenna, resulting in an increase in air resistance of the aircraft. It is also possible to use a material with a low dielectric constant partially, but with this method, the antenna is composed of different materials and has different thermal expansion coefficients, so in an environment of extremely low temperature in the sky. There is a problem that the antenna is mechanically deformed due to the difference in the coefficient of thermal expansion and is remarkably broken.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above problems and is desired without increasing the thickness of the antenna and without fear of breakage due to thermal expansion. It is an object of the present invention to provide a dual frequency antenna that obtains a bandwidth of.

[0008]

[Means for Solving the Problems] To achieve the above object,
According to the invention of claim 1, a circular patch antenna is laminated on an annular patch antenna formed on the upper surface of a lower dielectric substrate having a ground conductor on the lower surface via an upper dielectric substrate, and the ground is provided. A microstrip antenna in which a conductor and an annular patch antenna are connected by a conductor tube penetrating a lower dielectric substrate is characterized in that an air layer is provided in a part or all of the inside of the conductor tube.

A second aspect of the present invention is characterized in that two or more types of dielectric layers having different permittivities are provided inside the conductor tube of the circular patch antenna.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on the illustrated embodiment. 1 and 2 are a vertical sectional view and a plan view showing a first embodiment of the present invention. As shown in the figure, the microstrip antenna according to this embodiment has a dielectric substrate 3
A thin plate-shaped grounding conductor 32 made of a conductive metal is formed on almost the entire lower surface of 1 and an annular patch antenna 33 made of a thin plate-shaped conductive metal is integrally formed on the upper surface. here,
The inner circumference of the radiating conductor 33 and the ground conductor 32 are electrically connected by a conductor cylinder 34 having a diameter equal to the inner diameter of the annular patch antenna 33. Further, the inside of the conductor cylinder 34 has a dielectric removed. It is a hollow portion (air layer) 34a. The dielectric substrate 35 is provided on the dielectric substrate 31.
On the upper surface of the dielectric substrate 35. The circular patch antenna 3 is made of a thin conductive metal and is concentric with the circular patch.
6 are formed. Further, coaxial cables 37 and 38 extending from below are connected to the circular patch antenna 33, and coaxial cables 39 and 40 are connected to the circular patch antenna 36 as power feeding cables. That is, for the circular patch antenna 33, the center conductors 37a, 38 of the coaxial cables 37, 38 connected to the lower surface of the substrate 31 are connected.
a is pierced through the inside of the substrate 31 and connected to the circular patch antenna 36. The center conductors 39a, 40a of the coaxial cables 39, 40 connected to the lower surface of the substrate 31 penetrate through the hollow portion 34a. It is connected. Each outer conductor 37b, 38 of each coaxial cable 37, 38, 39, 40
All of b, 39b, and 40b are connected to the ground conductor 32. That is, the feature of this embodiment is that the inside of the conductor tube in the central portion of the annular patch antenna is hollow, and it has been proved that an excellent effect is exhibited due to this structural difference.

By constructing the antenna as described above, it is possible to excite the circular patch antenna 36 via the feeding coaxial cable 39 and the circular patch antenna 33 via the coaxial cable 37. By making the resonance frequency of 36 different from the resonance frequency of the circular patch antenna 33, the above antenna can be used as a dual frequency microstrip antenna. This point is the same as the conventional antenna. For example, here, the two resonance frequencies can be used as the transmission frequency and the reception frequency. Further, in this dual frequency transmission / reception microstrip antenna, by using another power feeding cable connected to each patch antenna 33, 36, the phase of the power feeding line input to each patch antenna is shifted by 90 °, thereby causing a circular polarization. Waves can be generated, but as is well known, circular polarization can be generated by providing a notch in the patch portion even if there is only one feeder line.

As described above, according to the present invention, the inner circumference of the circular ring antenna 33 of the dual frequency microstrip antenna and the ground conductor 32 are electrically connected by the conductor tube 34.
In addition, since the inside of the conductor cylinder 34 is formed as an air layer, the dielectric substrate 31 partially becomes an air layer for the upper circular patch antenna 36, and the dielectric constant of the upper circular patch antenna 36 becomes equivalent. As a result, the bandwidth can be widened as described above without changing the thickness and the dielectric constant of the dielectric substrate 35 of the upper circular patch antenna 36. Therefore, for example, when the antenna is mounted on an aircraft and the antenna is provided outside the fuselage, the air resistance of the aircraft does not increase because the thickness of the entire antenna does not change even if the bandwidth is widened. Further, since the dielectric portion of the antenna is made of the same material, it is possible to prevent the antenna from being mechanically deformed and destroyed due to a difference in coefficient of thermal expansion when mounted on a moving body. Further, by electrically connecting the inner circumference of the circular patch antenna 33 and the ground conductor 32 with the conductor tube 34, it is possible to increase the isolation between the transmitting antenna and the receiving antenna and reduce the load on the duplexer.

FIG. 3 is a vertical sectional view showing a modified embodiment (second embodiment) of the present invention. The feature of this embodiment is that the dielectric substrate 31 is formed in a part of the hollow portion 34a in the conductor tube 34. , 35
A dielectric layer (dielectric layer) 50 made of the same material as that of FIG. Therefore, the bandwidth of the upper circular patch antenna 36 can be adjusted by selecting the dielectric 50 having an arbitrary thickness, as compared with the case of the above embodiment in which the inside of the conductor tube 34 is entirely an air layer. In the present embodiment, as described above, the inner circumference of the circular antenna 33 of the dual-frequency microstrip antenna and the ground conductor 32 are electrically connected by the conductor tube, and the dielectric substrate is formed in a part of the hollow portion 34a. The equivalent dielectric constant of the upper circular patch antenna 36 can be adjusted by inserting the dielectric layer 50 made of the same material as 31 and 35 and changing the thickness of the dielectric layer 50. Therefore, even after the dual-strip microstrip antenna is manufactured, the dielectric layer 50 in the conductor tube is formed.
, The bandwidth of the upper circular patch antenna 36 can be adjusted arbitrarily.

FIG. 4 is a diagram showing another embodiment (third embodiment) of the present invention. In this embodiment, a dielectric substrate is provided in all or part of the hollow portion 34a of the conductor tube 34. 31, 3
5 is characterized in that a dielectric material (dielectric layer) 60 having a thermal expansion coefficient almost the same as that of No. 5 and a different dielectric constant is filled and arranged. The bandwidth can be adjusted by arbitrarily selecting the dielectric constant and the thickness of the dielectric material 60. The dielectric material 60 does not have to be one type, and a plurality of types may be used in combination. For example, the dielectric substrate 31,
You may combine the thing of the same dielectric constant as 35, and the thing of a different dielectric constant. In this embodiment, as described above, the inner circumference of the circular antenna 33 of the dual frequency microstrip antenna and the ground conductor 32 are electrically connected by the conductor tube 34, and a part or all of the inside of the hollow portion 34a is connected. Dielectric substrate 31,
By inserting a dielectric layer 60 of a material different from 35,
The equivalent dielectric constant of the upper circular patch antenna 36 can be adjusted more broadly, and the upper circular patch antenna can be changed by changing the dielectric layer 60 inside the conductive tube even after the dual frequency microstrip antenna is manufactured. The bandwidth of 36 can be broadly and arbitrarily adjusted.

Next, FIGS. 5 and 6 are a vertical sectional view and a plan view of another embodiment (fourth embodiment) of the present invention. In the dual frequency microstrip antenna shown in this example, a part of the central portion of the lower surface of the dielectric substrate 35 is carved into an arbitrary size,
It differs from the above-described embodiments in that the cavity 70 is formed and communicated with the lower hollow portion 34a. With this configuration, the bandwidth of the upper circular patch antenna 36 can be further widened. That is, in the present embodiment, as described above, a part of the dielectric substrate 35 of the dual frequency microstrip antenna is cut out to an arbitrary size to form the cavity 70, and the cavity 70 is communicated with the hollow portion 34a. Because
The equivalent dielectric constant of the upper circular patch antenna 36 can be further lowered, the adjustable bandwidth can be further widened, and the cavity can be expanded even after the dual frequency microstrip antenna is manufactured. By performing the processing, the bandwidth of the upper circular patch antenna can be adjusted broadly and arbitrarily.

Next, FIG. 7 is a diagram showing another modified example of the present invention, in which a structure in which the thickness of the dielectric substrate 35 is made thin is added to the structure of any of the above four modified examples. The feature is the point. That is, in addition to the configuration of each of the above-described embodiments for expanding the dielectric constant of the upper circular patch antenna equivalently to increase the bandwidth, the present embodiment has a dielectric substrate on the upper side of the dual frequency dual-use microstrip antenna. The feature is that the substrate thickness of 35 is thin. That is, if the portion of the dielectric substrate 35 is thinned, the bandwidth is narrowed as described above. Therefore, by adjusting both structures appropriately,
Since it is possible to reduce the thickness of the dielectric substrate while keeping the bandwidth constant, and it is possible to reduce the thickness of the entire antenna, it is possible to reduce the air resistance when the antenna is mounted outside the aircraft, for example. Will provide the benefits that you have.

FIG. 8 is a diagram showing another modification of the present invention. In this example, while keeping the thickness of the entire antenna constant, the thickness of the lower dielectric substrate 31 is increased, and the thickness of the upper dielectric substrate 35 is reduced by an amount corresponding to the increase in thickness, so that each of the above-described embodiments is performed. The band of the upper circular antenna is secured by any of the methods shown in the examples. That is, this embodiment can also be applied in combination with each of the first, second, third, and fourth embodiments. As described above, in the present embodiment, by increasing the substrate thickness of the one dielectric substrate 31 of the dual frequency microstrip antenna, the bandwidth of the lower annular patch antenna 33 is widened as described above, In addition, in order to prevent an increase in the thickness of the entire antenna, the thickness of the dielectric substrate 35 is reduced, and at the same time, the bandwidth of the upper circular patch antenna 36 is reduced by combining any of the methods shown in the first, second, third, and fourth embodiments. It has been secured. Therefore, for example, when the frequencies of the circular patch antenna 33 and the circular patch antenna 36 are used as the reception and transmission frequencies, respectively, the bandwidth can be widened for both transmission and reception, and the thickness of the entire antenna does not increase. When the antenna is mounted outside the aircraft, air resistance does not increase.

[0018]

As described above, the present invention has two upper and lower sides.
Layer dielectric substrate, a ground conductor formed on the lower surface of the lower substrate, and an annular patch antenna formed on the upper surface of the lower substrate,
A dual-frequency shared microstrip antenna comprising a conductor tube for connecting the inner diameter of the ring patch antenna to a ground conductor, and a circular patch antenna coaxially arranged with the ring patch antenna on the upper surface of the upper substrate. By making all or part of the inside an air layer (hollow part),
The bandwidth can be increased without increasing the thickness of the antenna. Furthermore, since the dielectric constant of the upper circular patch antenna is equivalently reduced by forming the whole or part of the inside of the conductor tube as an air layer, even if the upper dielectric substrate thickness is reduced by that amount, as described above. The bandwidth can be constant. When only a part of the inside of the conductor tube is used as an air layer, the remaining space is filled with a dielectric material having a different permittivity or the same as that of the substrate to further adjust the bandwidth. It becomes possible to do. Therefore, since it is possible to reduce the thickness of the entire antenna while securing a desired bandwidth, it is possible to provide a dual-frequency microstrip antenna that is thinner and lighter than conventional ones. Furthermore, by electrically connecting the inner circumference of the annular patch antenna and its ground conductor with a conductor tube, the isolation between the transmitting antenna and the receiving antenna is increased, and the load on the duplexer can be further reduced.

[Brief description of the drawings]

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

FIG. 2 is a plan view of the embodiment shown in FIG. 1;

FIG. 3 is a longitudinal sectional view of a dual frequency microstrip antenna according to a second embodiment of the present invention.

FIG. 4 is a vertical sectional view of a dual frequency microstrip antenna according to a third embodiment of the present invention.

FIG. 5 is a vertical sectional view of a dual frequency microstrip antenna according to a fourth embodiment of the present invention.

6 is a plan view of the dual frequency dual-use microstrip antenna of the embodiment example of FIG. 5;

FIG. 7 is a vertical sectional view of a dual frequency microstrip antenna according to another embodiment of the present invention.

FIG. 8 is a vertical cross-sectional view of a dual frequency microstrip antenna according to another embodiment of the present invention.

FIG. 9 is a sectional view of a conventional dual-strip microstrip antenna.

FIG. 10 is a plan view of a conventional dual frequency dual-use microstrip antenna.

FIG. 11 is a diagram showing a usage pattern when a conventional dual frequency microstrip antenna is used as a mobile satellite communication antenna.

[Explanation of symbols]

1, 5, 31, 35 ·· Dielectric substrate 2, 32 · · Grounding conductor 3, 33 · · Circular patch 4, 34 · · Conductor cylinder 6 · · Circular patch 7, 12, 9, 14, 37, 39 , 40, 38 ·· Coaxial feed line 10 · · Radiating conductor center 50, 60, 80 · · Dielectric 70 · · Cavity

Claims (2)

[Claims] 1. A circular patch antenna is laminated on an annular patch antenna formed on the upper surface of a lower dielectric substrate having a ground conductor on the lower surface via an upper dielectric substrate, and the above-mentioned ground conductor is provided. A microstrip antenna in which an annular patch antenna is connected by a conductor tube penetrating a lower dielectric substrate, wherein an air layer is provided in a part or all of the inside of the conductor tube. antenna. 2. The dual frequency dual-use microstrip antenna according to claim 1, wherein two or more types of dielectric layers having different permittivities are provided inside the conductor cylinder of the circular patch antenna.