# Patent

## Title
Antenna board

## Abstract

An antenna board includes a first dielectric layer, a strip conductor, a ground conductor layer, a second dielectric layer, a first patch conductor, a third dielectric layer, a second patch conductor, a through conductor, and a waveguide including upper and lower ground conductors and a ground through conductor. The upper and lower ground conductors are disposed so as to hold therebetween at least one of the first, second, and third dielectric layers. The ground through conductor is disposed in such a manner that at least one lies on each of both sides in a direction orthogonal to an extending direction of the strip conductor, and extends through the dielectric layers lying between the upper and lower ground conductors.

## Background
BACKGROUND OF THE INVENTION
1. Field of the Invention
An embodiment of the present invention relates to an antenna board obtainable by laminating dielectric layers and conductor layers into a multilayer.
2. Description of Related Art
Frequency bands used for wireless personal area networks differ from country to country. It is therefore necessary to widen antenna frequency bands in order to use an antenna board in different countries. This type of antenna board is disclosed in, for example, Japanese Unexamined Patent Publication No. HEI 5-145327. In recent years there has been a demand for an antenna board having a still wider frequency band (57-66 GHz) as an antenna board usable all over the world.
SUMMARY OF THE INVENTION
It is an object of an embodiment of the present invention to provide a wide band antenna board that is rich in directionality for transmitting and receiving signals in a wide frequency band of, for example, 57-66 GHz.
The antenna board according to the embodiment of the present invention includes a first dielectric layer, a strip conductor, a ground conductor layer, a second dielectric layer, a first patch conductor, a third dielectric layer, a second patch conductor, a through conductor, and a waveguide. The strip conductor is disposed on an upper surface of the first dielectric layer, extends in one direction from a peripheral part of the first dielectric layer, and has a terminal portion. The ground conductor layer is disposed on a lower surface of the first dielectric layer. The second dielectric layer is laminated on the upper surface of the first dielectric layer and an upper surface of the strip conductor. The first patch conductor is disposed on an upper surface of the second dielectric layer so as to overlie a location of the terminal portion. The third dielectric layer is laminated on the second dielectric layer and the first patch conductor. The second patch conductor is electrically independent and disposed on an upper surface of the third dielectric layer. The second patch conductor at least partially overlies a location at which the first patch conductor is disposed. A center of the second patch conductor is deviated from a center of the first patch conductor in an extending direction of the strip conductor. The through conductor extends through the second dielectric layer and connects the terminal portion and the first patch conductor. The waveguide includes upper and lower ground conductors and a ground through conductor, and is disposed in a region closer to the extending direction of the strip conductor than the first and second patch conductors. The upper and lower ground conductors are disposed so as to hold therebetween at least one of the first, second, and third dielectric layers. The ground through conductor is disposed in such a manner that at least one lies on each of both sides in a direction orthogonal to the extending direction of the strip conductor and extends through the dielectric layers lying between the upper and lower ground conductors.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a top view showing an antenna board according to a first embodiment of the present invention, FIG. 1B is a sectional view taken along line X-X in FIG. 1A, and FIG. 1C is a sectional view taken along line Y-Y in FIG. 1A;
FIG. 2A is a top view showing an antenna board according to a second embodiment of the present invention, FIG. 2B is a sectional view taken along line X-X in FIG. 2A, and FIG. 2C is a sectional view taken along line Y-Y in FIG. 2A;
FIG. 3A is a top view showing an antenna board according to a third embodiment of the present invention, FIG. 3B is a sectional view taken along line X-X in FIG. 3A, and FIG. 3C is a sectional view taken along line Y-Y in FIG. 3A;
FIG. 4A is a top view showing an antenna board according to a fourth embodiment of the present invention, FIG. 4B is a sectional view taken along line X-X in FIG. 4A, and FIG. 4C is a sectional view taken along line Y-Y in FIG. 4A; and
FIG. 5A is a top view showing an antenna board according to a fifth embodiment of the present invention, and FIG. 5B is a sectional view taken along line X-X in FIG. 5A.



DESCRIPTION OF THE EMBODIMENTS
An antenna board according to a first embodiment of the present invention is described with reference to FIGS. 1A to 1C. FIG. 1B is a sectional view taken along line X-X in FIG. 1A. FIG. 1C is a sectional view taken along line Y-Y in FIG. 1A. As shown in FIGS. 1A to 1C, the antenna board of the first embodiment includes a dielectric board 1 having thereon a plurality of dielectric layers 1a to 1e laminated one upon another, a ground conductor layer 2 for shielding, a strip conductor 3 for inputting and outputting high frequency signals, a patch conductor 4 for transmitting and receiving electromagnetic waves, an auxiliary patch conductor 7, and a waveguide D.
The dielectric layers 1a to 1e are composed of, for example, a resin-based dielectric material made of glass cloth impregnated with a thermosetting resin, such as an epoxy resin, a bismaleimide triazine resin, and an acrylic modified polyphenylene ether resin. The dielectric layers 1a to 1e respectively have a thickness of approximately 30-100 μm. The dielectric layers 1a to 1e have a dielectric constant of approximately 3-5. The dielectric layers 1a to 1e are made up of the first dielectric layer 1a, the intermediate dielectric layer 1b, the second dielectric layer 1c, the third dielectric layer 1d, and the fourth dielectric layer 1e. 
The ground conductor layer 2 is deposited over the entire lower surface of the lowermost dielectric layer 1a. The ground conductor layer 2 functions as a shield. The ground conductor layer 2 has a thickness of approximately 5-20 μm. The ground conductor layer 2 is composed of, for example, copper.
The strip conductor 3 is opposed to the ground conductor layer 2 with the first dielectric layer 1a interposed therebetween, and is disposed between the first dielectric layer 1a and the intermediate dielectric layer 1b. The strip conductor 3 is a narrow strip-shaped conductor having a terminal portion 3a in a middle part of the dielectric board 1, and extends inside the dielectric board 1 in one direction (hereinafter referred to as “extending direction”) toward the terminal portion 3a. In the antenna board of the first embodiment, the strip conductor 3 functions as a transmission line, through which a high frequency signal is inputted and outputted, and the high frequency signal is to be transmitted to the strip conductor 3. The strip conductor 3 has a width of approximately 50-350 μm. The strip conductor 3 has a thickness of approximately 5-20 μm. The strip conductor 3 is composed of, for example, copper.
The patch conductor 4 is made up of a first patch conductor 4a, a second patch conductor 4b, and a third patch conductor 4c. These patch conductors 4a to 4c are electrically independent of one another. The patch conductors 4a to 4c have a square shape that has sides parallel to the extending direction of the strip conductor 3 (hereinafter referred to as “longitudinal sides”) and sides parallel in a direction perpendicular to the extending direction (hereinafter referred to as “lateral sides”). The sides of each of the patch conductors 4a to 4c respectively have a length of approximately 0.5-5 mm. The patch conductors 4a to 4c respectively have a thickness of approximately 5-20 μm. The patch conductors 4a to 4c are composed of, for example, copper.
The first patch conductor 4a is disposed between the second dielectric layer 1c and the third dielectric layer 1d so as to overlie a location above the terminal portion 3a of the strip conductor 3. Therefore, the intermediate dielectric layer 1b and the second dielectric layer 1c are interposed between the first patch conductor 4a and the strip conductor 3. The first patch conductor 4a is connected to the terminal portion 3a of the strip conductor 3 by interposing therebetween a through conductor 5 extending through the second dielectric layer 1c, and a through conductor 6 extending through the intermediate dielectric layer 1b. The through conductor 5 has a cylindrical shape with a diameter of approximately 50-200 μm and a thickness of approximately 5-20 μm. The through conductor 6 has a columnar shape or circular truncated cone shape with a diameter of approximately 30-100 μm. The through conductors 5 and 6 are respectively composed of, for example, copper. The first patch conductor 4a radiates an electromagnetic wave to the outside upon receipt of supply of a high frequency signal from the strip conductor 3. Alternatively, the first patch conductor 4a causes the strip conductor 3 to generate a high frequency signal upon receipt of an electromagnetic wave from the outside.
The second patch conductor 4b is disposed between the third dielectric layer 1d and the fourth dielectric layer 1e so as to at least partially overlie a location above the first patch conductor 4a. The second patch conductor 4b is consequently subjected to electrostatic capacity coupling to the first patch conductor 4a with the third dielectric layer 1d interposed therebetween. A center of the second patch conductor 4b is deviated from a center of the first patch conductor 4a in the extending direction of the strip conductor 3. The center of the patch conductor denotes an intersection of two diagonals when the patch conductor has the square shape. The deviation of the second patch conductor 4b reaches such a degree that the second patch conductor 4b overlies an area of 80% or more of the location at which the first patch conductor 4a is disposed. Upon receipt of the electromagnetic wave from the first patch conductor 4a, the second patch conductor 4b radiates an electromagnetic wave corresponding thereto to the outside. Alternatively, upon receipt of the electromagnetic wave from the outside, the second patch conductor 4b supplies an electromagnetic wave corresponding thereto to the first patch conductor 4a. The second patch conductor 4b has sides that are preferably approximately 0.05-0.5 mm larger than those of the first patch conductor 4a. 
The third patch conductor 4c is disposed on an upper surface of the uppermost fourth dielectric layer 1e so as to at least partially overlie a location above the second patch conductor 4b. The third patch conductor 4c is consequently subjected to electrostatic capacity coupling to the second patch conductor 4b with the fourth dielectric layer 1e interposed therebetween. The third patch conductor 4c is disposed with a deviation from the second patch conductor 4b in the extending direction of the strip conductor 3. The deviation of the third patch conductor 4c reaches such a degree that the third patch conductor 4c overlies an area of 80% or more of a location at which the second patch conductor 4b is disposed. Upon receipt of the electromagnetic wave from the second patch conductor 4b, the third patch conductor 4c radiates an electromagnetic wave corresponding thereto to the outside. Alternatively, upon receipt of the electromagnetic wave from the outside, the third patch conductor 4c supplies an electromagnetic wave corresponding thereto to the second patch conductor 4b. The third patch conductor 4c has sides that are preferably approximately 0.05-0.5 mm larger than those of the second patch conductor 4b. 
In particular, a wider frequency band of high frequency signals is ensured by disposing so that the second patch conductor 4b overlies the area of 80% or more of the location at which the first patch conductor 4a is disposed, and the third patch conductor 4c overlies the area of 80% or more of the location at which the second patch conductor 4b is disposed.
The auxiliary patch conductors 7 are disposed on an upper surface of the fourth dielectric layer 1e so as not to overlie the locations at which the first patch conductor 4a and the second patch conductor 4b are respectively disposed, on both sides in a direction orthogonal to the extending direction of the strip conductor 3 on the third patch conductor 4c. The auxiliary patch conductors 7 are electrically independent of one another. The auxiliary patch conductors 7 have a square shape that has sides parallel to the extending direction of the strip conductor 3 (hereinafter referred to as “longitudinal sides”) and sides parallel in the direction perpendicular to the extending direction of the strip conductor 3 (hereinafter referred to as “lateral sides”). The sides of the auxiliary patch conductors 7 respectively have a length of approximately 0.5-5 mm. The auxiliary patch conductors 7 respectively have a thickness of approximately 5-20 μm. The auxiliary patch conductors 7 are composed of, for example, copper. The auxiliary patch conductors 7 are respectively spaced approximately 0.1-1 mm from the longitudinal sides of the third patch conductor 4c. 
Thus, the center of the second patch conductor 4b is deviated from the center of the first patch conductor 4a in the extending direction of the strip conductor 3, and the center of the third patch conductor 4c is deviated from the center of the second patch conductor 4b in the extending direction of the strip conductor 3. Therefore, for example, when an electromagnetic wave corresponding to a high frequency signal is radiated through the patch conductors 4a to 4c, the electromagnetic wave is radiated so that the electromagnetic wave sequentially expands from the underlying patch conductor 4a and along peripheral edges of the overlying patch conductors 4b and 4c. Consequently, a composite resonance due to the deviations occurs and is then radiated. Further, a composite resonance occurs between the third patch conductor 4c and the auxiliary patch conductors 7 and through end portions of the auxiliary patch conductors 7, and the composite resonance is then radiated. This leads to a wide frequency band of high frequency signals to be radiated through the first to third patch conductors 4a to 4c and the auxiliary patch conductors 7.
The waveguide D is made up of the upper and lower ground conductor layers D1 disposed in a region closer to the extending direction of the strip conductor 3 than the patch conductor 4, and the ground through conductors D2. In the first embodiment, the upper and lower ground conductor layers D1 are made up of, for example, the ground conductor layer 2 disposed on the lower surface of the lowermost first dielectric layer 1a, and the ground conductor 2a disposed on the upper surface of the third dielectric layer 1d. The upper and lower ground conductor layers D1 respectively have a thickness of approximately 5-20 μm. The upper and lower ground conductor layers D1 are composed of, for example, copper.
In the first embodiment, the ground through conductors D2 are made up of a plurality of through conductors 5a to 5d that respectively coaxially extend through the dielectric layers 1a to 1d interposed between the upper and lower ground conductors D1. The through conductor 5a is connected to the ground conductor layer 2, and the through conductor 5d is connected to the ground conductor 2a. The ground through conductors D2 are serially disposed along the extending direction of the strip conductor 3 on each of both sides in the direction orthogonal to the extending direction of the strip conductor 3. The through conductors 5a, 5b, and 5d have a columnar shape or circular truncated cone shape with a diameter of approximately 30-100 μm. The through conductor 5c has a columnar shape with a diameter of approximately 50-200 μm. The ground through conductors D2 are composed of, for example, copper.
The ground through conductors D2 are preferably respectively disposed closer to the periphery than the right and left auxiliary patch conductors 7 on at least the patch conductor 4. This configuration contributes to further enhancing electromagnetic waves to be propagated from the patch conductor 4 and the auxiliary patch conductors 7 to the waveguide D.
Thus, with the antenna board according to the first embodiment, the waveguide D made up of the upper and lower ground conductor layers D1 and the ground through conductors D2 is disposed in the region closer to the extending direction of the strip conductor 3 than the patch conductor 4 and the auxiliary patch conductors 7. Therefore, part of electromagnetic waves corresponding to high frequency signals to be radiated from the third patch conductor 4 and the auxiliary patch conductors 7 is also to be radiated in the extending direction of the strip conductor 3 through the waveguide D. This makes it possible to transmit and receive the signals in the extending direction of the strip conductor 3 in addition to an upward direction with respect to the third patch conductor 4 and the auxiliary patch conductors 7. It is consequently possible to provide a wide-band antenna board that is rich in transmitting and receiving directions of signals in a wide frequency band of, for example 57-66 GHz.
An antenna board according to a second embodiment is described below. In the antenna board of the first embodiment, the upper and lower ground conductor layers D1 are respectively disposed on the first dielectric layer 1a and the third dielectric layer 1d. In the antenna board of the second embodiment, for example, the upper and lower ground conductor layers D1 are respectively disposed on the lower surface of the first dielectric layer 1a and the upper surface of the second dielectric layer 1c and the upper surface of the third dielectric layer 1d as shown in FIGS. 2A to 2C. That is, in the antenna board of the second embodiment, as shown in FIG. 2B, the ground conductor layer 2 is disposed on the lower surface of the first dielectric layer 1a, the ground conductor 2b is disposed on the upper surface of the second dielectric layer 1c, and the ground conductor 2a is disposed on the upper surface of the third dielectric layer 1d. 
Antenna boards respectively according to third and fourth embodiments are described below. In the antenna board of the first embodiment, the ground through conductors D2 are disposed serially (namely, in two rows) along the extending direction of the strip conductor 3 on both sides in the direction orthogonal to the extending direction of the strip conductor 3. In the antenna boards of the third and fourth embodiments, some of the ground through conductors D2 are disposed with a deviation from other ground through conductors D2 disposed serially along the extending direction of the strip conductor 3 as shown in FIGS. 3A and 4A.
In the antenna board of the third embodiment, a distance W1 between the rows of the ground through conductors D2 close to the periphery is smaller than a distance W2 between the rows of the ground through conductors D2 close to the patch conductor as shown in FIGS. 3A to 3C. In the antenna board of the fourth embodiment, a distance W3 between the rows of the ground through conductors D2 close to the periphery is larger than a distance W4 between the rows of the ground through conductors D2 close to the patch conductor as shown in FIGS. 4A to 4C.
The antenna board capable of efficiently transmitting and receiving signals according to the frequency of high frequency signals is providable by so disposing the waveguide D including the upper and lower ground conductor layers D1 and the ground through conductors D2.
An antenna board according to a fifth embodiment is described below. In the antenna board of the first embodiment, the first patch conductor 4a and the terminal portion 3a of the strip conductor 3 are connected to each other by a pair of the through conductors 5 and 6. In the antenna board of the fifth embodiment, the first patch conductor 4a and the terminal portion 3a of the strip conductor 3 may be connected to each other by two pairs of the through conductors 5 and 6 and through conductors 5′ and 6′, which are disposed adjacent to each other along the extending direction of the strip conductor 3 as shown in FIGS. 5A and 5B. It is possible to generate a composite resonance by adjacently disposing the two pairs of through conductors 5 and 6 and through conductors 5′ and 6′ so as to ensure a capacity therebetween. This makes it possible to further widen the frequency band of high frequency signals.
The distance between the through conductors 5 and 6 and the through conductors 5′ and 6′ is preferably not more than half the wavelength of high frequency signals to be transmitted to the strip conductor 3. It is possible to generate a further composite resonance and further widen the frequency band of high frequency signals by setting the distance to not more than the half.
As described above, the antenna boards disclosed in the present application respectively have the waveguide in the region closer to the extending direction of the strip conductor than the first and second patch conductors. The waveguide includes the upper and lower ground conductors disposed so as to hold therebetween at least one of the first, second, and third dielectric layers, and the ground through conductors disposed in the manner that at least one lies on each of both sides in the direction orthogonal to the extending direction of the strip conductor and extends through the dielectric layers lying between the upper and lower ground conductors. Hence, part of electromagnetic waves corresponding to high frequency signals to be radiated from the second patch conductor is to be radiated through the waveguide in the extending direction of the strip conductor. This makes it possible to transmit and receive the signals also in the extending direction of the strip conductor in addition to the upward direction with respect to the second patch conductor. It is consequently possible to provide the wide-band antenna board that is rich in transmitting and receiving directions of signals in the wide frequency band of, for example 57-66 GHz.
It is to be understood that the present invention is not limited to the foregoing embodiments, and that various changes may be made so far as they do not deviate from the gist of the present invention. For example, though the patch conductors and the auxiliary patch conductors have the square shape in the antenna boards according to the first to firth embodiments, these patch conductors may have a different shape, such as a circular shape, and a polygonal shape other than the square shape.

## Claims

1. An antenna board comprising:
a first dielectric layer;
a strip conductor that is disposed on an upper surface of the first dielectric layer, extends in one direction from a peripheral part of the first dielectric layer, and has a terminal portion;
a ground conductor layer disposed on a lower surface of the first dielectric layer;
a second dielectric layer laminated on the upper surface of the first dielectric layer and an upper surface of the strip conductor;
a first patch conductor disposed on an upper surface of the second dielectric layer so as to overlie a location of the terminal portion;
a third dielectric layer laminated on the second dielectric layer and the first patch conductor;
an electrically independent second patch conductor disposed on an upper surface of the third dielectric layer, the second patch conductor at least partially overlying a location at which the first patch conductor is disposed, a center of the second patch conductor being deviated from a center of the first patch conductor in an extending direction of the strip conductor;
a through conductor extending through the second dielectric layer and connecting the terminal portion and the first patch conductor; and
a waveguide comprising upper and lower ground conductors and a ground through conductor, the wave guide being disposed in a region closer to the extending direction of the strip conductor than the first and second patch conductors,
wherein the upper and lower ground conductors are disposed so as to hold therebetween at least one of the first, second, and third dielectric layers, and
wherein the ground through conductor is disposed in such a manner that at least one lies on each of both sides in a direction orthogonal to the extending direction of the strip conductor and extends through the dielectric layers lying between the upper and lower ground conductors.

2. The antenna board according to claim 1, wherein a plurality of the ground through conductors are disposed on each of both sides in the direction orthogonal to the extending direction of the strip conductor, and are disposed serially along the extending direction of the strip conductor.

3. The antenna board according to claim 1, wherein a plurality of the ground through conductors are disposed on each of both sides in the direction orthogonal to the extending direction of the strip conductor, and some of the ground through conductors are disposed with a deviation from other ground through conductors serially disposed along the extending direction of the strip conductor.

4. The antenna board according to claim 1, wherein the second patch conductor is disposed so as to overlie an area of 80% or more of the location at which the first patch conductor is disposed.

5. The antenna board according to claim 1, further comprising, on an upper surface of the third dielectric layer, auxiliary patch conductors respectively disposed on both sides of the second patch conductor in the direction orthogonal to the extending direction of the strip conductor so as not to overlie a location at which the first and second patch conductor is disposed, the auxiliary patch conductors being electrically independent from the first and second patch conductors.

6. The antenna board according to claim 1, wherein the terminal portion and the first patch conductor are connected to each other by a plurality of the through conductors disposed adjacent to each other along the extending direction of the strip conductor.

7. The antenna board according to claim 6, wherein a distance between the through conductors is not more than half a wavelength of a high frequency signal to be transmitted to the strip conductor.

8. The antenna board according to claim 1, further comprising:
a fourth dielectric layer laminated on the third dielectric layer and the second patch conductor; and
a third patch conductor disposed on an upper surface of the fourth dielectric layer so as to at least partially overlie the location at which the second patch conductor is disposed, the third patch conductor being electrically independent from the second patch conductor,
wherein a center of the third patch conductor is deviated from a center of the second patch conductor in the extending direction of the strip conductor.

9. The antenna board according to claim 8, wherein the third patch conductor is disposed so as to overlie an area of 80% or more of the location at which the second patch conductor is disposed.

10. The antenna board according to claim 8, further comprising, on the upper surface of the fourth dielectric layer, auxiliary patch conductors respectively disposed on both sides of the third patch conductor in the direction orthogonal to the extending direction of the strip conductor so as not to overlie a location at which the third patch conductor is disposed, the auxiliary patch conductors being electrically independent from the first, second, and third patch conductors.