JPH0412043B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a printed dipole antenna suitable as a basic radiating element for a radar antenna or an array antenna for communication lines.

Prior Art Figure 9 is a plan view showing a conventional printed dipole antenna, and Figure 10 is a side view. In both figures, 1 is a dielectric substrate formed to a thickness approximately 1/10 or less of the radiation wavelength. It has been done. 12 ₁ and 12 ₂ are radiating elements consisting of strips or thin wires whose width is sufficiently small compared to the radiation wavelength, and are made of copper foil or the like which is adhered to the surface of the dielectric substrate 1 by means such as printed wiring or vapor deposition. It is formed by Reference numeral 3 denotes a ground conductor, which is made of copper foil or the like that is deposited on the back surface of the dielectric substrate 1 by means such as printed wiring or vapor deposition. Reference numeral 4 denotes a coaxial line forming a feeder line, the outer conductor of which is connected to the grounding conductor 3 at high frequency directly or via a capacitor, and also connected to the grounding side radiating element 12 ₁ via the connecting conductor 5 ₁ .
and connect the internal conductor to transformer 6 and connecting conductor 5 ₂
It is connected to the core side radiating element 12 ₂ via.

Problems to be Solved by the Invention According to the research results of the present inventor, the radiating element 12 ₁ in the above-mentioned conventional printed dipole antenna
It was revealed that there is a relationship shown in FIG. 11 between the total axial length L of 12 ₂ and the input impedance.

In FIG. 11, the horizontal axis is the ratio L/λ ₀ of the radiation wavelength λ ₀ and the total axial length L of the radiating elements 12 ₁ and 12 ₂ , the vertical axis is the input impedance (Ω), and the curve R is the resistance of the input impedance. The curve x is the reactance.

As is clear from the figure, the reactance component of the input impedance is determined according to the ratio L/λ ₀ of the radiation wavelength λ ₀ and the total axial length L of the radiating element, so the radiation wavelength λ ₀
If , the length of the radiating element that resonates with this radiation wavelength is uniquely determined, and in order to arbitrarily select the length of the radiating element, it is necessary to transform the inner conductor of the coaxial line 4 and the connecting conductor ₅ A radiating element 12 ₁ with a vessel 6 interposed therebetween.
It is necessary to match the input impedance of 12 ₂ and the characteristic impedance of the coaxial line 4,
As a result, the configuration of the power feeding section inevitably becomes complicated.

Means for Solving the Problems The antenna of the present invention is characterized in that the outer end of the radiating element is formed into a bent portion.

Function By bending the outer end of the radiating element as described above, impedance matching between the radiating element and the feeder line can be achieved without intervening a transformer as in the conventional case, and it is possible to achieve impedance matching over a relatively narrow range. It becomes possible to arrange a radiating element of a required length within the radiating element.

Embodiment FIG. 1 is a plan view showing an embodiment of the present invention, and FIG. 2 is a side view thereof. In both figures, 1 is a dielectric substrate, and 2 ₁ and 2 ₂ are surfaces of the dielectric substrate 1. A dipole radiating element is provided in the radiating element, and the outer end of each radiating element is bent to form bent portions 2 ₁₁ and 2 ₂₁ .
3 is a ground conductor provided on the back surface of the dielectric substrate 1.

In addition, the thickness of the dielectric substrate 1, the radiating elements 2 ₁ and 2
_2. The materials of the bent portions 2 ₁₁ and 2 ₂₁ , the ground conductor 3, and the means for attaching it to the front and back surfaces of the dielectric substrate 1 are the same as those of the conventional printed dipole antenna.

4 is a coaxial line forming a power supply line, and its outer conductor is connected to the ground conductor 3 at high frequency directly or through a capacitor.
It is also connected to the inner end of the ground side radiating element 2 ₁ via the connecting conductor 5 ₁ , and the internal conductor of the coaxial line 4 is connected to the core side radiating element 2 ₂ via the connecting conductor 5 ₂ .
It is connected to the inner end of the

Figure 3 shows the total length L _B of the radiating elements 2 ₁ and 2 ₂ .
The present invention relates to the relationship between the bending angle of the bent portions 2 ₁₁ and 2 ₂₁ and _the input impedance when the axial length of the bent portions 2 ₁₁ and 2 21 is selected to be 0.4λ ₀ and the axial length of the bent portions 2 11 and 2 ₂₁ to be 0.1λ 0. This is a curve diagram showing the results obtained by the authors based on experiments. The horizontal axis represents the bending angle τ in degrees, the vertical axis represents the input impedance Z _io in Ω, and R _io represents the change in the resistance component in the input impedance. The curve x _io is a curve showing the change in the reactance component in the input impedance, and as is clear from the figure, when the bending angle τ is selected to be approximately 90°, the reactance component becomes zero and resonance occurs at the emission wavelength λ ₀ . I can do it.

Although FIG. 1 shows an example in which the bent portions 2 ₁₁ and 2 ₂₁ of the radiating elements 2 ₁ and 2 ₂ are both bent upward toward the drawing, as shown in FIG. It may be bent downwards toward
The present invention can also be carried out by bending ₁₁ upwardly toward the drawing and the other bent portion ₂₂₁ downward.

Note that when the outer ends of the radiating elements 2 ₁ and 2 ₂ are bent, even if the bending angle is small, a different polarization component is generated, albeit in a small amount, as shown in FIG. 6.

Figure 6 shows the total length L _B of the radiating elements 2 ₁ and 2 ₂ .
0.4λ ₀ , each axis length of bent portions 2 ₁₁ and 2 ₂₁ is 0.1λ ₀ ,
This is a diagram showing an example of the radiation directivity characteristics of prototypes of the antenna of the present invention formed with a bending angle τ of 30° _.
and ₂ The origin is set on the surface of the ground conductor 3 corresponding to the center point of the opposing gap at each inner end of 2, and
This is a curve diagram expressed in spatial polar coordinates when the X coordinate axis, Y coordinate axis, and Z coordinate axis are taken in the Y direction and Z direction, respectively.The curve shown by the solid line is the directional characteristic of the same polarized wave component in the YZ plane, and the broken line shows it. The curves are different polarization components.

_In order to eliminate this different polarization component, as _shown in _the plan view in _FIG . By providing the portions 2 ₁₂ and 2 ₂₂ , different polarization components can be canceled vectorwise.

In addition, by appropriately selecting the total length L _B of the radiating elements 2 ₁ and 2 ₂ , the axial lengths and bending angles τ of the bent portions 2 ₁₁ and 2 ₂₁ , etc., the reactance of the input impedance can be made zero. At the same time, the amount of different polarization components can be reduced to a practically negligible level.

In the above embodiment, the feeder line is formed using the coaxial line 4, but the feeder line may also be formed using parallel lines.

Effects of the Invention The antenna of the present invention has the same features as the conventional printed dipole antenna, in that the radiating element and the ground conductor are provided on the front and back surfaces of the dielectric substrate by means such as printed wiring or vapor deposition. By bending the outer end of the radiating element, it is possible to achieve impedance matching between the radiating element and the feed line without intervening a transformer as in the conventional case, making it possible to simplify the structure of the feed section. Furthermore, by bending the outer end of the radiating element, the radiating element of the required length can be arranged within a relatively narrow range, which is compatible with simplifying the configuration of the power feeding section. The entire structure can be made compact.

FIG. 8 is a diagram showing an example of the radiation directivity characteristic of the antenna of the present invention, in which the directivity characteristic in the XZ plane in the spatial polar coordinate representation explained with reference to FIG. 6 is shown by a broken line.

[Brief explanation of drawings]

FIG. 1 is a plan view showing one embodiment of the present invention, FIG. 2 is a side view thereof, FIG. 3 is a diagram showing the relationship between the bending angle of the bent portion of the radiating element and the input impedance, and FIG. 5 and 7 are plan views showing other embodiments of the present invention, FIGS. 6 and 8 are diagrams showing an example of radiation directivity characteristics of the antenna of the present invention, and FIG. 9 is a plan view showing another embodiment of the present invention. FIG. 10 is a side view of a conventional printed dipole antenna, and FIG. 11 is a diagram showing the relationship between the radiation wavelength, the ratio of the total axial length of the radiating element, and the input impedance in the conventional printed dipole antenna. , 1: dielectric substrate,
2 ₁ and 2 ₂ : radiating element, 2 ₁₁ , 2 ₁₂ , 2 ₂₁ and 2
₂₂ : Bent part of radiating element, 3: Ground conductor, 4: Coaxial line, 5 ₁ and 5 ₂ : Connection conductor, 6: Transformer, 1
2 ₁ and 12 ₂ : radiating elements.

Claims (1)

[Claims] 1. A dipole consisting of a metal coating deposited on the surface of a dielectric substrate that is thinner than the radiation wavelength, with a total length of 1/2 or less of the radiation wavelength, and with each outer end bent. A printed dipole antenna comprising a radiating element and a ground conductor made of a metal film deposited on the back surface of the dielectric substrate. 2. A dipole radiation element consisting of a metal coating deposited on the surface of a dielectric substrate that is thinner than the radiation wavelength, with a total length of 1/2 or less of the radiation wavelength, and with a branched and bent portion at each outer end. and a ground conductor made of a metal film deposited on the back surface of the dielectric substrate.