JPH0794934A - Compact plane patch antenna - Google Patents

Abstract

PURPOSE:To provide a compact plate antenna having high infrequency temperature characteristics and high reliability by using magnesium titanate ceramic having comparatively high dielectric constant as a main material for a dielectric material and adding the proper quantity of lithium niobate, alumina, manganese oxide, etc., indivisually or their combin at ions to the main material to mold the antenna. CONSTITUTION:The compact plane patch antenna is provided with dielectric 2', a radiation electrode 3 laminated on one face of the dielectric 2' and a ground conductor 4 laminated on the other face of the dielectric 2' in parallel with the electrode 3. The dielectric constant of the dielectric 2' is set up to 18 to 20. When the main component of the dielectric 2' is constituted of magnesium oxide, calcium oxide and titanium oxide and the composition ratio of magnesium oxide to calcium oxide is 95:5, 0.5 to 1.0Wt% lithium niobate, 0.1 to 0.5Wt% alumina and 0.3 to 1.0 Wt% manganese oxide are contained in ceramics. The temperature coefficient of resonance frequency of the antenna is + or -15ppm/ deg.C and the dispersion of resonance frequency is + or -5 MHz.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small planar patch antenna used in a global positioning system (GPS) or the like.

[0002]

2. Description of the Related Art In recent years, with the development of mobile communication and the like, a small GPS device has been developed, and accordingly, a GPS antenna has been required to be further downsized.

A conventional small planar patch antenna will be described below. FIG. 3 is a perspective view of a general small planar patch antenna. 1 is a conventional small planar patch antenna,
Reference numeral 2 is a dielectric made of resin or ceramic material, 3 is a radiation electrode formed on one surface of the dielectric 2, 4 is a ground conductor formed on the other surface of the dielectric 2, and 5 is a feeding point.

With respect to the small planar patch antenna 1 having the above-mentioned structure, the relationship between the dielectric 2 and the size of the antenna will be described below. As the material of the dielectric 2, a resin-based dielectric 2 such as Teflon or epoxy, or a ceramic dielectric 2 having a low relative dielectric constant such as forsterite or alumina is used. The relative permittivity of 2 is about 3 to 10. The resonance frequency and relative permittivity in such a small planar patch antenna 1,
The relationship with the size of the radiation electrode 3 is shown in (Equation 1).

[0005]

[Equation 1]

As is clear from (Equation 1), in the conventional small patch antenna 1, since the relative permittivity is on the denominator side of the equation, the size of the radiation electrode 3 is larger than the relative permittivity of the dielectric 2. Dependent.

[0007]

However, in the above-mentioned conventional structure, since the relative permittivity of the dielectric material is about 3 to 10, even if an attempt is made to downsize the planar patch antenna, the radiation electrode size is restricted to 30 to 50 mm. Therefore, when the planar patch antenna is mounted on the GPS receiving device, the receiving device itself becomes large, and there is a problem that it is not portable. Also, when trying to downsize the entire receiving device, the flat patch antenna itself cannot be downsized in order to obtain a certain antenna characteristic, and therefore the operation unit, the display unit, etc. must be made even smaller. It had a problem that it lacked. Also, using a dielectric with a low relative permittivity, 1
Although it is possible to fabricate a / 4λ type planar patch antenna, complicated processing such as short-circuiting between the end face of the radiating electrode and the ground conductor is required, resulting in lack of productivity, and miniaturization results in high frequency characteristics. There was a problem that it deteriorated and lacked in reliability. Furthermore, when a magnesium titanate-based ceramic dielectric material having a high relative dielectric constant of 19 composed of magnesium oxide-calcium oxide-titanium oxide is used, the antenna can be downsized, but the temperature characteristic of the resonance frequency is-. There is 100 ppm or more in the range of 20 ° C to 75 ° C, and the resonance frequency varies by about 20 MHz depending on the temperature used. Therefore, the frequency bandwidth must be widened, and if the frequency bandwidth is widened, the gain decreases and the sensitivity decreases. It had a problem of lack of reliability. In addition, since the resonance frequency varies by ± 1 MHz due to the variation in relative permittivity, the resonance frequency does not exceed ± 1 MHz even if a flat antenna having the same size of the radiation electrode is manufactured.
There was a problem that it varied in the range of 30.

The present invention solves the above-mentioned conventional problems and is excellent in portability and has high frequency temperature characteristics.
An object of the present invention is to provide a small-sized planar patch antenna that has small variations in resonance frequency, is highly reliable, and can be manufactured extremely easily and has excellent productivity.

[0009]

In order to achieve this object, a small planar patch antenna according to a first aspect of the present invention comprises a dielectric, a radiation electrode laminated on one surface of the dielectric, and A compact planar patch antenna comprising: a grounding conductor laminated on the other surface of the dielectric in parallel to a radiation electrode, wherein the dielectric has a relative permittivity of 18 to 20. Therefore, the compact planar patch antenna according to claim 2 is the compact planar patch antenna according to claim 1, wherein the dielectric contains magnesium titanate-based ceramics composed of magnesium oxide-calcium oxide-titanium oxide as a main component, and the magnesium oxide and the magnesium oxide. The composition ratio of calcium oxide is 9
0:10 to 97: 3, preferably 95: 5,
0.1 to 1.5 wt% of lithium niobate is added to the ceramic
%, Preferably 0.5 to 1.0 wt%, and has a configuration in which the temperature coefficient of the resonance frequency of the antenna is ± 15 ppm / ° C., and the small planar patch antenna according to claim 3 is In Claim 1, the said dielectric body has a magnesium titanate ceramics which consists of magnesium oxide-calcium oxide-titanium oxide as a main component, and the composition ratio of the said magnesium oxide and the said calcium oxide is 90:
10 to 97: 3, preferably 95: 5, the ceramic is 0.1 to 1.0 wt% alumina, preferably 0.1 to 0.5 wt%, and manganese oxide is 0.1 to 1.5 wt%.
The compact planar patch antenna according to claim 4, wherein the content is 0.3 wt% to 1.0 wt% and the variation of the resonance frequency of the antenna is ± 10 MHz, preferably ± 5 MHz. Is the magnesium titanate-based ceramics composed of magnesium oxide-calcium oxide-titanium oxide as a main component, and the composition ratio of the magnesium oxide and the calcium oxide is 90:10 to 97: 3. Preferably 95: 5
Then, 0.1 to 1.5 wt%, preferably 0.5 to 1.0 wt%, of lithium niobate, and 0.1 to 1.0 wt%, preferably 0.1 to 0.5 wt% of alumina are added to the ceramics.
wt%, manganese oxide 0.1-1.5 wt%, preferably 0.3-1.0 wt%, and the antenna resonance frequency temperature coefficient is ± 25 ppm / ° C, preferably ± 15 pp.
m / ° C., and the variation of the resonance frequency is ± 10 MHz, preferably ± 5 MHz.

[0010]

With this configuration, since magnesium titanate-based ceramics having a relatively high relative dielectric constant is used for the dielectric, the size of the radiation electrode is ¼ to 1/2 that of conventional alumina or forsterite. It can be miniaturized. Further, by adding a predetermined amount of lithium niobate, alumina, manganese oxide or the like to the base magnesium titanate-based ceramics, it is possible to improve the variation in frequency temperature characteristics and resonance frequency of the magnesium titanate-based ceramics.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall perspective view of a small planar patch antenna according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of essential parts of a small planar patch antenna according to an embodiment of the present invention. Reference numeral 3 is a radiation electrode, 4 is a ground conductor, and 5 is a feeding point. Since these are the same as those in the conventional example, the same reference numerals are given and description thereof is omitted. 1'is a small planar patch antenna of the present invention, and 2'is a dielectric with improved frequency characteristics while having a high relative dielectric constant by adding a predetermined amount of lithium niobate, alumina, manganese oxide or the like to magnesium titanate ceramics. A body, 6 is a coaxial connector, and 7 is solder.

The manufacturing method of the small planar patch antenna 1'having the above structure will be described below. First, the molding process of the dielectric 2'will be described. With magnesium titanate-based ceramics composed of magnesium oxide-calcium oxide-titanium oxide having a composition ratio of magnesium oxide and calcium oxide of 95: 5 as a main material, lithium niobate, alumina, and manganese oxide as additives,
Predetermined amounts as shown in (Table 1) are weighed and blended, mixed in a ball mill for 20 hours, and then dried all day and night. Next, add binder and water to the dried powder and mix,
After having an appropriate viscosity, it is granulated with a spray dryer and dried. Next, using a hydraulic press, 1000 kg /
It is molded into a predetermined shape with a pressure of cm ² . Next, this molded body is placed in a batch type high temperature electric furnace and fired in a predetermined firing pattern in the range of 1350 to 1400 ° C. for 2 hours to obtain a dielectric body 2 ′. Next, the electrode forming step will be described. The radiation electrode 3 is provided on one surface of the dielectric 2 ', and the ground conductor 4 is provided on the other surface. The size of the radiation electrode 3 is as described above (Equation 1).
After obtaining by, make a mask for screen printing,
Using this mask, a predetermined portion of the dielectric 2 ′ is coated, dried, and then baked at 800 ° C. for 5 minutes to be formed. Further, the ground conductor 4 is similarly formed by stacking.

Next, the outer portion of the SMA type coaxial connector 6 for connecting to a receiving device (not shown) is soldered to the ground conductor 4 on the dielectric 2'on which the radiation electrode 3 and the ground conductor 4 are formed. Adhere with 7 or the like. On the other hand, the core wire of the coaxial connector 6 is insulated from the ground conductor 4, penetrates through the dielectric 2'and is bonded to the feeding point 5 (impedance matching point) of the radiating electrode 3 with solder 7 or the like to form a small planar patch antenna 1 '. To complete.

With respect to each of the small planar patch antennas 1'manufactured as described above, the temperature characteristics and the frequency variations were measured. The results are shown in (Table 1). In addition, dielectric materials using alumina and forsterite, respectively, were manufactured, and similar temperature characteristics and frequency variations were measured. The results are shown in (Table 1).

[0015]

[Table 1]

As is clear from Table 1, according to this embodiment, the dielectric material 2'of magnesium titanate-based ceramics is used as compared with the conventional planar antenna using the dielectric material 2'of alumina or forsterite. The size of the radiation electrode 3 of the used planar antenna can be reduced to 1/4 to 1/2. Further, by adding an appropriate amount of lithium niobate, alumina, manganese oxide or the like to magnesium titanate-based ceramics having a relatively high relative permittivity of 19, a dielectric substance having a low relative permittivity of 3 to 10 is added. It was possible to obtain a small planar patch antenna 1'having excellent antenna characteristics equivalent to those of 2 '.

[0017]

As described above, according to the present invention, the dielectric material is mainly composed of magnesium titanate-based ceramics having a relatively high relative permittivity of 19, and lithium niobate, alumina, manganese oxide, etc. are added in appropriate amounts, By using a dielectric that is added individually or in combination, the size of the radiation electrode can be reduced by about 1/4 to 1/2 compared with the conventional radiation electrode, and it is excellent in portability and frequency temperature. It is possible to realize a small-sized planar patch antenna which has stable characteristics, small variations in resonance frequency, excellent reliability, and easy manufacturing, and excellent productivity.

[Brief description of drawings]

FIG. 1 is an overall perspective view of a small planar patch antenna according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a small planar patch antenna according to an embodiment of the present invention.

FIG. 3 is a perspective view of a general small planar patch antenna.

[Explanation of symbols]

 1,1 'Small planar patch antenna 2,2' Dielectric 3 Radiating electrode 4 Grounding conductor 5 Feed point 6 Coaxial connector 7 Solder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Daimitsu Shimazaki 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. A small planar patch comprising a dielectric, a radiation electrode laminated on one surface of the dielectric, and a ground conductor laminated on the other surface of the dielectric parallel to the radiation electrode. An antenna having a relative dielectric constant of 18 to 20
A small planar patch antenna. 2. The dielectric contains magnesium titanate-based ceramics composed of magnesium oxide-calcium oxide-titanium oxide as a main component, and the composition ratio of the magnesium oxide and the calcium oxide is 90:10 to 97: 3. At times, lithium niobate is added to the ceramics in an amount of 0.
1 to 1.5 wt%, preferably 0.5 to 1.0 wt%,
Moreover, the temperature coefficient of the resonance frequency of the antenna is ± 15ppm.
The small planar patch antenna according to claim 1, wherein the temperature is / ° C. 3. The dielectric material contains magnesium titanate-based ceramics composed of magnesium oxide-calcium oxide-titanium oxide as a main component, and the composition ratio of the magnesium oxide and the calcium oxide is 90:10 to 97: 3. Sometimes, alumina is added to the ceramics in an amount of 0.1 to 1.
0 wt%, preferably 0.1 to 0.5 wt%, manganese oxide 0.1 to 1.5 wt%, preferably 0.3 to 1.0 wt%, and the variation of the resonance frequency of the antenna is ± 10M.
The small planar patch antenna according to claim 1, wherein the frequency is preferably ± 5 MHz. 4. The dielectric material contains magnesium titanate-based ceramics composed of magnesium oxide-calcium oxide-titanium oxide as a main component, and the composition ratio of the magnesium oxide and the calcium oxide is 90:10 to 97: 3. At times, lithium niobate is added to the ceramics in an amount of 0.
1-1.5 wt%, preferably 0.5-1.0 wt%, alumina 0.1-1.0 wt%, preferably 0.1-0.5 wt%
%, 0.1 to 1.5 wt% of manganese oxide, preferably 0.1.
The content of 3 to 1.0 wt%, the temperature coefficient of the resonance frequency of the antenna is ± 25, preferably ± 15 ppm / ° C, and the variation of the resonance frequency is ± 10 MHz, preferably ± 5 MHz. Small flat patch antenna.