JPH09270628A - Plane antenna and radio equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a post-stage filter by using a high dielectric constant material with a special specific dielectric constant for a dielectric board so as to make the plane antenna small in size, making an operating frequency band of the plane antenna narrow and providing an out-band attenuation characteristic to the plane antenna itself thereby adding a filter function to the antenna apparently. SOLUTION: In the plane antenna formed by arranging thin film conductors 2, 3, 4 onto a dielectric board 1, a high dielectric constant material whose specific dielectric constant εr is 10 or over is employed for the dielectric board 1 so as to make the operating frequency band narrow thereby simplifying a filter of a post stage. The more the specific dielectric constant εr is increased, the narrower the operating frequency band becomes, and then the more the specific dielectric constant εr is increased, the smaller the antenna area for the operating frequency band is. For example, when the specific dielectric constant εr is selected to be 10 or over, a transmission antenna 13a and a reception antenna 13b themselves have a filter function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar antenna and a wireless device suitable for use in, for example, a mobile phone.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 3, a mobile phone transmits a transmission signal of, for example, 824 to 849 MHz from a transmission side block 10 to a base station via an isolator 11, a transmission filter of a transmission / reception filter 12 and an antenna 13. And from the base station, for example, 869 to 894 MHz
The reception signal of is supplied to the reception side block 14 via the antenna 13 and the reception filter of the transmission / reception filter 12.

Conventionally, a whip type or helical type bar antenna is mounted as the transmitting / receiving antenna 13. Since this bar antenna has a wide frequency band to be used, there is an advantage that only one antenna is required even if the transmission frequency is different from 824 to 849 MHz and the reception frequency is different from 869 to 894 MHz as described above.

Further, there is also one in which a planar antenna which is an inverted F-shaped antenna composed of a radiation conductor composed of a thin film conductor, a ground conductor and a short-circuit conductor is used on a dielectric substrate having a relative permittivity εr of 4 to 5. Proposed.

[0005]

In such a conventional radio telephone, the attenuation amount at a certain frequency, for example, 849 MHz after passing through the reception filter of the transmission / reception filter 12 is, for example, as shown by the one-dot chain line c in FIG. -30 dB is required, and this conventional antenna 13 has a wide operating frequency and its attenuation characteristic is almost zero as shown by the broken line a in FIG. 5, and only the reception filter of this transmission / reception filter 12 is shown by the solid line b in FIG. Therefore, it is necessary to attenuate it by -30 dB.

Such a filter having a steep attenuation characteristic for attenuating −30 dB can be composed of, for example, a multi-stage dielectric filter, but it has a disadvantage that it is large in size and expensive.

The performance of the filter is mainly discussed in terms of insertion loss and out-of-band attenuation band characteristics. However, this filter having a steep attenuation characteristic for attenuating −30 dB requires insertion loss because the elements must be configured in multiple stages. Is increased and the performance of the filter is deteriorated.

In view of the above point, the present invention has an object to simplify the filter at the latter stage of the antenna and to reduce the size and cost.

[0009]

A planar antenna of the present invention is a planar antenna in which a thin film conductor is arranged on a dielectric substrate,
A high dielectric constant material having a relative permittivity εr of 10 or more is used as this dielectric substrate, the frequency band used is narrowed, and the function of a filter is apparently added to simplify the subsequent filter. is there.

According to the present invention, since the high dielectric constant material having the relative dielectric constant εr of 10 or more is used for the dielectric substrate, the planar antenna is downsized and the frequency band used is narrowed. Since the device itself has the out-of-band attenuation characteristic, a filter in the latter stage may be unnecessary or may be a simple filter having a gentle attenuation characteristic depending on the system design.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the planar antenna and the wireless device of the present invention will be described below with reference to the drawings.

The wireless device according to this example also has a configuration as shown in FIG.
The frequency band from the transmission side block 10 is, for example, 824 to 8.
The transmission signal of 49 MHz is transmitted to the base station via the isolator 11, the transmission filter of the transmission / reception filter 12 and the antenna 13, and the reception signal of the frequency band from the base station, for example, 869 to 894 MHz is transmitted to the antenna 13 and the transmission / reception filter 12. The signal is supplied to the reception side block 14 via the reception filter of the above.

The transmitting side block 10 and the isolator 1
1 and the receiving-side block 14 each have a well-known configuration similar to the conventional one.

In this example, the antenna 13 is shown in FIG.
A planar antenna as shown in is used. In FIG.
Reference numeral 1 denotes a dielectric substrate. As the dielectric substrate 1, magnesium titanate (MgTiO ₃ ) which is a high dielectric constant material having a relative dielectric constant εr of 20, for example, is used.

The size of this dielectric substrate 1 is, for example, lateral d ₁
Was 40 mm, the vertical d ₂ was 30 mm, and the height d ₃ was 5 mm.

On the upper surface of the dielectric substrate 1, a transmission side radiation conductor 2 and a reception side radiation conductor 3 each made of a thin film conductor and having a predetermined size.
Are separated from each other for a predetermined period of time and attached.

The size of each of the transmission side radiation conductor 2 and the reception side radiation conductor 3 is such that the center frequency of the transmission signal is 836.5.
It has a size corresponding to MHz and the center frequency of the received signal of 881.5 MHz.

A ground conductor 4 made of a thin film conductor is deposited over the entire lower surface of the dielectric substrate 1, and the transmission side radiation conductor 2 and the reception side radiation conductor 3 are respectively disposed between the grounding conductor 4 and the transmission side. The short-circuit conductor 5 and the reception-side short-circuit conductor 6 are provided to form a planar transmission antenna 13a and reception antenna 13b which are microstrip inverted F antennas.

In this case, the relative permittivity εr of the transmitting antenna 13a and the receiving antenna 13b which are planar antennas.
4 and the bandwidth are as shown in FIG. 4. When the relative permittivity εr of the dielectric substrate 1 of the receiving antenna 13b is 20, as shown in FIG.
B is attenuated. Further, as shown in FIG. 4, when the relative permittivity εr of this dielectric substrate 1 is 5, the blocking frequency is -5.
When the relative dielectric constant εr is set to 90, the attenuation is -15 dB at this blocking frequency.

As is clear from FIG. 4, the higher the relative permittivity εr of the dielectric substrate 1 used, the narrower the frequency band used (for example, the bandwidth of the antenna gain drop by 3 dB) and the like. As is well known, the higher the relative permittivity εr of the dielectric substrate 1, the smaller the area of the antenna in the frequency band used.

That is, when the relative permittivity εr of the dielectric substrate 1 of the transmitting antenna 13a and the receiving antenna 13b is increased to, for example, 10 or more, the transmitting antenna 13a is
And the receiving antenna 13b itself has a filter function.

In this example, the output signal output terminal of the transmission / reception filter 12 is connected to the transmission side radiation conductor 2 of the transmission antenna 13a, and the reception signal input terminal of the transmission / reception filter 12 is connected to the reception side radiation conductor of the reception antenna 13b. Three
So that it is connected to

Further, in this example, the receiving antenna 13b
The frequency characteristic of the blocking frequency is 8 as shown by the broken line a ₀ in FIG.
Since it is attenuated by -10 dB at 49 MHz, this blocking frequency 849 after passing through the reception filter of the transmission / reception filter 12 is 849.
When the attenuation amount at MHz is required to be, for example, -30 dB as indicated by the one-dot chain line c ₀ in FIG. 6, the reception filter of the transmission / reception filter 12 is -20 dB at the stop frequency 849 MHz as shown by the solid line b ₀ in FIG. Anything that attenuates may be used.

Therefore, as the reception filter of the transmission / reception filter 12, a simple filter having a loose attenuation characteristic can be used, and a small and inexpensive filter can be used. Further, since the number of stages of elements constituting the filter may be small, the insertion loss is reduced accordingly, and the filter performance is improved.

The transmission filter of the transmission / reception filter 12 is the same as the above-mentioned reception filter.

According to the transmitting antenna 13a and the receiving antenna 13b of this example, since the dielectric substrate 1 is made of a high dielectric constant material having a relative permittivity εr of 20, the transmitting antenna 1
3a and the receiving antenna 13b and the planar antenna which is an inverted F antenna are downsized, and the use frequency band of the transmitting antenna 13a and the receiving antenna 13b is narrowed, and the transmitting antenna 13a and the receiving antenna 13b are
Since it itself has the out-of-band attenuation characteristic, it has an apparent filter function, and there is an advantage that the transmission filter and the reception filter in the subsequent stage can be simplified.

Further, since the radio telephone according to the present embodiment uses the above-mentioned transmitting antenna 13a and receiving antenna 13b, two antennas are used. The size is, for example, 40 mm in width d ₁ and 30 mm in length d _2. Height d ₃ is 5m
m, the size is relatively small, and a simple filter having a loose attenuation characteristic can be used as the transmission filter and the reception filter used in the transmission / reception filter 12, so that a small and inexpensive filter can be used, and the wireless telephone can be made small and low. There is a benefit that can be priced.

In the example shown in FIG. 1, the transmitting antenna 13a and the receiving antenna 13b are provided on the single dielectric substrate 1, but the transmitting antenna 13 as shown in FIG.
Of course, the a and the receiving antenna 13b may be provided separately. It can be easily understood that the same effect as described above can be obtained even if the transmitting antenna 13a and the receiving antenna 13b are separately provided as shown in FIG.

Further, in the above-mentioned embodiment, a high dielectric constant material having a relative permittivity εr of 20 is used as the dielectric substrate 1. However, if the relative permittivity εr is 10 or more, the same operation as in the above-mentioned embodiment is performed. The effect is obtained.

Further, in the above embodiment, the transmission / reception filter 1
As the receiving filter of No. 2, the attenuation characteristic of the stop frequency is -20.
Although a dB filter is used, the attenuation characteristic of this reception filter is determined by the attenuation characteristic of the reception antenna 13b to be used, and the latter filter can be unnecessary depending on the system design.

Further, in the above-mentioned embodiment, the example in which the present invention is applied to the inverted F antenna using the dielectric substrate has been described, but it goes without saying that the present invention can be applied to other planar antennas using the dielectric substrate. is there.

Further, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0033]

According to the planar antenna of the present invention, since the high dielectric constant material having the relative permittivity εr of 10 or more is used for the dielectric substrate, the planar antenna can be downsized and the planar antenna Since the frequency band used is narrowed and the planar antenna itself has the out-of-band attenuation characteristic, it has an apparent filter function and has the advantage of simplifying the subsequent filter.

Since the radio device of the present invention uses the above-mentioned planar antenna, the antenna can be miniaturized, and a simple filter having a loose attenuation characteristic can be used as a subsequent filter, so that a small and inexpensive filter can be used. As a wireless device, there is an advantage that it can be downsized and reduced in price.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing another example of the planar antenna according to the present invention.

FIG. 3 is a configuration diagram showing an example of a wireless telephone.

FIG. 4 is a diagram for describing the present invention.

FIG. 5 is a diagram used for explanation.

FIG. 6 is a diagram for describing the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 dielectric substrate, 2 transmission side radiation conductor, 3 reception side radiation conductor, 4 grounding conductor, 5 transmission side short-circuit conductor, 6 reception side short-circuit conductor, 10 transmission side block, 11 isolator, 12 transmission / reception filter, 13a transmission antenna, 13
b reception antenna, 14 reception blocks

Claims (2)

[Claims] 1. A planar antenna in which a thin film conductor is arranged on a dielectric substrate, wherein a high dielectric constant material having a relative permittivity εr of 10 or more is used as the dielectric substrate, and a usable frequency band is narrowed, and apparently. A planar antenna characterized by adding the function of a filter so that the subsequent filter can be simplified. 2. A wireless device comprising the planar antenna according to claim 1.