JP3934840B2 - antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an antenna for radiating or receiving microwaves or millimeter waves, and more particularly to a high-performance and low-cost antenna using an NRD guide as a feed line.
[0002]
[Prior art]
NRD guides are one of the transmission lines that propagate microwaves and millimeter waves, and have excellent characteristics such as low transmission loss in high-frequency regions, so they can be applied to microwave and millimeter wave band products. Development is underway.
[0003]
In a microwave or millimeter wave apparatus using an NRD guide as a transmission line, in order to have a function of radiation or reception of microwave or millimeter wave, an antenna element is excited by an NRD guide antenna or an NRD guide. is necessary.
[0004]
As a structure for exciting the antenna element with the NRD guide, conventionally, as shown in FIG. 7, an NRD comprising a dielectric strip 21 and upper and lower metal plates 22 sandwiching the dielectric strip 21 (the upper metal plate is not shown). There is a structure in which tapered portions 21a and 21b are formed on both side surfaces of the tip of the dielectric strip 21 of the guide 23, and a horn antenna 24 as an antenna element is attached to the tip of the NRD guide 23. There is also a structure in which a rectangular waveguide is attached to the tip of the NRD guide 23 and a horn antenna 24 is attached to the tip.
[0005]
[Problems to be solved by the invention]
Conventionally, the operation mode generally used in the NRD guide is the LSM01 mode, and this mode is not the lowest-order mode but is widely used because it has a small transmission loss.
[0006]
However, it has recently become clear that the LSE01 mode, which is a lower-order mode than the LSM01 mode, can obtain characteristics equal to or higher than those of the LSM01 mode by using a dielectric having a high dielectric constant for the dielectric strip.
[0007]
As for the operation mode, the low-order mode has less problem of mode competition and can operate the apparatus more stably. Therefore, if the LSE01 mode, which is a low-order mode, can be used, the merit is great.
[0008]
The present invention has been made in view of the above points. An antenna is configured at the end of a low-order LSE01 mode transmission NRD guide, and does not require a special horn antenna or the like, and is ideal as an antenna element. An antenna capable of forming a point wave source with a wide directivity is provided.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the first invention is an antenna using an LSE01 mode transmission NRD guide having a structure in which a dielectric strip is sandwiched between two metal plates, and the end of the dielectric strip is connected to the end of the dielectric strip. A notch portion which is located between two metal plates and has an asymmetric shape on the surface of the end portion of the dielectric strip facing the metal plate and faces the external space in the axial direction of the dielectric strip forming a divided portion between at least one of the dielectric strip end portion and the two metal plates are formed, radio waves are emitted from an end of the dielectric strip to the external space so that Configured.
[0010]
According to a second invention, in the first invention, another material different from the dielectric strip is inserted into the spacing portion, and the other material is a dielectric material having a dielectric constant different from that of the dielectric strip, or a metal. Oh was so that configuration.
[0011]
According to a third invention, in the first or second invention, the notch portion is configured such that at least a part of the end portion is a tapered portion formed obliquely with respect to a traveling direction of the radio wave .
[0012]
According to a fourth aspect of the invention , a plurality of antennas according to any one of the first to third aspects are arranged in parallel at a predetermined pitch, and the plurality of antennas are excited using an LSE01 mode transmission NRD guide as a feeder line .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
1 and 2 are views showing an antenna according to a first embodiment of the present invention. FIG. 1 is a perspective view in which a part of the upper metal plate is removed, and FIG. 2 is a longitudinal sectional view. In these drawings, 1 is a dielectric strip made of a dielectric having a high dielectric constant, and 2 and 3 are metal plates that sandwich the dielectric strip 1 from above and below, and an NRD guide 4 is constituted by these.
[0015]
Further, in the present embodiment, a taper portion 1a is formed by notching the end surface (tip surface) of the dielectric strip 1 in a direction facing the metal plates 2 and 3, and the dielectric strip 1 and the metal plate are formed by the taper portion 1a. A separation portion 5 (see FIG. 2) is formed between the two.
[0016]
Since the NRD guide 4 transmits the LSE01 mode, the dimensions and the dielectric constant of the dielectric strip 1 are selected to be appropriate values according to the operating frequency. For example, when the operating frequency is 60 GHz, aluminum nitride (relative dielectric constant: 8.5) is used as the material of the dielectric strip 1, its height is 1.6 mm, its width is 0.6 mm, and the length L of the tapered portion 1 a is set. 7 mm (equivalent to about twice the wavelength of the transmission line).
[0017]
When radiating high-frequency radio waves, high-frequency radio waves are supplied to the NRD guide 4 from the left side of FIGS. 1 and 2 and radiated from the taper portion 1 a to the space of the separation portion 5. The same applies to reception when the flow of radio waves is reversed.
[0018]
The LSE01 mode has a vertically symmetric high-frequency electric field as shown in FIG. 2, but the end surface of the dielectric strip 1 is cut into the shape of the tapered portion 1a as shown in FIG. The high-frequency electric field is distorted in the asymmetrical direction of the plates 2 and 3, and a high-frequency electric field component perpendicular to the metal plates 2 and 3 is formed and radiated into the space. The length L of the tapered portion 1a is set to a dimension that is an integral multiple of 1/2 of the wavelength on the transmission line so that reflection when a desired radio wave is radiated from the NRD guide 4 to the space is reduced.
[0019]
In order to radiate a radio wave from the LSE01 mode transmission NRD guide 4, it is only necessary to distort a vertically symmetric high-frequency electric field as shown in FIG.
[0020]
[Second Embodiment]
FIG. 3 is a view showing the antenna of the second embodiment, in which a rectangular cutout portion 1b is formed from the end face of the dielectric strip 1 over a length L, and a spacing portion is provided between the metal plate 2 and the upper portion. It has a structure. Even in this configuration, the distribution of the high-frequency electric field is different between the dielectric strip 1 in which the spacing portion and the notch portion 1b are formed, so that a high-frequency electric field component in a direction perpendicular to the metal plates 2 and 3 is formed. Is done.
[0021]
Note that the length L of the cutout portion 1b of the dielectric strip 1 is a dimension that is an integral multiple of 1/2 of the wavelength in the transmission line, as in the case of FIG.
[0022]
[Third Embodiment]
FIG. 4 is a diagram showing an antenna according to the third embodiment. As shown in FIG. 3, the notch 1b formed from the end face of the dielectric strip 1 over the length L is different from the dielectric strip 1 in FIG. The dielectric materials 6 having different dielectric constants are superposed to form a continuous shape. This is a structure in which the dielectric material 6 having a relative dielectric constant larger than 1 is packed in the part of the separated portion (relative dielectric constant is 1) in FIG. 3, and the operation is the same as in FIG.
[0023]
[Fourth Embodiment]
FIG. 5 is a diagram showing an antenna according to the fourth embodiment. As shown in FIG. 3, a metal plate 7 is superimposed on a cutout portion 1b formed from the front end of the dielectric strip 1 over a length L. Is made continuous. In this structure, since the metal plate 7 is integrated with the upper metal plate 2, the distance between the metal plate 3 is changed at a portion sandwiching the metal plate 7, thereby forming a discontinuous portion. In this discontinuous portion, the high-frequency electric field is also disturbed, and a high-frequency electric field component perpendicular to the metal plates 2 and 3 is formed.
[0024]
[Fifth Embodiment]
FIG. 6 is a diagram showing an antenna according to a fifth embodiment, in which a plurality of antennas having the structure shown in FIG. 1 are arranged in parallel to form an array type antenna. An LSE01 mode transmission NRD guide 4 using a feeding dielectric strip 8 is used for the feeding line, and each antenna element (dielectric strip 1 having a tapered portion 1a) is arranged at an interval that becomes an effective wavelength at the operating frequency. And they are excited in the same phase. In order to excite in the same phase, microwave and millimeter wave radiation is oriented at right angles to the surface (end surface) of the dielectric strip 8 constituting the antenna.
[0025]
Since the effective wavelength in the LSE01 mode is shorter than the free space wavelength, the spacing between the antenna elements is narrower than the free space wavelength, and there is no grayite globe, that is, the sensitivity distribution in the direction other than the target is small and directivity is reduced. A good array antenna can be formed. In FIG. 6, the antenna element dielectric strip 1 is separated from the feeding dielectric strip 8 in order to improve the matching.
[0026]
[Other Embodiments]
In each of the above embodiments, the taper 1a and the notch 1b are formed on only one side of the dielectric strip 1 (the side facing the upper metal plate 2), but the side facing the lower metal plate 3 is formed. Similarly, a notch may be formed. However, at this time, the upper and lower shapes are asymmetric.
[0027]
【The invention's effect】
As described above, according to the present invention, since the end of the NRD guide functions directly as an antenna element, the structure requiring a horn antenna or the like is simple and the manufacturing cost can be reduced. In addition, since it is close to an ideal point wave source, there is no grayite globe when arrayed, and there is little disturbance in the antenna pattern.
[Brief description of the drawings]
FIG. 1 is a perspective view of an antenna according to a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of FIG.
FIG. 3 is a perspective view of an antenna according to a second embodiment.
FIG. 4 is a perspective view of an antenna according to a third embodiment.
FIG. 5 is a perspective view of an antenna according to a fourth embodiment.
FIG. 6 is a perspective view of an array antenna according to a fifth embodiment.
FIG. 7 is an explanatory diagram of a conventional antenna.
[Explanation of symbols]
1: Dielectric strip, 1a: Tapered portion, 1b: Notched portion, 2, 3: Metal plate, 4: LSE01 mode transmission NRD guide, 5: Separating portion, 6: Dielectric, 7: Metal plate, 8: Power feeding Dielectric strip.

Claims (4)

An antenna using an LSE01 mode transmission NRD guide having a structure in which a dielectric strip is sandwiched between two metal plates,
The end of the dielectric strip is positioned between the two metal plates, and the end of the dielectric strip has an asymmetric shape on the surface facing the metal plate , and the axis of the dielectric strip forming a cutout portion facing the direction of the external space, spaced portion between the at least one of the dielectric strip end portion and the two metal plates are formed from the end of the dielectric strip antenna radio waves outside space, characterized in that the so that the radiation. Wherein the said another material different from the dielectric strip is inserted into the separation portion, the material of said further, the dielectric strip and the dielectric constant of different dielectric materials, or according to claim 1, wherein a metal der Rukoto Antenna. The antenna according to claim 1 or 2 , wherein the notch is a tapered portion in which at least a part of the end portion is formed obliquely with respect to a traveling direction of radio waves . 4. An array-type antenna , wherein a plurality of antennas according to claim 1 are arranged in parallel at a predetermined pitch, and the plurality of antennas are excited using an LSE01 mode transmission NRD guide as a feed line .

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