JPH08250917A - Antenna for radio equipment - Google Patents

Abstract

PURPOSE: To obtain an inverted-F shaped antenna for a radio equipment which is light and rigid and not breakable by a deep notch and whose resonance frequency is adjusted simply after the manufacturing process. CONSTITUTION: The antenna is made up of a printed circuit board 2 with a radiation element mounted thereon, a spacer 8 used to set the printed circuit board 2 at a prescribed interval in parallel with respect to the ground of a printed circuit board 1 of a portable radio equipment, a feeding point 3 for feeding power to the radiation element, and a short stub 4 interconnecting the ground and the radiation element. The radiation element is made up of a copper foil pattern on which slit patterns 9, 10 are formed to adjust the resonance frequency of the antenna for the radio equipment before and after the manufacture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio antenna used in a mobile phone, a mobile radio, etc., and more particularly to a plate-shaped inverted F antenna built in the radio or the like.

[0002]

2. Description of the Related Art Conventionally, an inverted F of a type built into a radio device or the like
There was an antenna as shown in FIG. Figure 7
FIG. 6 is a perspective view showing an inverted F antenna when a metal substrate is used as a conventional example. In FIG. 7, 1 is a ground plane or a circuit board of a radio device, 6 is a metal plate acting as a radiating element of an inverted F antenna, 3 is a feeding point for feeding the inverted F antenna, 4 is a metal plate 6 and the circuit board 1. Short stub for connecting to the earth pattern, 7 is a notch for adjusting the resonance frequency of the inverted F antenna or for downsizing the device,
Reference numeral 18 denotes a non-metal spacer that holds the metal plate 6 on the circuit board 1 and defines a gap between the metal plate 6 and the circuit board 1. Here, the metal plate 6, the feeding point 3, and the short stub 4
And the spacer 18 form an inverted F antenna.

When a plate-shaped inverted F antenna is constructed in such a limited occupied area, the resonance frequency thereof is the metal plate 6
Since the length of the circumference of the side of is equal to λ / 2, the length normally resonates at a high frequency. The resonance frequency becomes lower as the length of the side of the metal plate 6 serving as the radiating element is increased. Therefore, in order to make the perimeter of the metal plate 6 a length corresponding to the frequency used, the notch 7 is formed in the metal plate 6. As described above, by increasing the depth of the cut 7 of the metal plate 6, it is possible to adjust the perimeter of the metal plate 6 to be apparently longer and lower the resonance frequency of the inverted F antenna.

That is, when using an inverted F antenna having a small area such as built in a mobile phone, it is necessary to obtain a desired low resonance frequency within a limited area, and for that purpose, a deep cut 7 is required. Become. As a concrete example, when trying to obtain a desired resonance frequency within an area of 30 mm × 25 mm used as a built-in antenna of an 800 MHz band mobile phone, a cut of 20 mm or more is required.

Another conventional example uses a double-sided printed board (not shown) instead of the metal plate 6 and the spacer 18 in the above-mentioned conventional example. A radiating element is printed on the upper surface of the double-sided printed board, and a ground plane is printed or mounted on the back surface.
Therefore, in this case, it is not necessary to use a spacer 18 or the like, but a thick double-sided printed circuit board having excellent high frequency dielectric properties must be used.

[0006]

However, although the conventional inverted-F antenna as described above basically functions effectively, the inverted-F antenna according to the above-described conventional example is temporarily operated in the manufacturing process. Since the depth of the cut 7 cannot be easily changed, there is a problem that it is difficult to finely adjust the frequency of the inverted F antenna in the manufacturing process.

In addition, the deeper the notch 7 becomes, the weaker the strength becomes. Therefore, a large-sized spacer 18 for holding the metal plate 6 is required, and it is slightly thicker so as not to be deformed when an impact is applied. However, there is a problem that the whole metal plate 6 becomes heavy.

In the inverted F antenna according to the second conventional example, the radiating element is printed on the upper surface of the double-sided printed circuit board and the ground plane is printed or mounted on the rear surface. The distance between them, that is, the thickness of the double-sided printed circuit board is a factor for determining the resonance frequency bandwidth of the plate-shaped inverted F antenna, and it has to be considerably thick and heavy. Further, the double-sided printed circuit board must use a material having excellent high-frequency dielectric properties, and there is a problem in terms of material selection and manufacturing cost.

The present invention has been made in view of the above problems, and is a plate-shaped inverted F for radio equipment in which the resonance frequency can be easily adjusted during and after the manufacturing process.
The purpose is to provide an antenna. Further, the present invention has been made in view of the above problems, and has a solid structure despite its freedom of material selection and lightness, and its strength is not affected by deep cuts. F
The purpose is to provide an antenna.

[0010]

In order to achieve the above object, a radio antenna according to the present invention is provided with a printed circuit board having a radiating element mounted thereon and a ground on a circuit board of a portable radio. An antenna for a wireless device, comprising a spacer for setting a base at a predetermined interval and setting it in parallel, a feeding point for feeding a radiating element, and a short stub for connecting a ground and the radiating element, wherein the radiating element is a copper foil. A slit pattern for adjusting the resonance frequency of the antenna for a wireless device before and after manufacturing is held.

The radio antenna according to the present invention comprises:
In order to achieve the above object, the slit pattern is a slit pattern cut in order to lower the resonance frequency in its production from one side around the copper foil pattern to the inside, and a predetermined interval on the extension of the slit pattern. A slit pattern for adjustment, which is placed in a window shape to reduce the resonance frequency after manufacturing, and at least 2 around the copper foil pattern.
It consists of an adjusting slit pattern for increasing the resonance frequency after manufacturing consisting of notches provided, and the adjusting slit pattern is characterized by lowering or increasing the resonance frequency by a predetermined amount by cutting between them. .

The radio antenna according to the present invention comprises:
In order to achieve the above-mentioned object, the printed circuit board is made of a material such as a rigid and low-cost paper-phenolic board which does not require high frequency characteristics.

The radio antenna according to the present invention comprises:
In order to achieve the above object, the spacer is a small-sized spacer that is partially arranged. In order to achieve the above-mentioned object, the radio antenna according to the present invention is characterized in that the feeding point and the short stub are composed of a pin and a connector that can be inserted and removed.

[0014]

The radio antenna according to the present invention is constructed as described above. In particular, an inverted F antenna in which a thin copper foil pattern is mounted as a radiating element on one side of a thin, light and solid printed board is used. Since the slit pattern provided on the foil pattern can be easily changed after the manufacturing process, it is light and durable without using thick and heavy spacers or printed boards unlike the conventional example. Even if you lengthen the
The frequency can be adjusted after assembly.

The radio antenna according to the present invention comprises:
With the configuration as described above, in particular, the slit pattern for adjustment is provided on the extension of the slit pattern of the copper foil pattern, and the desired frequency is obtained by cutting between the slit patterns for adjustment after the manufacturing process is completed. As a result, it is possible to easily and quickly adjust the resonance frequency to lower or increase it after the manufacturing process is completed.

Further, the radio antenna according to the present invention comprises:
With the structure as described above, the high-frequency characteristics are not required, and the solid and low-cost printed board made of a material such as paper phenolic board is used. Since it is not necessary to use a different spacer, the spacer can be made smaller,
It is possible to reduce the weight of the inverted F antenna.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings and FIGS. 1A and 1B are diagrams showing an inverted F antenna for a portable wireless device formed on a circuit board according to an embodiment of the present invention. FIG. 1A is a perspective view thereof, and FIG. 1B is an adjustment slit pattern for lowering a resonance frequency. FIG. 2C is a plan view showing an adjustment slit pattern for increasing the resonance frequency, and FIG. 2 is a perspective view showing a state in which the inverted F antenna shown in FIG. 1 is specifically attached to a portable wireless device (mobile phone). FIG. 3 and FIG. 3 are views showing the actual measurement data of the frequency characteristics of the inverted F antenna for the portable wireless device according to the present embodiment, (a)
Is a voltage standing wave ratio / frequency characteristic diagram, and (b) is an impedance / frequency characteristic diagram (Smith chart).

FIG. 4 is a diagram showing measured data of the radiation characteristic of the inverted F antenna for portable radio according to the present embodiment,
(A) is a figure which shows the direction of a portable radio | wireless machine, (b) is a figure which shows a radiation directivity with respect to a perpendicular direction (it sees at XZ plane),
FIG. 5C is a diagram showing the radiation directivity in the horizontal direction (viewed in the XY plane), FIG. 5 is a diagram showing an adjustment slit pattern used in this embodiment, which is easy to adjust, and FIG. 5A is a slit pattern. In the case of extending the slit pattern in the vertical direction, (b) in the case of extending the slit pattern in the horizontal direction, (c) in the case of extending the slit pattern in a hook shape, and FIG. 6 for the portable wireless device according to the present embodiment. It is a figure which shows the electric power feeding system of an inverted F antenna, (a) is a figure when a short stub and a feeding point are comprised by another component, (b) is a figure when it is comprised by one component, (c). [Fig. 3] is a diagram when it is configured by separate pins.

First, an inverted F antenna according to an embodiment of the present invention will be described with reference to FIG. In FIG.
1 is a base plate or a circuit board of a portable radio device, 2 is a printed board supporting a copper foil pattern, and 15 is a printed board 2
The copper foil pattern mounted on the surface opposite to the side of the circuit board 1 and acting as a radiating element of the inverted F antenna having an area smaller than the outer shape of the printed board 2, 3 is a feeding point for feeding the inverted F antenna, 4 is a copper foil pattern It is a short stub that connects 15 and the ground pattern of the circuit board 1.

Further, 5 is a slit pattern for adjusting the resonance frequency of the inverted F antenna (corresponding to the notch 7 in the above-mentioned conventional example), 8 is a printed board 2 held in parallel on the circuit board 1, and is made of copper. A small non-metallic spacer that defines the gap between the foil pattern 15 and the ground pattern of the circuit board 1, 9 is an adjustment slit pattern for adjusting to reduce the resonance frequency of the inverted F antenna, 1
Reference numeral 0 is an adjusting slit pattern for adjusting to increase the resonance frequency of the inverted F antenna.

In the present embodiment, the printed circuit board 2 having the copper foil pattern 15, the feeding point 3, the short stub 4 and the spacer 8 constitute an inverted F antenna. Further, the copper foil pattern 15 on the printed board 2 and the ground pattern of the circuit board 1 have to be arranged in parallel as described above, but other portions on the surface of the circuit board 1 may be different. A shield (or an earth pattern) may be provided, and the printed circuit board 2 may be formed on the copper foil pattern 15 so that the shield and the shield are arranged in parallel.

Next, the operation of the inverted F antenna according to this embodiment will be described with reference to FIG. The area occupied by the printed circuit board 2 of the inverted F antenna, which is a built-in antenna, is 20 mm x 30 depending on the size of the portable wireless device (mobile phone).
Although it is limited to mm, the resonance frequency of the plate-shaped inverted F antenna is as high as 1.5 GHz as it is because the length of the circumference of the metal surface corresponds to λ / 2. Since the frequency used in the portable wireless device (mobile phone) according to this embodiment is in the 800 MHz band, first, the slit pattern 5 is inserted in the copper foil pattern 15 to increase the apparent perimeter, thereby causing the resonance of the inverted F antenna. Try lowering the frequency.

At this time, in one embodiment of the present invention, since the metal surface is formed by the copper foil pattern 15 on the printed board 2, even if a slit is formed in the copper foil pattern 15, the strength of the inverted F antenna is reduced. It doesn't become weak,
Since the printed board 2 supporting the copper foil pattern 15 can be rigid, the spacer 8 holding it can be small, and the inverted F antenna can be lightened.

Further, in the printed circuit board antenna using the double-sided board as shown in the second conventional example, a thick double-sided printed circuit board excellent in high frequency dielectric property must be used. Since the purpose of use is different as long as it can stably support the copper foil pattern 15, there is no fear of deterioration in characteristics even if a substrate made of a thin material having insufficient high frequency characteristics is used. for that reason,
It has the advantage of being very cheap and lightweight. In this embodiment, the glass epoxy substrate is used for the print substrate 2, but it is possible to further reduce the weight by using a material having a low specific gravity such as a paper phenol substrate.

Next, referring to FIG. 1, and particularly to FIGS. 1B and 1C, regarding the adjustment slit patterns 9 and 10 for adjusting (lowering or raising) the resonance frequency after the manufacturing process. explain. The adjustment slit pattern 9 shown in FIG. 1B is for lowering the resonance frequency, and A of 9 is arranged on the extension of the slit pattern 5 cut in the lateral direction or upward from the vicinity of the feeding point, Further, B and C of the adjustment slit pattern 9 are arranged further ahead.

First, in order to reduce the resonance frequency, the slit pattern 5 and the slit A for adjustment 9 are cut off from each other as indicated by the arrow in FIG. 1 (b). Thereby, the apparent length of the slit pattern 5, that is,
Since the peripheral length of the copper foil pattern 15 becomes long, the resonance frequency can be lowered. Furthermore, the resonance frequency can be lowered by a fixed amount by cutting the adjustment slit pattern 9 between A and B and between B and C one after another.

Next, when increasing the resonance frequency, A-1 and B- of the adjustment slit patterns 10 arranged around the copper foil pattern 15 are indicated by the arrows in FIG.
The convex part between 1 and 1 is cut at its root. As a result, the apparent length of the slit pattern 5, that is, the peripheral length of the copper foil pattern 15 is shortened, so that the resonance frequency can be increased. Further, the adjustment slit pattern 10
By cutting the convex portion between B-1 and C-1 of
The resonance frequency can be lowered by a certain amount.

As described above, not only the resonance frequency can be lowered, but also the resonance frequency can be increased for correction when it is cut too much, so that the productivity in the manufacturing process can be improved and further, The adjustment is very easy because it can be done on an occasional basis. Further, the positions and configurations of the slit pattern 5 and the adjustment slit patterns 9 and 10 can be selected in consideration of easiness of cutting between slits and improvement of productivity in the manufacturing process.
By increasing the number of adjustment slit patterns 9 and 10 as needed, it is possible to expand the range of adjustable frequency range.

Next, with reference to FIG. 2, the inverted F antenna prepared according to the present embodiment will be specifically described as a portable radio device (mobile phone).
The state of being attached to will be described. In FIG. 2, 11
Is a telescopic whip antenna with a length of λ / 4 to λ / 4, 1
Reference numeral 2 is a battery pack, 13 is a body of the portable wireless device, 14 is a receiver, 15 is a copper foil pattern, and other elements having the same reference numerals as those shown in FIG. 1 are the same as those shown in FIG. Further, on the right side of the drawing, the copper foil pattern 15 of the inverted F antenna mounted on the portable wireless device is enlarged and shown, and three adjustment slit patterns 9, 9-1 and 10 are shown therein. Further, details of the adjustment slit patterns 9 and 10 will be described later in detail with reference to FIG.

Next, with reference to FIG. 3, the frequency characteristics measured for the inverted F antenna manufactured according to this embodiment will be described. As can be seen from the voltage standing wave ratio / frequency characteristic diagram shown in FIG. 3A, the resonance frequency of the inverted F antenna according to the present embodiment is a desired reception frequency of 860 MHz to 885.
At MHz, it can be seen that the voltage standing wave ratio (SWR) <2 is sufficiently ensured and that the band as an antenna is sufficient. The dominant factor that determines the bandwidth of the resonant frequency of the plate-shaped inverted F antenna is the distance between the copper foil pattern 15 that is a radiating element and the ground pattern surface of the circuit board 1. The distance is 4.5 mm.

Referring to the impedance characteristic diagram of the inverted F antenna shown in FIG. 3B, the optimum impedance value of 50 ohms is shown near the center of the figure, but the impedance value of the inverted F antenna according to this embodiment is shown. It can be seen that is almost in the vicinity.

Next, with reference to FIG. 4, the radiation directivity characteristic measured for the inverted F antenna prepared according to this embodiment will be described. FIG. 4A shows a vertical direction (Z direction) and a horizontal direction (X, Y directions) with respect to the portable wireless device. As for the radiation directivity of the inverted F antenna according to the present embodiment, as shown in FIG. 4B, the radiation is small in the vertical direction and the largest in the horizontal direction with respect to the housing of the portable wireless device.
Further, as shown in FIG. 4 (c), a uniform omnidirectional pattern can be obtained, and therefore, it can be seen that the radiation pattern is a very good radiation pattern particularly when considering the application as a mobile phone. .

It can be seen that the vertical polarization average gain in the horizontal plane is about -1 dB as compared with the dipole antenna, which is sufficient as an antenna attached to a small ground such as a mobile phone. Further, this value is comparable to that of a plate-shaped inverted F antenna using a metal plate which is a conventional example.

Next, referring to FIGS. 5A, 5B and 5C, an example of the structure of the copper foil pattern 15 formed on the printed board 2 used for the inverted F antenna according to this embodiment. Will be described. In each drawing, a slit pattern 5 for lowering the resonance frequency of the inverted F antenna, and an adjustment slit pattern 9 for lowering or raising the resonance frequency of the inverted F antenna created after or during the manufacturing process, respectively. And 10.

FIG. 5A shows an example in which the slit pattern 5 is provided downward from the vicinity of the feeding point 3 and the short stub 4, and FIG. 5B shows the vicinity of the feeding point 3 and the short stub 4. 5C shows an example in which the slit pattern 5 is inserted laterally, and FIG. 5C shows an example in which when the slit pattern 5 needs to be lengthened, it is bent into a hook shape and extended. . As described above, the longer the slit pattern 5 is, the lower the resonance frequency is.
Further, the closer the installation position is to the feeding point 3, the greater the frequency reduction rate per length.

Next, the operation principle of the adjusting slit pattern 9 will be described. The adjustment slit pattern 9 arranged near the slit pattern 5 is A,
Hereinafter, as the distance from the slit pattern 5 increases, they are referred to as B and C. Here, when it is desired to lower the resonance frequency, a thin pattern between the slit pattern 5 and A of the adjustment slit pattern 9 is cut by a laser trimming method or the like. As a result, the slit pattern 5 becomes longer, and the resonance frequency of the inverted F antenna can be lowered by a fixed value.

Similarly, the resonance frequency can be lowered at a predetermined reduction rate by sequentially cutting the adjustment slit patterns 9 between A and B and between B and C. According to the present embodiment (specifically shown in FIG. 2), one pattern is cut between the slit pattern 5 and A of the adjustment slit pattern 9, between A and B of the adjustment slit pattern 9, and between B and C. Each time, the resonance frequency decreases by about 8 MHz from around 900 MHz, and in the case of the second adjustment slit pattern 9-1 (see Fig. 2), it decreases by about 4 MHz each time one pattern is cut. Has been confirmed.

Next, the operation principle of the adjusting slit pattern 10 will be described. Adjustment slit pattern 1
By cutting between A-1 and B-1 of 0 and between B-1 and C-1, the apparent perimeter of the entire copper foil pattern 15 is shortened, so that the inverse F antenna has The resonance frequency can be increased. As a result, it is possible to raise the resonance frequency, which has been lowered too much, to the original direction. In the case of the present embodiment shown in FIG. 2, about 2 is cut each time one is cut between A-1 and B-1 and between B-1 and C-1 of the adjustment slit pattern 10. It has been confirmed that the MHz resonance frequency increases.

As described above, as a method of actually adjusting the resonance frequency in the manufacturing process, it is performed by cutting the pattern between the slit patterns whose resonance frequency shift amount is known in advance, and ,
We have realized an easy-to-adjust resonance frequency adjustment method, in which it is possible to raise the resonance frequency if it is too low. Furthermore, since it is not necessary to add an adjustment component for adjustment, adjustment is possible at low cost. Further, since the pattern can be cut in a short time by using the conventional technique such as the laser trimming method, the manufacturing cost can be reduced by shortening the manufacturing tact.

Next, a method for supplying power to the copper foil pattern 15 on the printed board 2 will be described with reference to FIG. In FIG. 6A, the feeding point 3 and the short stub 4 are provided.
Are made of metal parts obtained by processing flat metal plates, and the copper foil pattern 15 on the printed board 2 and the circuit board 1 are formed.
Fig. 6 shows an example of connecting to and by soldering.
6 (b) shows an example of the case where the above metal component is formed in one form, and in FIG. 6 (c), a hole is formed on the printed board 2, a pin is inserted, and soldering is performed. An example of inserting and connecting to the connector 16 mounted on the circuit board 1 will be shown. In any of these cases, there is no difference in characteristics as an inverted F antenna, and it has been confirmed that similar effects can be obtained with respect to the ease of adjusting the resonance frequency, and all can be considered as a configuration method in the power feeding portion. It is a suitable configuration example.

[0041]

The radio antenna according to the present invention is constructed as described above, and in particular, it is not necessary to consider high frequency characteristics, and it is not necessary to use a thick metal plate used for maintaining strength. A thin and light printed board is used, a copper foil pattern is mounted on it as a radiating element, and an adjustment slit pattern is formed on it, so that it is the same as a conventional plate-shaped inverted F antenna using a metal plate. While having the performance of, it is possible to easily and quickly adjust the resonance frequency after the manufacturing process with little variation.
It is possible to manufacture an inverted F antenna having a low manufacturing cost, a light weight, and a solid structure.

[Brief description of drawings]

FIG. 1 is a diagram showing an inverted F antenna for a portable wireless device formed on a circuit board according to an embodiment of the present invention, in which (a) is a perspective view thereof and (b) shows an adjusting slit pattern for lowering a resonance frequency. The plan view (c) is a plan view showing an adjustment slit pattern for increasing the resonance frequency.

FIG. 2 is a perspective view showing a state in which the inverted F antenna shown in FIG. 1 is specifically attached to a portable wireless device (mobile phone).

FIG. 3 is a diagram showing measured data of frequency characteristics of an inverted F antenna for a portable wireless device according to the present embodiment, where (a) is a voltage standing wave ratio / frequency characteristic diagram and (b) is an impedance / frequency characteristic diagram ( Smith chart)

FIG. 4 is a diagram showing measured data of radiation characteristics of an inverted F antenna for a portable wireless device according to the present embodiment, (a) showing a direction of the portable wireless device, and (b) showing a vertical direction (XZ plane). FIG. 7C is a diagram showing the radiation directivity with respect to the horizontal direction (as seen in the XY plane).

FIG. 5 is a diagram showing an adjustment slit pattern that is easy to adjust and is used in the present embodiment. FIG. 5A is a diagram when the slit pattern is extended in the vertical direction, and FIG. 5B is a diagram when the slit pattern is extended in the horizontal direction. Figure (c) shows the case where the slit pattern is extended into a hook shape.

FIG. 6 is a diagram showing a power feeding system of an inverted F antenna for a portable wireless device according to the present embodiment, where (a) shows a case where a short stub and a power feeding point are formed by different parts, and (b) shows one. Figure when configured with parts (c) is a figure when configured with separate pins

FIG. 7 is a perspective view showing an inverted F antenna using a metal substrate as a conventional example.

[Explanation of symbols]

 1 Circuit Board 2 Printed Circuit Board 3 Feeding Point 4 Short Stub 5 Slit Pattern 6 Metal Plate 7 Cut 8 Spacer 9 Adjustment Slit Pattern 9-1 Adjustment Slit Pattern 10 Adjustment Slit Pattern 11 Telescopic Whip Antenna 12 Battery Pack 13 Body 15 Copper foil pattern 16 Connector 18 Spacer

Claims (5)

[Claims] 1. A spacer for setting the printed board at a predetermined interval in parallel between a printed board on which a radiating element is mounted and a ground on a circuit board of a portable wireless device, and to feed power to the radiating element. A radio device antenna comprising a feeding point and a short stub for connecting between the ground and the radiating element, wherein the radiating element is a copper foil pattern, and a slit for adjusting the resonance frequency of the radio device antenna before and after manufacturing. An antenna for a wireless device, which holds a pattern. 2. The slit pattern is a slit pattern that is cut inward from one side of the periphery of the copper foil pattern to reduce the resonance frequency in its manufacture, and a predetermined interval is provided on the extension of the slit pattern. An adjustment slit pattern provided in a window shape to lower the resonance frequency after manufacturing, and an adjustment slit pattern having at least two cuts provided around the copper foil pattern to increase the resonance frequency after manufacturing. 2. The antenna for a radio device according to claim 1, wherein the adjustment slit pattern lowers or increases the resonance frequency by a predetermined amount by cutting the gap between them. 3. The antenna for a radio device according to claim 1, wherein the printed circuit board is made of a material such as a paper phenol substrate which is robust and low in cost regardless of high frequency characteristics. 4. The spacer according to claim 1, 2 or 3, wherein the spacer is a small spacer that is partially disposed.
The described antenna for the radio. 5. The antenna for a radio device according to claim 1, wherein the feeding point and the short stub are composed of pins and connectors which can be inserted and removed.