JPH07122928A - Microstrip slot antenna - Google Patents

Abstract

PURPOSE:To improve the cross polarized wave characteristics of a microstrip slot antenna. CONSTITUTION:In this microstrip slot antenna composed of a dielectric plate 5 provided with a ground conductor surface provided with a power feeding slot 6 on a surface and a band-like power feeding circuit pattern 7 in a direction crossing the approximate center part of the power feeding slot on a back surface and the dielectric plate 1 provided with a radiation circuit pattern 2 and stacked on the ground conductor surface of the dielectric plate 5, plural slits 8-13 are provided around the power feeding slot 6 of the dielectric plate 5 in the direction where a longitudinal direction crosses the longitudinal direction of the power feeding slot 6 and a radio wave absorber plate 14 is provided on the side of the back surface of the dielectric plate 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microstrip slot antenna used as a satellite receiving antenna.

[0002]

2. Description of the Related Art In a conventional microstrip slot antenna, as shown in FIG. 5, a radiation circuit pattern 2 having a substantially circular shape is provided on the surface of a dielectric plate 1, and the radiation circuit pattern 2 is provided on the opposite circumference. A pair of recesses 3 and 4 are provided, and the surface of the dielectric plate 5 is a ground conductor surface having a feeding slot 6,
A strip-shaped feeding circuit pattern 7 is provided on the back surface in a direction orthogonal to the substantially central portion of the feeding slot 6, the dielectric plate 1 is overlaid on the dielectric plate 5, and the centers connecting the centers of the recesses 3 and 4 are formed. The angle between the line and the longitudinal center line of the feeding slot 6 is 45
So that the circularly polarized wave incident on the radiation circuit pattern 2 is fed through the feeding slot 6 to the feeding circuit pattern 7
And the received signal is taken out through the feeding circuit pattern 7.

[0003]

Therefore, the polarized waves to be received can be coupled to the feeding circuit pattern 7 through the feeding slot 6 and output, but the cross polarized waves are generated on the ground conductor surface of the dielectric plate 5. Part of it is reflected by a radome or the like provided above the dielectric plate 1 to prevent rainwater and dust from passing through the dielectric plate 1 and entering the same direction as the received polarization. There is a problem that the cross-polarized wave characteristics are inferior because the circularly polarized wave that swirls in the direction becomes circularly polarized light and is incident on the radiation circuit pattern 2. An object of the present invention is to improve the cross polarization characteristics of the microstrip slot antenna by absorbing the cross polarization that is reflected by the ground conductor surface of the dielectric plate.

[0004]

A microstrip slot antenna of the present invention is provided with a ground conductor surface having a feeding slot on the front surface, and a strip-shaped feeding circuit on the back surface so as to intersect with a substantially central portion of the feeding slot. A microstrip slot antenna comprising a first dielectric plate provided with a pattern and a second dielectric plate provided with a radiation circuit pattern, which is superposed on a ground conductor surface of the first dielectric plate, wherein: A plurality of slits are provided around the power feeding slot of the first dielectric plate such that a longitudinal direction thereof intersects with a longitudinal direction of the power feeding slot, and a radio wave absorber plate is provided on a back surface side of the first dielectric plate. Is provided.

[0005]

The present invention is configured as described above, and the circularly polarized wave incident on the radiation circuit pattern is converted into the linearly polarized wave by the radiation circuit pattern, and the converted linearly polarized wave is fed through the feeding slot. By connecting to the circuit pattern and outputting the received signal from the feeding circuit pattern, the cross polarization of the reverse polarization is converted into the linear polarization by the radiation circuit pattern, and the direction of the electric field of the linear polarization is the feeding slot. Is parallel to the longitudinal direction of the power supply slot, passes through a plurality of slits around the power supply slot with the longitudinal direction intersecting the longitudinal direction of the power supply slot, and is absorbed by the electromagnetic wave absorber plate provided on the back side. Therefore, the cross polarization characteristic of the microstrip slot antenna can be improved.

[0006]

1 is an exploded perspective view showing the structure of an embodiment of a microstrip slot antenna according to the present invention.
A substantially circular radiation circuit pattern 2 is formed on the surface of the dielectric plate 1.
And a ground conductor provided with a substantially rectangular feed slot 6 on the front surface of the dielectric plate 5, and a strip-shaped feed circuit pattern 7 on the back surface in a direction orthogonal to the center of the long side of the feed slot 6.
Are provided, the dielectric plates 1 are stacked on the surface of the dielectric plate 5 so that the side on which the radiation circuit pattern 2 of the dielectric plate 1 is provided is the upper side, and the radio wave absorber plate 14 is placed below the dielectric plate 5. It is arranged. Around the power feeding slot 6, a plurality of substantially rectangular slits 8 to 13 whose longitudinal direction is orthogonal to the longitudinal direction of the power feeding slot 6 are provided.

FIG. 2 is an enlarged plan view of the microstrip slot antenna of FIG. In the figure, when the horizontal direction is the X axis and the vertical direction is the Y axis, the center line of the feed slot 6 in the longitudinal direction overlaps the X axis, and the center lines of the slits 8 to 13 in the longitudinal direction are Y. It is arranged so as to be parallel to the axis, and the center line of the feeding circuit pattern 7 in the longitudinal direction overlaps with the Y axis. The radiation circuit pattern 2 having a substantially circular shape is provided with a pair of concave portions 3 and 4 on opposite circumferences, an axis connecting the centers of the concave portions 3 and 4 is defined as an X1 axis, and an axis orthogonal to the X1 axis is defined as a Y1 axis. Then, the X1 axis and the X axis are arranged so as to form an angle of about 45 degrees.

The circularly polarized wave is obtained by combining two orthogonal linearly polarized waves having the same amplitude and a phase difference of 90 degrees, so that the circularly polarized wave is incident on the radiation circuit pattern 2. And resonates in the X1 axis direction and the Y1 axis direction,
Resonant currents flow in the X1 axis direction and the Y1 axis direction, respectively. By setting the recesses 3 and 4 to have a predetermined size, the phase in the X1 axis direction can be advanced by 45 degrees and the phase in the Y1 axis direction can be delayed by 45 degrees. When right-handed circularly polarized wave (the phase of the linearly polarized wave component in the X1 axis direction is delayed by 90 degrees with respect to the linearly polarized wave component in the Y1 axis direction) is incident on the radiation circuit pattern 2,
In the radiation circuit pattern 2, the resonance current in the Y1 axis direction and the resonance current in the X1 axis direction can be in phase with each other, and the combined one becomes the Y axis direction current, so that the electric field direction is in the Y axis direction. It can be converted into linearly polarized waves.

Therefore, it becomes possible to couple the linearly polarized wave to the feeding circuit pattern 7 through the feeding slot 6.
A signal is output by the power feeding circuit pattern 7. In the left-handed circularly polarized wave, which is a cross-polarized wave with respect to the right-handed circularly polarized wave, the phase of the linearly polarized wave component in the Y1 axis direction is delayed by 90 degrees with respect to the linearly polarized wave component in the X1 axis direction. Since it is converted into a linearly polarized wave having an electric field direction in the X-axis direction, it passes through the slits 8 to 13 and reaches the radio wave absorber plate 14 shown in FIG. As the radio wave absorber plate 14, for example, a dielectric plate coated with a carbon film or the like is used, and the linearly polarized wave converted from the cross polarization is coupled to the carbon film or the like to make a current flow through the carbon film or the like. Cross polarization is absorbed by attenuating the propagation energy of the same polarization.

Therefore, it is possible to improve the cross polarization characteristics of the microstrip slot antenna. In addition, the slit 8 is provided so that desired cross polarization characteristics can be obtained.
Alternatively, the number and size of 13 to 13 may be increased or decreased before use. When the left-handed circularly polarized wave is received, the feeding slot 6, the feeding circuit pattern 7 and the slits 8 to 13 are rotated by 90 degrees so that the center line of the feeding slot 6 in the longitudinal direction overlaps with the Y axis. , So that the longitudinal center lines of the slits 8 to 13 are parallel to the X axis,
The center line in the longitudinal direction of the power feeding circuit pattern 7 may be arranged so as to overlap the X axis. In this embodiment, the radiating circuit pattern 2 has a shape in which a pair of concave portions 3 and 4 are provided on the circumference of a circle, but a circular polarization patch antenna element having another shape of a single-point feeding type, for example, a square or The same can be applied to an elliptical shape or the like.

FIG. 3 is a partially cutaway perspective view showing an embodiment in which the microstrip slot antenna of the present invention is used in a feed horn. In the figure, the same parts as those shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. The circular waveguide 15 has a shape capable of propagating an electromagnetic wave of TE11 mode, and is provided with a horn-shaped opening 16 at one end so that the electromagnetic wave can be efficiently introduced.
The dielectric plate 1 is provided at the other end to close it, the radiation circuit pattern 2 is arranged on the side of the dielectric plate 1 facing the circular waveguide 15, and the feeding slot 6 and the slits 8 to 8 are provided under the dielectric plate 1. The dielectric plate 5 provided with 13 is arranged, and the radio wave absorber plate 14 is arranged below the dielectric plate 5. The circular waveguide 15 is arranged so that its tube axis passes through the center of the radiation circuit pattern 2, and the other configurations are the same as those of the embodiment of FIG. The received signal is taken out and input to the input circuit of the LNB or the like so that the satellite signal can be received.

FIG. 4 is a layout showing an embodiment in which a plurality of microstrip slot antennas according to the present invention are used. In the figure, the same parts as those shown in FIG. And the description is omitted. A dielectric plate 18 is arranged below the dielectric plate 17, and a radio wave absorber plate 19 is arranged below the dielectric plate 18, and the radiation circuit pattern 2 shown in FIG. 1 is arranged on the surface of the dielectric plate 17. A plurality of power supply slots 6 shown in FIG. 1 are provided for each radiation circuit pattern 2,
The slits 8 to 13 and the feeding circuit pattern 7 are combined and provided on the dielectric plate 18 to form a planar antenna. The received signal is taken out from each feeding circuit pattern 7 and connected to the feeding point so that they are in phase with each other by a microstrip line formed by the feeding circuit pattern 7 and the ground conductor provided on the upper surface of the dielectric plate 18. From the same feeding point to L
The NB is input to an input circuit or the like so that satellite signals can be received.

[0013]

As described above, according to the present invention,
The desired circularly polarized wave is output through the feeding slot provided on the dielectric plate, and the crossed polarized wave is passed through a plurality of slits provided around the feeding slot in a direction intersecting with the feeding slot,
A cross-polarized wave can be absorbed by a radio wave absorber plate provided below the dielectric plate, and a microstrip slot antenna with improved cross-polarized wave characteristics can be provided.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a configuration of an embodiment of a microstrip slot antenna of the present invention.

FIG. 2 is an enlarged plan view of the microstrip slot antenna of FIG.

FIG. 3 is a partially cutaway perspective view showing an embodiment in which the microstrip slot antenna of the present invention is used in a feed horn.

FIG. 4 is a layout view showing an embodiment when a plurality of microstrip slot antennas according to the present invention are used.

FIG. 5 is an exploded perspective view of a conventional microstrip slot antenna.

[Explanation of symbols]

 1 Dielectric Plate 2 Radiation Circuit Pattern 3 Recess 4 Recess 5 Dielectric Plate 6 Feed Slot 7 Feed Circuit Pattern 8 Slit 9 Slit 10 Slit 11 Slit 12 Slit 13 Slit 14 Radio Wave Absorber Plate 15 Circular Waveguide 16 Opening 17 Dielectric Body plate 18 Dielectric plate 19 Radio wave absorber plate

Claims (3)

[Claims] 1. A first dielectric plate having a ground conductor surface provided with a feeding slot on the front surface thereof, and a strip-shaped feeding circuit pattern provided on the back surface in a direction intersecting with a substantially central portion of the feeding slot. A microstrip slot antenna comprising a second dielectric plate provided with a radiation circuit pattern, which is superposed on the ground conductor surface of the first dielectric plate, wherein a microstrip slot antenna is provided around the feed slot of the first dielectric plate. A microstrip slot antenna characterized in that a plurality of slits are provided so that a longitudinal direction thereof intersects with a longitudinal direction of the feeding slot, and a radio wave absorber plate is provided on a back surface side of the first dielectric plate. 2. The microstrip slot antenna according to claim 1, wherein a circular waveguide provided with an opening through which an electromagnetic wave can be introduced is arranged on a surface of the microstrip slot antenna on which a radiation circuit pattern is formed. . 3. The microstrip slot antenna according to claim 1, wherein a plurality of the microstrip slot antennas are provided and are connected to a feeding point so that they have the same phase in the feeding circuit pattern.