JPH04369902A - On-vehicle antenna - Google Patents

Abstract

PURPOSE:To realize the small sized diversity reception on-vehicle antenna with a low height and small inter-element coupling. CONSTITUTION:First and second radiation elements 21, 31 are arranged at a prescribed interval around the middle and around the end of a ground conductor plate 14 respectively while their vertical feeding flat plates are made orthogonal to each other. Coaxial feeders 15-1, 15-2 whose insulations are stripped are wired to the upper side of the ground conductor plate 14 and exposed outer conductors 62-1, 62-2 are connected electrically to the upper side of the ground conductor plate by soldering or the like. The 1st radiation element 21 is fixed to the upper side of the ground conductor plate 14 by a support jig 65 and a core wire 61-1 of the coaxial feeder 15-2 is connected to the middle of the lower end by soldering or the like. The 2nd radiation element is fixed onto the ground conductor plate 14 by using a support jig 67 and a core wire 61-2 of the coaxial feeder 15-2 is connected to the middle of the lower end by soldering or the like. Then entire components are contained in a case 64.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-vehicle antenna mounted on an automobile or the like for transmitting and receiving radio waves.

0002

2. Description of the Related Art In recent years, various antennas have been proposed as so-called vehicle-mounted antennas intended to be mounted on automobiles and the like. Such vehicle-mounted antennas are particularly required to be small and low-profile in order to be accommodated in a limited space and to minimize air resistance during driving. As small-sized, low-profile antennas that have been proposed in the past, there are inverted F antennas, loop antennas, table-type antennas, T-type antennas, and the like.

Among these, regarding the T-type antenna, FIG.
The explanation will be based on. In the figure, the radiating element 11 consists of a table 12 and a vertical feeding flat plate 13 joined to the table, and is installed above the ground conductor plate 14 so that the table 12 is parallel to the ground conductor plate 14. A core wire of a coaxial feed line 15 is connected to the feed point at the lower end of the vertical feed flat plate 13 by soldering or the like through a hole provided in the ground conductor plate 14 from below. is connected to the outer conductor of the coaxial feeder line 15. In such a T-shaped antenna, since the current flows to the table 12 via the vertical feeding flat plate 13, it resonates at a propagation wavelength λg that satisfies the following equation (1).

[0004]TH+TL/2=λg/4...(1
) Here, TL is the length of the table 12, TH is the distance between the table 12 and the ground conductor plate 14, and TH > T
It is L/2.

[0005] In such a conventional example, as is clear from equation (1), it is necessary to increase TL in order to realize a lower profile. However, if TH is made smaller, TL
If , the stray capacitance between the ground conductor plate 14 and the table 12 increases, so that the impedance becomes capacitive and the radiation resistance also decreases. For this reason, there is a problem in that it becomes difficult to match the impedance of the antenna seen from the coaxial feed line 15 and the feed point, resulting in a reduction in the usable bandwidth of the antenna.

Related Art On the other hand, as shown in FIG. 22, a normal table-type antenna is arranged on a ground conductor plate 14 by a distance ht and a diameter D.
In addition to arranging table 17 of t, this table 1
7 is connected to a ground conductor plate 14 by four posts 19 provided around the periphery thereof. Further, the core wire of the coaxial feeder line 15 is connected to the center of the table 17. Therefore, the current I supplied to the center of the table 17 flows radially toward the periphery of the table 17.

[0007] Also in this table type antenna, the size Dt and height ht of the table determine its resonant frequency, but in order to make it smaller, a structure as shown in FIG. 23 can be considered. In the figure, table 1
7 is placed above and parallel to the ground conductor plate 14 at a predetermined distance. A vertical power feeding post 18 is connected to one end of the table 17, and a shorting post 19 is connected to the other end. In addition, both posts 18,
19 are joined to the center portions of the ends thereof. The core wire of the coaxial feed line 15 is connected to the feed point at the lower end of the vertical feed post 18 by soldering or the like through a hole provided in the ground conductor plate 14 from below. The lower end of is connected to the ground conductor plate 14. Note that the outer conductor of the coaxial feeder line 15 is connected to the ground conductor plate 14.

In the antenna having such a structure, the current supplied from the coaxial feed line 15 to the vertical feed post 18 not only flows through the table 17 directly to the post 19, but also flows around the table 17 to the post. Currents I2, I3 towards 19 can also occur. And table 1
The path of the currents I2 and I3 flowing around the antenna 7 is longer than the radial path in the above-mentioned table-type antenna having four posts, and as a result has a lower resonant frequency. Therefore, if the resonance frequency is the same, the antenna can be made smaller.

However, if the vertical feeding post 18 and the shorting post 19 are simply placed on the table 17, the radiation impedance of the antenna will increase, and the posts 19
Since the impedance characteristics become inductive due to the current flowing through, there is a problem that matching with the impedance of the coaxial feed line 15 of about 50Ω cannot be achieved in a wide frequency band.

[0010] Since the reception state of a vehicle changes as the vehicle travels, it is necessary to take measures to deal with this change. In particular, under multiple wave propagation conditions such as in urban areas,
Since multipath facing occurs, sufficient reception cannot be ensured with only one antenna. Therefore, in the past, multiple antennas (usually two) were installed at a predetermined distance apart, and the antenna was automatically switched to the one with the higher level of signal received by each antenna, or the signal received by each antenna was A diversity reception method is used to combine the received signals.

[0011]

[Problems to be Solved by the Invention] However, in the conventional diversity antenna that performs diversity reception, in order to reduce the inter-element coupling between the two antennas, they must be separated sufficiently, and the antenna is large. There were problems such as the number of places where it could be installed was limited, making it difficult to use. Furthermore, there is a problem in that if each antenna is made smaller, sufficient performance cannot be obtained.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain a diversity antenna that is small in size and has sufficient functions.

[0013]

[Means for Solving the Problems] The present invention is an on-vehicle antenna having a ground conductor plate, and a first radiating element and a second radiating element arranged at a predetermined interval on the ground conductor plate. , the first radiating element includes a vertical feeding flat plate whose one end face is arranged perpendicular to the plane at a predetermined interval on the ground conductor plate, and which is fed to the center of the lower end, and a vertical feeding flat plate having one end face perpendicular to the plane at the lower end of the vertical feeding flat plate. A conductive plate for adding capacitance is connected, a parallel plate is connected perpendicular to the upper end of the vertical feeding flat plate, and one end of the parallel plate is connected near the center of one end in a direction orthogonal to the vertical feeding flat plate. , a rod-shaped or narrow plate-shaped post whose other end is connected to a ground conductor plate, and the second
The radiating element includes a vertical feeding flat plate whose one end face is arranged perpendicular to the plane at a predetermined interval on a ground conductor plate, and which is fed to the center of the lower end, and a parallel flat plate connected perpendicularly to the top end of the vertical feeding flat plate. a vertical additional plate connected to both ends parallel to the vertical feeding flat plate of the parallel flat plate and extending toward the ground conductor plate;
It is characterized by comprising the following.

[0014]

[Operation] In the present invention, by making the vertical feeding flat plates in the first radiating element and the second radiating element plate-shaped, current paths of various lengths are possible in both vertical feeding flat plates,
The resonant frequency band becomes wider. Then, a capacitance adding plate is added to the lower end of the vertical feeding flat plate of the first radiating element to add a capacitance component to the antenna, thereby canceling out the inductivity generated at the post and creating an impedance between the feeder line that feeds the antenna and the antenna. This allows for consistency. The impedance of the antenna can be adjusted by adjusting the size of the capacitance adding plate, the distance between the vertical feeding flat plate and the ground conductor plate, the thickness of the post, etc.

Further, vertical additional plates are provided at both ends of the parallel plate of the second radiating element, and an inductive component is added to the antenna by the current flowing there. Therefore, the capacitance component generated by the parallel plate can be canceled by this inductive component, and impedance matching with the power supply line can be achieved in a wide frequency band.

By combining two radiating elements with different characteristics in this manner, the coupling between the two elements can be reduced, and diversity reception with sufficient characteristics can be achieved in a small size.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. The in-vehicle antenna according to the present invention has two radiating elements with different characteristics mounted on one ground conductor plate to achieve diversity reception, and the configuration of each antenna made of these two radiating elements will be explained.

Configuration of the first radiating element FIG. 1 shows an antenna consisting of the first radiating element. The radiating element 21 of this antenna has a length L0,
A table 22 with a width W0, a vertical power supply plate 23 with a height H0 and a width K0 connected perpendicularly to the table 22, and a capacitor with a length K0 and a width C0 connected perpendicularly to the lower end of the vertical power supply flat plate 23. It consists of an additional plate 25 and a post 24 with a height HM vertically joined to the table 22 at a distance P0 from the center of the vertical feeding flat plate 23. The table 22 is arranged parallel to the ground conductor plate 14 at a distance HM. A core wire of a coaxial power supply line 15 is connected to a power supply point at the center of the lower end of the vertical power supply flat plate 23 by soldering or the like through a hole provided in the ground conductor plate 14 from below. Capacity addition plate 25 and ground conductor plate 1
A gap of distance t0 is provided between the post 24 and the post 24, and the lower end of the post 24 is joined to the ground conductor plate 14.

FIG. 2 is a plan view of this antenna as seen from arrow 27, and FIG. 3 is a side view as seen from arrow 28. As shown in these figures, from the coaxial feed line 15 to the vertical feed plate 23
When power is supplied to the vertical power supply plate 23, a current I1
, I2 will flow toward the table 22 along the path shown in FIG. 3, and within the table 22, the current I3 will flow toward the post 24 along the path shown in FIG.

By employing the plate-shaped vertical feeding flat plate 23 and widening the width K0 of the vertical feeding flat plate 23 in this way, current paths with various different lengths are generated, and the so-called so-called "resonance strength" indicating the strength of antenna resonance is generated. The Q of the antenna can be lowered, and the usable frequency bandwidth (fractional bandwidth) for which the voltage standing wave ratio VSWR is 2 or less, for example, can be made sufficiently wide.

Furthermore, by adding the capacitance adding plate 25, the inductivity generated in the post 24 is canceled out, and impedance matching between the radiating element 21 and the coaxial feed line 15 becomes possible over a wide band. That is, when the post 24 is made thinner (D0 is made smaller), the inductive component becomes larger, and the width C of the capacitance adding plate 25 becomes smaller.
0 or increase the capacitance addition plate 25 and ground conductor plate 14.
The capacitance component increases by decreasing the distance to. Therefore, by adjusting these t0, K0, and C0, the input impedance of the antenna can be adjusted, and the Q of the antenna can also be adjusted.

However, the width K0 of the vertical feeding flat plate 23 is smaller than the wavelength λ0 at the transmitting/receiving center frequency f0.
If it is sufficiently large (for example, 0.1λ0 or more), the Q of the antenna becomes too small, the impedance of the antenna decreases, and even if the above-mentioned D0, C0, and t0 are adjusted, matching with the coaxial feed line 15 cannot be achieved. It's gone. Therefore, the fractional bandwidth increases as the width K0 increases, but when it exceeds a certain value, it begins to decrease and a maximum value exists. Therefore, when determining the width K0, it is necessary to take this point into consideration and set the width K0 to a value that can maintain a sufficiently large bandwidth.

Here, the antenna of this embodiment has the following (2)
) It resonates near the center wavelength λ0 that satisfies the equation.

2HM +P0 +W0 ~=λ0/2...(2)(
Here, ~= indicates almost equal. ) In the antenna in this example, the dimensions of each part are as follows (3) to (13).
) By setting the value as shown in the formula, suitable characteristics can be obtained.

2HM +P0 +W0 =0.504λ0...(3
)HM =0.156λ0...(4) P0 =0.102λ0...(5) W0 =0.090λ0...(6) D0 =0.012λ0...(7) t0 =0.003λ0...(8 ) M0 = 0.048λ0 ... (9) L0 = 0.219λ0 ... (10) K0 = 0.0
74λ0...(11)H0 =0.153λ0...
(12) C0 = 0.012λ0 (13) Here, M0 indicates the distance between one side 29 of the table 22 and the post 24. The frequency characteristics of the VSWR of this antenna are shown in FIG. However, here, the center wavelength λ0
It is normalized by the center frequency f0 corresponding to . As shown in this figure, the fractional band with a standing wave ratio of 2 or less is approximately 20%.
It can sufficiently cover the bandwidth required for normal mobile communication, and has sufficient characteristics as a transmitting and receiving antenna. Note that the communication frequency of the antenna varies depending on its purpose, but for example, in a car phone, etc.
Radio waves in the 900MHz band are used.

[0026] Furthermore, the directivity in the horizontal plane of this antenna is
As shown in FIG. 4, it is almost non-directional and fully satisfies the performance required for an on-vehicle antenna. In this embodiment, a plate-shaped post is used as the post 24, but it may also be a rod-shaped post. In addition, as shown in FIG. 6, the position of the capacitance addition plate 25 is
It may be arranged on the opposite side of the vertical power feeding flat plate 23 from that in FIG.

[0027] Furthermore, if both ends of the vertical power supply plate and the capacitance addition plate are cut off so that the width becomes smaller toward the bottom,
This makes it possible to reduce the capacitance component and adjust the impedance over a wide range. moreover,
As shown in FIG. 7, by inserting a dielectric material 30 between the ground conductor plate 14 and the table 22, it is possible to further downsize the antenna and to securely fix the radiating element 11.

On the other hand, a vehicle has many metal members such as a vehicle body, and when an antenna is installed in a vehicle, its input impedance may change. Therefore, even if the antenna itself is matched over a sufficiently wide range, when installed in a vehicle, the input impedance may change and the bandwidth may deteriorate. However, according to the antenna of this embodiment, the input impedance of the antenna can be easily adjusted by adjusting the size of the capacitance addition plate 25. Therefore, depending on the vehicle in which this capacity addition plate 25 is installed,
By adjusting the size of the antenna, the input impedance of the antenna can be adjusted over a wide range, and the antenna characteristics can always be set to sufficient values.

Configuration of Second Radiating Element Next, the configuration of the antenna consisting of the second radiating element 31 used in combination with the first radiating element 21 will be explained. FIG. 8 shows this antenna. The radiating element 31 of this antenna includes a table 32 forming a parallel plate having a width W1 and a length L1 arranged in parallel with the ground conductor plate 14, and a ground conductor plate 14 on opposite sides of the table 32 in the length direction. It is composed of vertical additional plates 34 and 35 having a width W1 and a height M1, which are joined so as to hang down toward the vertical direction. In the center of the table 32 in the longitudinal direction,
A vertical power supply flat plate 33 with a width K1 and a height H1 is joined to the vertical additional plates 34 and 35 in parallel, and a hole provided in the ground conductor plate 14 is inserted from below to the power supply point at the lower end. The core wires of the coaxial feeder line 15 are connected with solder or the like. Further, the outer conductor of the coaxial feed line 15 is connected to the ground conductor plate 14.

FIGS. 10 and 11 show arrows 36 and 36, respectively.
37 shows a side view. Figure 8 and Figure 1
1, the table 32 is arranged at a distance HL from the ground conductor plate 14, and the table 32 is arranged at a distance HL from the ground conductor plate 14.
The lower end of is spaced a distance t0 from the ground conductor plate 14.

[0031] Thus, the antenna consisting of the second radiating element has the vertical feeding plate 33, and current paths of various lengths are created by the vertical feeding plate 33. Therefore, the fractional bandwidth can be widened.

By the way, in this antenna, since the table 32 faces the ground conductor plate 14, capacitance is generated between the table 32 and the ground conductor plate 14, as in the conventional antenna shown in FIG. The input impedance of the antenna becomes capacitive, making it difficult to match the feeding end impedance of the antenna and the coaxial feed line 15, resulting in a narrow usable bandwidth. However, in this embodiment, vertical additional plates 34 and 35 are provided. By providing the vertical additional plates 34 and 35, the capacitance between the ground conductor plate 14 and the table 32 can be reduced. Therefore, it becomes possible to match the impedance of the antenna seen from the feed point to the coaxial feed line 15 over a wide band.

However, the length M of the vertical additional plates 34 and 35
As 1 is increased, the induced component increases. Therefore, when the length of the vertical additional plates 34 and 35 is gradually increased from 0, the bandwidth increases at first, but as the induced component increases beyond a certain value, the bandwidth increases. On the contrary, it begins to decrease. Therefore, there is an optimum value for the vertical additional plates 34 and 35. This optimal value varies depending on the dimensions of each part of the antenna, but is usually 0.05λ0 ~ 0
．． 1λ0 (here, λ0 is the center wavelength of the communication radio wave)
It will be about the same length.

Here, this antenna resonates near the center wavelength λ0 that satisfies the following equation (14), but by using the vertical additional plates 34 and 35, the table 32, and the vertical feeding flat plate 33, it can be used over a wide range. It enables a wide current path and has a wide frequency band.

HL +L1/2+M1 ~=λ0/4...(14
) (Here, ~= indicates nearly equal.) Also,
In this antenna, by adjusting the width K1 of the vertical feeding flat plate 33 and the distance t0 between the vertical feeding flat plate 33 and the ground conductor plate 14, the Q of the antenna and the capacitive component in the antenna impedance can be adjusted. Therefore, as shown by the solid line 38 in FIG. 9, impedance matching is possible over a wide frequency band. In addition,
In this figure, a broken line 39 indicates the frequency characteristics of the conventional example (FIG. 21).

Furthermore, as shown in FIG. 12, in a modified example, the side portion near the lower end of the vertical feeding flat plate 33 is cut off.
The width of the lower end of the vertical power supply flat plate 33 is adjusted. In this way, by cutting off the side part of the vertical power supply flat plate 33,
The length of the lower end of the vertical power supply flat plate 33 facing the ground conductor plate 14 can be shortened, and the capacitance component can be reduced. Therefore, according to this example, when the antenna is actually mounted on a vehicle, the input impedance of the antenna can be easily adjusted by adjusting the amount of cut off of this side portion. Therefore, the characteristics of the antenna can be maintained under various conditions.

Furthermore, as shown in FIG. 13, the table 32
By inserting dielectrics 41 and 42 into the area surrounded by the vertical feeding flat plate 33 and the vertical additional plates 34 and 35, the dimensions of each component can be reduced, resulting in further miniaturization and cost reduction of the antenna. It becomes possible to position the radiation element 31, and the fixation of the radiation element 31 becomes reliable.

In the antenna of this embodiment, suitable characteristics can be obtained by setting the dimensions of each part to values as shown in equations (15) to (22) below.

HL +L1 /2+M1 =0.267λ0...(
15) P1 = 0.060λ0 ... (16) W1 =
0.060λ0 ...(17) t1 =0.003λ0
...(18) M1 =0.066λ0 ...(19)
L1 =0.090λ0...(20)K1 =0.0
45λ0...(21)H1 =0.153λ0...
(22) Configuration of diversity antenna FIG. 14 shows a diversity-type vehicle-mounted antenna of the present invention. This antenna is constructed by arranging the first radiating element 21 shown in FIG. 1 and the second radiating element 31 shown in FIG. 8 on a single ground conductor plate 14 having a width We and a length Le. ing. The first radiating element 21 is connected to the ground conductor plate 14
The second radiating element 31 is placed near the end of the ground conductor plate 14 . Here, the distances from the feeding point of the first radiating element 21 to the ends 53 and 55 of the ground conductor plate 14 are respectively S0 and R0, and
The distances from the feeding point of the radiating element 31 to the ends 54 and 55 of the ground conductor plate 14 are S1 and R1, respectively.

Here, FIG. 16 shows the results of measuring the bandwidth by placing the first radiating element 21 and the second radiating element 31 individually on the ground conductor plate 14 and changing their positions (S0, S1). show. In this way, the antenna consisting of the first radiating element 21 has a reduced bandwidth near both ends of the ground conductor plate 14. On the other hand, the antenna made up of the second radiating element 31 has a substantially constant bandwidth regardless of its position on the ground conductor plate 14. Therefore, in this embodiment, the first radiating element 21 is arranged near the center of the ground conductive plate 14, and the second radiating element 31 is arranged at the end of the ground conductive plate 14. The two radiating elements are arranged so that the longitudinal directions of the table are parallel to each other. In this way, the inter-element coupling between both the radiating elements 21, 31 is reduced by making the interval between the radiating elements 21, 31 as large as possible. That is, the first radiating element 21 and the second radiating element 21
Figure 17 shows the relationship between the distance M of the radiating elements 31 and the amount of coupling between the elements.
Shown below. From this, it is understood that in order to reduce the amount of inter-element coupling to -10 dB or less, it is necessary to set it to 0.3λ0 (λ0 is the center wavelength of radio waves transmitted and received by the antenna) or more.

In the diversity antenna of this embodiment, the first radiating element 21 is used for transmission and reception, and the second radiating element 31 is used only for reception, thereby achieving diversity reception. The first radiating element 21 can obtain omnidirectionality without being affected by the second radiating element 31, making it suitable as a transmitting and receiving antenna, and since the coupling between elements is small, the second radiating element 31 can be used as a receiving antenna. When a dedicated antenna is used, a sufficient diversity effect can be obtained.

In the antenna of this embodiment, suitable characteristics can be obtained by setting the dimensions of each part to values as shown in equations (23) to (28) below.

Le=0.480λ0...(23)We
=0.300λ0...(24) S0 =0.168λ0...(25) R0 =0.1
26λ0 ... (26) S1 =0.030λ0 ...
(27) R1 = 0.150λ0 ... (28) By arranging the two radiating elements with different characteristics on the common ground conductor plate 14 with a predetermined distance apart, as shown in FIG.
As shown in FIG. 5, the inter-element coupling between the antennas made up of the two radiating elements 21 and 31 can be sufficiently reduced. Therefore, sufficient characteristics can be obtained in both the radiating elements 21 and 31, respectively.

Overall Configuration Next, a preferred configuration example of the above-mentioned diversity antenna will be explained based on FIGS. 18 to 20. Here, FIG. 18 is a front sectional view, FIG. 19 is a top plan view seen from arrow 67, and FIG.
is a side sectional view seen from arrow 68.

A first radiating element 21 and a second radiating element 31 are arranged on the ground conductor plate 14 at a predetermined interval. In order to further reduce the size of the entire antenna including the case, a coaxial feeder line 1 is installed on the top surface of the ground conductor plate 14.
5-1 and 15-2 remove the coating to form an outer conductor 62-1,
62-2 is laid out in an exposed state, and all parts that contact the upper surface of the ground conductor plate 14 are electrically and mechanically connected and fixed by soldering or the like.

The first radiating element 21 is connected to the ground conductor plate 14 via a support 65 made of polystyrene foam or the like having a predetermined thickness.
is fixed on the top surface. Note that this fixing is performed using adhesive or double-sided tape. The core wire 61-1 of the coaxial feed line 15-1 is connected to the center of the lower end of the radiating element 21 by soldering or the like (see FIG. 18(B)). On the other hand, the second radiating element 31 is fixed on the ground conductor plate 14 via a support 67 made of styrofoam or the like. A coaxial feed line 15-2 is provided at the lower center of the radiating element 31.
The core wires 62-2 are connected by soldering or the like.

The antenna consisting of the ground conductor plate 14 and the first and second radiating elements 21 and 31 is entirely connected to A.
It is housed in a case 64 made of BS resin or the like, and the coaxial feed lines 15-1 and 15-2 are taken out from a part of the case 64.

In the on-vehicle antenna configured as above, the outer conductors 62-1, 6 of the coaxial feed lines 15-1, 15-2
The reason why 2-2 is electrically connected to the ground conductor plate 14 at all its contacting parts is as follows. That is, if the connection between the outer conductor and the ground conductor plate is not electrically perfect, stray capacitance will occur between them. This creates a potential difference between the two, causing unnecessary radiation,
Directivity will be disturbed.

On the other hand, by electrically connecting the outer conductor of the coaxial feeder to the grounding conductor plate at all the contacting parts as in this embodiment, the above-mentioned stray capacitance can be eliminated. , Also, frequency fluctuations are suppressed.

Note that, instead of fixedly connecting the outer conductor of the coaxial feed line and the ground conductor plate in close contact as in this embodiment, the distance between them is sufficiently short compared to the wavelength used (for example, 0.1λ). It may also be possible to electrically connect with a certain degree.

Furthermore, the antenna according to the present invention can be suitably used not only for use in a vehicle but also as a stationary type for residential use.

[0052]

[Effects of the Invention] As explained above, according to the diversity antenna according to the present invention, two antenna elements with different characteristics can be made small, and since antenna elements with different characteristics are used, the amount of coupling between the two elements can be reduced. can be made smaller. Therefore, sufficient performance can be obtained even if both elements are placed relatively close to each other. This allows the entire device to be made smaller while maintaining antenna performance.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view showing a vehicle-mounted antenna comprising a first radiating element of the present invention.

FIG. 2 is a plan view of this vehicle-mounted antenna.

FIG. 3 is a side view of this vehicle-mounted antenna.

FIG. 4 is a characteristic diagram showing the directivity in the horizontal plane of this vehicle-mounted antenna.

FIG. 5 is a characteristic diagram showing the frequency characteristics of this vehicle-mounted antenna.

FIG. 6 is an external perspective view showing a modification of this vehicle-mounted antenna.

FIG. 7 is an external perspective view showing another modification of this vehicle-mounted antenna.

FIG. 8 is an external perspective view showing an in-vehicle antenna comprising a second radiating element of the present invention.

FIG. 9 is a characteristic diagram showing the frequency characteristics of this vehicle-mounted antenna.

FIG. 10 is a side view of this vehicle-mounted antenna.

FIG. 11 is a side view of this vehicle-mounted antenna.

FIG. 12 is a side view of a modification of this vehicle-mounted antenna.

FIG. 13 is a side view showing a modification of this vehicle-mounted antenna.

FIG. 14 is an external perspective view showing an in-vehicle antenna according to an embodiment of the present invention.

FIG. 15 is a characteristic diagram showing frequency characteristics of inter-element coupling of this vehicle-mounted antenna.

FIG. 16 is a characteristic diagram showing the bandwidths of two radiating elements.

FIG. 17 is a characteristic diagram showing the relationship between the distance between two radiating elements and inter-element coupling.

FIG. 18 is a cross-sectional view showing an example of the configuration of the in-vehicle antenna of the present invention.

FIG. 19 is a plan view of this vehicle-mounted antenna.

FIG. 20 is a side sectional view of this vehicle-mounted antenna.

FIG. 21 is an external perspective view showing the configuration of a conventional T-shaped antenna.

FIG. 22 is an external perspective view showing a configuration example of a conventional table-shaped antenna.

FIG. 23 is an external perspective view showing a configuration example of a table-shaped antenna according to related technology.

[Explanation of symbols]

14 Ground conductor plate 15, 15-1, 15-2 Coaxial feeder line 21 1st
Radiating element 22 Table 23 Vertical feeding flat plate 24 Post 25 Capacity addition plate 31 Second radiating element 32 Table (parallel flat plate) 33 Vertical feeding flat plate 34, 35 Vertical feeding plate 61-1, 61-2 Core wires 62-1, 62 -2 Outer conductor 64 Case 65, 67 Support

Claims (1)

[Claims] 1. An on-vehicle antenna comprising a grounded conductor plate, and a first radiating element and a second radiating element arranged on the grounded conductor plate, wherein the first radiating element is arranged on the grounded conductor plate. A vertical feeding flat plate with one end face arranged perpendicular to the plane at a predetermined interval on the top and feeding power to the center of the lower end, a conductive plate for adding capacitance connected to the lower end of the vertical feeding flat plate perpendicular to the plane thereof, A parallel plate connected perpendicularly to the upper end of the power supply plate, and a bar-shaped parallel plate whose one end is connected near the center of one end in a direction orthogonal to the vertical power supply plate, and the other end is connected to a ground conductor plate. Alternatively, the second radiating element includes a vertical feeding flat plate whose one end face is arranged perpendicularly to the plane with a predetermined interval on the ground conductor plate and whose lower end is fed with power to the central part of the ground conductor plate. , a parallel flat plate connected perpendicularly to the upper end of the vertical feeding flat plate, and vertical additional plates connected to both ends of the parallel flat plate parallel to the vertical feeding flat plate and extending toward the ground conductor plate. Features of the on-vehicle antenna.