JPS6329441B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a waveguide mechanism that controls the radiation pattern of an electromagnetic field radiated from an electromagnetic wave radiating element, and particularly relates to a waveguide mechanism using a dielectric plate. .

[Prior Art] US Pat. No. 3,234,558 is a conventional technique aiming at an effect similar to this type of waveguide mechanism. This patent relates to a slot array antenna system. In this antenna device, as shown in FIG. 7, a waveguide mechanism formed by bending a dielectric plate 4 into a U-shape is provided in front of a slot waveguide S.

[Problems to be solved by the invention] However, this conventional antenna device has some aspects in which its operating principle is not clearly understood.
In principle, its structure is flawed, and it is hardly ever put to practical use as a radar antenna. This defect appears as deterioration of the waveguide characteristics, especially when the length of the dielectric plate 4 becomes as short as about one wavelength, and this is also observed in actual measurements.

The deterioration of the waveguiding characteristics is caused by a considerable increase in the proportion of electromagnetic wave energy from the antenna wave source that does not enter the parallel portion of the dielectric plate 4 but instead goes toward the U-shaped curved surface of the dielectric plate 4, and this electromagnetic wave energy U of body plate 4
It is presumed that this is because the light is unnecessarily refracted by the curved surface portion of the letter shape, thereby preventing the action of forming a single lobe in the forward direction, that is, in the direction along the parallel portion of the dielectric plate.

The above US patent is flawed in this very point.
Although the U-shaped curved surface is intended to prevent the reflected waves from returning to the wave source in phase, this aim conflicts with the formation of a single forward lobe as described above. It lacks practicality.

The present invention has been made in order to solve the above problems, and is attached to an electromagnetic wave radiating element that radiates electromagnetic energy over a wide space, and concentrates the electromagnetic energy in a space in between in a direction parallel to the dielectric plate. It is an object of the present invention to provide a waveguide mechanism that can form a single lobe in the waveguide and can be constructed using an inexpensive dielectric plate.

[Means for Solving the Problems] The first invention of the present application, as a means for solving the above problems, comprises: arranging a pair of dielectric plates in parallel with a space in front of the radiating element in between; , the plate thickness is set so that the phase difference is such that the electromagnetic waves reflected on the surface of the dielectric plate and directed between the plates and the electromagnetic waves transmitted through the plate and reflected at the opposite interface and directed between the plates cancel each other out. We propose a waveguide mechanism characterized by the following.

In addition, the second invention of the present application, as a solution to the above-mentioned problem, arranges dielectric plates in parallel to form a pair across the space in front of the radiating element, and arranges two pairs of these plates so as to be perpendicular to each other. to form a square tube,
A radiating element is disposed at one end of the interior of the square cylinder, and the dielectric plate is configured to transmit electromagnetic waves reflected from the surface of the dielectric plate and directed between the plates and transmitted through the plate to an interface on the opposite side. We propose a waveguide mechanism characterized in that the plate thickness is set to such a phase difference that the reflected electromagnetic waves traveling between the plates cancel each other out.

Furthermore, the third invention of the present application, as a means for solving the above problem, includes: forming a rectangular parallelepiped-shaped casing with a dielectric plate, arranging a radiating element at one end in the longitudinal direction inside the casing; The body plate has a phase difference in which electromagnetic waves reflected on the surface of the dielectric plate and directed between the plates and electromagnetic waves transmitted through the plate and reflected at the opposite interface and directed between the plates cancel each other out. We propose a waveguide mechanism characterized by a thick waveguide.

In the first, second and third aspects of the invention, preferably, the thickness of the dielectric plate is approximately 1/20 or less of the wavelength of the electromagnetic wave emitted from the radiating element. Also,
It is more preferable to fill and solidify the space between the dielectric plates with a foam material whose dielectric constant is close to that of air.

[Function] Since the inventions of the present application are basically based on the same function, the functions of these inventions are as follows.
The operation of the first invention of the present application will be mainly explained. In the description, reference will be made to FIGS. 2 to 5, FIG. 12, and FIG. 13.

In FIG. 12, a pair of dielectric plates 2 and 3 constituting the waveguide mechanism each have a thickness h and are arranged in parallel with a distance d between them. Assuming that the electromagnetic wave incident between these two thin dielectric plates 2 and 3 is a spherical wave, it is replaced by a point wave source I placed at the phase center. In this case, the point wave source I is assumed to be located at the center of the interval d. It is also assumed that this point wave source I radiates an electric field E in a direction perpendicular to the plane of the paper and a magnetic field H in a direction perpendicular to the dielectric plates 2 and 3, as shown in FIG.

Now, as shown in FIG. 12, the radiation wave 11 emitted from the wave source I is incident on a point A on the surface of the dielectric plate 2 having a dielectric constant ε ₁ . The radiation wave 11 is divided into a reflected wave 11'' that is reflected at point A and a refracted wave that passes through the inside of the dielectric plate 2 and heads toward point B. Here, at point A, the incident angle of the radiation wave 11 is θ. ₁ , the refraction angle of the refracted wave is θ ₂ .

The refracted wave that has reached point B is divided into a refracted wave 11' that is refracted again and goes toward space, and a reflected wave that is reflected at point B and goes toward point C. In the same manner as described above, the reflected wave is refracted at point C and divided into a refracted wave 11 heading toward space and a reflected wave heading toward point D.

Furthermore, at point D, this reflected wave is refracted and split into a refracted wave 11'''' which heads toward space and a reflected wave. However, the amplitude of the refracted wave 11''''' is already smaller than that of the refracted wave 11', and it can almost be ignored.

By the way, regarding the relationship between θ ₁ and θ ₂ mentioned above,
This will be explained with reference to FIG.

As is well known, the angle of incidence θ ₁ and the angle of refraction θ ₂
The relationship with is determined by Snell's law sinθ ₁ /sinθ ₂ =√ ₁ .

Therefore, the refraction angle θ ₂ is is given by Therefore, if the incident angle θ ₁ is 75°≦θ ₁ ≦85° and ε ₁ =5, then the refraction angle θ ₂ is 25.6°≦θ ₂ ≦26.5°.

This means that even if the angle of incidence θ ₁ on the dielectric plate 2 changes significantly near 90°, the angle of refraction θ ₂ hardly changes. When the distance d between the plates is significantly smaller than the length of the dielectric plates 2, it can be said that this relationship holds for most of the inner surfaces of the dielectric plates 2 in the longitudinal direction.

Incidentally, in the previous example, in FIG. 12, the incident angle θ ₁
Point A, which is at a position of 75 degrees, is approximately 1.9 d from the foot of the perpendicular line drawn from the position of wave source I to dielectric plate 2, and point A is very close to wave source I. It can be said that.

In FIG. 12, if the incident angle θ ₁ is an angle that satisfies the above relationship, and if E is the intersection of the normal line drawn to point B and the surface on the interplate side of dielectric plate 2, then ∠ABE=∠ CBE=θ ₂ , = .

Next, when the radiation source 12 emitted from the wave source I enters the point C, the reflected wave 1 is reflected at the point C and goes toward the space between the plates.
2'' and a refracted wave that is refracted at point C and directed toward point D.

The phase difference between the refracted wave 11 at point C of the radiated wave 11 and the reflected wave 12'' at point C of the radiated wave 12 is:
Propagation path of radiation wave 11 to point C++
and the propagation path of the radiation wave 12 to point C, and the phase difference △φ caused by the radiation wave 12 entering from a sparse medium (air) and a dense medium (dielectric plate 2).
The sum of the phase difference, π, caused by phase inversion when reflected at the interface with , is π + Δφ.

In addition, when the refracted wave of the radiation wave 11 is incident on point B, when it is incident from a dense medium (dielectric plate 2) and reflected at the interface with a sparse medium (air), the incident wave The above-mentioned phase difference π does not occur between the reflected wave and the reflected wave.

Now, the above phase difference Δφ is given by the following equation.

r ₂ and r ₁ shown in the above formula are the distances and λ ₀ is the free space wavelength of the electromagnetic wave. In this case, r ₂ − r ₁ = △r can be considered to be very small, and the plate thickness h is very small, less than 1/20 of the wavelength λ ₀ , so the phase difference △φ is small and the refracted wave 11
The phase difference between and the reflected wave 12″ is considered to be close to π,
They will cancel each other out. Therefore, it can be said that the existence of electromagnetic waves propagating between the pair of dielectric plates 2 and 3 is extremely small.

Next, the refracted wave of the radiation wave 12 heading toward point D is
It is divided into a refracted wave 12' which is refracted and directed toward free space, and a reflected wave which is reflected and directed into the dielectric plate 2.
In this case, when the angle of incidence θ ₁ is large enough,
and can be considered almost parallel.

Therefore, we set the incident angle θ ₁ to a sufficiently large angle close to 90°,
For example, assume that θ ₁ =75°, and that the length from point A to the tip of dielectric plate 2 is L, and that L is equally divided into n stores. As a result, the length l ₁ of one divided piece is l ₁ =L/(n-1).

Considering the radiated waves 11 and 12 on each division point having such a relationship from FIG. 12, the phase difference δ between the refracted waves 11' and 12' to the outside of the plate is:
Assuming that the angle of incidence of the radiation wave 11 is θ ₁ and the angle of incidence of the radiation wave 12 is (θ ₁ +Δθ), it is determined as follows.

l ₁ = d/2 {tan(θ ₁ +△θ)} ≒d/2・d/dθ ₁ tanθ ₁・△θ=d△θ/2cos ² θ ₁ ∴△θ=2l ₁ cos ² θ ₁ / d δ=2π/λ ₀ (r ₂ − r ₁ ) =2π/λ ₀・d/2{1/cos(θ ₁ +△θ)−1
/cosθ ₁ } ≒πd/λ ₀ cos ² θ ₁・sinθ ₁・△θ Substituting the above △θ into this, the following equation is obtained.

δ=2π/λ ₀ · l ₁ sin θ ₁ In the above equation, sin θ ₁ is a value slightly smaller than 1, and increases very slowly toward 1 as θ ₁ increases. Therefore, for the total length of L,
By substituting an average value m slightly smaller than 1, it can be expressed as δ=2πml ₁ /λ ₀ .

This means that a considerable part of the radiation wave from the wave source I is approximately at the n-divided points B, D... on the dielectric plate 2.
... indicates that it will be replaced by a new wave source placed above. That is, the radiation pattern by the wave source I placed across the dielectric plate 2 is approximated to a composite radiation pattern of n point wave sources placed at an interval of l ₁ based on Huygens' principle. The phase difference between adjacent wave source arrays is 2πml ₁ /λ ₀ .

Considering the above phenomenon from another perspective, the interval l ₁
This is the same as when power is supplied from point B to n wave sources placed at point B with a traveling wave having a phase velocity v _p =mc, and each wave source is excited. Here, c is the speed of light.

Therefore, in this case, since m<1, it can be seen that v _p is slightly slower than the speed of light c. That is, it can be said that the dielectric plate 2, which is sufficiently thin compared to the wavelength, operates as a so-called slow-wave fed endfire antenna.

The direction of the maximum value of the composite directivity characteristic of such an endfire antenna is determined by the phase velocity v _p . In this case, since v _p is slightly smaller than the speed of light, the maximum value of the directivity is as follows for the dielectric plate 2 in FIG. 12, assuming that its longitudinal direction is 0°.
It will appear at a slight angle at the top.
On the other hand, the maximum value of the directivity due to the other dielectric plate 3 forming a pair with this dielectric plate appears at a slight angle on the lower side. That is, since the directional characteristics of both the dielectric plates 2 and 3 appear vertically symmetrical, the maximum value of the combined directional characteristic appears at 0°, that is, in the longitudinal direction between the two dielectric plates 2 and 3.

Furthermore, the directivity characteristics of the so-called endfire array created by the n point wave sources as described above will be described.

In FIG. 13, the electric field strength at an infinite point Q in the direction of an angle φ from the array axis is determined. Here, for simplicity, it is assumed that each wave source has the same amplitude. In reality, this amplitude is inversely proportional to the distance from the wave source, but since changes in amplitude have little effect on the maximum value of the directional characteristics, there is no need to worry about this assumption deriving results that deviate greatly from reality. .

Now, on the array, the phase difference △q between adjacent wave sources in the φ direction is given by △q=2πρ/λ ₀ (√ ₁ sinθ ₂ −cosφ). Note that ρ is the interval between wave sources and is L/(n-1).

When the amplitude of the traveling wave on the plate is E, the amplitude of each wave source is assumed to be ΔE=E/n, and the electric field strength at point Q is given by the following equation.

This equation corresponds to the equation given for an endfire array antenna with maximum radiation direction along the array axis if √ ₁ sin θ ₂ =1.

Generally, √ ₁ sin θ ₂ is a value slightly smaller than 1, so the maximum radiation direction presented above is slightly shifted in the + direction from the array axis.

The above equation is given for an independent wave source, but in reality, the surface of the dielectric plate 2 is continuous, and an infinite number of radiated waves are generated between the radiated waves 11 and 12 in FIG. All of the wave sources of adjacent radiation waves have the same phase difference. This means that n→∞ in the above equation.

Here, considering that when α is close to 0, sin α≈α, and setting n→∞ in the above equation, the following equation is obtained.

Since dielectric plates 2 and 3 exist and the distance between them is d, the combined electric field |E| _TOT is given by the following equation.

It can be seen that the maximum value of the combined electric field |E| _TOT given by the above equation is φ=0, and exhibits a directivity characteristic with a large main lobe in the direction of φ=0.

In this way, when a wave source is placed between the pair of dielectric plates 2 and 3, the dielectric plates 2 and 3 have the function of guiding electromagnetic waves in their longitudinal direction.

Although the present invention operates as described above, all of the energy radiated from the wave source is not guided, but the electromagnetic waves that are incident on the dielectric plate at a small angle of incidence are directly transmitted to free space. This will progress to. The large side lobes in the directivity characteristics shown in FIG. 5 are created by these electromagnetic wave energies.

[Example] An example of the present invention will be described with reference to the drawings. The following embodiment is an example in which a half-wavelength antenna 1 having a reflector 1b behind an antenna conductor 1a is used as a radiating element, as shown in FIG.

<Configuration of First Embodiment> FIGS. 2 and 3 show an outline of a first embodiment of the waveguide mechanism of the present invention.

As shown in FIGS. 2 and 3, the first aspect of the present invention
The waveguide mechanism of the embodiment includes a pair of dielectric plates 2 and 3.
are arranged in parallel across the space in front of the half-wavelength antenna 1.

The dielectric plates 2 and 3 are made of a dielectric material having a thickness of about 1/20 or less, for example, several tenths or less of the wavelength of the electromagnetic waves radiated from the half-wave antenna 1. dielectric plate 2,
3, where the length of the longest side is L, the longitudinal direction is as shown in FIGS. 2 and 3.
It is arranged in accordance with the propagation direction D of electromagnetic waves radiated from the half-wavelength antenna 1. In this embodiment, the wavelength is λ, the plate thickness h=0.05λ, the inter-plate distance d=0.6λ, and the length L=5.5λ.

In addition, as shown in FIG. 3, a half-wavelength antenna 1
is arranged so that the antenna conductor 1a is placed at a position approximately 1/2 of the distance d between the dielectric plates 2 and 3, and the plane including the antenna conductor 1a is parallel to the dielectric plates 2 and 3. will be placed in

<Operation of the first embodiment> As described above, when an electromagnetic wave is radiated from the half-wavelength antenna 1 equipped with a waveguide mechanism consisting of a pair of dielectric plates 2 and 3, the electromagnetic wave is emitted as shown in FIGS. As shown in FIG. 3, the light passes through the dielectric plates 2 and 3 and diffuses into space. FIG. 4 shows the situation at this time in terms of geometrical optics.

In Figure 4, the electromagnetic wave with point O as the wave source is
It reaches the dielectric plate 2 shown in the figure, is refracted and propagated into the dielectric plate 2 according to the ratio of the dielectric constant ε ₀ of air to the dielectric constant ε ₁ of the dielectric plate 2, and some Reflect and proceed. This reflected wave hardly returns to the wave source. This is considered to be the reason why the input impedance of the antenna at the wave source O is not affected.

Here, since the dielectric plates 2 and 3 are extremely thin,
The electromagnetic energy propagating within the plate thickness is negligible. However, the phase distribution created by the transmitted waves on the upper surface of the dielectric plate 2 is significantly different from when the dielectric plate 2 is not present. This difference becomes larger as the angle of incidence on the dielectric plate 2 becomes lower. Therefore, the phase velocity observed on the upper surface of the dielectric plate 2 is delayed compared to the case without the dielectric plate 2. This is very similar to the operation of an endfire antenna, as detailed in the operation section above.

As described above, the dielectric plates 2 and 3 function to concentrate electromagnetic energy in the direction of arrow D shown in FIGS. 2 and 3. That is, the two dielectric plates 2 and 3 act as an array of two endfire antennas separated from each other by a distance d.

The results of demonstrating this effect are shown in FIG. This figure is an actually measured directivity diagram showing the effect of the waveguide mechanism, where the broken line shows the directivity in a vertical plane that bisects the antenna conductor of the half-wavelength antenna shown in Figure 1 at right angles, and the solid line shows the directional characteristics in the vertical plane of the device shown in FIG. 2 in which the waveguide mechanism of this embodiment is attached.

As is clear from FIG. 5, by installing the waveguide mechanism of this embodiment, the directivity can be increased and a single lobe can be formed in a direction parallel to the dielectric plate.

In this embodiment, when the dielectric plates 2 and 3 are arranged in parallel, this parallelism is not so strictly required. However, as shown in FIG. 6, for example, the dielectric plate 3 is tilted, and the dielectric plates 2 and 3
If the parallelism is significantly lost, side lobes will increase, and desirable waveguide characteristics will no longer be exhibited. Therefore, it is preferable to increase the degree of parallelism.

<Second Embodiment> The waveguide mechanism of the second embodiment of the present invention shown in FIG.
A dielectric plate 5a is provided on a pair of dielectric plates 2 and 3 constituting the waveguide mechanism of the first embodiment so as to vertically cover the tip sides of the dielectric plates 2 and 3. be done.

This dielectric plate 5a is composed of the dielectric plates 2 and 3.
Similarly, the plate thickness should be sufficiently thin compared to the electromagnetic wave wavelength used. In this embodiment, the dielectric plates 2 and 3 are integrally molded in a U-shape. Of course, this dielectric plate 5a and dielectric plates 2 and 3 may be separate bodies.

In this embodiment, since the dielectric plate 5a is provided perpendicularly to the dielectric plates 2 and 3, electromagnetic energy is not unnecessarily refracted. Therefore, unlike the U-shaped structure shown in FIG. 7, the waveguide characteristics are not deteriorated.

<Third Embodiment> The waveguide mechanism of the third embodiment of the present invention shown in FIG.
Unlike the waveguide mechanisms of the first and second embodiments, a pair of parallel dielectric plates 7a and 7b are arranged perpendicularly to the antenna conductor 1a of the half-wavelength antenna 1. Ru.

The dielectric plates 7a and 7b are also made to have a thickness that is one-twentieth or less of the wavelength of the electromagnetic waves used, as in the first embodiment.

The waveguide mechanism of this embodiment controls electromagnetic wave directivity in a horizontal plane including the antenna conductor 1a using dielectric plates 7a and 7b.

Note that this example and the first example or the second example described above
It is also possible to combine it with the embodiments. That is, dielectric plates having a thickness of about 1/20th or less of the wavelength of electromagnetic waves are arranged in parallel to form a pair, and two pairs of these are arranged orthogonally to each other to form a square cylinder. The radiation element may be arranged at one end in the longitudinal direction inside the cylinder. Although not shown, this example is the same as the waveguide mechanism shown in FIG. 10, which will be described later, except that the dielectric plates 5a and 5b are removed.

<Fourth Embodiment> The waveguide mechanism of the fourth embodiment of the present invention shown in FIG.
It is constructed by forming a rectangular parallelepiped-shaped casing 6 having six sides in b, and a half-wavelength antenna 1 is disposed as an electromagnetic wave radiating element at one end in the longitudinal direction inside the casing 6.

Dielectric plates 2, 3, 5a, 5b, 7a and 7b
For this, use a plate with a thickness that is approximately 1/20th or less of the wavelength of the radiated electromagnetic waves. The housing 6 includes dielectric plates 2, 3, 5
a, 5b, 7a and 7b are each independent pieces,
It may be formed by joining them, but
It is also possible to form a structure in which the dielectric plates 2, 3, 5a, 5b, 7a, and 7b are appropriately combined and integrally molded and then joined together.

According to this embodiment, electromagnetic waves propagate in the direction D perpendicular to the dielectric plate 5a, and at this time, the directivity of the electromagnetic waves can be controlled both vertically and horizontally. Further, according to this embodiment, the half-wavelength antenna 1
Since the antenna 1 is housed inside the housing 6, the antenna 1 can be protected from the natural environment and its reliability can be improved. This is particularly effective when used in locations subject to severe salt damage.

<Fifth Embodiment> The waveguide mechanism according to the fifth embodiment of the present invention shown in FIG. A reflection layer 8 is provided on the surface of the housing 6 located behind the antenna conductor 1a.
(shown with diagonal lines in FIG. 11).

The reflective layer 8 may be formed by providing a layer that reflects electromagnetic waves on the surface of the housing 6 located behind the antenna conductor 1a, and may be formed by, for example, applying metal plating or arranging a metal plate. can.

According to this embodiment, since the reflective layer 8 functions as a reflector, the half-wave antenna 1 housed inside
, only the antenna conductor 1a without the reflector is required. Moreover, according to this reflective layer 8, it is possible to improve the front-to-back ratio of the directional characteristics.

<Modifications of Embodiments> In each of the above embodiments, the half-wavelength antenna, which is a radiating element, is placed at the center between the pair of dielectric plates, that is, at a position 1/2 of the distance d between the plates. , this position can be changed. As a result, the position of the wave source changes, and the maximum directivity direction and directivity characteristics can be changed.

Further, the directivity characteristics can also be changed by changing the distance between the dielectric plates and the length L in the electromagnetic wave propagation direction.

Since each of the above embodiments is constructed of a thin dielectric plate, the mechanical strength may be insufficient depending on the application. As a countermeasure for this, the dielectric constant is approximately 1.
By filling the space between the dielectric plates with a foam material such as styrene foam, which has a dielectric constant similar to that of air, it is possible to eliminate hollow parts within the structure, solidify it, and strengthen the structural strength.

Further, in each of the above embodiments, the waveguide mechanism is applied to a half-wavelength antenna, but it goes without saying that it can be applied to other electromagnetic wave radiating elements that require the same.

[Effects of the Invention] As explained above, the present invention is attached to an electromagnetic wave radiating element that radiates electromagnetic energy over a wide space, concentrates the electromagnetic energy in a narrow space, and radiates it in a single direction parallel to the dielectric plate. This has the advantage that lobes can be formed and the waveguide mechanism can be constructed using inexpensive dielectric plates.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a half-wavelength antenna, which is an example of a radiating element to which the waveguide mechanism of the present invention is applied;
The figure is a perspective view showing an outline of the first embodiment of the waveguide mechanism of the present invention, FIG. 3 is a side view thereof, and FIG. FIG. 5 is a characteristic diagram showing the actually measured directivity characteristics of the half-wavelength antenna with and without the waveguide mechanism of the first embodiment, and FIG. 6 shows an unfavorable state in which the dielectric plate is tilted. FIG. 7 is an explanatory diagram showing a conventionally proposed dielectric waveguide mechanism, and FIGS. 8 to 11 show second to fifth embodiments of the present invention, respectively. 8 is a side view, FIGS. 9, 10 and 11 are perspective views, and FIGS. 12 and 13 are diagrams for explaining the operation of the waveguide mechanism of the present invention. It is an explanatory diagram. DESCRIPTION OF SYMBOLS 1...Half wavelength antenna, 1a...Antenna conductor, 2, 3, 5a, 5b, 7a, 7b...Dielectric plate, 8...Reflection layer.

Claims (1)

[Scope of Claims] 1. A pair of dielectric plates are arranged in parallel with a space in front of the radiating element in between, and the dielectric plates are used to prevent electromagnetic waves reflected from the surfaces of the dielectric plates and directed between the plates. A waveguide mechanism, characterized in that the plate thickness is set to such a phase difference that electromagnetic waves transmitted through the plate, reflected at the interface on the opposite side, and directed between the plates cancel each other out. 2. The waveguide mechanism according to claim 1, wherein the thickness of the dielectric plate is approximately 1/20th or less of the wavelength of the electromagnetic wave emitted from the radiating element. 3. Dielectric plates are arranged in parallel across the space in front of the radiating element to form a pair, and two pairs of these are arranged perpendicularly to each other to form a square tube, and one end side inside the square tube is formed. A radiating element is arranged, and the dielectric plate is configured to transmit electromagnetic waves that are reflected on the surface of the dielectric plate and go between the plates, and electromagnetic waves that are transmitted through the plate and reflected at the interface on the opposite side and go between the plates. A waveguide mechanism characterized in that the plate thickness is set such that the phase difference between and cancels each other out. 4. The waveguide mechanism according to claim 3, wherein the thickness of the dielectric plate is approximately 1/20th or less of the wavelength of the electromagnetic wave emitted from the radiating element. 5 A rectangular parallelepiped casing is formed with a dielectric plate, a radiating element is arranged at one end in the longitudinal direction inside the casing, and the dielectric plate is arranged such that the radiating element is arranged so that the radiating element is not reflected on the surface of the dielectric plate. A waveguide mechanism characterized in that the plate thickness is set to such a phase difference that an electromagnetic wave directed between the plates and an electromagnetic wave transmitted through the plate and reflected at the opposite interface and directed towards the plate cancel each other out. 6. The waveguide mechanism according to claim 5, wherein the thickness of the dielectric plate is approximately 1/20th or less of the wavelength of the electromagnetic wave emitted from the radiating element. 7. The waveguide mechanism according to claim 5 or 6, wherein a reflective layer is formed on the rear surface of the radiation element of the housing.