JP4180768B2 - Patch antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a patch antenna having a plurality of patch antenna elements.
[0002]
[Prior art]
Conventionally, patch antennas are mainly used for obtaining small antennas. In the patch antenna, a patch antenna element is disposed on the other surface of a substrate having a ground conductor provided on one entire surface.
[0003]
[Problems to be solved by the invention]
In this patch antenna, the use frequency band tends to be narrow. For this reason, it is not used as an antenna that desirably has a relatively wide band, such as a receiving antenna for television broadcasting. As a receiving antenna for television broadcasting, a Yagi-type antenna provided with a large number of directors is often used, which has become large.
[0004]
An object of the present invention is to provide a patch antenna having a small size and a wide band.
[0005]
[Means for Solving the Problems]
In the patch antenna according to the present invention, a plurality of patch antenna elements having different resonance frequencies in the same transmission / reception frequency band and each having independent feeding points are arranged in an array on an insulating plate . Each patch antenna element is fed in phase to each feeding point. This patch antenna can be used for both transmission and reception. Although various frequency bands can be considered as the transmission / reception frequency band, for example, the UHF band, the VHF band, or a GHz band that is a higher frequency than these can also be used. The number of patch antenna elements used may be two or more. The resonant frequencies of these patch antenna elements are desirably separated from each other in the same frequency band.
[0006]
In this patch antenna, since the resonance frequency of each patch antenna element is arranged in the frequency band to be transmitted / received, the overall frequency characteristic of this patch antenna can be a wide band, and it is a single patch antenna. A broadband antenna can be obtained.
[0007]
Each patch antenna element, they are bent in the inverted V-shape along the E-plane of the radio waves to be transmitted and received, its apex away from the insulating plate, the patch antenna elements bent at both ends is in contact on an insulating plate is there. Each patch antenna element is arranged at an interval of 1/2 or more of the center wavelength of the transmission / reception frequency band. Since this folded antenna has a relatively wide band, if the resonance frequency of this wide folded patch antenna element is varied within the same transmission / reception frequency band, the patch antenna has a wider overall frequency characteristic.
[0008]
In the patch antenna using the folded patch antenna element, a case can be provided in which each folded patch antenna element is accommodated inside and can be attached so that the E surface is substantially positioned on a horizontal or vertical surface.
[0009]
If comprised in this way, the radio wave of desired polarization can be received among a vertical polarization and a horizontal polarization, and the appearance of the appearance becomes good.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The patch antenna 1 according to the first embodiment of the present invention is a planar antenna for receiving, for example, a television broadcast in the UHF band (specifically, 470 MHz to 800 MHz). As shown in FIGS. 1A to 1C, the patch antenna 1 has an insulator, for example, a foam 2. A ground conductor 4 is formed on one surface of the foam 2, for example, the entire back surface. On the other surface of the foam 2, a plurality of patch antenna elements, for example, three bent patch antenna elements 6, 8, 10 are provided.
[0011]
As shown in FIG. 1A, these folded patch antenna elements 6, 8, and 10 are each formed by bending a patch antenna element formed in a rectangular shape in the vicinity of its center. As shown in FIG. 1 (a), these folded patch antenna elements 6, 8, and 10 are formed so that they are bent so that they are substantially orthogonal to the E-plane of the UHF band television broadcast radio wave to be received. , Bent along the E-plane direction.
[0012]
As shown in FIGS. 1B and 1C, the folded patch antenna element 6 has a length d1 of 145 mm, a width W1 of 220 mm, a height h1 of 72 mm, and a hypotenuse L1 of 100 mm. The frequency with the largest gain in the gain-frequency characteristic of 2 (a) is formed to be around 560 MHz. That is, the resonance frequency is formed at about 560 MHz.
[0013]
As shown in FIGS. 1B and 1C, the folded patch antenna element 8 has a length d2 of 120 mm, a width W2 of 195 mm, a height h2 of 67 mm, and a hypotenuse L2 of 90 mm. The frequency with the largest gain in the gain-frequency characteristic of 2 (b) is formed to be around 620 MHz. That is, the resonance frequency is formed at about 620 MHz.
[0014]
As shown in FIGS. 1B and 1C, the folded patch antenna element 10 has a length d3 of 110 mm, a width W3 of 182 mm, a height h3 of 61 mm, and a hypotenuse L3 of 82 mm. The frequency with the largest gain in the gain-frequency characteristic of 2 (c) is formed to be around 680 MHz. That is, the resonance frequency is formed at about 680 MHz.
[0015]
In this manner, the bending patch antenna elements 6, 8, and 10 have resonance frequencies selected at three relatively different frequencies (for example, at intervals of about 60 MHz) within the reception frequency band 470 to 800 MHz. As is apparent from FIGS. 2A to 2C, each of the folded patch antenna elements 6, 8, and 10 is a wideband antenna that has a relatively small gain reduction in a relatively wide band.
[0016]
As shown in FIG. 1B, each of the folded patch antenna elements 6, 8, and 10 has a feeding portion 12 having a width d (= 20 mm) formed continuously to the lower end portion of one oblique side. . The bent patch antenna elements 6, 8, and 10 are fed from a feeding point 12a formed at the center thereof. It is to be noted that power is fed to each feeding point 12a using a coaxial cable having the same length. That is, in-phase power feeding is performed. Of course, other methods, for example, a phase shifter may be used for in-phase power feeding.
[0017]
As shown in FIG. 1 (b), these folded patch antenna elements 6, 8, and 10 are placed on the foam 2 with an interval of, for example, D3 and D2 separated by a half or more of the center wavelength λ of the reception frequency band. Arranged in a row. That is, the patch antenna elements 6, 8, 10 bent to the array over shape is arranged.
[0018]
FIG. 3 shows the gain vs. frequency characteristics of the patch antenna 1, the 8-element Yagi antenna for low frequency, and the same high frequency. As is apparent from FIG. 3, the patch antenna 1 has a gain that is higher than about 8 dB between about 500 MHz and 680 MHz and is almost constant. At a frequency higher than 680 MHz, a gain of at least about 5 dB is obtained. Therefore, the patch antenna 1 is a high gain antenna. Of course, if a bent patch antenna element having a resonance frequency of, for example, 740 MHz is added, a gain in the vicinity of 8 dB can be obtained even at a frequency higher than 680 MHz. On the other hand, the 8-element Yagi-type antenna for low frequency has a frequency characteristic that rises to the right at a frequency lower than 680 MHz, and a substantially constant gain is only in a small range from about 570 MHz to about 620 MHz. The value is smaller than the gain of the patch antenna 1 in the range of about 570 MHz to about 620 MHz. The 8-element Yagi-type antenna has high frequency characteristics even for high frequencies, and there is no frequency band that maintains a substantially constant gain. Moreover, a gain exceeding 8 dB can be obtained only at a frequency higher than 680 MHz. It can be understood from FIG. 3 that the patch antenna 1 can be used as a wideband UHF band receiving antenna as compared with the 8-element Yagi type antenna for low frequency and high frequency.
[0019]
FIG. 4 shows the reflection loss vs. frequency characteristics of the patch antenna 1 and the patch antenna elements 6, 8 and 10 constituting the patch antenna 1. The reflection loss vs. frequency characteristic of the patch antenna 1, which is a combination of these, is larger than the reflection loss vs. frequency characteristic of each patch antenna element 6, 8, and 10. As a result, the frequency is a stable characteristic. It can be understood that the band is obtained and the antenna is a wide band.
[0020]
Thus, the patch antenna 1 has a wide band because the plurality of bent patch antenna elements 6, 8, and 10 having different resonance frequencies in the same frequency band are combined. Moreover, since the patch antenna elements 6, 8, and 10 are bent, the plane area is reduced, the installation space is reduced, and the size can be further reduced.
[0021]
For example, as shown in FIG. 5, the patch antenna 1 is arranged so that the folded patch antenna elements 6, 8, and 10 are accommodated in the case 12 along the length direction thereof. The patch antenna 1 disposed in the case 12 is attached to the roof of a house or a veranda as indicated by reference numerals 12a and 12b in FIG. In this case, when horizontally polarized waves are received, they are arranged in a vertically placed state as indicated by reference numeral 12a, that is, with the E plane shown in FIG. 1 (a) being horizontal. When receiving vertically polarized waves, they are arranged in a horizontal state as indicated by reference numeral 12b, that is, so that the E plane shown in FIG. Thus, since it is accommodated in the case 12, installation is easy and aesthetics are also preferable.
[0022]
A patch antenna 1a of the second embodiment is shown in FIG. In the patch antenna 1 of the first embodiment, the folded patch antenna elements 6, 8, and 10 are arranged in a line. However, in the patch antenna 1a of the second embodiment, a plurality of, for example, four folded patch antenna elements are used. 14, 16, 18, and 20 are arranged in a plurality of rows, for example, two rows. These bent patch antenna elements 14, 16, 18, and 20 are also bent along the E plane so that their ends are substantially orthogonal to the E plane of the radio wave to be received. The dimensions of the respective parts are selected so that the resonance frequencies of the folded patch antenna elements 14, 16, 18, and 20 are separated from each other in the reception frequency band of the UHF band. The patch antenna 1a is also accommodated in a case (not shown) and is arranged on a roof, a veranda or the like. In this case, now, in FIG. 7, when the E plane is orthogonal to the tops of the folded patch antenna elements 14, 16, 18 and 20, that is, when the E plane is located in the horizontal plane, horizontal polarization can be received. it can. In the case of receiving vertically polarized waves, it may be rotated 90 degrees from the state shown in FIG.
[0023]
In the first embodiment, three folded patch antenna elements are used. In the second embodiment, four folded patch antenna elements are used. However, the present invention is not limited to this, and a larger number of folded patches are used. The antenna elements can be arranged in one or more rows. In this case, it is desirable that the resonant frequencies of the folded patch antenna elements are different, but for example, a part of the folded patch antenna elements having the same resonant frequency may be included in order to increase the gain. In the first embodiment, the resonant frequencies of the folded patch antenna elements 6, 8, and 10 are different from each other by about 60 MHz. However, the present invention is not necessarily limited to this, and the folded patch antenna having a far away resonant frequency. When the elements are combined, the gain of the entire band is lowered. Therefore, the resonance frequency may be set so as to prevent such a gain reduction, for example, 40 MHz to 80 MHz. Further, although the folded patch antenna elements are used in the first and second embodiments, a planar patch antenna element may be used instead. However, the resonance frequency of each planar patch antenna element is different. In the first and second embodiments described above, the reception frequency band is the UHF band. However, the present invention is not limited to this, and may be, for example, a VHF band or an SHF band.
[0024]
【The invention's effect】
As described above, according to the present invention, since the resonance frequencies of the patch antenna elements are made different, a wideband patch antenna can be obtained. In particular, since the patch antenna element is a folded patch antenna element, a patch antenna having a wider band can be obtained and the size can be reduced. Since the patch antenna including such a folded patch antenna element is accommodated in the case, it is possible to select and receive either horizontally polarized waves or vertically polarized waves.
[Brief description of the drawings]
FIG. 1 is a perspective view, a plan view, and a side view of a patch antenna according to a first embodiment of the present invention.
2 is a gain vs. frequency characteristic diagram of three bent patch antenna elements included in the patch antenna of FIG. 1; FIG.
3 is a gain vs. frequency characteristic diagram for the patch antenna of FIG. 1 and an 8-element Yagi type antenna for low frequency and high frequency. FIG.
4 is a reflection loss versus frequency characteristic diagram of the patch antenna of FIG. 1 and each patch antenna element constituting the patch antenna 1. FIG.
5 is a perspective view showing a state in which the patch antenna of FIG. 1 is housed in a case. FIG.
FIG. 6 is a view showing a state of attachment in a state of being accommodated in this case.
FIG. 7 is a plan view of a patch antenna according to a second embodiment.
[Explanation of symbols]
1 Patch antenna 6 8 10 Folded patch antenna element

Claims (2)

A plurality of patch antenna elements having different resonance frequencies in the same transmission / reception frequency band and each having independent feeding points are arranged in an array on an insulating plate ,
Each of the patch antenna elements is a folded patch antenna which is bent in an inverted V shape along the E plane of the radio wave to be transmitted / received, the apex thereof being separated from the insulating plate and both ends being in contact with the insulating plate. These patch antenna elements are arranged at intervals of 1/2 or more of the center wavelength of the transmission / reception frequency band, and the feed points are combined in phase with each other.   2. The patch antenna according to claim 1, further comprising: a case in which each of the folded patch antenna elements is accommodated inside and can be attached so that the E surface is substantially positioned on a horizontal or vertical surface.

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