JPH10200315A - Antenna for radio equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna with a wide band and a high gain at the time of extending and retracting a whip antenna in a detachable type at the time of housing with a top end helical antenna used for a portable mobile radio equipment. SOLUTION: A serial resonance circuit is formed by inserting an extremely micro-electrostatic capacitor 20 between a helical antenna 11 and a pedestal 12 being a power feeding point. Thus, the impedance of the helical antenna 11 is made equivalent to the impedance of a monopole antenna 15, and the impedance characteristics of the helical antenna 11 viewed from a matching circuit edge matching over a wide band based on the impedance of the monopole antenna 15 can be made equivalent to the impedance characteristics of the monopole antenna 15, and the helical antenna with wide band characteristics can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio antenna for use in portable telephones, mobile radios and the like, and more particularly to a technique for preventing gain deterioration when the antenna is stored.

[0002]

2. Description of the Related Art With the opening of the market for portable telephones, demand for portable telephones is rapidly increasing. Hereinafter, a conventional mobile phone antenna will be described.

FIG. 7 shows a whip antenna used in a conventional portable telephone, which is a detachable whip antenna with a helical tip at the time of storage. In FIG. 7A, reference numeral 1 denotes a helical antenna, which is connected to the pedestal 2. Reference numeral 3 denotes a sleeve whose upper end is connected to the pedestal 2 and whose lower end is integrated with the monopole antenna 5 via an insulator 4. 6 is a mounting bracket,
The base 5 a of the monopole antenna 5 is connected to the wireless circuit input terminal 8 via the contact piece 7. 9 is a helical antenna 1
And a pedestal 2.

The helical antenna 1 is electrically connected to the pedestal 2 and the sleeve 3, and the sleeve 3 and the monopole antenna 5 are electrically disconnected by the insulator 4. Thus, when the whip antenna shown in FIG. 7A is extended, power is supplied only from the wireless circuit input end 8 to the monopole antenna 5 by the antenna base 5a through the contact piece 7 and the mounting bracket 6, and the effective equivalent electrical length is 3/8. It operates as a monopole antenna of about the wavelength. On the other hand, when the whip antenna shown in FIG. 7B is housed, power is supplied only to the helical antenna 1 from the wireless circuit input end 8 through the contact piece 7 and the mounting bracket 6 by the sleeve 3, and the substantially equivalent electric length is about 3/8 wavelength. Operates as a helical antenna.

[0005]

The ratio band of the transmission and reception bands of the current digital cellular system in Japan is 2%, and any one band can be covered by a single helical antenna. However, current systems have transmission and reception bands spaced apart by 112 MHz, and require a wide band of 148 MHz as the entire system band. To enable the use of helical antennas in systems where such transmission and reception bands are separated,
In Japanese Patent Application Laid-Open No. 6-204726, a helical antenna has a wider band with a structure as shown in FIG. That is, the first helical antenna 1a tuned to include the first frequency and the second helical antenna 1b tuned to include a second frequency different from the first frequency are made of a common resin. Enclosing in mold 9 covers both the transmit and receive bands of a conventional system.

However, it will be developed in the future.
In the GHz band, the frequency interval for transmission and reception is 130 MHz.
z, the bandwidth of the entire system is 250 MHz, and the ratio band of the transmission / reception band is 3%. Therefore, in a system having such a wide transmission / reception interval and a wide ratio band, a single unit as in the related art is required. Since the band of the helical antenna is limited, the communication quality is significantly degraded even in either the transmission or reception band, and the configuration of the two helical antennas has a problem that the structure is complicated and expensive. Was.

An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide an inexpensive radio antenna having a simple structure, a wide band, and a high gain.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a whip antenna with a tip helical antenna and a detachable type at the time of storage, in which a very small capacitance or space is provided at a feeding point of the helical antenna. This changes the impedance of the helical antenna, making it almost equivalent to the impedance of the monopole antenna, regardless of the expansion and contraction of the whip antenna.
A wide band and high gain radio antenna can be realized.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An antenna for a wireless device according to a first aspect of the present invention is a whip antenna type wireless device antenna with a helical antenna at the time of storage, wherein the impedance of the helical antenna is represented by a monopole on a Smith chart. The antenna for radio equipment is characterized in that the diameter, pitch and number of turns are determined so as to be axially symmetric with the antenna, and a very small capacity is inserted between the helical antenna and the feeding point. The impedance of the helical antenna is equivalent to the impedance of the monopole antenna by inserting a very small capacitance between the The impedance characteristics of the helical antenna viewed from the end of the matching circuit matched to the broadband It will have an impedance characteristic similar to wideband characteristics of the pole antenna, an effect that high gain characteristic is obtained structure compared to the antenna in a simple and inexpensive and broadband shown in the conventional example.

According to a second aspect of the present invention, in the antenna for a detachable whip antenna type wireless device with a helical antenna at the tip, the impedance of the helical antenna is axially symmetric with the monopole antenna on a Smith chart. The radio antenna is characterized in that a very small space is provided between the helical antenna part and the feed point, and the diameter, pitch and number of turns are determined so that By inserting a minute space between the two, this space is equivalent to loading a minute capacitance, and forms a series resonance circuit. As a result, the impedance of the helical antenna becomes equivalent to the impedance of the monopole antenna, and the impedance characteristic of the helical antenna viewed from the end of the matching circuit that is broadly matched based on the impedance of the monopole antenna is The antenna has a broadband characteristic similar to the impedance characteristic, and has an effect that an antenna that is cheaper and stronger than the antenna according to the first aspect can be realized.

According to a third aspect of the present invention, in the antenna for a detachable whip antenna type wireless device with a tip helical antenna, the impedance of the helical antenna is equivalent to the impedance of the monopole antenna on a Smith chart. As described above, this is an antenna for a radio device in which the size and / or position of an extremely small capacity inserted between the helical antenna and the feeding point is set, and the antenna is provided between the helical antenna and the feeding point. By changing the size and / or position of the loaded minute capacitance, the degree of freedom of impedance conversion increases, so that the impedance of the helical antenna can be made equivalent to the impedance of the monopole antenna. Broadband matching based on pole antenna impedance The impedance characteristics of the helical antenna viewed from the end of the combined circuit have the same broadband characteristics as the impedance characteristics of the monopole antenna. Has the effect that high gain characteristics can be obtained.

According to a fourth aspect of the present invention, in the antenna for a detachable whip antenna-type wireless device with a helical antenna at the tip, the impedance of the helical antenna is made equivalent to the impedance of a monopole antenna on a Smith chart. The size of a very small space and / or position inserted between the helical antenna and the feeding point is set so as to be as follows. By changing the size and / or position of the very small space between them, this space is equivalent to loading a small capacitance, and the degree of freedom of impedance conversion is increased. It can be made equivalent to the impedance of the pole antenna, Impedance characteristic of the helical antenna as viewed through the matching circuit end matched to the broadband impedance based on the antenna is will have the same wide-band characteristic and impedance characteristics of the monopole antenna,
This has the effect that an antenna that is more inexpensive and stronger than the antenna described in claim 3 can be realized.

Embodiment 1 Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a configuration of a first embodiment corresponding to the first aspect. In FIG. 1, reference numeral 11 denotes a helical antenna,
3 and supported by the pedestal 12 via a very small capacitance 20. The power supply end 23 has a capacitance 20
Is connected to the helical antenna 11 and the lower end is integrated with the monopole antenna 15 via the insulator 14. Reference numeral 16 denotes a mounting bracket, which is a monopole antenna 1
5 is connected to the radio circuit input terminal 18 via the contact piece 17.
Connected to Reference numeral 19 denotes a resin mold that integrates the helical antenna 11, the capacitance 20, and the power supply end 23.

The helical antenna 11 and the power supply terminal 23 are electrically disconnected by the capacitance 20.
The monopole antenna 3 and the monopole antenna 15 are electrically disconnected by the insulator 14. Thus, when the whip antenna is extended, power is supplied only to the monopole antenna 15 by the antenna base 15a from the wireless circuit input end 18 through the contact piece 17 and the mounting bracket 16, and the substantial equivalent electrical length is reduced by half.
It operates as a monopole antenna with a wavelength of about ± α. On the other hand, when the whip antenna is stored,
The power is supplied only to the helical antenna 11 via the power supply end 23 and the capacitance 20 through the contact piece 17 and the mounting bracket 16, and operates as a helical antenna having a substantially equivalent electrical length of about ／ wavelength.

FIG. 2A shows, at a center frequency of 1920 MHz, the impedance characteristic of the monopole antenna 15 having a substantial equivalent electrical length of about 波長 wavelength ± α, and the substantial equivalent electrical length conjugate to the monopole antenna 15. 3 shows impedance characteristics of the helical antenna 11 alone. As described above, the diameter, pitch, and number of turns of the helical antenna 11 are determined so that the impedance thereof is axially symmetric with the monopole antenna 15 on the Smith chart. By loading an extremely small capacitance 20 between the helical antenna 11 and the feeding end 23 serving as a feeding point, the impedance characteristic of the helical antenna 11 becomes as shown in FIG. Approaching the impedance of As shown in FIG. 2C, the impedance of the helical antenna 11 loaded with a small capacitance has a wide band characteristic, as well as the impedance seen from the end of the matching circuit matched to the monopole antenna 15 when extended. In addition, a wideband whip antenna can be realized both in storage and in storage. Here, FIG. 2D shows the impedance characteristics of the helical antenna 1 loaded with a very small capacitance as viewed from the end of the matching circuit.

(Embodiment 2) FIG. 3 shows the configuration of an embodiment 2 according to the second aspect of the present invention. In FIG. 3, reference numeral 11 denotes a helical antenna, which is connected to a pedestal 12 from a sleeve 13 through a feeding end 23 and an extremely thin space 22.
It is connected to the. The feeding end 23 has an upper end connected to the space 22 and a lower end integrated with the monopole antenna 15 via the insulator 14. Reference numeral 16 denotes a mounting bracket, which connects the base 15 a of the monopole antenna 15 to a wireless circuit input terminal 18 via a connecting piece 17. Reference numeral 19 denotes a resin mold for integrating the helical antenna 11 and the pedestal 12. In the first embodiment shown in FIG. 1, the capacitance 20 is inserted between the helical antenna 11 and the feeding end 23. In the second embodiment, however, a spacer such as an extremely thin Teflon (trade name) is used. Space 2 between sleeve 13 and power supply end 23
By providing 2, a capacitance equivalent to the capacitance 20 of FIG. 1 is configured at a high frequency, and has the same operation and effect as the first embodiment.

(Embodiment 3) FIG. 4 shows the configuration of Embodiment 3 according to the third aspect.
Is the same as that of the second embodiment except that the capacitance 20 is made extremely small and the position of the provided capacitance is different, and the duplicated description of the reference numerals is omitted. In the second embodiment shown in FIG. 2, the space 22 is provided between the sleeve 13 and the power supply end 23.
In the third embodiment, the capacitance 20 is loaded between the helical antenna 11 and the pedestal 12, and the size and / or the loading position of the capacitance 20 are changed, as shown in FIG. As shown, since the degree of freedom of impedance conversion is higher than that of the helical antenna 11 used in the first embodiment, the number of turns, the pitch, and the loading position of the small capacity of the helical antenna 11 are determined, so that the monolith having various element lengths can be obtained. The impedance of the monopole antenna 15 can be made equivalent to the impedance of the pole antenna 15.
A helical antenna 11 loaded with a very small capacity, like the impedance seen from the end of the matching circuit matched to
Has a wide band characteristic, and a whip antenna having a wide band can be realized both during extension and storage.

(Embodiment 4) FIG. 6 shows the configuration of Embodiment 4 according to the fourth aspect of the present invention.
The second embodiment is the same as the second embodiment except for the difference in the position where the symbol is provided, and the duplicated description of the reference numerals is omitted. In the second embodiment shown in FIG.
3, a very small space 22 is provided between the helical antenna 11 and the pedestal 12. In the fourth embodiment, a very small space 22 is provided between the helical antenna 11 and the pedestal 12. By changing, the degree of freedom of impedance conversion is increased as compared with the helical antenna 11 used in the first embodiment as in the third embodiment. Therefore, the number of turns, the pitch, and the loading position of the small capacity of the helical antenna 11 are determined. Accordingly, the impedance can be made equivalent to the impedance of the monopole antenna 15 having various element lengths, and the helical antenna 11 loaded with the minute capacitance is similar to the impedance seen from the end of the matching circuit matched to the monopole antenna 15. Has a wide band characteristic, and a whip antenna having a wide band can be realized both during extension and storage.

[0019]

As described above, according to the present invention, an extremely small capacitance or space is provided between a retractable whip antenna with a helical antenna at the tip of a mobile communication terminal such as a portable telephone and a feeding point. To form a series resonance circuit, an impedance equivalent to that of a monopole antenna can be obtained, and an antenna having a wide band and a high gain can be formed when the antenna is extended and stored.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an antenna device according to a first embodiment of the present invention.

FIG. 2 (a) Impedance characteristics of a monopole antenna and a helical antenna conjugate to a monopole antenna when the effective equivalent electrical length is 波長 wavelength + α (b) a monopole antenna loaded with an extremely small capacitance Characteristic diagram of a helical antenna conjugate with the (c) Impedance characteristic diagram of a monopole antenna when the effective equivalent electrical length viewed from the matching circuit end is 波長 wavelength ± α (d) Extremely viewed from the matching circuit end Impedance characteristic diagram of a helical antenna conjugate with a monopole antenna loaded with a small capacitance

FIG. 3 is a configuration diagram of an antenna device according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram of an antenna device according to a third embodiment of the present invention.

5 (a) is an impedance characteristic diagram of a helical antenna loaded with a capacitance different from that of FIG. 2 (b); and (b) an impedance characteristic diagram of a helical antenna loaded with an extremely small capacitance at a position different from that of FIG. 2 (b).

FIG. 6 is a configuration diagram of an antenna device according to a fourth embodiment of the present invention.

FIG. 7 is a configuration diagram showing an example of a whip antenna in a conventional example.

FIG. 8 is a configuration diagram showing another example of a whip antenna in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Helical antenna 12 Pedestal 13 Sleeve 14 Insulator 15 Monopole antenna 15a Antenna base 16 Mounting bracket 17 Contact piece 18 Wireless circuit input end 19 Resin mold 20 Capacitance 21 Pedestal 22 Space 23 Feeding end

Claims (4)

[Claims] 1. An antenna for a detachable whip antenna type wireless device with a tip helical antenna, wherein a diameter, a pitch and a number of turns are determined so that the impedance of the helical antenna is axially symmetric with a monopole antenna on a Smith chart. A very small capacity is inserted between the helical antenna portion and a feeding point. 2. An antenna for a detachable whip antenna type wireless device with a tip helical antenna, wherein a diameter, a pitch and a number of turns are determined so that the impedance of the helical antenna is axially symmetric with a monopole antenna on a Smith chart. An extremely small space is provided between the helical antenna section and a feeding point. 3. An antenna for a detachable whip antenna type wireless device with a tip helical antenna, wherein the helical antenna and the feeding point are set so that the impedance of the helical antenna is equivalent to the impedance of a monopole antenna on a Smith chart. An antenna for a radio, wherein the size and / or position of an extremely small capacity inserted between the antenna and the antenna are set. 4. An antenna for a detachable whip antenna type wireless device with a tip helical antenna, wherein the helical antenna and the feeding point are set so that the impedance of the helical antenna is equivalent to the impedance of a monopole antenna on a Smith chart. Characterized in that the size and / or position of an extremely small space inserted between the antenna is set.