JP3201736B2 - Multilayer medium dielectric antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multilayer medium dielectric antenna.

[0002]

2. Description of the Related Art Conventionally, an antenna using a dielectric line (hereinafter referred to as a dielectric antenna) is a primary antenna such as an opening of a waveguide or an electromagnetic horn for exciting a surface wave mode in the dielectric line. Elements have been used and have been put to practical use.

[0003]

However, the above-mentioned conventional dielectric antenna has the following disadvantages. That is, since the primary antenna element is used to excite the surface acoustic wave mode in the dielectric antenna as described above, when the transmission energy transmitted through the transmission line is converted into the radiant energy, the direct transmission from the feeding portion is performed. Radiation is present and conversion efficiency to surface wave mode is poor,
It was extremely difficult to predict the directivity at the design stage.

SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned disadvantages of the prior art, and combines a TEM mode of two parallel lines with a hybrid dipole mode (surface wave mode) of a multilayer medium. It is an object of the present invention to provide a small-sized multilayer medium antenna capable of efficiently converting TEM mode energy to a hybrid dipole mode.

[0005]

According to the present invention, the line diameter is d,
Two parallel lines with a line length of L and a line interval of S
Has a relative dielectric constant of ε, which covers the two parallel lines of_r1Outside
Diameter r₁And the relative permittivity is ε_r2And the outer diameter is r
_TwoConsisting of a dielectric line composed of a second medium
A multi-layer medium dielectric antenna, comprising:
Length L is 0.5 λ ₀~ 3λ₀(Λ₀; Wavelength of operating frequency)
And the outer diameter r of the first medium₁And the outer diameter r of the second medium_Two
The ratio r₁/ R_TwoIs between 0.1 and 0.9,
The interval S is 0.1 r₁~ 0.4 r₁It is characterized by
This is a multilayer medium dielectric antenna. In addition, the second medium
Outer diameter r_TwoIs 0.5 λ₀Desirably smaller.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a front view showing an embodiment of a multilayer medium dielectric antenna according to the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG.

[0007] In these figures, reference numeral 1 denotes a dielectric line, which has a line diameter d, a line length L, and a line interval S, and is made of a two-conductor parallel material whose material is, for example, copper or the like and whose surface is plated with silver. It comprises a path 2 and a multilayer medium 3 that covers the two parallel lines 2 in a circular concentric manner. The multilayer medium 3 is, for example, a first medium 3 having a relative permittivity of ε _r1 and an outer diameter of r _1.
a and a second medium 3 having a relative permittivity of ε _r2 and an outer diameter of r ₂
b and a multilayer medium. Reference numeral 4 denotes a load resistor connected between one ends 2a of the two parallel lines 2. Reference numeral 5 denotes a high-frequency oscillator that feeds the TEM mode between the other end 2b of the two parallel lines 2 via the line 6.

By configuring the multilayer medium dielectric antenna 7 as described above, the transmission energy in the TEM mode fed from the high-frequency oscillator 5 is reduced by the multilayer medium 3 having a circular cross section with the center of the parallel two-line 2. When the center coincides, the hybrid dipole mode is mainly excited. As a result, most of the transmission energy in the TEM mode is converted to the hybrid dipole mode of the dielectric line 1 of the multilayer medium. Then, this energy is radiated as an end-fire type electromagnetic wave having strong directivity in the axial direction of the arrow R of the dielectric line 1.

This antenna is considered to be a type of array antenna composed of a continuous wave source that uniformly radiates an electromagnetic wave from each part of the line. The directivity of each wave source in the array is 8 in the H plane.
, The E-plane is omnidirectional and has the same directivity as the loop antenna. Therefore, the overall directivity has the end fire directivity in the axial direction of arrow R, and the H plane has a slightly sharper directivity than the E plane. Therefore, the TE of the two parallel lines 2
Since the impedance matching between the M mode and the hybrid dipole mode of the dielectric line 1 is good, high radiation efficiency can be obtained. The directivity pattern can be controlled by changing the relative permittivity ε _r1 of the first medium 3a, the line spacing S, or the line length L.

Here, as the first medium 3a, the relative dielectric constant ε
_Although air having _r1 of 1 is suitable, it is possible to control the directivity by delaying the phase velocity by using Teflon or polyethylene having a relative dielectric constant ε _r1 of about 2.55 other than air. The second medium 3b has a relative permittivity ε _r2 of, for example, 2 such as water or a barium titanate-based ceramic dielectric.
It is preferable to use a material having a high dielectric loss and a small dielectric loss.

Next, the length of the multilayer medium dielectric antenna 7, that is, the line length L of the two parallel lines 2, is practically 0.5
λ _{0 to} 3λ ₀ (λ ₀ ; wavelength of the used frequency) is appropriate, but H depends on the TEM mode of the two parallel lines 2.
Electromagnetic waves from transient portion to E ₁₁ mode is excited is emitted, since the electromagnetic wave when the HE ₁₁ mode from being established is no longer emitted, the line becomes longer influence of dielectric loss becomes large. Accordingly, since those who had radiated as an electromagnetic wave before HE ₁₁ mode transmission mode is established less susceptible to dielectric loss, for example, 1λ
₀ better to the relatively short lines as ～2Ramuda ₀ is desirable.

Also, the outer diameter of the multilayer medium dielectric antenna 7,
That is, the outer diameter r ₂ of the second medium 3 b is H
It is desirable smaller than 0.5 lambda ₀ as the magnitude of E ₁₁ mode is induced, the value is the dielectric constant of the second medium 3b epsilon _r2
Can be reduced by increasing. That is, if the relative dielectric constant epsilon _r2 of the second medium 3b example 90, the outer diameter r ₂ of the second medium 3b can be reduced and 0.11λ _0.

On the other hand, the outer diameter r of the first medium 3a₁about
Is the outer diameter r of the second medium 3b._TwoAnd the ratio r ₁/ R_Two0.1 to
0.9 is desirable. The reason is r₁/ R_TwoIs 0.
If it is less than 1, the inside diameter is too small and the line spacing between two parallel lines 2
S cannot be taken properly, and if it exceeds 0.9, the layer thickness is too thin.
TEM mode and HE₁₁Coupling between modes
Is likely to decrease.

Further, it is desirable that the line interval S between the two parallel lines 2 is 0.1 r _{1 to} 0.4 r ₁ . The reason for the experiment will be described below. That is, the line diameter d is 2 mmφ, and the line length L is 1.1
λ ₀ (= 386 mm constant) in parallel two lines 2, air having an outer diameter r ₁ of 30.6 mmφ as the first medium 3a (relative permittivity ε _r1
= 1), and using a barium titanate-based ceramic dielectric having a relative dielectric constant ε _r2 of 90 and an outer diameter r ₂ of 38.6 mmφ as the second medium 3b, a multilayer medium dielectric antenna of the present invention is constructed. The radiation efficiency was examined by changing the interval S from 4 mm to 16 mm at 2 mm intervals. The center frequency of the electromagnetic wave used at this time is 860 MHz.

As is apparent from FIG. 3, the radiation efficiency of the multilayer medium dielectric antenna of the present invention exceeds the radiation efficiency of the conventional half-wavelength dipole antenna indicated by the dotted line when the line spacing S is in the range of 4 to 12 mm. I have. Therefore, it can be seen that there is an optimum value of the line spacing S that is strongly coupled to the multilayer medium line when the line spacing S is 4 to 12 mm. From the results of the above experiments, as described above, to increase the radiation efficiency,
0.1 to 0 with respect to the line spacing S outside diameter r ₁ of the first medium 3a.
A good value is four.

Although the cross section of the medium has been described as being circular in the above example, the present invention is not limited to this. For example, similar effects can be obtained by making the medium elliptical or square.

[0017]

[Embodiment] The line diameter d is 2 mm and the line length L is 386 mm (= 1.
09λ₀), Line spacing S is 4mm (S / r₁= 0.13)
And the relative permittivity ε of the first medium_r1Is 1, outer diameter
r ₁Is 30.6mmφ and the relative dielectric constant is 2nd medium.
Rate ε_r2Is 90, outer diameter r_TwoIs 38.6mmφ (r₁/ R_Two= 0.79)
Using barium titanate-based ceramic dielectric
At one end of a multilayer medium dielectric antenna composed of multilayer media
Connect a 200 Ω load resistor and connect the other end to a high-frequency oscillator
850 MHz TEM mode was supplied from the device. Water at that time
FIG. 4 shows the characteristics of the planar directivity. It is clear from this figure
Thus, the extremely sharp H-plane with a directional gain of 9 dB
It can be seen that directivity can be obtained.

[0018]

As described above, the multilayer medium of the present invention
According to the dielectric antenna, the length L of the two parallel lines is 0.5
λ₀~ 3λ₀And the outer diameter r of the first medium₁And of the second medium
Outer diameter r _TwoThe ratio r₁/ R_TwoIs between 0.1 and 0.9,
Line spacing S is 0.1 r₁~ 0.4 r ₁And is characterized by
High conversion efficiency and directivity at the design stage.
It is possible to provide a small antenna that can be measured.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a multilayer medium dielectric antenna according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a characteristic diagram showing a change state of radiation efficiency.

FIG. 4 is a characteristic diagram of horizontal directivity obtained by the multilayer medium dielectric antenna of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric line 2 Parallel two lines 3 Multilayer medium 3a 1st medium 3b 2nd medium 4 Load resistance 5 High frequency oscillator 6 Line 7 Multilayer medium dielectric antenna

──────────────────────────────────────────────────の Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01Q 1/42 H01Q 9/16 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A line diameter is d, a line length is L, and a line interval is S.
And a first medium having a relative permittivity of ε _r1 and an outer diameter of r ₁ covering the parallel two lines concentrically, and a relative permittivity of ε _r2 and an outer diameter of r a multilayer medium dielectric antenna consisting constructed dielectric waveguide with a second medium that is _2, the length L of the parallel two lines is _{0.5 λ 0 ~3λ 0 (λ 0} ;
Is the wavelength of the used frequency), the outer diameter r ₁ of the first medium ratio magnitude of r ₁ / r ₂ of the outer diameter r ₂ of the second medium from 0.1 to 0.
9. The multilayer medium dielectric antenna according to claim ₁ , wherein the line spacing S is 0.1 r _{1 to} 0.4 r ₁ . 2. The multilayer medium dielectric antenna according to claim 1, wherein the outer diameter r ₂ of the second medium is smaller than 0.5 λ ₀ .