JPH0458603A - Non-grounded type ultra high frequency antenna - Google Patents

Abstract

PURPOSE:To attain automatic and contactless changeover attended with an insertion/withdrawal operation of an antenna element, to avoid increase in the volumical space factor and to attain the operation with high reliability for a long time by setting in a required way a static capacitance and an inductance of a 2nd metallic member whose electric length is a specific value arranged in parallel with a lst metallic member connecting to a static coupler coupling with an inductive antenna element whose electric length is a specific value. CONSTITUTION:When an antenna element 10 whose electric length is 1/2 of a wavelength A of an operating frequency band or below is extracted from a container groove 53, a static coupler 22 and the element 10 are contactless-coupled through electrostatic coupling. A thin and long lst metallic member 20 whose one terminal connects to the coupler 22 and a 2nd metallic member 30 whose electric length is lambda/4 and whose one terminal connects to the coupler 22 in parallel with the member 20 at a prescribed interval with the member 20 are provided and the element 10 gets a high impedance through the parallel resonance of a static capacitance between the members 22,30 and the inductance of the member 22 with respect to the operating frequency band while the element 10 is stretched out. The impedance matching between the element 10 and a feeder 60 is simply obtained through the required setting of the connecting point position of the feeder 60 with respect to the members 22,30, and the member 30 whose electric length is nearly lambda/4 with respect to the operating frequency band is used as an ground-wire, then the installation space for the antenna base end is not increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a non-grounded extremely high frequency antenna which is preferable as an antenna for a hand-held radio telephone, which is applied, for example, to a cellular one-way radio telephone system.

[Prior Art] Handy-type radio telephones applied to cellular one-way radio telephone systems are required to be smaller and lighter than ever before. At the same time, improvements in performance, ease of handling, etc., as well as novelty in design, are strongly desired.

An antenna for a hand-held wireless telephone is required to be an ungrounded antenna or something close to it in order to maintain constant performance regardless of whether it is in use or not. Furthermore, since a radio telephone is a bidirectional communication means, it is necessary to be able to receive a calling signal from the other party at all times.

For this reason, early handheld wireless telephone antennas used antennas in which the antenna element was fixed and kept protruding outside the wireless telephone set at all times in order to maintain reception sensitivity above a certain level. was.

However, in the above configuration, the antenna element, which has the same length as the radio telephone set, always protrudes in a fixed state, which is a serious nuisance when not in use. Therefore, in terms of handling, it is preferable to use a type that allows the antenna element to be stored in the radio telephone set after use. However, when the antenna element is simply housed in a wireless telephone set, it becomes obvious that the three main elements of the antenna are gain.

Directivity and impedance are all significantly reduced. Therefore, there is a high possibility that a calling signal from the other party cannot be received.

In order to solve this problem, in addition to the main antenna element, which can be inserted and removed at will, a built-in antenna is pre-housed inside the non-TTF' handset set, and is configured so that a certain level of receiving sensitivity can be obtained even when it is housed. An antenna has been proposed in which an element is provided separately and a micro-switch is used to switch between the main antenna element and the built-in antenna element depending on whether the antenna is in use or not.

In another method, an inductive auxiliary element is provided in the wireless telephone set in order to suppress the deterioration of antenna performance by canceling the capacitance that occurs when the main antenna element is retracted. A structure has been proposed in which the element is automatically connected to the end when stored.

[Problems to be Solved by the Invention] Among the above-mentioned improvement proposals, the former has the possibility of meeting antenna performance and user demands to some extent. However, since a micro-switch and a mechanism for operating the micro-switch are required, there is a concern that the wireless telephone set will become larger and more complex. Moreover, as a result of interposing a minute changeover switch in the ultra-high frequency transmission line, it has an essential defect in that it is difficult to guarantee sufficient performance. Thus, new problems arise such as lack of reliability during long-term use.

The latter also provides a certain degree of reception sensitivity when left unused (not in use). However, because the auxiliary elements are placed in the exact same position as the hand when holding the wireless telephone set, the required functions cannot be fully demonstrated while the wireless telephone set is being held in the hand. .

Therefore, an object of the present invention is to automatically and non-contact switch the removable main antenna element and the built-in antenna element into a used state and a non-used state as the main antenna element is inserted and removed. In addition to exhibiting optimal broadband antenna characteristics depending on the situation, there is no need for any mechanism for switching antenna elements, there is no risk of increasing the space occupancy of the wireless telephone set, and it is highly reliable over a long period of time. To provide a non-grounded extremely short wave antenna that can be expected to operate and, in addition, has almost no adverse effect when holding a wireless telephone set in the hand.

[Means for Solving the Problems] In order to solve the above problems and achieve the 17 objectives, the present invention has the following features:
The following measures were taken:

1) A rod-shaped antenna element that is removably inserted into the antenna element storage part provided in the wireless telephone case, and has an electrical length of less than λ/2, where λ is the wavelength of radio waves in the frequency band used. an inductive antenna element having an inductive antenna element; a capacitive coupler disposed close to the antenna element in the vicinity of the entrance of the antenna element housing so as to be electrostatically coupled to the antenna element; and the capacitive coupler. a first metal member having an elongated shape, one end of which is connected to the antenna element, and the other end of which is extended in a direction perpendicular to the axis of the antenna element; a second metal member having an electrical length of λ/4, which is connected to the first metal member, and a power supply line having one end connected near a connection point between the second metal member and the first metal member. , and set so that when the antenna element is extended, the capacitance between the first and second metal members and the inductance of the first metal member resonate in parallel with respect to the frequency band used. did.

2) Add the following means to the means 1) above.1. Ta.

The capacitance in the capacitive coupling section consisting of the antenna element and the capacitive coupler and the residual inductance of the antenna element are 1. The filter was constructed so as to form a fixed type bandpass filter.

3) The following means were added to the means of 1) above.

A grounding piece is provided at a position separated by λ/4 from the electrostatic coupler in the antenna element housing, and when the antenna element is housed in the housing, the base end of the antenna element is directly or indirectly grounded. The electrostatic coupler functions as an isolator, and the first metal member operates as a modified inverted F-shaped built-in antenna element.

4) The following means were added to the first stage of 1) above.

1st. A zigzag-shaped cut for improving antenna radiation efficiency was provided in the second metal part along a direction perpendicular to the longitudinal direction of each member.

[Effect] As a result of taking the above measures, the following effects occur.

1) When the antenna element is extended, the capacitance between the first and second metal members and the inductance of the first metal member resonate in parallel with the frequency band used, so the antenna element becomes high impedance, and an ungrounded antenna is realized.

Since one end of the feeder line is connected near the connection point between the first metal member and the second metal member, impedance matching between the antenna element and the feeder line can be achieved by setting the connection point position to a required position. can be easily obtained. Note that since the second metal member having an electrical length of approximately λ/4 of the operating frequency is used as the ground wire, the installation space for the base end of the antenna does not need to be so large.

2) The capacitance in the capacitive coupling section consisting of the antenna element and the capacitive coupler and the residual inductance of the antenna element form a constant type bandpass filter for the frequency band used, so the frequency band used This will lead to wider bandwidth.

3) The antenna element stored in the antenna element storage section is directly or indirectly grounded via a grounding piece provided at a distance of λ/4 from the electrostatic coupler, so that the antenna element is When the antenna element is housed in the housing, the parallel resonance phenomenon caused by the inductance of the antenna element and the capacitance between the antenna element and the inner wall surface of the housing is eliminated.

Further, unnecessary radiation to the inside of the wireless telephone set can be prevented. When the antenna element is placed in the retracted state, the residual inductance of the antenna element changes, so that the above-described type bandpass filter no longer holds true. Therefore, the electrostatic coupling portion becomes an isolator, and the first metal member functions as a built-in modified inverted F-shaped antenna element.

4) First. Since the second metal member is provided with a zigzag-shaped cut along a direction perpendicular to the longitudinal direction of each member, a loading effect is produced and a required electrical length is ensured. This improves antenna radiation efficiency.

[Embodiment] FIGS. 1(a) and 1(b) are an exploded perspective view showing the main parts of an ungrounded ultrahigh frequency antenna according to an embodiment of the present invention, and a perspective view showing the external appearance. Fig. 2 is a cross-sectional view of the main part showing the state in which the antenna element of the same embodiment is stored in the storage part;
The figure is a perspective view showing a modification of the electrostatic coupler, and FIG. 4 is a perspective view showing a modification of the second metal member.

In FIGS. 1(a) and 2, 10 is a rod-shaped antenna element, which is an inductive antenna element having an electrical length of less than λ/2, where λ is the wavelength of radio waves in the frequency band used. It is an antenna element. The antenna element 10 is removably inserted into antenna element storage portions (tI53, etc.) provided in the upper and lower radio telephone cases 50a, 50b.

Note that the upper case 50a is a case that accommodates the antenna matching section and the built-in antenna, and is made of plastic because it is necessary to radiate radio waves to the outside. The lower case 50b is a case that houses an electric circuit, and in order to prevent unnecessary radio waves from being radiated to the outside and to prevent radiated radio waves from the antenna element 10 from entering the inside, It is made of metal with a completely shielded structure.

An upper end contact part 11 is provided at the upper end of the antenna element 10, and a lower end contact part 12 is provided at the lower end. Furthermore, an antenna top 13 is attached to the upper end contact portion 11 for pinching with fingers when pulling out the antenna element.

Further, a stopper 14 for preventing the antenna element from coming off is attached to the lower end contact portion 12. In addition, a second
As shown in the figure, an insulator 15 is placed over the antenna element 10 in order to protect and insulate the antenna element 10 and also in consideration of the design.

The antenna element 10 is fitted into an antenna holder 16. The antenna holder 16 is made of a metal member and is formed into a cylindrical shape.
Threaded portion 1 for screwing and fixing to threaded portion 51 of 0a
7 is formed.

An elastic portion 18 is provided at the tip of the antenna holder 16. This elastic portion 18 has a function of slidingly contacting the outer peripheral surface of the antenna element with an appropriate sliding force when the antenna element 10 is pulled out or stored. Furthermore, when the antenna element 10 is extended, the elastic portion 18
It contacts the lower end contact portion 12 to establish electrical continuity, and has a holding function to prevent the antenna element 10 from falling due to its own weight or the like. Furthermore, when the antenna element 1o is stored, it contacts the upper end contact portion 11 to establish electrical continuity, and also has the function of holding the antenna element 10 so that it does not jump out due to vibration or the like. .

20 is an elongated first metal member, one end 21 of which
For example, an electrostatic coupler 22 having a ring shape (or a plate shape or the like) is integrally provided in the vicinity of the capacitor. In this embodiment, the electrostatic coupler 22 connects the antenna element 10 to the antenna element 10 near the entrance of the antenna element storage section, that is, at the position where the antenna holder 16 is disposed. It is arranged so as to coaxially surround the. Note that an insulating ring 25 may be inserted into the electrostatic coupler 22 as shown in FIG.

The other end portion 23 of the first metal member 20 extends in a direction perpendicular to the axis of the antenna element 10, and its extended end is connected to one end of a second metal member 30, which will be described below.

Near the other end portion 23 of the first metal member 20, this first
A zigzag cut 24 is provided in the metal member 20 to provide a required inductance L2.

The second metal member 30 is a metal member having an electrical length of λ/4, and corresponds to the ground wire of the Brown antenna. This number? The metal member 30 is arranged parallel to the first metal member 20 with a predetermined gap (several mm) therebetween. One end is connected to the other end of the first metal member 20, and is grounded via an external conductor of a power supply line, etc., as will be described later.

Similar to the first metal member 20, a zigzag-shaped cut 3] for improving antenna radiation efficiency is provided approximately at the center of the second metal member 30 along a direction perpendicular to the longitudinal direction of the member. . By providing this zigzag-shaped cut 31, a loading coil having an inductance of L3 is obtained in this second metal portion 4J30. Note that both sides of the second metal member 30 are bent in the shape of 7.

This is achieved by increasing the width relative to the length of the second metal member 30.
By lowering this, it contributes to widening the band of frequencies used. Of course, this also leads to an improvement in mechanical strength. Similar measures may also be taken for the first metal member 20. Furthermore, as shown in FIG. 4, bends similar to those described above may also be provided at the longitudinal ends of the member. In this way, not only the bandwidth can be increased by 2t, but also the shortening rate is improved and the efficiency is improved.

Reference numeral 60 denotes a power supply line made of a coaxial cable, one end of which is connected near the connection point between the second metal member 30 and the first metal member 20. That is, the core wire of the feeder line 60 is connected to the tap position P of the first metal member 20, and the outer conductor of the feeder line 60 is connected to a portion Q of the second metal member 30.

In order to match the impedance ZO seen from the antenna element 10 side to the signal source side with the antenna human input impedance 50Ω, the tap position P of the first metal member 20 may be changed. That is, the above 1. As described above, by adjusting and setting the tap position P where the core wire of the feeder line 60 is connected to the first metal member 20 to a desired position, the impedance matching between the antenna element 10 and the feeder line 60 can be achieved relatively easily. can be obtained.

The lower surface of the second metal member 30 is a dielectric material 4 having an appropriate thickness.
0 on the upper surface 52 of the lower case 50b. At this time, an electrostatic capacitance ff1c2 exists between the first metal member 20 and the second metal member 30, and the second metal member 3
Structurally, a stray capacity C3 occurs between the lower surface of the case 0 and the -F surface 52 of the lower case 5ob. This strike 1
The no-capacity C3 has the effect of lowering the parallel resonance frequency of the ground wire. Therefore, it has the effect of shortening the electrical length of the second metal member 30 in order to cause it to resonate at the frequency used. That is, if f r −1/2πJTτ is 1 and r knee is constant, as C becomes larger, L becomes smaller. Therefore, the length of the ground wire, that is, the second metal member 30 can be shortened.

Thus, when the antenna element 10 is extended, the capacitance C2 between the first metal member 20 and the second metal member 30 and the inductance L of the first metal member 20 are
2 are set so as to resonate in parallel with the frequency band used. Therefore, a non-grounded antenna is constructed.

On the other hand, the capacitance J! in the capacitive coupling section consisting of the antenna element 10 and the capacitive coupler 22! icl and the residual inductance La of the antenna element 10 having an electrical length slightly shorter than λ/2 are configured to form a constant bandpass filter for the frequency band used. Therefore, efforts are being made to widen the band.

Figures 5 to 7 are diagrams that clearly show the electrical relationships noted in "-", and Figure 5 is a diagram showing the electrical configuration of this antenna, and Figure 6
This figure shows an equivalent circuit of FIG. 5, and FIG. 7 shows the characteristics of this antenna.

The electrical length of the antenna element 10 is λ, as shown in FIG.
/4 and λ/2, ie, λ/2-α1. It is. As a result, the antenna element 10 is made slightly shorter than the parallel tuning point to provide wideband and high performance characteristics.

The length of the antenna element 10 is as follows:
When stored in the storage section, the length is such that it does not reach the battery storage section below the lower case 50b. In other words, the volume occupation rate of the antenna element 10 is extremely small.

When the antenna element 10 is housed in the set, the antenna holder 16 and the upper end contact portion 11 are electrically connected as shown in the second diagram, and the antenna element 10. The lower end contact portion 12 of the insulator 15 is housed in an antenna element housing groove 53 provided in the case 50b. The inner surface of the groove 53 is covered with an insulating member 54 in order to prevent the lower end contact portion 12 from making incomplete contact with the antenna element when the antenna element is stored, thereby causing noise and other unpleasant sensations. It is being said.

λ/4 from the electrostatic coupler 22 in the antenna element storage groove 53
A grounding piece 55 is provided at a position apart from the base end, that is, the lower end contact portion 1 of the antenna element 10 when the antenna element 10 is stored in the storage groove 53.
2 to ground the antenna element 10 directly or indirectly. Note that the ground piece 55 is connected to a metal part of the case 50b.

Thus, when the antenna element 10 is housed in the housing groove 53, the parallel resonance phenomenon caused by the inductance La of the antenna element 10 and the stray capacity between the antenna element and the inner wall surface of the housing groove is eliminated. In addition, unnecessary radiation to the inside of the wireless telephone can be prevented.

Furthermore, it is useful for maintaining VSWR when the antenna element is stored. When the antenna element 10 is placed in the retracted state, the residual inductance La when the antenna element 10 is extended changes. Therefore, a type bandpass filter cannot be established in the chamber. Therefore, the impedance seen from the end 23 of the first metal member 20 toward the antenna element becomes high, and the electrostatic coupling portion changes into an isolator. Therefore, the first metal member 20 functions as a built-in modified inverted F-shaped antenna element.

That is, the vicinity of the connection point between the first metal member 20 and the second metal member 30, that is, the other end 23 of the first metal member 20 is grounded, and power is supplied from the tap P of the inductance L2 of the first metal member 20. This becomes an inverted F-shaped antenna element. In other words, it is a built-in antenna that allows transmission and reception with the main antenna element 10 housed.

FIGS. 8(a) and 8(b) are diagrams showing experimental data of SWR characteristics and impedance characteristics when the antenna is extended in the above embodiment. The SWR is 1.5 or less over the entire band, indicating wideband characteristics. The frequency band used in the example is 870 to 960 MHz.

FIGS. 9(a) and 9(b) are diagrams showing experimental data of SWR characteristics and impedance characteristics when the antenna is housed in the above embodiment. The SWR is 3.0 or less in all bands, indicating good characteristics.

FIGS. 10(a) and 10(b) are diagrams showing the radio wave vertical plane pattern when the antenna is extended in the above embodiment, and the gain is 0 ±
The maximum radiation direction is in the horizontal direction in all directions.

FIGS. 11(a) and 11(b) are diagrams showing the radio wave vertical plane pattern when the antenna is stored in the above embodiment, and its gain is -7 in the frequency band used compared to the standard dipole antenna.
The maximum radiation direction is in the horizontal direction in all directions.

As mentioned above, it was confirmed that the impedance characteristics and gain can also be used for practical purposes. It has also been found that the volume occupancy rate can be reduced to 1/2 or less than that of the conventional method, and the weight can also be reduced to less than that of the conventional method.

The approximate size of the first metal member 20, second metal member 30, and dielectric 40 of the antenna used in the above experiment was 45L x 14
It is 'X7'.

Note that the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As explained above, according to the present invention, the detachable main antenna element and the built-in antenna element are automatically and contactlessly switched as the main antenna element is inserted and removed. In addition to exhibiting optimal broadband antenna characteristics depending on the usage and non-use conditions, there is no need for any mechanism for switching antenna elements, which increases the space occupancy of the wireless telephone set. Therefore, it is possible to provide an ungrounded ultra-short wave antenna that can be expected to operate with high reliability over a long period of time, and in addition, has almost no adverse effects when the wireless telephone set is held in the hand.

[Brief explanation of the drawing]

Fig. 1(a)(b) to Fig. 11(a)(b) are diagrams showing an embodiment of the present invention, and Fig. 1(a)(b) shows a non-grounded type pole according to the present invention. An exploded perspective view of the main parts of the ultra-high frequency antenna and a perspective view showing the external appearance. Figure 2 is a sectional view of the main parts showing the state in which the antenna element is stored in the storage part. Figure 3 is a perspective view of the capacitive coupling magazine part. FIG. 4 is a perspective view showing a partial modification of the second metal member, FIG. 5 is a diagram showing the electrical configuration of this antenna, and FIG. 6 is the equal reef circuit of FIG. 5. FIG. 7 is a diagram showing the characteristics of this antenna, and FIGS. be. 10... Antenna element 20... First metal member 22
...Ring-shaped electrostatic coupler 24.31...Zigzag-shaped notch 30...Second metal member 50a. 50b... Upper and lower cases 53... Antenna element storage groove 55... Grounding piece 60... Power feeder applicant's agent Patent attorney Takehiko Suzue's drawing No. 2-c+' Figure 7 of the drawing Engraving (no change in content) Engraving of Figure 10 drawing (no change in content) START 800.000000MHz STOP 1
000.000000 Ml-Lz! Surface engraving (no change in content) Frequency Hz n. Figure 11 Procedural City Correction (Method) % Formula % Name of the invention Person who corrects ungrounded extremely high frequency antenna 3゜in IIi Relationship with the case Special amendment Applicant Harada Kogyo Co., Ltd. 4, Agent 5゜Amendment Date of order: September 25, 1990 As shown in the attached sheet (no change in content)

Claims (4)

[Claims] (1) A rod-shaped antenna element that is removably inserted into the antenna element storage part provided in the wireless telephone case, and where λ is the wavelength of radio waves in the frequency band used, λ/2
an inductive antenna element having an electrical length of less than or equal to 100 m, an electrostatic coupler disposed close to the antenna element in the vicinity of the entrance of the antenna element storage portion so as to be electrostatically coupled to the antenna element; an elongated first metal member having one end connected to the electrostatic coupler and the other end extending in a direction perpendicular to the axis of the antenna element; and a first metal member arranged parallel to the first metal member with a predetermined gap therebetween. a second metal member having an electrical length of λ/4, one end of which is connected to the first metal member, and one end of which is connected near the connection point between the second metal member and the first metal member; a feeder line, and in a state where the antenna element is extended, the capacitance between the first and second metal members and the inductance of the first metal member are set to An ungrounded extremely short wave antenna characterized by being set to resonate in parallel. (2) The capacitance in the capacitive coupling section consisting of the antenna element and the capacitive coupler and the residual inductance of the antenna element are configured to form a constant K type bandpass filter for the frequency band used. The ungrounded extremely short wave antenna according to claim 1, characterized in that: (3) A grounding piece is provided at a position λ/4 away from the capacitive coupler in the antenna element housing, and when the antenna element is housed in the housing, the base end of the antenna element is directly or indirectly connected. 2. The ungrounded ultrahigh frequency antenna according to claim 1, wherein the electrostatic coupler functions as an isolator, and the first metal member operates as a modified inverted F-shaped built-in antenna element. . (4) The first and second metal members are provided with zigzag-shaped cuts for improving antenna radiation efficiency along a direction perpendicular to the longitudinal direction of each member. 3. The ungrounded extremely short wave antenna according to 3.