JPH05327331A - Printed antenna - Google Patents

Abstract

PURPOSE:To provide a printed antenna which enlarges the band of an impedance characteristic and reduces the inserting loss of a matching means. CONSTITUTION:For this printed antenna, a ground conductor layer 3 is formed on the lower face by using a printed wiring board, and antenna conductor layers 1 to be apex part capacity loading boards 8 are formed on both sides of the upper face. A parallel resonance circuit composed of an inductance conductor part 6 and a capacitance conductor part 7 is provided on the upper face of the printed wiring board between the antenna conductor layers 1 and 1 on both sides and integrated with an antenna element part. Feeding to a pair of feeding points parallelly connecting the parallel resonance circuit is performed by feeding conductors 4 and 4 passed from patterns 1a and 1a integrally linked to the antenna conductor layers 1 and 1 through a dielectric layer 2 and ground conductor layer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small printed antenna suitable for incorporation in mobile communication equipment.

[0002]

2. Description of the Related Art A printed antenna is a microstrip type antenna using a printed wiring board having good reproducibility of electric characteristics by a photo-etching technique, and is composed of one multilayer copper clad laminated printed wiring board. Printed antennas are widely used in mobile communication devices because they are small in size, have uniform characteristics, and are suitable for mass production.

Such a printed antenna is basically composed of an antenna conductor layer 1, a dielectric layer 2, a ground conductor layer 3 and a feeding conductor 4, as shown in FIGS. The printed antenna shown in FIG. 2 is an example of a printed antenna having a non-grounded antenna element portion. In the illustrated example, the feed conductors 4 and 4 formed of through holes or feed pins are provided from the antenna conductor layer 1 to the dielectric layer. 2. The ground conductor layer 3 is provided so as to penetrate therethrough.

The printed antenna shown in FIG. 10 is an example of an antenna having a grounded antenna element portion. Further, FIG. 11 shows an example of a printed antenna having a shortened inverted-F antenna element portion. This printed antenna has an antenna conductor layer 3 and an earth conductor layer 3 in addition to the feeding conductor 4.
This is different from the antenna shown in FIG. 10 in that a ground conductor 5 for electrically connecting and is added by a hole or a conductor pin.

In the case of any of the above printed antennas,
An example in which an inductance element and a capacitance element are loaded in the antenna element section is shown. With these loads,
Although the outer shape of the antenna is small, the antenna characteristic has a narrow band. On the other hand, the printed antenna has good reproducibility of electric characteristics by the photo-etching technique and has little variation, so that it can be put into practical use even in a slightly narrow band, and is often loaded as described above.

However, in recent years, the demand for mobile communication has increased, the frequency allocation bandwidth has expanded, and in the case of antennas for mobile phones, in particular, there has been an increasing demand for a wider band in addition to the miniaturization. Conventionally, as a means for widening the antenna bandwidth,
The susceptance compensation method has been used. This susceptance compensation method will be briefly described. The frequency locus of the normal antenna impedance is similar to the impedance locus of the series resonant circuit at frequencies near the resonance point. 12
(A) shows the frequency characteristic of the reactance component of the antenna impedance, and it is necessary to cancel the capacitance component on the low frequency side centering on the resonance frequency f ₀ .

FIG. 12B is a diagram showing the frequency characteristic of the reactance component of the parallel resonant circuit which resonates at the same frequency f _{0 as the} antenna. In this case, the resonance frequency f ₀
The lower frequency side exhibits an inductance component, and the higher frequency side exhibits a capacitance component. Therefore, it is understood that the reactance component can be canceled by inserting the parallel resonance circuit in parallel with the feeding point of the antenna. For example, when f ₁ is selected as the representative frequency on the low frequency side and f ₂ is selected as the representative frequency on the high frequency side, and Q of the parallel resonant circuit is selected so that the absolute values of the reactances are equal and the signs are opposite at each frequency. good. In this case, FIG.
Since the reactances in (a) and FIG. 12 (b) are combined in parallel, they may be converted into susceptance components (reciprocals), added, and converted into reactance components again.
FIG. 12C shows the synthesis result. It can be seen that the reactance component after synthesis has a low value over a sufficiently wide band, and has a wide band.

[0008]

Conventionally, the above matching circuit portion has been added to the circuit portion separately from the antenna element portion. Therefore, there is a drawback in that after the antenna element is manufactured, it is necessary to adjust the total combination with the circuit section. In addition, since the circuit part is generally of low Q design, unlike the antenna element part, a substrate material with a large dielectric loss is often used. In such a case, however, the loss in the circuit part for wide band matching is low. There was a flaw that occurred.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to broaden the impedance characteristic band and to cope with the multichannel communication.
(EN) A printed antenna having improved manufacturing yield and reduced insertion loss of matching means.

[0010]

In order to achieve the above object, the invention of claim 1 provides a ground conductor layer on one surface of a printed wiring board having a low dielectric loss and the other surface of the other is opposed to the ground conductor layer. In a printed antenna in which an antenna conductor layer is provided on a surface, and at least a feeding conductor that penetrates from the antenna conductor layer to the earth conductor layer and reaches the antenna back surface is provided, a matching formed by a parallel resonant circuit in a part of the antenna conductor layer. Means is provided, and at least a part of the matching means is electrically connected to a connecting portion between the antenna conductor layer and the feeding conductor.

Even when the dipole antenna element is formed on the antenna conductor layer and the parallel resonance circuit is connected in parallel to the pair of feed conductors feeding the dipole antenna element, the parallel resonance circuit is connected in parallel. Also, as in the invention of claim 3, a parallel resonance circuit in which a monopole antenna element is formed on the antenna conductor layer and one end is grounded to one feed conductor for feeding the monopole antenna element The ends may be connected.

[0012]

According to the structure of the present invention, in the printed antenna composed of only the antenna element portion, the matching means composed of the parallel resonant circuit is provided in a part of the antenna conductor layer, and the matching means is provided. Since at least a part of the matching means is electrically connected to the connection portion with the feeding conductor, the antenna element portion and the matching means are integrated with each other, and the impedance characteristic band of the antenna element portion itself can be widened,
As a result, it becomes possible to support multiple channels,
Moreover, it is not necessary to adjust the combination of the antenna element parts after manufacturing, and the manufacturing yield is improved.

Further, since the matching means is provided on the printed wiring board in which the dielectric loss of the antenna element portion is low, the insertion loss of the matching means is small and the antenna gain is not reduced.

[0014]

EXAMPLES The present invention will be described below with reference to examples. (Embodiment 1) In this embodiment, a non-grounded (dipole) antenna is constructed as shown in FIG. 1, a printed wiring board having double-sided copper foil laminated is used, and a ground conductor layer 3 is provided on the lower surface.
An antenna conductor layer 1 serving as the top capacitive loading plate 8 is formed on both sides of the upper surface, and the inductance conductor is formed by a zigzag-shaped conductor on the upper surface of the printed wiring board between the antenna conductor layers 1 and 1. A parallel resonance circuit is provided which includes the portion 6 and the capacitance conductor portion 7 formed of a comb-shaped conductor. This parallel resonance circuit constitutes a matching means, and is electrically connected in parallel between a pair of feeding points in the electrically equivalent circuit shown in FIG. The feeding to the feeding point is performed from the patterns 1a and 1a integrally connected to the antenna conductor layers 1 and 1 by the feeding conductors 4 and 4 formed of through holes or feeding pins penetrating the dielectric layer 2 and the earth conductor layer 3. ..

(Embodiment 2) In this embodiment, a ground type (monopole type) antenna is constructed as shown in FIG.
A grounded conductor layer 3 is formed on the lower surface and an antenna conductor layer 1 serving as the top capacitance loading plate 12 is formed on one side of the upper surface using a printed wiring board having double-sided copper foil laminated.
A parallel resonance circuit including an inductance conductor portion 11 and a capacitance conductor portion 10 is provided on the upper surface of the side of the printed wiring board. One end of the parallel resonance circuit is electrically connected to the ground conductor layer 3 through a ground conductor 9 formed of a ground pin or a through hole penetrating the dielectric layer 2, and the other end is integrally connected to the antenna conductor layer 1. The pattern 1a is connected near the feeding point. The power supply to the power supply point is performed from the pattern 1a through the dielectric layer 2 and the ground conductor layer 3 through the through hole or the power supply conductor 4 including a power supply pin.
By. FIG. 4 shows an electrically equivalent circuit of this embodiment.

(Embodiment 3) In this embodiment, an inverted F-type antenna is constructed as shown in FIG. 5, a printed wiring board having double-sided copper foil laminated is used, and a ground conductor layer 3 is provided on the lower surface. An antenna conductor layer 1 to be a top capacitance loading plate 15 is formed on one side of the upper surface, and an inductance conductor portion 13 also serving as a part of the antenna element portion and a capacitance are formed on the upper surface of the printed wiring board on the side of the antenna conductor layer 1. A parallel resonant circuit including the conductor portion 14 is provided. This parallel resonant circuit
As shown in the electrical equivalent circuit of FIG. 6, the antenna conductor layer 1
Is inserted and connected between the grounding point of the pattern 1a integrally connected to and the feeding point.

The ground conductor layer 3 and the ground point are connected by a ground conductor 5 consisting of a through hole penetrating the dielectric layer 2 or a ground pin, and this ground conductor 5 serves as an inductance component. Further, the power feeding to the power feeding point is performed from the pattern 1a through the through hole penetrating the dielectric layer 2 and the ground conductor layer 3 or the power feeding conductor 4 formed of the power feeding pin as in the first and second embodiments.

In the structure of this embodiment, the size of the antenna element portion is 35 × 15 × 5 mm, and the impedance Smith chart and VSW when the printed antenna having the dielectric constant of 3.5 and the design frequency of 820 MHz is formed.
The R characteristics are as shown in FIGS. 7 and 8, respectively. That is, as in the embodiment, the bandwidth before widening the bandwidth without the matching means composed of the parallel resonant circuit provided integrally is 19 at VSWR = 2.
However, in the case of the present embodiment in which the matching means composed of the parallel resonant circuit is provided, as shown in FIG.
= 2, a double bandwidth of 40 MHz was achieved. Further, the antenna gain is plus 2.3 dBi, which is about 0.3 dB less than that before the wide band.

In each of the first to third embodiments, the parallel resonance circuit constituting the matching means is provided in the same plane as the antenna conductor layer 1, but a three-layer printed wiring board is used in the inner layer. You may make it form a parallel resonance circuit,
The present invention is not limited to the configurations of Examples 1 to 3.

[0020]

According to the present invention, a matching means composed of a parallel resonant circuit is provided in a part of the antenna conductor layer, and at least a part of the matching means is electrically connected to the connecting portion between the antenna conductor layer and the feeding conductor. Since the antenna is connected to the printed antenna, the antenna element part and the matching means are integrated in the printed antenna, which is conventionally composed of only the antenna element part, and the antenna element part itself can widen the impedance characteristic band, resulting in multi-channels. In addition, since the antenna element and the matching means are integrated, design evaluation is easy, and there is no need for post-fabrication combination adjustment, which improves the manufacturing yield. Moreover, since the matching means is provided on the printed wiring board in which the dielectric loss of the antenna element is low, the insertion loss of the matching means is small and the antenna gain is small. There is an effect that does not decrease.

[Brief description of drawings]

FIG. 1 is a perspective view of a first embodiment of the present invention.

FIG. 2 is an electrical equivalent circuit diagram of the above.

FIG. 3 is a perspective view of a second embodiment of the present invention.

FIG. 4 is an electrical equivalent circuit diagram of the above.

FIG. 5 is a perspective view of a third embodiment of the present invention.

FIG. 6 is an electrical equivalent circuit diagram of the above.

FIG. 7 is an explanatory diagram showing an impedance Smith chart of the specific example of the above.

FIG. 8 is a VSWR characteristic diagram of a specific example of the above.

FIG. 9 is a perspective view of a conventional example.

FIG. 10 is a perspective view of another conventional example.

FIG. 11 is a perspective view of another conventional example.

FIG. 12 is a diagram illustrating the principle of the present invention.

[Explanation of symbols]

 1 Antenna Conductor Layer 1a Pattern 2 Dielectric Layer 3 Earth Conductor Layer 4 Feeding Conductor 6 Inductance Conductor 7 Capacitance Conductor

Claims (3)

[Claims] 1. A printed wiring board having a low dielectric loss is provided with a ground conductor layer on one surface and an antenna conductor layer is provided on the other surface facing the ground conductor layer, and at least:
In a printed antenna provided with a feeding conductor that extends from the antenna conductor layer to the back surface of the antenna through the earth conductor layer, a matching means formed of a parallel resonance circuit is provided in a part of the antenna conductor layer, A printed antenna, wherein at least a part of the matching means is electrically connected to a connecting portion with the power feeding conductor means. 2. A dipole antenna element is formed on an antenna conductor layer, and a parallel resonant circuit is connected in parallel to a pair of feeding conductors feeding the dipole antenna element. Printed antenna as described. 3. A monopole antenna element is formed on an antenna conductor layer, and one feed conductor feeding the monopole antenna element is connected to the other end of a parallel resonance circuit whose one end is grounded. Characterized printed antenna.