JP3338864B2 - Planar antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simple planar antenna having a structure in which dielectrics having different dielectric constants are formed on the same plane.

[0002]

2. Description of the Related Art Hitherto, a dielectric resonance antenna has a smaller conductor loss than a microstrip antenna and can be made wider or smaller (A. Petosa).
Et al., AP Magazine Vol. 40, no. 3,
p. 35-48 June 1998. reference).

[0003]

However, since the conventional dielectric resonance antenna has dielectrics having different dielectric constants stacked in the thickness direction, the surface becomes uneven, and there is a problem in making the antenna thinner, lighter, and smaller. Was.

[0004] The present invention has been proposed in view of the above,
It is an object of the present invention to provide a planar antenna that can be reduced in thickness, weight, and size.

[0005]

In order to achieve the above object, a planar antenna according to the present invention has a dielectric structure in which a conductor is formed in a lower layer and a second dielectric is incorporated in a first dielectric in an upper layer. Objects are stacked, and the power is supplied to the second dielectric through a power supply path provided in the first dielectric.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings.

The planar antenna proposed by the present invention has a structure in which dielectrics having different dielectric constants are combined on the same plane. In other words, the structure is such that a dielectric having a high dielectric constant is incorporated in the center of a dielectric having a low dielectric constant, and power is supplied by a coplanar power supply line (CPW) and a slot provided in a conductor plate on the back side. .

Since the dielectric and the conductor are each one layer, the thickness, weight and size can be reduced. Since the upper portion is flat, it is possible to realize an antenna having various characteristics by laminating another dielectric or the like. Degree occurs.

[0009]

Embodiment 1 FIG. 1 is a diagram showing the entire structure of a dielectric resonance antenna according to the present invention. The dielectric resonance antenna (planar antenna) 22 is a low dielectric constant (relative dielectric constant: εr1 = 2.15) dielectric 1 (size L × L ×
h), a high permittivity (relative permittivity: εr 2 = 10.
2) The dielectric 2 (size a × b × h) is incorporated. The conductor plate 3 is provided on the back side of the plane where the dielectrics 1 and 2 are combined. The power supply to the dielectric 2 is performed by the coplanar power supply line 50 provided on the conductor plate 3 and the slot 4. This coplanar feeder line 5
0 denotes two feeding slits 5, 6 and a conductor portion 5 between them.
And 1.

The condition under which resonance occurs in the dielectric 2 having a length a and a height h and a high dielectric constant is based on the wavelength λg of the portion of the dielectric 2.
The following equation (1) can be given by using Equation (2) (Haneshi et al., IEICE Technical Report, "A Consideration on Dielectric Cavity Antenna" AP
83-127, p67-70).

(Equation 1) On the other hand, the condition under which resonance does not occur in the outer dielectric 1 is given by the following equation (2) using the wavelength λg1 of the portion of the dielectric 1.

(Equation 2) From equations (1) and (2), the radio wave resonated by the dielectric 2 is
The condition that does not easily propagate to the dielectric 1 is given by the following equation (3).

(Equation 3) In this embodiment, the frequency f =
6.33 GHz, a = 8.75 mm, aspect ratio a /
h = 1.25.

FIG. 2 is a plan view showing in detail a slot of a conductor on the back side of the dielectric resonance antenna. One of the two power supply slits 5 and 6 forming the coplanar power supply line 50 has a first slit 10 having a wide width s ″ and a narrow and narrow portion formed in the middle of the first slit 10. The other slit 9 also has a second slit 9 having a width s ', and the other feeding slit 6 also has a first slit 12 having a wide width s "and a second slit 11 having a narrow width s'. The width of the conductor portion 51 between the first slits 10 and 12 is W ", the width of the conductor portion 51 between the second slits 9 and 11 is W ', and W' is smaller than W". The impedance of the coplanar feeder line 50 is determined by the dielectric constant and thickness h of the surface dielectric, the widths W 'and W "of the conductor portions 51, the widths s" of the first slits 10 and 12, and the second slits. The width is determined by the width s' of 9 and 11, and here, it is set to be 50Ω. The second slits 9 and 11 are respectively connected to the slots 4.

In this embodiment, an experiment was conducted using Teflon (registered trademark) (εr1 = 2.15) as the dielectric 1. In FIG. 2, an experimental result was obtained in which the provision of the protruding portion 7 enabled alignment. Therefore, b, l, s, and x in FIGS. 1 and 2 are selected to have the values shown in Table 1 below, and the antennas (ant1, ant2, ant) are selected.
3, ant4) was prototyped.

[Table 1] Here, b is one side of the dielectric 2, l is the length of the slot 4,
s is the distance between the side of the slot 4 opposite to the part to which the coplanar feeder line 50 is coupled and the protrusion 7, and x is the distance from the end of the first slits 10, 12 having a large width to the dielectric 2. .

FIG. 3 is a diagram showing the measurement results of the return loss of the prototype antenna. The horizontal axis is the frequency of the power supply signal,
The vertical axis is the amount of reflection. Here, the amount of reflection indicates the amount of power that is incident on the coplanar feeder line 50 and is reflected at various junctions and returns. The amount of reflection at the junction is small, and the amount of reflection from the antenna (dielectric 2) is small. If the radiation of is large, the amount of reflection is small. Therefore, it is understood that the radio wave is efficiently radiated from the antenna with the small amount of reflection. As shown in FIG.
For t2 and ant3, the designed frequency is 6.33G.
In the vicinity of Hz, the amount of reflection decreases and almost matches, and ant4
Was not matched. Here, matching means that if the impedance between the lines or between the line and the antenna is different, the feed signal is reflected at the junction (junction), but the impedance is equalized at these junctions. This refers to a state where the power supply signal can be efficiently transmitted first without reflection.

FIG. 4 shows the E-plane at ant1.
It is a figure which shows the measurement result of the directivity of (E plane) and H-plane (H plane). In the figure, the horizontal axis indicates the angle, the vertical axis indicates the amplitude (power, level), the broken line indicates the directivity on the E plane, and the solid line indicates the directivity on the H plane. co
-Pol. (Main polarization component) indicates the directivity of the electric field component in the E plane direction on each of the E and H planes. cross-
pol. (Cross polarization component) indicates the directivity on each of the E and H planes of the electric field line segment in the H plane direction. The directivity calculated based on the above-mentioned literature on the feathers (the IEICE technical report) is also shown in FIG.

From FIG. 4, the dielectric resonance antenna 22 emits more electromagnetic radiation toward the front side (the side where the dielectrics 1 and 2 are exposed) than the back side (the side where the dielectrics 1 and 2 are exposed) as compared with the back side (the side where the dielectrics 1 and 2 are exposed). It can be seen that it is radiated. In the front direction, a cross polarization discrimination of about 20 dB is obtained. E
Since the directivity of the surface is easily affected by the conductor plate 3, the experimental results in FIG. 4 show ripples not seen in the calculation results. The directivity of the H plane is -90 ° to 90 ° in the calculation results.
Has directivity only in the front direction of
The range having a level of 0 dB is from −120 ° to 120 °, and the beam width is wider in the experimental result. The reason for this is presumed to be that the conductive plate (conductive plate) 3 has an infinite width in calculation, but is actually finite. Although the directivity of ant2 and ant3 is almost equal to ant1, ant4 has a narrow beam width on the H plane, and the cross polarization discrimination is low at the design frequency of 6.33 GHz, but is approximately equal at the resonance frequency f = 4.22 GHz. It was 20 dB (FIG. 3).

[0016]

Embodiment 2 When an application using the dielectric resonance antenna 22 as an array element is considered, it is estimated that mutual coupling due to radio waves transmitted along the dielectric occurs due to the presence of the dielectric between the elements. Then, ant1 and ant3 were arranged side by side, and the conductor plates were joined to each other with a copper tape, and the amount of transmission of radio waves between antennas (S12) was measured. FIG. 5 shows how the two dielectric resonance antennas 22 and 23 are arranged. The arrangement in which the power supply lines (coplanar power supply lines) were arranged in parallel was arranged as A, and the arrangement in which the power supply lines faced in a straight line was arranged as B. FIG. 6 shows the measurement results.

FIG. 6 is a diagram showing mutual coupling characteristics in rows A and B. The horizontal axis is the frequency of the supplied signal, and the vertical axis is the transmitted signal intensity. The coupling amount is about 30d for A
B or less, but in line B, there is about 18 dB coupling near the designed resonance frequency. From the above results,
It is presumed that the mutual coupling in the E-plane direction (array B) is stronger than in the H-plane direction (array A). The above conclusion is consistent with the result estimated from the fact that the beam width of the E-plane is wider.

[0018]

Third Embodiment FIG. 7 is a view showing a dielectric resonance antenna according to a third embodiment of the present invention. Since the dielectric resonance antenna 22 in which the dielectric 1 and the dielectric 2 are arranged on the conductor plate 3 described in the first embodiment has a flat upper surface, another dielectric 13 is arranged as shown in FIG. can do. This dielectric resonance antenna 22A hides the antenna portion and has a protective or aesthetic function. Further, by selecting the thickness of the dielectric 13, an improvement in matching and an improvement in directivity gain are realized.

[0019]

Fourth Embodiment FIG. 8 is a diagram showing a dielectric resonance antenna according to a fourth embodiment of the present invention. As shown in the drawing, the dielectric resonance antenna 22B of the fourth embodiment has a directivity 16 when only the dielectric resonance antenna 22 is provided by disposing the dielectric 15 on the dielectric resonance antenna 22. It can be narrowed down as in the directivity 17. By changing the shape of the dielectric 15, the directivity 17 can be variously changed. Also,
A planar antenna that operates even at the resonance frequency of the dielectric 15 can be realized.

[0020]

Embodiment 5 FIG. 9 is a diagram showing a dielectric resonance antenna according to Embodiment 5 of the present invention. The dielectric resonance antenna 22C according to the fifth embodiment has the dielectric 15 according to the fourth embodiment arranged obliquely. That is, as shown in FIG.
By arranging the dielectric 14 at an angle from the vertical and horizontal directions of the dielectric resonance antenna 22 at an angle, the polarization radiated by the dielectric resonance antenna 22 is excited by the dielectric 14 and has an angle with respect to the polarization. The generated polarization is generated. And
The polarization radiated by the dielectric resonance antenna 22 and the polarization radiated by the dielectric 14 are combined, so that a circular polarization or an elliptical polarization can be combined as the whole antenna.

[0021]

Embodiment 6 FIG. 10 is a view showing a dielectric resonance antenna according to Embodiment 6 of the present invention. As shown in FIG. 10, the dielectric resonance antenna 22D according to the sixth embodiment is configured by superposing a dielectric 18 in which a dielectric 19 is incorporated in a dielectric 18 on the dielectric resonance antenna 22. is there. Dielectric 18
And the dielectric 19 have different dielectric constants. The same effects as in the fourth and fifth embodiments can be obtained after eliminating the surface irregularities.

[0022]

Seventh Embodiment FIG. 11 is a view showing a dielectric resonance antenna according to a seventh embodiment of the present invention. As shown in FIG. 11, the dielectric resonance antenna 22E according to the seventh embodiment is configured by disposing a dielectric plate (printed circuit board) 20 on which a metal plate 21 is attached, on the dielectric resonance antenna 22. And
It is possible to realize a planar antenna in which the antenna characteristics of the dielectric resonance antenna 22 and the antenna characteristics of the resonator formed by the metal plate 21 and the conductor plate 3 are combined.

[0023]

According to the present invention, a planar antenna is realized by arranging dielectrics having different dielectric constants on the same plane on a conductor plate. Since the structure is simple, it is possible to reduce the thickness, weight, and size. By changing the dielectric constant of the dielectric or the shape of the dielectric, planar antennas having various characteristics can be realized. In addition, since the top surface of the planar antenna is flat, a dielectric can be stacked on the top, and an antenna having various characteristics such as a multi-frequency antenna can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the entire structure of a planar antenna according to the present invention.

FIG. 2 is an explanatory view showing a feeding portion of the planar antenna according to the present invention in detail.

FIG. 3 is a diagram showing a trial production of a plurality of planar antennas according to the present invention and a measurement result of matching characteristics of each antenna.

FIG. 4 is a graph showing a measurement result of directivity of the planar antenna according to the present invention.

FIG. 5 is a diagram showing a method of arranging two antennas for measuring mutual coupling characteristics in the planar antenna according to the present invention.

FIG. 6 is a diagram showing mutual coupling characteristics when two planar antennas according to the present invention are arranged.

FIG. 7 is a diagram illustrating a planar antenna according to a third embodiment of the present invention.

FIG. 8 is a diagram illustrating a planar antenna according to a fourth embodiment of the present invention.

FIG. 9 is a diagram illustrating a planar antenna according to a fifth embodiment of the present invention.

FIG. 10 is a diagram illustrating a planar antenna according to a sixth embodiment of the present invention.

FIG. 11 is a diagram illustrating a planar antenna according to a seventh embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric 2 Dielectric 3 Conductor plate (conductor) 4 Slot 7 Projection part 13 Dielectric 14 Dielectric 15 Dielectric 16 Directivity 17 Directivity 18 Dielectric 19 Dielectric 21 Metal plate 22 Dielectric resonance antenna 22A Dielectric 22B Dielectric Resonant Antenna 22C Dielectric Resonant Antenna 22D Dielectric Resonant Antenna 22E Dielectric Resonant Antenna 23 Dielectric Resonant Antenna 50 Coplanar Feeding Line 51 Conductor Part 5 Feeding Slit 9 Second Slit 10 First Slit 6 Feeding Slit 11 Second Slit 12 First slit

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-10-51226 (JP, A) JP-A-2001-266646 (JP, A) MICROWAVE AND OPTICAL TECHNOLOGY LE TTERS, Vol. 22, No. 2, 1999, pp. 96-97 IEICE Technical Report, MW 95-111 (58) Fields investigated (Int. Cl. ⁷ , DB name) H01Q 13/00 H01P 7/10 H01Q 1/40 H01Q 21/06

Claims (6)

(57) [Claims] 1. A dielectric structure formed by incorporating a conductor portion in a lower layer and a second dielectric material in a first dielectric material in an upper layer, and forming the first dielectric material by a power supply path provided in the first dielectric material. 2. A planar antenna, characterized in that it feeds a second dielectric. 2. The planar antenna according to claim 1, wherein the feed line is a coplanar feed line. 3. The planar antenna according to claim 1, wherein a plurality of the planar antennas are arranged on the same plane. 4. The planar antenna according to claim 1, wherein a third dielectric is laminated on the planar antenna. 5. The planar antenna according to claim 1, wherein the dielectric structure is laminated on the planar antenna. 6. The planar antenna according to claim 1, wherein a metal plate is laminated on the planar antenna.