JPH04134907A - Low posture antenna - Google Patents

Abstract

PURPOSE:To realize a low posture antenna which can be easily mounted to a house with a low posture by extending a parallel plate in an inverted-F antenna to both sides of a feeding point and providing two resonance amplifier characteristics on the antenna. CONSTITUTION:The surface of a radiation conductor element 20 is perpendicular to a ground conductor plate 10 and the lower end of the element 20 is arranged at a prescribed interval on the ground conductor plate 10. Also this antenna is provided with a vertical flat plate 24 power-fed in the middle of the lower end and a parallel plate 22 arranged in parallel with the ground conductor plate 10 to a position apart by a prescribed distance from the middle part where the upper end of the vertical flat plate 24 is connected, and a short-circuit post 26 of a linear shape or a plate with a narrow width interconnecting the parallel flat plate 22 and the ground conductor plate 10 arranged in the vicinity of the vertical flat plate 24. Thus, the structure is similar to that of an inverse-F antenna, the low height is attained for the antenna, which is easily integrated with a housing member, and the external appearance of the house in the case of integration is not lost, and since the antenna has a broad band characteristic and a directivity, the antenna is suitable as the TV broadcast reception antenna.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a low-profile antenna suitable for receiving wideband radio waves such as TV broadcasting.

[Prior Art] Radio communication has been widely used as a means of transmitting information. In order to achieve this radio wave communication, an antenna for transmitting and receiving radio waves is required, and various antennas are used depending on the type of radio waves.

As one of the most widely used radio communications,
There is television (TV) broadcasting, and most homes are equipped with a television receiver and are using TV broadcasting.

Usually, a TV antenna is installed in each house to receive TV broadcasts.

Here, as a TV antenna for residential use, an antenna as shown in FIG. 13 has conventionally been used. The antenna includes a vHF Yagi antenna 60 and a UHF Yagi antenna 62, both of which are mounted on a shaft 66 extending upwardly from a roof horse 64. The shaft 66 is then pressed toward the roof by the branch line 68 and fixed on the roof.

Broadcast waves are received by directing the antennas 60 and 62 toward the TV broadcast station.

However, since such conventional antennas protrude above the roof, they have the problem of greatly detracting from the aesthetic appearance of the house and being susceptible to the effects of wind and the like.

On the other hand, if a residential TV antenna is built into a part of the house in advance, it is possible to construct a TV antenna that does not spoil the appearance of the house.

However, one of the problems when incorporating the antenna into housing components is as follows. Normally, the T■ receiving antenna needs to have directivity to prevent ghosts. Even if a directional antenna is built into a housing component and installed in the house, the orientation of the transmitting station differs depending on the house, so the direction of the antenna and the direction of the transmitting station do not necessarily match, and good reception may not be possible. occurs.

Therefore, it becomes necessary to adjust the direction of directivity according to each individual house. However, it is very labor-intensive and impractical to install and adjust antennas in different locations and methods for attachment to housing components for each house. Therefore, it is desired that the antenna itself has a function of controlling directivity.

In addition, in order to achieve effective radio wave reception, the antenna
The antenna should be installed at a high location, and it is preferable to incorporate the antenna near the roof.

In a house, a decorative chimney 70 is sometimes installed on the roof as shown in FIG. 14, and it is thought that it is a good idea to incorporate an antenna into this decorative chimney. Therefore, Japanese Unexamined Patent Publication No. 1-181303 discloses incorporating an antenna into a decorative chimney.

That is, a rectangular loop antenna 72 as shown in FIG. 15 is arranged at the top of the decorative chimney.

A coaxial feed line 76 is connected to a feed point 74 on one side of the loop antenna 72 to feed power, and three impedance elements 78 are connected to the other three sides of the loop antenna 72.
The impedance value of the impedance element 78 is changed to change the directivity of the loop antenna.

According to this method, since the antenna has a relatively low profile and the loop antenna is arranged at the top of the decorative chimney, the influence on the appearance of the house is very small, and it is possible to provide a suitable TV antenna for the house.

[Problems to be Solved by the Invention] However, as shown in FIG. 16, the directivity direction of a TV antenna using such a conventional loop-loaded antenna is as small as about ±45° around the feeding point 74. . For this reason, when installing a loop antenna on a decorative chimney,
The pointing direction must be aligned with the direction of the broadcast station. That is, the position of the feed point 74 must be selected from among four positions that differ by 90''.
After determining the position of 4, the impedance value of the impedance element 78 is adjusted to determine the directivity direction. For this reason, although directivity can be controlled, its installation and
There was a problem in that adjustments could not be made easily.

Furthermore, a loaded loop antenna cannot be installed on the side of a residential chimney or the like because its characteristics will deteriorate due to the influence of nearby objects. Therefore, it is necessary to place it at the top of the chimney, on the roof, etc., which poses a problem in that there are significant restrictions in terms of installation location and integration with housing components.

OBJECTS OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a low-profile antenna that is low-profile and easy to incorporate into a house.

Solution Principle Here, as a low-attitude antenna, an inverted F antenna as shown in Fig. 17 has been known for a long time, and if this inverted F antenna can be used, it can be installed in a part of a house (for example, a decorative chimney).
It is thought that it can be easily incorporated into

This inverted F antenna connects a coaxial feed line 86 to a feed point 84 near one end of a parallel plate 82 placed on a ground conductor plate 80.
The parallel plate 82 is connected to the inner conductor 86a to supply power to the parallel plate 82, and one point on the end of the parallel plate 82 on the feed point 84 side and the ground conductor plate 80 are short-circuited by a shorting post 88.

Note that the outer conductor of the coaxial feeder line 86 is connected to the ground conductor plate 80.

In this inverted F antenna, when the width W of the parallel plate 82 is narrower than the wavelength, the height (distance between the ground conductor plate 80 and the parallel plate 82) is Ll, and the length of the parallel plate 82 is L2. , resonates at a frequency where L1+L2 is approximately 174 wavelengths. Therefore, it is possible to transmit and receive radio waves at a frequency near this resonant frequency.

However, since this inverted F antenna has a structure in which the resonant frequency is determined by L1 + L2, the frequency ratio bandwidth that can be used is as narrow as about 10% (ratio of resonance to the center frequency), and it is used for broadband radio waves such as TV broadcasting. (VHF band 90~
108, 170 to 222 MHz) and cannot be used as a TV antenna.

Note that in the inverted F antenna, the radiation impedance is matched to the characteristic impedance of the feed line 86 by changing the position and width of the shorting post 88.

The present inventors extended the parallel plate 82 on both sides of the feed point 84 in the inverted F antenna shown in FIG.
We considered providing two resonance characteristics.

[Means for Solving the Problem] As shown in FIG. 1, the low attitude antenna according to the present invention has the following features:
A vertical flat plate 24 in which the radiation conductor element 20 is perpendicular to the ground conductor plate 10 and is arranged at a predetermined interval on the lower end of the earth conductor plate 10 and is supplied with power to the center of the lower end; A parallel plate 22 connected to the upper end with an intermediate portion shifted by a predetermined distance from the center and arranged parallel to the ground conductor plate 10; and a linear plate 22 arranged near the vertical plate 24 to connect the parallel plate 22 and the ground conductor plate 10. Alternatively, it is characterized by being provided with a narrow plate-shaped shorting post 26.

As described above, in the present invention, power is supplied to the parallel flat plate 22 via the plate-shaped vertical flat plate 24 instead of directly connecting the power supply line. This vertical flat plate 24 is connected to an intermediate portion of the parallel flat plate 22 that is offset from the center. In addition, it is preferable to attach it to a decorative chimney, and in that case, it is good to use the constituent members of the decorative chimney as the ground conductor plate 10.

Another feature is that the ground conductor plate 10 and the parallel flat plate 22 are bent at the middle. In this case, the bending angle is 0
~90° vicinity is preferred. Here, when attaching to a decorative chimney, it is preferable that the bent portion corresponds to a part of the corner of the decorative chimney.

[Operations] According to the present invention, it is possible to perform radio wave communication near the resonance frequency of the radiating element 20, but the parallel plate 22 has a height Ll.
It extends with lengths L2 and L3 on both sides of the vertical flat plate 24. Therefore, in this antenna, L1+L2 is 174
It has a multi-resonance characteristic in which it resonates not only at a frequency that is the wavelength but also at a frequency where L1+L3 is a quarter wavelength. Therefore, radio waves can be transmitted and received around the two resonant frequencies, and the frequency band used by the antenna can be greatly expanded.

The shorting post 26 also adds an inductive reactance, thereby matching the impedance of the radiating element to the impedance of the feed line.

Here, the connection position of the shorting post 26 needs to be arranged so that the bandwidth of the two resonance characteristics is the widest. FIG. 16 shows changes in two resonance characteristic bandwidths depending on the distance Lp from the vertical flat plate 24 to the shorting post 26. Depending on each resonance p, the impedance characteristics of the antenna change, and t and p are determined that best match the characteristic impedance of the feed line over a wide band. However, the effects of the shorting posts on the two resonance characteristics are different. Therefore, as shown in the figure, the position where the resonance bandwidth is widest, j'pl: the shorting post, may be placed.

Here, an example has been explained in which the plate-shaped shorting post 26 is arranged on the edge of the parallel plate 22, but the bandwidth changes by changing the width, shape, and position of the shorting post inside the parallel plate 22. do.

In this case, similarly, the point where the bandwidth of the two resonance characteristics is appropriate is determined, and the shorting post may be placed.

In some cases, an optimal Lp does not necessarily exist. In that case, it is necessary to change the width, shape, and arrangement of the shorting posts.

Further, when the shorting post 26 is separated from the vertical flat plate 24, the set resonance frequency changes to a higher value, so it is preferable that the shorting post 26 be located near the vertical flat plate 24.

Furthermore, in the present invention, in order to further widen this matching band, the feeder line is not directly connected to the parallel plate 22, but the feeder line and the parallel plate 22 are connected via the vertical plate 24 to supply power. Therefore, power is fed linearly to the parallel plate 22, making it possible to reduce the Q (a value representing the strength of resonance) of the antenna, and reducing the radiation impedance of the radiating element seen from the feeding point. Matching with the feeder line can be easily achieved over a wide band.

Further, the impedance of the radiating element can be adjusted by adjusting the length W3 of the lower end while maintaining the upper end length W2 of the vertical flat plate 24 at a predetermined size.

Fig. 17 shows a case where the vertical plate 24 is rectangular (W2-W
3) shows the voltage standing wave ratio (VSWR) of the antenna when W3 is made small and the vertical flat plate 24 is made trapezoidal. In this way, by adjusting the length W3 of the lower end of the vertical plate, matching with the feeder line can be achieved over a wider band. Further, the capacitance component can also be adjusted by adjusting the gap t between the lower end of the vertical flat plate 24 and the ground conductor plate 10.

Further, even if the antenna has a structure in which the ground conductor plate 10 and the parallel flat plate 22 are bent at an arbitrary angle along the lower end and the upper end of the vertical flat plate 24 in the vicinity of the power supply, it similarly has multiple resonance characteristics. By bending, the directivity can be widened. For example, when the bending angle is 90'', the directivity expands from 90° to about 180'.

[Effects of the Invention] As explained above, according to the present invention, by adopting a configuration similar to an inverted F antenna, the antenna can have a low profile, so it can be easily integrated with housing components, and when integrated, it can be There is very little damage to the aesthetic appearance. Furthermore, since the antenna has a wide band and has directivity, it is suitable as a TV broadcast receiving antenna.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

Example 1 In this example, the antenna shown in FIG. 1 is incorporated into the side surface of a decorative chimney 70 shown in FIG. 4.

FIG. 4 is a perspective view showing this antenna attached to the side surface of a decorative chimney 70, and FIG. 5 is a sectional view thereof.

In this example, a metal part of a decorative chimney is used as the ground conductor plate 10. Radiating elements 20 are arranged on the ground conductor plate 10 at predetermined intervals, and the inner conductor 28a of the coaxial feed line 28 is connected to the radiating element 20. Here, the radiating element 20 includes a parallel plate 22 arranged parallel to the ground conductor plate 10, a vertical plate 24 facing perpendicularly, and the parallel plate 22 and the ground conductor plate to which the outer conductor 28b is connected. It consists of a shorting post 26 made of a plate-shaped conductor that connects the terminals 10 to 10. The inner conductor 28a of the coaxial feeder line 28 is connected to a point in the center of the lower end of the vertical plate 24, and
The upper end of is linearly connected to the parallel plate 22.

In an antenna having such a configuration, the parallel plate 2
The height of the parallel plate 22 is Ll, and the length from the position where the vertical plate 24 of the parallel plate 22 is connected to both ends of the parallel plate 22 is L2. When L3 is assumed, resonance occurs at a frequency where L1+L2 or L1+L3 is approximately 1/4 wavelength.

Here, in the VHF band TV broadcast receiving antenna, the frequency f
=90~108. Radio waves in the range of 170~222MHz must be received.

Therefore, the dimensions of each part of an antenna suitable for receiving VHF band TV broadcasting in which the center frequency of the two frequency bands of VHF band TV broadcasting is fl=103 MHz and the two resonance frequencies are f2-196 MHz will be explained.

That is, the height of the radiating element 20 (distance from the ground conductor plate 10 to the parallel plate 22) Ll, and the length L2 of the parallel plate 22.
．． L3. Width W1, M of the upper and lower ends of the vertical flat plate 24
W2. W3, width Wp of the shorting post 26, distance L from the connection position of the vertical plate 24 of the parallel plate 22 to the shorting post 26
It is preferable to set p and the gap t between the vertical flat plate 24 and the ground conductor plate 10 as follows.

L1=100mm L2=650mm L3=250mm Wl-100mm W2=100mm W3=10mm Wp=50mm Lp-30mm t=3mm FIG. 6 shows the VSWR of the antenna of the present invention manufactured under these conditions. Here, fl.

f2 is the two center frequencies of the above-mentioned VHF band TV broadcast. From the figure, the antenna of this example has multiple resonance characteristics, and one antenna has VH
It is understood that the frequency band of F-band TV broadcasting is sufficiently covered.

Further, FIG. 7 shows the directivity pattern of water-handed polarized waves in the horizontal plane of the antenna of this embodiment. From the figure, it is understood that the antenna of this embodiment has directivity on the parallel plate 22 side and has a ghost prevention effect as a TV antenna.

Note that since the antenna of this embodiment has a relatively wide band, the above dimensions may be slightly changed. Furthermore, by changing the dimensions, it can be suitably used as an antenna for UHF band TV reception.

Assembly Structure The antenna of this embodiment is preferably attached to each of the four sides of the decorative chimney 70, as shown in FIG. Then, these four radiating elements 20 are connected to a switch 30, and the radiating elements 2 used in this switch 3° are
o to adjust the directivity to the direction of the broadcast station.

Therefore, when installing the decorative chimney 70 in a house, there is no need to consider its direction, and the installation work can be performed. By setting the directivity of the antenna using the switch 30, a good received signal can be supplied to the receiver.

The antenna of this embodiment is preferably covered with a decoration 40 to further improve the aesthetic appearance of the house.

That is, as shown in FIG. 9, a decoration 32 is attached around the radiating element 2°. This decoration 32 is preferably structured to cover the entire circumference of the decorative chimney 70.

Furthermore, it is preferable that the decoration 32 be formed into a shape that matches the exterior appearance of the house. This decoration 32 not only improves the appearance of the house, but also serves to protect the antenna from wind and rain.

Note that this decoration 32 covers the antenna and needs to be a radio wave transparent material. Furthermore, since it is to be installed outdoors and durability is required, it is preferable to construct it from a plastic material such as vinyl chloride.

Example 2 In areas where there are few tall buildings and few ghosts, the antenna is not required to have such narrow directivity. Therefore, in this embodiment, the directivity is wider than that of the antenna of the first embodiment.

That is, as shown in FIG. 10, one radiating element 50 is provided for each ground conductor plate 40a, 40b forming two sides around the decorative chimney. And ground conductor plates 40a, 40b
A vertical flat plate 54 that projects obliquely is arranged at the corner that is the connection part of the. The opposite side of this vertical flat plate 54 has a length L2. Parallel flat plates 52a and 52b which are orthogonal to each other are connected by L3. That is, the antenna of this embodiment has a structure in which the parallel flat plate 52 of the radiating element is bent at right angles to match the structure of the decorative chimney 70.

In this embodiment, if the height H of the parallel plate 52 is the same as in the first embodiment, the vertical plate 54 is oblique to the two ground conductor plates 40a and 40b which are orthogonal to each other, so its length is The length will be slightly longer.

Therefore, the lengths of the parallel plates 52a and 52b are adjusted accordingly, and the resonant frequency is adjusted to the center frequency (fl) of the TV broadcast.
, f2). Furthermore, since the shape of the antenna is different from that in Example 1, the position and width of the shorting post 56 must be adjusted to achieve impedance matching with the coaxial feeder line 58.

FIG. 11 shows the frequency f2 (196M
3 shows a directivity pattern centered on the feeding point of horizontally polarized waves (Hz). From the figure, it is understood that the antenna of this embodiment has a wider directivity than that of the first embodiment.

Therefore, as shown in FIG. 12, the antenna of this embodiment is attached to the two diagonal parts of the decorative chimney, and
By connecting the antenna to the antenna switching device 59 via the feeder line 56, the two antennas can be switched and the pointing direction can be adjusted toward the broadcasting station.

As described above, according to this embodiment, the number of radiating elements can be reduced to two, the structure can be simplified, and manufacturing costs can be reduced, among other advantages.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the configuration of the low-attitude antenna according to the present invention, Fig. 2 is a characteristic diagram showing the relationship between the mounting position of the shorting post and the bandwidth, and Fig. 3 is the relationship between the shape of the vertical plate and VSWR. FIG. 4 is a perspective view showing the configuration of Example 1, FIG. 5 is a sectional view showing the configuration of Example 1, and FIG. 6 shows the VSWR in the VHF television broadcasting frequency band of Example 1. A characteristic diagram, FIG. 7 is a characteristic diagram showing the directivity direction of Example 1, FIG. 8 is an explanatory diagram showing an example of incorporating Example 1, and FIG. 9 is a sectional view showing an example of the configuration when covered with a decoration. Fig. 10 is a perspective view showing the configuration of the second embodiment, Fig. 11 is a characteristic diagram showing the orientation direction of the second embodiment, Fig. 12 is an explanatory diagram showing an example of incorporating the second embodiment, and Fig. 13 is a conventional Fig. 14 is a perspective view showing the position of a decorative chimney, Fig. 15 is an explanatory diagram showing an example of the structure of a conventional loop antenna, Fig. 16 is a directivity direction of a conventional loop antenna. FIG. 17 is a perspective view showing the configuration of an inverted F antenna. 10... Ground conductor plate 20... Radiation element 22... Parallel plate 24... Vertical plate 26... Short circuit post 28... Coaxial feeder line Applicant Toyota Central Research Institute Co., Ltd.

Claims (2)

[Claims] (1) A low-profile antenna having a ground conductor plate and a radiating element arranged at a predetermined interval on the ground conductor plate, wherein the radiating conductor element is perpendicular to the plane of the ground conductor plate; A vertical flat plate whose lower end is placed on a grounding conductor plate at a predetermined interval and where power is supplied to the center of the lower end, and an intermediate portion offset from the center by a predetermined distance is connected to the upper end of this vertical flat plate, and the grounding conductor A parallel plate arranged parallel to the plate, and a linear or narrow plate-shaped shorting post arranged near the vertical plate and connecting the parallel plate and the ground conductor plate. Low profile antenna. (2) The low-position antenna according to claim (1), wherein both the ground conductor plate and the parallel plate are bent at an intermediate portion.