JPH08186425A - Miniaturized antenna and diversity antenna - Google Patents

Abstract

PURPOSE: To provide the miniaturized non-directivity antenna and to provide a diversity effect in all directions with the miniaturized antenna by feeding power to a first radiating member while connecting both the first terminal of the first radiating member and the second terminal of a second radiating member to a ground conductor respectively as specified. CONSTITUTION: First and second radiating conductors 2 and 3 are parallelly provided with a gap between while setting its electric length at the almost 1/4 length of a wavelength to be used, and a first terminal 4 of the conductor 2 and a first terminal 5 of the conductor 3 are electrically connected with a ground conductor 6. When power is supplied from a microstrip line, currents in the form of a standing wave with an equal amplitude and mutually inverted phases are excited at the conductors 2 and 3. Besides, between the terminals 4 and 5, the currents flow just near the conductors 2 and 3 on the conductor 6. On the conductor 6 far away from the conductors 2 and 3, the currents on the conductors 2 and 3 almost equalize their amplitude but invert their phases so that those currents can be canceled each other and turned to zero. Therefore, the unwanted current of an external conductor can be stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small antenna used as an antenna for radio equipment for various data communications, mobile communications, etc. and a diversity antenna using a plurality of these small antennas.

[0002]

2. Description of the Related Art In recent years, various types of mobile communication in the quasi-microwave band have been in the limelight, and miniaturization of mobile station antennas such as mobile terminals has become an important issue.

In the case of the mobile station antenna described above, when data communication is performed indoors or outdoors, the radio wave propagates as a multiple wave while being reflected and diffracted by a building or tree, and therefore propagates as a multiple wave at the receiving point. The received electric field strength of is accompanied by fading. The envelope level of this fading reception wave frequently drops to the thermal noise level of the receiver, which is an obstacle to realizing high quality communication.

As a technique for reducing the influence of such fading, diversity reception using two or more receptions is known. Generally, a combination of a plurality of antennas is used as an antenna for performing diversity reception. Therefore, it is desired to reduce the size of the diversity antenna as well as the size of the antenna itself.

Here, a conventional mobile station antenna will be introduced. FIG. 20 is an example of a 1/4 wavelength monopole antenna. In this antenna, a conductor rod 82 having a length of 1/4 of a used wavelength is placed upright on a relatively large ground plate 81,
The gap between the conductor rod 82 and the ground plate 81 is set to the coaxial wire 83.
It has a structure that is powered by. The conductor rod operates as a ½ wavelength dipole antenna due to the mirror image effect of the ground conductor 81.

FIG. 21 shows an example of a sleeve antenna. This antenna is a conductor rod 9 with a quarter wavelength of the used wavelength.
1 and a skirt portion 92, and the structure is such that the gap between the conductor rod 91 and the skirt portion 92 is fed by the coaxial line 93. In this structure, the conductor rod 91 and the skirt portion 9
By appropriately selecting the length of 2 and 2, the unnecessary current to the outer conductor of the coaxial wire 93 is blocked at the used frequency, and the antenna operates without the ground conductor. FIG. 22 is an example of a space diversity antenna using two of the above sleeve antennas. In this antenna, the first sleeve antenna 101 and the second sleeve antenna 102 are about half the wavelength used.
They are spatially separated by the wavelength. This space diversity antenna is about 1 / th in an environment where multiple waves propagate.
It utilizes the property that the correlations of the electric field strengths at locations separated by two wavelengths become smaller.

As a conventional diversity antenna, the above monopole and sleeve antennas are spatially separated by about 1
Spatial diversity antennas that are placed apart by / 2 wavelengths are common. In addition, using the sleeve antenna, etc.,
A polarization diversity antenna that utilizes the property that received radio waves of mutually orthogonal polarized waves are uncorrelated, a directional diversity antenna that has different directivity between the antennas, and the like are used.

[0008]

However, the conventional antenna has the following problems.

Since the conventional monopole antenna utilizes the mirror image effect of the ground plane, it basically requires an infinite grounding conductor. However, since a finite ground plane is actually used, the distribution of current flowing on the ground plane changes depending on the size of the finite ground plane, and the antenna characteristics such as input impedance and directivity change. Especially with mobile terminals, the ground plane is originally small, and the ground plane changes depending on how people hold it,
The antenna characteristics change as described above.

The conventional sleeve antenna does not require a ground conductor because it has a skirt portion, but it is large because it requires a length of about ½ wavelength in total for the sleeve portion and the skirt portion. Also, since neither the sleeve antenna nor the monopole emits radio waves in the axial direction of the conductor rod, there is a problem that when the radio waves arrive in the axial direction, they cannot be received.

In the conventional diversity antenna, since the antenna branches are spatially separated by about 1/2 wavelength in order to reduce mutual coupling and mutual correlation, the overall size of the diversity antenna is as large as about 1/2 wavelength or more. Become.
Further, in the case of the space diversity shown in FIG. 22, since the configured basic antenna cannot receive in the axial direction of the conductor as described above, the radio wave from the Z axis direction is received in the coordinate system shown in FIG. Can not. Also, in the case of the polarization diversity antenna or the directional diversity antenna described above, since the sleeve antenna or the like is used, the overall size of the diversity antenna becomes as large as about ½ wavelength or more, and the direction that cannot be received as described above. Exists.

The present invention has been made in order to solve the problems of the prior art, and provides a small omnidirectional antenna and a small diversity antenna capable of obtaining a diversity effect in all directions. With the goal.

[0013]

A small antenna according to the invention of claim 1 has a first conductive radiating member and a second conductive radiating member, both of which have an electric length of approximately ¼ of a used wavelength. However, the first radiating member and the second radiating member are arranged in parallel with a space therebetween, and the first terminal of the first radiating member and the first terminal of the second radiating member are both grounded. The first radiating member is connected to a conductor, and the first radiating member is supplied with power, whereby the above object is achieved.

According to a second aspect of the present invention, there is provided a small antenna having a first conductive radiating member and a second conductive radiating member both of which have an electric length of about ¼ of a used wavelength. The radiating member and the second radiating member are arranged side by side with a space therebetween, and the first terminal of the first radiating member and the first terminal of the second radiating member are both the third conductive radiating member. Connected to the third
The radiating member is connected to the ground conductor by a conductive connecting member, and the first radiating member is supplied with electric power, whereby the above object is achieved.

A small antenna according to a third aspect of the invention is the antenna according to the first or second aspect, in which the first radiating member is fed through an impedance transformer.

A diversity antenna according to a fourth aspect of the present invention is a diversity antenna in which a plurality of the basic antennas are used as a basic antenna, and each of the basic antennas has its own small antenna. The surfaces on which the first radiating member and the second radiating member provided on the basic antenna are formed are arranged so as to be substantially orthogonal to each other, whereby the above object is achieved.

[0017]

In the small antenna according to the first aspect of the present invention, the current supplied to the first radiating member and the current supplied to the second radiating member have substantially the same amplitude and their phases are inverted. On the ground conductor connected to the first terminals of the first and second radiating members, the respective currents cancel each other out to zero. Therefore, in the antenna of the present invention, a current flowing on the ground conductor can be blocked and a large ground conductor is not required.

In the antenna of the present invention, radio waves are radiated by a current flowing between the first radiating member, the second radiating member, and the first terminals of the first and second radiating members. Therefore, the first and second
Even on the axis of the radiating member, the electric wave is radiated by the current flowing between the first and second radiating members. In the plane including the first and second radiating members, in the direction perpendicular to the first and second radiating members, parallel to the first and second radiating members due to the current flowing through the first and second radiating members. Radio waves with different polarization are emitted.
In addition, in the direction perpendicular to the plane including the first and second radiating members, the currents flowing through the first and second radiating members have opposite phases, so they cancel each other out, and the first and second radiating members are cancelled. First of
Only electric waves of polarized waves perpendicular to the first and second radiating members are radiated by the current flowing between the terminals.

In the small antenna according to claim 2,
The current flowing between the first radiating member and the second radiating member of the antenna according to claim 1 flows only in the third radiating member.

In the small antenna according to claim 3,
With the impedance transformer, the impedance of the power feeding system,
By matching the input impedance of the antenna of the present invention according to claim 1 or 2, the efficiency of the antenna of the present invention is increased.

A diversity antenna according to a fourth aspect is
A plurality of antennas according to claim 1 or 2 or 3 are used, and a direction in which a radio wave of polarized waves parallel to the first and second radiating members is radiated and a direction of polarized waves perpendicular to the radiating member of another antenna. The direction in which the radio waves radiate will match.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a perspective view showing a small antenna according to this embodiment, FIG. 2 is a front view of the small antenna, and FIG. 3 is a rear view of the small antenna. This small antenna has a first radiating conductor 2, a second radiating conductor 3 and a grounding conductor 6 formed on the surface of the dielectric substrate 1 by etching or the like, on the surface side of the dielectric substrate 1. On the back surface side, the power supply line 9 is similarly formed on the surface by etching or the like. The first radiating conductor 2 and the second radiating conductor 3 have an electrical length of about ¼ of the used wavelength,
The first terminal 4 of the first radiating conductor 2 and the first terminal 5 of the second radiating conductor 3 are arranged side by side with a space therebetween, and are electrically connected to the ground conductor 6.

The second terminal 7 of the first radiation conductor 2 is electrically connected to the first terminal 10 of the feeding line 9 formed on the back side at the feeding point 8 through a through hole or the like. . The power feeding line 9 on the rear surface side is in a positional relationship of facing the first radiation conductor 2 and the ground conductor 6 provided on the front surface side.
It operates as a microstrip line using the radiating conductor 2 and the grounding conductor 6 as the ground plane.

The small antenna according to this embodiment having the above-mentioned structure is fed from the microstrip line and operates as an antenna. The operation will be described below. When powered by the microstrip line,
In the radiating conductor 2 and the second radiating conductor 3, standing wave currents having substantially the same amplitude and opposite phases are excited. In addition, the first terminal 4 and the second terminal of the first radiation conductor 2
Between the first terminals 5 of the radiation conductors 3, the current flows only in the vicinity of the first radiation conductor 2 and the second radiation conductor 3 on the ground conductor 6. In the ground conductor 6 at a position far from the first radiating conductor 2 and the second radiating conductor 3, the currents on the first radiating conductor 2 and the second radiating conductor 3 are almost equal in amplitude and out of phase with each other. Therefore, they cancel each other out and become zero. Therefore, the antenna of the present embodiment can block the external conductor unnecessary current.

By changing the length ratio of the first radiation conductor 2 and the second radiation conductor 3, the amplitude and phase of the current in the first radiation conductor 2 and the second radiation conductor 3 are changed. Can be controlled, and the external conductor unnecessary current can be efficiently blocked at the used frequency by changing the length ratio.

When the distance between the first radiating conductor 2 and the second radiating conductor 3 is changed, the input impedance or band of the antenna of this embodiment as seen from the feeding point 8 is changed. For example, if the distance between the first radiating conductor 2 and the second radiating conductor 3 is widened, the band of the antenna of this embodiment is widened and the input impedance seen from the feeding point 8 is lowered.
Therefore, it is desirable to determine the interval so as to satisfy the target frequency, band or input impedance.

In the present embodiment, the first of the feeding line 9 is
Although the terminal 10 is connected at the feeding point 8 on the second terminal 7 of the first radiation conductor 2, the feeding point 8 may be located at any place on the first radiation conductor 2. However, the position of the feeding point 8 is from the second terminal 7 to the first terminal 4 of the first radiation conductor 2.
Since the input impedance of the small antenna of the present embodiment seen from the feeding point 8 rises by moving to, the position of the feeding point 8 becomes the characteristic impedance of the microstrip line composed of the feeding line 9 and the ground plane. It is desirable to determine so that the input impedance of the antenna of this embodiment is equal.

FIG. 4 shows the directivity in the case where the small antenna of this embodiment is an S band and a glass epoxy substrate having a thickness of 0.8 mm is used as a substrate. FIG. 4 shows experimental values of directivity of the XY plane in the coordinate system shown in FIG. 1, and the solid line shows Eφ and the broken line shows Eθ.

As can be seen from FIG. 4, radio waves of polarized waves of Eθ and Eφ are both radiated on the XY plane, and the directivity of the radiated radio waves becomes the directivity of the figure 8 orthogonal to each other. .
Therefore, on the XY plane, some radio waves are emitted in all directions. Also, X-Z
The radiated electric field on the surface is only Eθ, and the directivity of the radiated electric field is almost omnidirectional (not shown). Similarly, the radiated electric field on the YZ plane is only Eφ, and the directivity of the radiated electric field is also almost non-directional (not shown).

As described above, the antenna of this embodiment is completely omnidirectional because radio waves of some polarization are radiated in all directions.

(Second Embodiment) FIG. 5 shows a front view of a small antenna according to this embodiment, and FIG. 6 shows a rear view thereof. The antenna of this embodiment is formed on the dielectric substrate 20 in substantially the same manner as in the first embodiment. In this embodiment, the first radiation conductor 21 and the second radiation conductor 22 on the dielectric substrate 20 are in a zigzag shape. Since the zigzag shape adds capacitance, the first radiation conductor 21
Distance between both terminals in the second radiation conductor 22
The distance between the two terminals can be shortened as compared with the case of the above-described first embodiment, and further miniaturization is realized. At this time, it is preferable that the feeding line 23 provided on the back surface side of the first radiation conductor 21 also has a zigzag shape like the first radiation conductor 21.

In this embodiment, the first radiating conductor 21 and the second radiating conductor 22 are formed in a zigzag shape, but the present invention is not limited to this, and is bent at one or more places. It may be a shape that adds capacitance, such as a curved shape, a spiral shape, a spiral shape, or a helical shape.

(Third Embodiment) FIG. 7 shows a front view of a small antenna of this embodiment, and FIG. 8 shows a rear view thereof. The antenna of the present embodiment is formed on the dielectric substrate 30 in substantially the same manner as in the first embodiment, and the impedance transformer 34 is added to the feeding line 33 provided on the back surface side. There is.

In the antenna of this embodiment, the input impedance of the antenna as viewed from the feeding point 35 is arbitrarily changed depending on the shapes, dimensions, locations of the first and second radiation conductors 31 and 32 provided on the front surface side. To do. At this time, as described in the first embodiment, the impedance matching is realized even if the position of the feeding point 35 is changed, but in the case of the present embodiment, the impedance matching is realized in a wider range.

The impedance transformer 34 is inserted between the feeding line 33 and the feeding point 35, and has a characteristic impedance of a microstrip line constituted by the feeding line 33 and the ground plane and an arbitrary radiation conductor. Impedance matching can be done with any input impedance of the antenna to the formation. Therefore, the efficiency of the antenna is increased.

(Fourth Embodiment) FIG. 9 shows a front view of a small antenna of this embodiment, and FIG. 10 shows a rear view thereof. The antenna of the present embodiment has a first radiation conductor 41 formed on the surface of the dielectric substrate 40 by etching or the like,
Second radiation conductor 42, third radiation conductor 43, connection conductor 4
4 and ground conductor 45. In addition, the dielectric substrate 40
Similarly, on the back surface side, there is a power supply line 46 formed by etching or the like.

The first radiating conductor 41 and the second radiating conductor 42 each have an electrical length of about 1/4 of the operating wavelength, are arranged in parallel at intervals, and First
And the first terminal of the second radiating conductor 42 are
Is electrically connected to the radiation conductor 43.

The third radiation conductor 43 is connected to the ground conductor 45 via the connection conductor 44. The second terminal of the first radiation conductor 41 is electrically connected to the first terminal of the feeding line 46 provided on the back surface at a feeding point 47 via a through hole or the like. The power supply line 46 has a first surface provided on the front side.
The radiation conductor 41, the third radiation conductor 43, the connection conductor 44, and the ground conductor 45 are opposed to each other, and the first radiation conductor 41, the third radiation conductor 43, and the ground conductor 45 are used as the ground plane. Operates as a microstrip line.

The thus constructed antenna of this embodiment is fed from the microstrip line and operates as an antenna. The first terminal of the feeding line 46 is connected to the first radiation conductor 41 at the feeding point 47 of the second terminal, but if it is on the first radiation conductor, the feeding point 4
7 may be any place.

In the case of this embodiment, the current flowing between the first terminal of the first radiation conductor 41 and the first terminal of the second radiation conductor 42 is applied only to the third radiation conductor 43. Flowing. Therefore, of the ground conductor 45, the change in the antenna characteristics due to the change in the shape of the ground conductor in the vicinity of the radiation conductor is significantly improved as compared with the first embodiment.

(Fifth Embodiment) FIG. 11 shows a front view of a small antenna of this embodiment, and FIG. 12 shows a rear view thereof. The antenna of the present embodiment is formed on the dielectric substrate 50 in substantially the same manner as the fourth embodiment, and has a configuration in which the impedance transformer 52 is added to the feeding line 51 provided on the back surface side. . The impedance transformer 52 is inserted between the feeding line 51 and the feeding point 53, and is connected to the feeding line 51.
Impedance matching is performed between the characteristic impedance of the microstrip line composed of the ground plane and the ground plane and the input impedance of the antenna.

(Sixth Embodiment) FIG. 13 shows a second embodiment.
FIG. 15 is a perspective view showing a branch diversity antenna, FIG. 14 shows a surface view of a first basic antenna 60, and FIG.
Shows the back view. 16 shows a front view of the second basic antenna 70, and FIG. 17 shows a rear view thereof.

As shown in FIG. 13, this diversity antenna is constructed by combining basic antennas 60 and 70 formed on a dielectric substrate in substantially the same manner as in the above-mentioned fourth embodiment. More specifically, the surface of the first basic antenna 60 where the first and second radiation conductors 61 and 62 are formed and the first and second radiation conductors 71 and 72 of the second basic antenna are formed. The side surface of the first basic antenna 60 on the side of the second radiation conductor 62 is located substantially in the center of the surface of the second basic antenna 70 in a state where the surfaces are orthogonal to each other (T shape when viewed from above). It is arranged to be located.

Ground conductor 6 of the first basic antenna 60
3 and the grounding conductor 73 of the second basic antenna 70 are electrically connected by the contact between the edge of the grounding conductor 63 and the surface of the grounding conductor 73 that accompanies the T-shaped arrangement.
The second terminal 75 of the feeding line 74 provided on the back side of the second basic antenna 70 is electrically connected to the second feeding line 64b of the first basic antenna via a pin or the like. To be done. At this time, the ground conductor 7 of the second basic antenna 70
3 is provided with a punching land 76 to prevent the ground conductor 73 of the second basic antenna 70 and the feeding line 74 of the second basic antenna 70 from coming into contact with each other.

The second feeding line 64b and the first feeding line 6 both of which are provided on the back side of the first basic antenna 60.
4a is a third feeding line 64c provided on the back surface side of the first basic antenna 60 via the RF signal switch 65.
Connected to. As the RF signal switch 65, a PIN diode switch or the like that switches between positive and negative DC bias is used.

FIG. 18 shows the experimental value of the directivity when the first basic antenna 60 operates, and FIG. 19 shows the experimental value of the directivity when the second basic antenna 70 operates. 18 and 19 show the directivity in the XY plane of the coordinate system shown in FIG. 13, and the solid line shows Eφ and the broken line shows Eθ.

As can be understood from these FIGS. 18 and 19, in the XY plane, the second basic antenna 70 is Eφ in the direction in which the Eθ electric field of the first basic antenna 60 is radiated.
In the direction in which the first antenna 60 radiates the electric field and the Eφ electric field radiates, the second basic antenna 70 radiates the Eθ electric field and complements the polarization planes with each other.

In the XZ plane, the first basic antenna 60 is Eθ omnidirectional (not shown), while the second basic antenna 60 is second.
The basic antenna 70 of E becomes omnidirectional (not shown). On the YZ plane, the first basic antenna 60 is Eφ omnidirectional (not shown), while the second basic antenna 70 is Eθ omnidirectional (not shown). Therefore, the polarization planes of the first basic antenna 60 and the second basic antenna 70 are orthogonal to each other in all directions, and the first and second basic antennas 6 are
When 0 and 70 are switched and used, Eθ is also Eφ in all directions.
Can also be received.

Next, a case where the diversity antenna of this embodiment operates as a transmitting antenna will be described. When a positive antenna switching DC bias is superimposed on the RF signal fed from the third feeding line 64c of the first basic antenna 60, the RF signal switching unit 65 causes the second basic antenna 60 And the second basic antenna 70 operates.

On the contrary, when a negative antenna switching DC bias is superimposed on the RF signal fed from the third feeding line 64c of the first basic antenna 60, R
The F signal switcher 65 is the first basic antenna 60 of the first basic antenna 60.
The first basic antenna 60 operates by switching to the side of the power feeding line 64a.

Although the diversity antenna of this embodiment has a built-in changeover switch on the premise that the changeover diversity is performed, it may be applied to a diversity method such as combining and selecting.

Further, although a small antenna having substantially the same structure as that of the fourth embodiment is used as the basic antenna of the diversity antenna of the present embodiment, the present invention is not limited to this, and the first, second, and third embodiments are used. An example small antenna may be used.

Further, the power feeding method for the small antenna and the diversity antenna according to each of the above-mentioned embodiments is not limited to the power feeding by the microstrip line, but may be the power feeding method by coaxial, parallel two wires or the like.

Further, the small-sized antenna according to each of the above-described embodiments and the dielectric substrate constituting the small-sized antenna used for the diversity antenna are the same as the dielectric substrate.
Any suitable material, type or thickness of conductor can be used. Further, the small antenna according to each of the embodiments and the small antenna used for the diversity antenna may not be formed on the dielectric substrate.

[0056]

As described above, the small antenna of the present invention can be miniaturized because it can be changed from the conventional λ / 2 to λ / 4. Further, although the electric length is about 1/4 wavelength, the unnecessary current of the external conductor can be efficiently blocked, and the change in the antenna characteristics due to the change in the ground plane such as the case can be suppressed. In addition, reception sensitivity can be obtained in all directions. Also, by incorporating an impedance transformer inside the antenna, without changing the size of the antenna,
Good impedance matching characteristics can be obtained regardless of the shape of the radiation conductor.

By using the antenna of the present invention as a diversity antenna, a small and uncorrelated antenna branch can be constructed, omnidirectionally polarized waves can be received, and a good diversity effect can be obtained in all directions.

[Brief description of drawings]

FIG. 1 is a perspective view showing a small antenna according to a first embodiment.

2 is a front view of the small antenna of FIG. 1. FIG.

3 is a rear view of the small antenna of FIG. 1. FIG.

FIG. 4 is a diagram showing the directivity of the small antenna according to the first embodiment.

FIG. 5 is a front view showing a small antenna according to a second embodiment.

6 is a rear view of the small antenna of FIG.

FIG. 7 is a front view showing a small antenna according to a third embodiment.

8 is a rear view of the small antenna of FIG.

FIG. 9 is a front view showing a small antenna according to a fourth embodiment.

FIG. 10 is a rear view of the small antenna of FIG.

FIG. 11 is a surface view showing a small antenna according to a fifth embodiment.

12 is a rear view of the small antenna of FIG.

FIG. 13 is a perspective view showing a diversity antenna according to a sixth embodiment.

FIG. 14 is a surface view of a first basic antenna forming the diversity antenna of FIG.

15 is a back view of a first basic antenna forming the diversity antenna of FIG. 13. FIG.

FIG. 16 is a surface view of a second basic antenna forming the diversity antenna of FIG.

FIG. 17 is a rear view of a second basic antenna forming the diversity antenna of FIG.

FIG. 18 is a diagram showing the directivity of the first basic antenna of the diversity antenna according to the sixth example.

FIG. 19 is a diagram showing the directivity of the second basic antenna of the diversity antenna according to the sixth example.

FIG. 20 is a perspective view showing a conventional monopole antenna.

FIG. 21 is a perspective view showing a conventional sleeve antenna.

FIG. 22 is a perspective view showing a conventional space diversity antenna.

[Explanation of symbols]

2, 21, 31, 41, 61, 71 First radiation conductor 3, 22, 32, 42, 62, 72 Second radiation conductor 6, 45, 63, 73 Ground conductor 34, 52 Impedance transformer 43 Third Radiating conductor 44 Connection conductor 60 First basic antenna 70 Second basic antenna 65 RF signal switch

Claims (4)

[Claims] 1. A first conductive radiating member and a second conductive radiating member, both of which have an electric length of about ¼ of a used wavelength, the first radiating member and the second radiating member. And the first radiating member and the first terminal of the second radiating member are both connected to a ground conductor, and the first radiating member is supplied with power. A small antenna configured. 2. A first conductive radiating member and a second conductive radiating member, both of which have an electric length of about ¼ of a used wavelength, the first radiating member and the second radiating member. And the first terminal of the first radiating member and the first terminal of the second radiating member are both connected to the third conductive radiating member, and the third radiating member A small antenna in which a member is connected to a ground conductor by a conductive connecting member, and the first radiating member is supplied with power. 3. The small antenna according to claim 1, wherein the first radiating member is fed with power via an impedance transformer. 4. A diversity antenna using the small antenna according to claim 1, 2 or 3 as a basic antenna and using a plurality of said basic antennas, wherein each basic antenna has a first radiation provided on each basic antenna. A diversity antenna arranged so that the surfaces on which the member and the second radiating member are formed are substantially orthogonal to each other.