JP3280716B2 - Microstrip 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 microstrip antenna having a wide frequency characteristic.

[0002]

2. Description of the Related Art A conventional microstrip antenna is
As shown in FIG. 10, a single dielectric plate 3 having a constant relative dielectric constant is sandwiched between a plurality of radiating microstrip patch elements 1 facing each other and a common ground conductor plate 2, and a feed circuit 4 The output of each radiating microstrip patch element 1 was synthesized and led to the feeding point (EP). In this case, the antenna gain has a narrow band as shown in FIG. 11 and the antenna voltage standing wave ratio (hereinafter, VSW).
R) was also a narrow band having a narrow frequency bandwidth as shown in FIG.

[0003]

As described above, the conventional microstrip antenna has a problem that the frequency characteristics of the antenna characteristics are narrow and the application range is limited.

An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a microstrip antenna having a wide frequency characteristic of the antenna.

[0005]

According to the present invention, in order to achieve the above object, at least two or more dielectric plates having different relative dielectric constants stacked on each other are used, and the thickness of each dielectric plate is reduced. The ratio is changed so that the total thickness when a plurality of dielectric plates are laminated is constant. At least two or more radiating microstrip patch elements, and the radiating microstrip A power supply circuit for synthesizing and branching the output of the patch element is provided, and the entire back surface is configured as a common ground conductor plate.

[0006]

According to the present invention, the relative permittivity of the dielectric laminate is equivalently changed in the direction of the change of the thickness ratio, and the resonance frequency of the radiating microstrip patch element is changed with the change of the relative permittivity. By changing the frequency and combining them in the power supply circuit, a wider frequency band is realized.

[0007]

1 is a perspective view of a microstrip antenna according to a first embodiment of the present invention, and FIG. 2 is a sectional view of the antenna. FIG. 2A shows a cross section in the yz direction,
(B) shows a cross section in the xz direction. 1 and 2, 11 (11a, 11b, 11c, 11d), 11 '
(11'a, 11'b, 11'c, 11'd) are radiating microstrip patch elements, 12 is a ground conductor plate, 13
Is a first dielectric plate, 14 is a second dielectric plate, and 15 is a power supply circuit. The radiating microstrip patch element 11 and the feeding circuit 15 are provided on both surfaces of each of the dielectric plates 13 and 14.
A conductive plate or a conductive layer of gold, silver, copper, aluminum or the like is laminated by thermocompression bonding or an adhesive or the like, and is formed on one surface thereof by means such as etching. Dielectric plates 13, 14
May be composed of two or more layers.

In the first embodiment, the first dielectric plate 13 and the second dielectric plate 1 having different relative dielectric constants are different from each other.
4 is d1 to d in the case of the first dielectric plate 13.
2, d3, and in the case of the second dielectric plate 14, from d4 to d5.
It changes to d6 linearly, stepwise or in a curve (linearly in the above embodiment), and its d1 and d4, d2 and d
5, so that the sum of d3 and d6 is always constant (d = d '). Further, with the first dielectric plate 13 and the second dielectric plate 14 interposed therebetween, radiating microstrip patch elements 11 and 11 'are provided on the upper surface, and the ground conductor plate 12 is provided on the lower surface.
A feeding circuit 15 is provided on the same surface as the radiating microstrip patch elements 11 and 11 '. In this case, the radiating microstrip patch element 11 comprises two dielectric plates 13, 1
It is necessary to have at least two or more in the thickness change direction of No. 4.

By the way, in general, the thickness d1 'of the first layer and the relative permittivity e1, the thickness d2' of the second layer and the relative permittivity e2 are two.
The relationship between the equivalent relative permittivity e and the dielectric thickness ratio d1 ′ / (d1 ′ + d2 ′) when two dielectric plates are stacked is as follows:
FIG. 7 shows that the equivalent relative permittivity e changes with a change in the ratio of the dielectric plate thickness. From this, as shown in the cross-sectional view of FIG. 2, when the first dielectric plate 13 and the second dielectric plate 14 having different relative dielectric constants are stacked, the equivalent relative dielectric constant in the direction of change of each dielectric thickness is obtained. It can be seen that the rate e also changes. With the change of the equivalent relative permittivity e, the radiating microstrip patch elements 11a, 11b, 11 of substantially the same dimensions arranged in the direction of change of the dielectric thickness in FIG.
The equivalent relative dielectric constants near the lower surfaces of c and 11d are e11 and e1.
2, e13 and e14, and the width dimensions of the radiating microstrip patch elements 11a, 11b, 11c and 11d are shown in FIG.
, The resonance frequency f is approximately expressed by the following equation (1). f = C0 / 2 × a (e) ^0.5 (1) where C0 is the speed of light. From the equation (1), the equivalent relative permittivity e
Changes to e11, e12, e13, e14, the radiation microstrip patch elements 11a, 11b, 11
The resonance frequencies of c and 11d are also as follows : f1 = C0 / 2 × a (e11) ^0.5 f2 = C0 / 2 × a (e12) ^0.5 f3 = C0 / 2 × a (e13) ^0.5 f4 = C0 / 2 × a (e14) ) It changes to ^0.5 . FIG. 3 shows this, where the horizontal axis represents the resonance frequency f and the vertical axis represents the antenna gain G, the resonance frequencies f are f1, f2, f3, and f4, respectively. Each radiating microstrip patch element 11 in this state is connected to a parallel as shown in FIG. 1, by combining with the feeder circuit 15, antenna gain seen across the antenna as shown in FIG. 4 is a wide band. Similarly, the antenna VSWR includes radiating microstrip patch elements 11a, 11b, 11
resonance frequencies f1, f2, which are best for c and 11d
f3, f4 becomes as shown in FIG. 5, they were paralleled, if synthesized in the feeder circuit 15, an antenna VSWR after synthesis becomes wide band as shown in FIG.

FIG. 8 is a sectional view of a microstrip antenna according to a second embodiment of the present invention, in which the thicknesses of two dielectric plates 23 and 24 having different relative dielectric constants are changed in a curved manner. The case is shown, and the plurality of dielectric plates 2 are shown.
It has a plurality of radiating microstrip patch elements 21 and a ground conductor plate 22 provided so as to face each other with 3 and 24 interposed therebetween. Such a configuration also has the same operation and effect.

FIG. 9 is a sectional view of a microstrip antenna according to a third embodiment of the present invention, in which the thicknesses of two dielectric plates 33 and 34 having different relative dielectric constants are changed stepwise. In this case, a plurality of radiating microstrip patch elements 31 and a ground conductor plate 32 are provided to face each other with the plurality of dielectric plates 33 and 34 interposed therebetween.
And Such a configuration also has the same operation and effect.

[0012]

According to the present invention, as is apparent from the above embodiment, the thickness of the dielectric plates having different relative dielectric constants stacked on each other is changed, and a plurality of radiating microstrip patches are formed in the changing direction of the thickness. By providing the elements and combining their outputs, the antenna gain and the antenna VSWR, which are the antenna characteristics of the entire antenna, can be widened.

[Brief description of the drawings]

FIG. 1 is a perspective view of a microstrip antenna according to a first embodiment of the present invention.

2A is a cross-sectional view of the antenna in the yz direction. FIG. 2B is a cross-sectional view of the antenna in the xz direction.

FIG. 3 is a diagram showing resonance frequency characteristics of individual radiation microstrip patch elements in the antenna.

FIG. 4 is an antenna gain-frequency characteristic diagram when a radiation microstrip patch element in the antenna is combined with a feed circuit.

FIG. 5 is a diagram showing an antenna VSWR frequency characteristic of each of the radiation microstrip patch elements in the antenna.

FIG. 6 is an antenna VSWR when the radiating microstrip patch element in the antenna is combined with a feed circuit.
Frequency characteristic diagram

FIG. 7 is a characteristic diagram showing a relationship between a substrate thickness ratio and an equivalent relative dielectric constant when two dielectric plates having different relative dielectric constants are stacked.

FIG. 8 is a sectional view of a microstrip antenna according to a second embodiment of the present invention.

FIG. 9 is a sectional view of a microstrip antenna according to a third embodiment of the present invention.

10A is a perspective view of a microstrip antenna in a conventional example, and FIG. 10B is a cross-sectional view of the antenna.

FIG. 11 is an antenna gain frequency characteristic diagram of the antenna.

FIG. 12 is a diagram showing an antenna VSWR frequency characteristic of the antenna.

[Explanation of symbols]

 11, 21, 31 Radiation microstrip patch element 12, 22, 32 Ground conductor plate 13, 23, 33 First dielectric plate 14, 24, 34 Second dielectric plate 15 Feed circuit FP Feed point

Claims (2)

(57) [Claims] 1. A plurality of dielectric plates having different relative dielectric constants laminated on each other, and a ground conductor plate common to a plurality of radiating microstrip patch elements provided to face each other with the plurality of dielectric plates interposed therebetween. Wherein the plurality of dielectric plates have respective thicknesses that are not constant, and the plane direction is the xy direction,
When the thickness direction is the z direction, the thickness in the z direction changes with the change in the x or y direction, and the common ground conductor plate
The thickness of the center of the first dielectric plate on the side is in the x or y direction
A microstrip antenna having a thickness greater than the thickness at both ends of the microstrip antenna and being stacked so that the total thickness when the plurality of dielectric plates are stacked is constant. 2. At least two or more radiating microstrip patch elements of substantially the same size are provided on the upper surface of a plurality of dielectric plates in the direction in which the thickness of the dielectric plate changes, and are flush with the radiating microstrip patch elements. 2. The microstrip antenna according to claim 1, further comprising a feeder circuit.