JP4871201B2 - Dielectric Leaky Wave Antenna - Google Patents

Description

  The present invention relates to a technique for optimizing the characteristics of an excitation part and a leakage part in a dielectric leakage wave antenna.

  For example, an antenna used in the quasi-millimeter wave band of 24.05 to 24.2 GHz allocated for Doppler radar and having a simple configuration and high efficiency includes a dielectric leakage wave antenna.

FIG. 11 shows a structural example of the dielectric leakage wave antenna 10. The dielectric leaky wave antenna 10 transmits electromagnetic waves in a direction orthogonal to the thickness direction of the dielectric substrate 11 by the dielectric substrate 11 and the ground plane conductor 12 provided on one surface (the lower surface in the drawing). In addition to forming a dielectric image line, a plurality of leakage metal strips 13 are provided at predetermined intervals on the opposite surface (upper surface in the figure) side of the dielectric substrate 11, and the fed electromagnetic waves cross the plurality of leakage metal strips 13. The electromagnetic wave in the dielectric substrate 11 is leaked from the surface of the dielectric substrate 11 by propagating in the direction in which it is transmitted.

  The radiation characteristics of the electromagnetic wave leaked from the surface of the dielectric substrate 11 are the width and interval of the leakage metal strip 13, the wavefront (equal phase surface) of the electromagnetic wave propagating in the dielectric substrate 11, and the leakage metal strip 13. Various settings are possible depending on the angle.

  For example, if the wavefront of the electromagnetic wave propagating in the dielectric substrate 11 is made parallel to the leakage metal strip 13, the beam direction of the electromagnetic wave leaking from the surface of the dielectric substrate 11 is orthogonal to the surface of the dielectric substrate 11 and It can be set in a plane perpendicular to the length direction of the leakage metal strip 13. Further, the beam direction in this plane is mainly determined by the interval between the leaking metal strips 13 and is, for example, substantially equal to the wavelength λg in the dielectric image line of the electromagnetic wave trying to radiate the interval between the leaking metal strips 13. By doing so, the beam direction can be set in a direction substantially orthogonal to the surface of the dielectric substrate 11, and the direction of the dielectric substrate 11 and the beam direction can be made substantially coincident.

  In a dielectric leaky wave antenna that radiates electromagnetic waves based on such a principle, an excitation unit 14 for propagating electromagnetic waves having a wavefront substantially parallel to the leakage metal strip 13 is required in the dielectric substrate 11.

As this excitation unit 14, it is possible to configure the excitation unit 14 with a simple configuration and high productivity at a low cost. In Patent Document 1, as shown in FIG. 11 , the dielectric substrate 11 is sandwiched between the ground plane conductor 12 and the dielectric substrate 11. A metal strip 15 for forming a microstrip line, and, for example, stubs 16 and 17 are provided at a predetermined interval with respect to the metal strip 15 for this line, and electromagnetic waves propagating through the microstrip line intersect with the leakage metal strip 13. Applicants have proposed a configuration that branches in a direction.

JP 2004-328291 A

  However, since the microstrip line is an open type line as described above, there is a problem that the leakage radiation of the electromagnetic wave for excitation itself is relatively large, the directivity is deteriorated such as a side lobe rise, and the efficiency is lowered. It was.

  Further, the applicant of the present application has also proposed a dielectric leaky wave antenna using a parallel plate line having a higher blocking property than a microstrip line as an excitation line (Patent Document 2). However, the problem of directivity degradation due to leakage radiation from the excitation line remains to some extent.

Japanese Patent No. 3822818

  When the metal strip for leakage and the line for excitation are formed on a common dielectric substrate as in these documents, the optimum substrate thickness for the excitation part differs from the optimum substrate thickness for the leakage part. In many cases, the optimum design for both is not possible, and it is difficult to increase the efficiency of the entire antenna.

  The present invention solves the above problems, suppresses the leakage radiation from the excitation line, and realizes the desired directivity by adopting a configuration in which the excitation line and the leakage portion can be optimized independently. The object is to realize a dielectric leakage wave antenna with high antenna efficiency. Furthermore, since the entire antenna can be manufactured only by a printing technique by adopting a two-layer dielectric structure, it is also an object to provide a low-cost dielectric leaky wave antenna excellent in mass productivity.

In order to achieve the above object, a dielectric leaky wave antenna according to claim 1 of the present invention comprises:
A dielectric substrate (21);
A ground plane conductor (22) provided to overlap one surface side of the dielectric substrate and forming a dielectric image line for propagating electromagnetic waves in a direction perpendicular to the thickness direction in the dielectric substrate;
A plurality of metal strips for leakage (23, 23 ') provided in parallel at a predetermined interval on a surface parallel to the one surface of the dielectric substrate;
A flat plate portion (40) provided on the opposite surface side of the dielectric substrate and extending in a direction parallel to the leakage metal strip to form a parallel plate line with the ground plane conductor; An excitation unit (24) for propagating a fed electromagnetic wave in a direction intersecting the plurality of leakage metal strips;
A dielectric leakage wave antenna comprising a power feeding part (50) for feeding electromagnetic waves to a parallel plate line of the excitation part,
The dielectric substrate has a first dielectric layer (21a) having a predetermined thickness overlapping one surface side of the ground plane conductor, and a dielectric constant smaller than the dielectric constant of the first dielectric layer and larger than the dielectric constant of air. And a second dielectric layer (21b) having a predetermined thickness and overlapping the first dielectric layer has a two-layer structure,
The plurality of leakage metal strips are formed between the first dielectric layer and the second dielectric layer;
The flat plate portion of the excitation unit is formed on the surface side of the second dielectric layer ,
Furthermore, the thickness of the first dielectric layer is t1, the dielectric constant is ε1, the thickness of the second dielectric layer is t2, the dielectric constant is ε2, and the free space wavelength of the electromagnetic wave supplied to the excitation unit Is λ ₀ ,
^{(Ε1 · t1) 1/2 + (} ε2 · t2) 1/2 ≦ λ 0/2
It is characterized by satisfying the above conditions .

The dielectric leaky wave antenna according to claim 2 of the present invention, the dielectric leaky wave antenna according to claim 1 Symbol placement,
The power feeding unit is
A plurality of slots (51) formed at predetermined intervals on the ground plane conductor so as to be aligned in a direction parallel to the plurality of leakage metal strips provided on the dielectric substrate at positions facing the flat plate portion; ,
A feeding dielectric substrate (53) provided so that one surface side overlaps the opposite surface side of the ground plane conductor in a state of covering a portion where the plurality of slots of the ground plane conductor are provided;
A microstrip line (55) that is formed on the opposite surface of the dielectric substrate for power supply, is coupled to the parallel plate line via the plurality of slots, and feeds electromagnetic waves to the parallel plate line. It is characterized by.

The dielectric leaky wave antenna according to claim 3 of the present invention, the dielectric leaky wave antenna according to claim 1 Symbol placement,
The power feeding unit is
A plurality of holes (22a) formed at predetermined intervals in the ground plane conductor so as to be aligned in a direction parallel to the plurality of metal strips for leakage at a position facing the flat plate portion;
A feeding dielectric substrate (53) formed so as to overlap the ground plane conductor on one side in a state of covering the hole of the ground plane conductor;
A plurality of metal pins (70) that penetrate the dielectric substrate for power supply, pass through each hole of the ground plane conductor in a non-contact manner, and enter the first dielectric layer;
A microstrip line (55) formed on the opposite surface of the power supply dielectric substrate, coupled to the parallel plate line via the plurality of metal pins, and supplying electromagnetic waves to the parallel plate line. It is characterized by that.

Moreover, the dielectric leaky wave antenna according to claim 4 of the present invention is the dielectric leaky wave antenna according to any one of claims 1 to 3 .
In the excitation unit,
Among the electromagnetic waves supplied to the parallel plate line, a reflection wall (42) is provided for reflecting the electromagnetic waves propagating to the side opposite to the leakage metal strip side to the leakage metal strip side. Features.

The dielectric leakage wave antenna according to claim 5 of the present invention is the dielectric leakage wave antenna according to any one of claims 1 to 3 .
The excitation part is provided at a substantially central part of the dielectric substrate, and a plurality of the metal strips for leakage are provided on both sides of the excitation part.

  As described above, the dielectric leaky wave antenna of the present invention has a parallel plate line type excitation unit and a dielectric substrate having a two-layer structure of the first dielectric layer and the second dielectric layer. The characteristics of the excitation part made of a flat line and the characteristics of the leakage part can be made the best, respectively, and the microstrip line for feeding can be arranged on the lower surface side of the ground plane conductor, so It is possible to realize a highly efficient antenna while preventing directivity deterioration due to leakage radiation.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 show the configuration of a dielectric leakage wave antenna 20 to which the present invention is applied.

  This dielectric leaky wave antenna 20 is an antenna that covers 24.05 to 24.2 GHz used for Doppler radar or the like in the quasi-millimeter wave band, and includes a dielectric substrate 21 and one surface side of the dielectric substrate 21. A dielectric image line that propagates electromagnetic waves in a direction perpendicular to the thickness direction (z direction in FIG. 1) in the dielectric substrate 21 is formed by the ground plane conductor 22 provided so as to overlap the (lower surface side) without any gap. Has been.

Here, the dielectric substrate 21 includes a first dielectric layer 21a having a thickness t1 and a dielectric constant ε1 (for example, ε1 = 6) overlapping the ground plane conductor 22, and a dielectric constant ε1 of the first dielectric layer 21a. The second dielectric layer 21b having a smaller dielectric constant ε2 (for example, ε2 = 2.2) and having a thickness t2 overlapping the first dielectric layer 21a forms a two-layer structure .

  The leakage metal strip 23 extending in the direction orthogonal to the thickness direction of the dielectric substrate 21 (the x direction in FIG. 1) is between the first dielectric layer 21a and the second dielectric layer 21b of the dielectric substrate 21. That is, it is provided in parallel on the upper surface side of the first dielectric layer 21a or the lower surface side of the second dielectric layer 21b at a predetermined interval, for example, an interval approximately equal to the in-line wavelength λg of the electromagnetic wave propagating in the dielectric image line. ing.

  The ground plane conductor 22 and the leakage metal strip 23 are formed by printing or etching a metal film on one dielectric layer of the dielectric substrate 21.

  Each leakage metal strip 23 is parallel to each other and is separated by approximately 1/4 of the in-line wavelength λg in order to suppress reflection components for electromagnetic waves propagating in a direction orthogonal to the metal strip 23 in the dielectric image line. It is constituted by metal strips 23a and 23b.

  That is, when the leakage metal strip 23 is composed only of the metal strips 23a having a distance substantially equal to the in-line wavelength λg, the reflected waves generated by the metal strips 23a are in phase with each other, and the efficiency is lowered. By providing the metal strips 23b having the same dimensions as the metal strips 23a at positions separated from the strips 23a by about ¼ of the in-line wavelength λg, the reflected waves of the two become opposite to each other and cancel the reflection components. can do.

  Here, as described above, the dielectric substrate 21 has a two-layer structure and the leakage metal strip 23 is between the two dielectric layers 21a and 21b, but the dielectric constant ε1 of the lower first dielectric layer 21a is the upper layer. Since the dielectric constant ε2 of the second dielectric layer 21b is larger than that of the second dielectric layer 21b, an electromagnetic wave is propagated mainly in the first dielectric layer 21a as an image line, and the in-line wavelength λg is also this This value greatly depends on the dielectric constant ε1 of the one dielectric layer 21a.

  In addition, since it has the effect | action which leaks electromagnetic waves with these metal strips 23a and 23b, when the metal strip 23 for a leak is comprised with two metal strips 23a and 23b as mentioned above, from the surface of the dielectric substrate 21 The radiation characteristics of the leaked electromagnetic wave are a combination of the radiation characteristics of the electromagnetic waves leaked by the two metal strips 23a and 23b.

  Moreover, in this embodiment and all the embodiments described below, the leakage metal strip 23 is constituted by two metal strips 23a and 23b, but this does not limit the present invention, and the metal strip is used. When the reflection component is so small that it can be ignored, the leakage metal strip 23 may be composed of one metal strip. In addition, it is possible to suppress the reflected wave by setting the interval between the leakage metal strips 23 to be shorter or longer than the in-line wavelength λg. In this case, the leakage metal strip 23 can also be constituted by one metal strip. it can.

  On the other hand, an excitation portion 24 is formed on one end side of the dielectric substrate 21 at a position away from the leakage metal strip 23.

  The excitation unit 24 extends in a strip shape in parallel with the leakage metal strip 23, and forms a parallel plate line 40 for propagating electromagnetic waves to and from the ground plate conductor 22 in the direction of the leakage metal strip 23. Among the electromagnetic waves that are formed so as to short-circuit between the end portion of 22 and the side edge of the flat plate portion 40 and are fed between the ground plane conductor 22 and the flat plate portion 40 through a slot 51 described later, the leakage metal strip 23. The reflection wall 42 reflects the electromagnetic wave propagating in the opposite direction to the leakage metal strip 23 direction.

  Here, the reflection wall 42 is a metal film deposited on the end face of the dielectric substrate 21. As shown in FIG. 3, a metal post 42a formed so as to penetrate the dielectric substrate 21 by through-hole processing is provided in the line. They may be formed side by side with a sufficiently narrow interval compared to the wavelength.

  Feeding of electromagnetic waves to the parallel plate line formed between the ground plane conductor 22 and the flat plate portion 40 is performed by a slot coupling type power feeding portion 50.

  That is, a plurality of slots 51, 51,... Are formed in parallel to the leakage metal strip 23 at predetermined intervals in the ground plane conductor 22 at a position facing the flat plate portion 40.

  Each slot 51 is covered with a feeding dielectric substrate 53 provided on the lower surface side of the ground plane conductor 22, and a microstrip line is formed between the lower surface side of the feeding dielectric substrate 53 and the ground plane conductor 22. A metal strip 55 to be formed is provided.

  As shown in FIG. 4, the metal strip 55 has a T-branch structure that is divided in two directions from the tip of the center portion 55a. Both the branch portions 55b and 55c pass through the vicinity of the positions facing the slots 51. The stub 56 which crosses each slot 51 is formed in the side edge of the branch parts 55b and 55c.

  The center portion 55a of the metal strip 55 is connected to a high-frequency circuit (not shown) (when the antenna and the circuit are integrated) or a coaxial connector (not shown) (when the antenna and the circuit are not integrated).

  Therefore, the electromagnetic wave E supplied to the center portion 55a and branched to the branch portions 55b and 55c is further branched by a predetermined amount at each stub 56, and is fed between the flat plate portion 40 and the ground plane conductor 22 via each slot 51. Will be.

  Here, the interval Q between the slot 51 and the stub 56 is formed by the metal strip 55 and the ground plane conductor 22 so that the electromagnetic waves fed from the flat plate portion 40 and the ground plane conductor 22 through the slot 51 are in phase. It is set to an integral multiple of the in-line wavelength λg ′ of the electromagnetic wave propagating through the microstrip line.

  Further, between the stubs 56, a notch portion 57 that is notched narrowly is formed so as to suppress the component reflected by the stub 56 toward the center portion 55a. As shown in FIG. 5B, the notch 57 generates a reflection component Er ′ having a phase opposite to that of the reflection component Er generated in the stub 56 so that the reflection components can be offset from each other by approximately λg. It is provided at a distance of '/ 4.

  The width and length of the slot 51 constituting the power feeding unit 50 described above, the width and length of the stub 56 of the metal strip 55, the distance between them, the crossing position, and the like are efficiently electromagnetic waves with respect to the parallel plate line of the excitation unit 24. Is set so that a desired radiation pattern can be obtained.

  That is, when the size of the slot 51 is constant, the amplitude of the electromagnetic wave output from the stub 56 to the excitation unit 24 via the slot 51 depends on the width and length of the stub 56 and depends on the width and length of the stub 56. The amplitude characteristics of the entire excitation wave can be set arbitrarily. Further, since the phase of the excitation wave output from each stub 56 depends on the stub interval Q, the phase characteristics of the entire excitation wave can be arbitrarily set by the stub interval Q.

  For example, if the stub interval Q is set equal to the in-line wavelength λg ′ (or an integral multiple thereof) (Q = λg ′), the phases of the electromagnetic waves supplied from the stubs 56 through the slots 51 become equal, and excitation is performed. The phase plane of the entire wave is parallel to the leakage metal strip 23, and an electromagnetic wave located on the plane where the center direction of the antenna beam is orthogonal to the surface of the dielectric substrate 21 and orthogonal to the leakage metal strip 23 is emitted. Can do.

  In the dielectric leakage wave antenna 20 configured as described above, the dielectric substrate 21 has a first dielectric layer 21a overlapping the ground plane conductor 22 and a dielectric constant ε1 of the first dielectric layer 21a. A two-layer structure having a dielectric constant ε2 and a second dielectric layer 21b overlapping the first dielectric layer 21a, and a flat plate constituting a parallel plate line of the excitation unit 24 with the ground plane conductor 22 Since the portion 40 is provided on the surface of the second dielectric layer 21b and the leakage metal strip 23 is provided between the first dielectric layer 21a and the second dielectric layer 21b, the excitation line and the leakage The transmission line can be optimally designed without sacrificing any transmission characteristics.

  The characteristics of the excitation unit 24 and the power supply unit 50 are the parameters shown in FIGS. 5A and 5B, that is, the thicknesses t1 and t2 of the dielectric layers 21a and 21b, the dielectric constants ε1 and ε2, and the slots. The distance a from the center to the reflecting wall 42, the distance b from the slot center to the tip of the flat plate portion 40, the slot length Ls, the slot width Ws, the stub width Wst, the distance Lst from the slot center to the stub tip, and the stub to the slot side It depends on the load impedance Z as seen.

When the power feeding unit 50 is coupled to the excitation unit 24 via the slot 51 as in the above embodiment, the condition for efficiently propagating electromagnetic waves from the excitation unit 24 to the leakage metal strip 23 side is as follows. The distance a to the reflecting wall 42 and the distance b to the tip of the flat plate portion 40 are set to the wavelength λg ′ of the electromagnetic wave in the parallel plate line.
a = λg ′ / 2, b ≧ λg ′
It has been confirmed that it is necessary to establish the relationship.

Further, as described later, when connecting via the metal pin 70 instead of the slot connection,
a = λg ′ / 4, b ≧ λg ′
It has been confirmed that it is necessary to establish the relationship.

In FIG. 6, a material having a dielectric constant ε1 = 6 and a thickness t1 = 1 mm is used as the first dielectric layer 21a, and a dielectric constant ε2 = 2.2 and a thickness t1 = 2. A material with a dielectric constant of ε1 = 6 and a thickness of t3 = 0.5 mm is used as the dielectric substrate 53 for feeding, using a material of 0 mm, a frequency of 24.15 GHz, an in-line wavelength of the excitation unit 24 of 7.02 mm, and feeding. The in-line wavelength of the section 50 is 6.11 mm, the stub width Wst is 0.3 mm, the load impedance Z is 76.5 ohms when the slot 51 is viewed from the stub 56, the slot length Ls is 2.96 mm, the slot width Ws is 0.97 mm, The distance b from the slot center line C to the tip of the flat plate 40 when the distance a = 3.51 mm from the reflection wall surface to the slot center line C and the length Lst = 2.3 mm from the slot center line C to the stub tip Feeding characteristics _{S 21} against (loss) _illustrates a change in the _{S 11} (reflection).

  As is apparent from this figure, under the above conditions, by setting the distance b from the slot center line C to the leading edge of the flat plate portion 40 to be approximately 3.5 mm (approximately ½ of the in-line wavelength), loss and The best state with minimal reflection can be set.

  As a result of various simulations with the above parameters changed, it was found that the following conditions were necessary.

ε1> ε2 (1)
^{(Ε1 · t1) 1/2 + (} ε2 · t2) 1/2 ≦ λ 0/2 ...... (2)
λ ₀ is free space wavelength

In the conditional expression (1), the better the larger the difference ε1 between .epsilon.2, in the conditional expression (2), but the left side is greater than lambda _0/2 higher-order mode occurs, the left side is lambda ₀ / so too small for 2 the stray radiation from the tip of the flat plate portion 40 is increased, it can be closer to lambda _0/2 to obtain good results.

  By using a two-layer dielectric structure in this way, the entire antenna can be manufactured only by printing technology. As a result, it is possible to manufacture a dielectric leaky wave antenna with high productivity and low cost.

  Although the example in which the excitation unit 24 supplies electromagnetic waves with a phase plane parallel to the leakage metal strip 23 has been described here, the excitation unit 24 supplies electromagnetic waves with a phase plane having an inclination with respect to the leakage metal strip 23. You may make it do.

Also, the feeding portion 50 of the dielectric leaky wave antenna 2 0 described above, although there was a so-called center feeding method using a T-branched microstrip line, as in Figure 7, one of the straight-type microstrip line Alternatively, an edge feeding method may be employed in which electromagnetic waves are fed from the edges. In the case of the center feeding method, if the length of the microstrip line is the same as that for the edge feeding, the loss (conductor loss and dielectric loss) generated in the line is almost halved, and the efficiency is increased.

Further, like the dielectric leakage wave antenna 60 shown in FIG. 8 , the excitation unit 24 and the power feeding unit 50 are provided in the center of the dielectric substrate 21, and the first dielectric layer 21a and the second dielectric layer 21b on both sides thereof are provided. It is also possible to arrange the leaking metal strips 23, 23 'in parallel between (which may be air layers).

  In this case, the reflection wall 42 of the excitation unit 24 is omitted, and the electromagnetic wave fed through the slot 51 is propagated to the left and right sides.

  When the distance d from the slot center C to the right leakage metal strip 23 is equal to the distance d 'from the slot center C to the left leakage metal strip 23', the electric field at the left and right leakage portions is equal. The y-direction component is in the opposite direction, and the beam does not radiate to the front. Therefore, in order to radiate the beam to the front, it is necessary to give a difference of half of the guide wavelength of the dielectric image line to the distances d and d 'between the two.

  Further, in each of the dielectric leakage wave antennas described above, the leakage metal strips 23, 23 'and the excitation unit 24 are formed so as to be substantially parallel to one side of the rectangular dielectric substrate 21, The present invention is not limited, and the orientation of the leakage metal strips 23, 23 ′ and the excitation unit 24 with respect to the outer shape of the dielectric substrate 21 can be arbitrarily set.

For example, like the dielectric leakage wave antenna 60 'shown in FIG. 9 , the excitation unit 24 and the power feeding unit 50 are provided along the diagonal line of the square dielectric substrate 21, and the metal strips 23, 23' for leakage are provided on both sides thereof. You may provide in parallel. In this case, if the electromagnetic wave of the phase plane parallel to the leakage metal strips 23 and 23 'on both sides is propagated from the excitation unit 24, the electromagnetic waves of the polarization orthogonal to the length direction from the leakage metal strips 23 and 23'. Can be leaked. The polarization direction of the electromagnetic wave is 45 degrees polarized with an inclination of 45 degrees with respect to one side of the rectangular dielectric substrate 21, which is suitable for an on-vehicle radar or the like.

In the embodiment, the electromagnetic wave is supplied to the excitation unit 24 by slot coupling. However, as shown in FIG. 10 , one end side is connected to the metal strip 55 (or stub 56), penetrates the dielectric substrate 53, Electromagnetic waves may be fed to the parallel plate line using the metal pin 70 that passes through the hole 22a of the ground plane conductor 22 in a non-contact manner and enters the first dielectric layer 21a of the dielectric substrate 21.

A perspective view of an embodiment of the present invention Exploded perspective view of the embodiment The figure which shows another structural example of a reflecting wall The figure which shows the structural example of an electric power feeding part Diagram showing parameters that determine antenna characteristics Change characteristics of loss and reflection with respect to the distance from the center of the slot to the tip of the flat plate Diagram showing an example of edge feeding The figure which shows the example which provided the excitation part in the center part of the dielectric substrate The figure which shows the example which changed the angle of the metal strip for leakage with respect to the edge of a dielectric substrate, and an excitation part The figure which shows the example which supplies electric power through a metal pin Configuration diagram of conventional dielectric leaky wave antenna

Explanation of symbols

20 , 60 , 60 '.... Dielectric leaky wave antenna, 21 ... Dielectric substrate, 21a ... First dielectric layer, 21b ... Second dielectric layer, 22 ... Ground plane conductor, 22a ... Hole , 23, 23 ′ …… leakage metal strip, 24 …… excitation part, 40 …… flat plate part, 42 …… reflection wall, 50 …… feeding part, 51 …… slot, 53 …… dielectric substrate for feeding, 55 …… Metal strip, 56 …… Stub, 57 …… Notch, 70 …… Metal pin

Claims (5)

A dielectric substrate (21);
A ground plane conductor (22) provided to overlap one surface side of the dielectric substrate and forming a dielectric image line for propagating electromagnetic waves in a direction perpendicular to the thickness direction in the dielectric substrate;
A plurality of metal strips for leakage (23, 23 ') provided in parallel at a predetermined interval on a surface parallel to the one surface of the dielectric substrate;
A flat plate portion (40) provided on the opposite surface side of the dielectric substrate and extending in a direction parallel to the leakage metal strip to form a parallel plate line with the ground plane conductor; An excitation unit (24) for propagating a fed electromagnetic wave in a direction intersecting the plurality of leakage metal strips;
A dielectric leakage wave antenna comprising a power feeding part (50) for feeding electromagnetic waves to a parallel plate line of the excitation part,
The dielectric substrate has a first dielectric layer (21a) having a predetermined thickness overlapping one surface side of the ground plane conductor, and a dielectric constant smaller than the dielectric constant of the first dielectric layer and larger than the dielectric constant of air. And a second dielectric layer (21b) having a predetermined thickness and overlapping the first dielectric layer has a two-layer structure,
The plurality of leakage metal strips are formed between the first dielectric layer and the second dielectric layer;
The flat plate portion of the excitation unit is formed on the surface side of the second dielectric layer ,
Furthermore, the thickness of the first dielectric layer is t1, the dielectric constant is ε1, the thickness of the second dielectric layer is t2, the dielectric constant is ε2, and the free space wavelength of the electromagnetic wave supplied to the excitation unit Is λ ₀ ,
^{(Ε1 · t1) 1/2 + (} ε2 · t2) 1/2 ≦ λ 0/2
A dielectric leaky wave antenna characterized by satisfying the above conditions . The power feeding unit is
A plurality of slots (51) formed at predetermined intervals on the ground plane conductor so as to be aligned in a direction parallel to the plurality of leakage metal strips provided on the dielectric substrate at positions facing the flat plate portion; ,
A feeding dielectric substrate (53) provided so that one surface side overlaps the opposite surface side of the ground plane conductor in a state of covering a portion where the plurality of slots of the ground plane conductor are provided;
A microstrip line (55) that is formed on the opposite surface of the dielectric substrate for power supply, is coupled to the parallel plate line via the plurality of slots, and feeds electromagnetic waves to the parallel plate line. The dielectric leakage wave antenna according to claim 1. The power feeding unit is
A plurality of holes (22a) formed at predetermined intervals in the ground plane conductor so as to be aligned in a direction parallel to the plurality of metal strips for leakage at a position facing the flat plate portion;
A feeding dielectric substrate (53) formed so as to overlap the ground plane conductor on one side in a state of covering the hole of the ground plane conductor;
A plurality of metal pins (70) that penetrate the dielectric substrate for power supply, pass through each hole of the ground plane conductor in a non-contact manner, and enter the first dielectric layer;
A microstrip line (55) formed on the opposite surface of the power supply dielectric substrate, coupled to the parallel plate line via the plurality of metal pins, and supplying electromagnetic waves to the parallel plate line. claim 1 Symbol placement of dielectric leaky-wave antenna, characterized in that. In the excitation unit,
Among the electromagnetic waves supplied to the parallel plate line, a reflection wall (42) is provided for reflecting the electromagnetic waves propagating to the side opposite to the leakage metal strip side to the leakage metal strip side. The dielectric leaky wave antenna according to any one of claims 1 to 3 . Substantially provided at the center, according to any one of claims 1 to 3, characterized in that on both sides of該励exciting units plurality of the seepage metal strips are provided in the excitation portion is the dielectric substrate Dielectric leaky wave antenna.

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