JP4649634B2 - Multiband monopole antenna - Google Patents

Description

  The present invention relates to a multiband monopole antenna for transmitting and receiving radio waves of a plurality of bands in a small wireless device such as a mobile phone.

  Despite the upper limit on the size that is convenient for carrying, mobile phones have various functions such as GPS receivers, television receivers, cameras, etc. In addition, there is a demand for further downsizing and space saving of the mounted antenna. Furthermore, since there is a demand for a multi-band mobile phone that can be used in various places such as Europe, Asia, and the United States, there is a need to realize a multi-band antenna that can realize a mobile phone with a built-in antenna.

  As the multi-band antenna, for example, for a frequency band over a plurality of continuous bands for OFDM communication used in the UWB band, and a plurality of frequency bands separated from each other, such as a mobile phone that can be used in a plurality of countries as described above. There are some that can be used. The present invention relates to the latter. For example, the following multiband antenna is disclosed.

  Patent Document 1 discloses an inverted F-type small multiband antenna. Patent Document 2 discloses a multiband antenna constituted by a plurality of small chip antennas. Patent Document 3 discloses a multiband antenna including at least two radiators that are galvanically connected in parallel and a carrier having a ground plane. Patent Document 4 discloses a flat antenna corresponding to a multiband.

  Patent Document 1 Inverted F-type small multiband antennas radiate both vertically polarized waves and horizontally polarized waves, so that the use efficiency of radio wave energy is poor. Further, the antenna constituted by a plurality of small chip antennas disclosed in Patent Document 2 has a drawback that the number of components increases. Further, the antenna of Patent Document 3 has a large size, which is an obstacle when used with a mobile phone. In addition, the antenna of Patent Document 4 has a size that is approximately ¼ of the wavelength to be used, and when used in the 800 MHz band, it is difficult to use for mobile phones. This has a shape that is relatively close to the present invention, but the radiating portion is transverse to the ground conductor and is horizontally polarized with respect to the ground conductor. On the other hand, in the case of the present invention, since the vertical polarization component is dominant as will be described later, this point is also different.

  In addition, as described in Patent Document 5, conventional antenna matching is performed by attaching a lumped constant element to the feeding circuit side, arranging a distributed constant line pattern on the feeding circuit side, or using a coil or capacitor in the antenna element. This is done by attaching a lumped constant. However, adjustment by separately attaching a lumped constant element requires cost and time. Also, when a distributed constant pattern is assembled on the circuit side, time is required for each adjustment.

  Also, as described in Non-Patent Document 1, regarding the low profile of the antenna, the inverted F type antenna has a structure called a plate-like inverted F type antenna and increases the antenna element area for impedance matching. Although a method has been adopted, there arises a problem that the area is increased in a trade-off with a low attitude.

JP 2004-172912 A JP-A-9-199939 JP 2004-194331 A JP 2005-94078 A JP 2003-249810 A

“New Antenna Engineering”; Hiroyuki Arai, Sogo Publishing Co., p109

  Built-in multiband antenna mounted on mobile communication terminals such as mobile phones, etc. Antenna that can be lowered while maintaining the characteristics of an ideal monopole antenna, and can easily adjust multiple frequency bands Is realized.

  According to the present invention, it is possible to realize a small multiband antenna having vertically polarized radiation characteristics that can be transmitted and received without switching in any frequency band of the separated frequency bands.

The configuration of the multiband monopole antenna is as follows.
A monopole radiating element having a length of 0.01 to 0.13 times the wavelength of the radio wave to be used; a feeding point provided on the ground conductor side of the monopole radiating element; and grounding of the monopole radiating element A plurality of matching lines provided on the opposite side of the conductor side or on the tip thereof, each of the matching lines is 0.10 to 0.25 times the wavelength of the radio wave used, A resistance value per unit length that is the same as or higher than that of the monopole radiating element, has a longitudinal direction perpendicular to the longitudinal direction of the monopole radiating element portion, and the opposite end on the monopole radiating element portion side is Open end.

  One of the above-mentioned matching lines is connected in series to the first matching line portion having a length of 0.05 to 0.20 times the wavelength of the radio wave used, and the first matching line portion, A second matching line portion having a resistance value equal to or higher than that of the first matching line portion and having a length of 0.05 to 0.15 times the frequency of the radio wave used; And a third matching line portion connecting the second matching line portion and the second matching line portion.

  Further, the matching line is branched from the first matching line portion having a length of 0.05 to 0.20 times the wavelength of the radio wave used, and the first matching line. A second matching line portion having a resistance value equal to or higher than that of the portion and having a length of 0.05 to 0.15 times the frequency of the radio wave used; and a first matching line portion; The third matching line portion is connected to the second matching line portion. However, the length of each radiating element and matching line is changed according to the dielectric constant of the dielectric material disposed around it.

  The monopole radiating element portion and the matching line are provided on the same plane or on the same plane obtained by bending the plane.

  Further, the monopole radiating element part and the matching line are formed using a printed circuit board.

  In particular, for example, the length of the monopole radiating element portion is in the range of 3 to 15 mm, the matching line is connected to the radiating element and the total length is in the range of 60 to 80 mm, and the total length is 10 to be connected to the radiating element. And a matching line in a range of 25 mm to 25 mm, and feeds any signal from 800 MHz to 1000 MHz and any signal from 1.9 to 2.2 GHz.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description, devices having the same function or similar functions are denoted by the same reference numerals unless there is a special reason.

  First, an embodiment of the present invention will be described with reference to FIG. The multiband monopole antenna of the present invention feeds high-frequency power between the ground conductor or circuit side substrate and the monopole radiating element (antenna). A plurality of matching lines that are thinner than the monopole radiating element are connected to the tip of the monopole radiating element. This matching line is provided as many as the number of frequency bands to be covered. As will be described later, the matching line radiates radio waves, but the monopole radiating element portion has a large current and the radiation is dominant.

  The length of the monopole radiating element portion can be adjusted over 1% to 13% of the wavelength used, and the length of the matching line can be adjusted over 10-25% of the wavelength used.

  For example, the multiband monopole antenna shown in FIG. 2 exhibits the radiation characteristics shown in FIG. When the monopole radiating element portion is vertical, the dotted line indicates horizontal polarization, and the solid line indicates vertical polarization. In FIGS. 3A and 3B, vertical polarization is dominant. This is mainly radiation from the monopole radiating element portion. Also, it can be seen that both 880 MHz and 1580 MHz have good radiation characteristics. FIG. 4 shows the voltage standing wave ratio (SWR) in this frequency band. The SWR is 2.61 and 1.7 at 880 and 1580 MHz, respectively.

  Also in FIGS. 3C and 3D, the vertical polarization is dominant. The reason why there is no constriction in the radiation characteristics as in the case of a pure monopole antenna is that the matching line in FIG. 2 is bent, and the above constriction is filled by the radiation from each portion 4 or 6. This is because. In addition, with respect to FIGS. 3 (e) and 3 (f), vertical polarization is dominant.

  Here, since the matching line hardly contributes to radiation, the matching line tip 5 may be made thin as shown in FIG. The purpose of thinning in this way is often downsizing. The matching line tip 5 may be replaced with a higher resistance line. The purpose at this time is to use a material having high resistance but high mechanical strength. In this case, the length of the monopole radiating element portion can be adjusted from 1% to 13% of the wavelength to be used, and the length of the matching line can be adjusted from 10% to 25% of the wavelength to be used.

Moreover, it is also possible to use a branched matching line section as shown in FIG.

  FIG. 7 is for a dual band of 800 / 900M band and 2 GHz band, and is assumed to be used for a normal mobile phone and an IMT2000 mobile phone. This multi-band monopole antenna has a built-in 800 / 900M band antenna, and can be used with the conventional mobile phone system and the current mainstream third-generation mobile phone system with a single antenna. It is.

  FIG. 8 shows a multiband monopole antenna for a dual-band 800 / 900M band and 1.5 GHz band for a mobile phone or a GPS receiver. As in this case, a flat plate can be provided at the tip to shorten the length of the matching line portion. The feature of this multi-band monopole antenna is that voice communication using a mobile phone and position information communication using GPS can be used with one antenna while incorporating an antenna of 800 / 900M band. In FIG. 8, the length of the monopole radiating element portion is 13 mm. However, when this is used in the 800 MHz to 1000 MHz band and the 1.9 to 2.2 GHz band, the length can be adjusted in the range of 3 to 15 mm. it can. In this case, the length of the longer matching line may be adjusted in the range of 60 to 80 mm, and the length of the shorter matching line may be adjusted in the range of 10 to 25 mm. In this adjustment, it is desirable to adjust the reflected wave standing wave ratio at 900 MHz and 2.05 GHz.

  FIG. 9 is for a dual band of 800 / 900M band and 1.8 GHz band, and is used for a digital global standard mobile phone (GSM mobile phone) adopted in a plurality of countries. The feature of this multi-band monopole antenna is that the use of two bands used for a GSM mobile phone can be made possible with one antenna while incorporating an antenna of 800 / 900M band.

  FIG. 10 is for a dual band of 1.5 G band and 2.4 GHz band, and is used for GPS and wireless LAN. The feature of this multiband monopole antenna is that it enables location information communication by GPS and network communication by wireless LAN to be used by one antenna in an information communication terminal such as a PDA or a notebook personal computer.

FIG. 11 shows a multiband monopole antenna for three bands of 800 MHz band, 1.8 GHz band, and 2.4 GHz band, which is used for a digital world standard mobile phone and a wireless LAN. The feature of this multi-band monopole antenna is that two antennas used for GSM mobile phones and wireless LAN can be used with one antenna while incorporating an 800 / 900M band antenna.

  In the above description, the frequency bands separated from each other have been described. However, it is easy to manufacture an antenna that covers continuous frequency bands and can be used in a wide band as a result according to the present invention.

It is a figure which shows the multiband monopole antenna of this invention. It is a figure which shows the example of a multiband monopole antenna. It is a figure which shows the radiation characteristic of the multiband monopole antenna of FIG. It is a figure which shows the voltage standing wave ratio of the multiband monopole antenna of FIG. It is a figure which shows the example of the multiband monopole antenna which made the matching line front-end | tip part thin. It is a figure which shows the example of a multiband monopole antenna with the branched matching line part. It is a figure which shows the multiband monopole antenna for dual bands of 800 / 900M band and 2 GHz band. It is a figure which shows the multiband monopole antenna for dual bands of 800 / 900M band and 1.5 GHz band. It is a figure which shows the multiband monopole antenna for dual bands of 800 / 900M band and 1.8 GHz band. It is a figure which shows the multiband monopole antenna for dual bands of 1.5G band and 2.4 GHz band. It is a figure which shows the multiband monopole antenna for 3 bands of 800 MHz band, 1.8 GHz band, and 2.4 GHz band.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Feed part 2 Monopole radiation element part 3, 4, 5, 6, 7, 8, 9 Matching line

Claims (6)

A monopole radiating element having a length of 0.01 to 0.13 times the wavelength of the radio wave used;
A feeding point provided on the ground conductor side of the monopole radiating element portion;
A plurality of matching lines provided on the opposite side of the ground conductor side of the monopole radiating element portion or on the tip thereof;
Each of the matching lines has a length of 0.10 to 0.25 times the wavelength of the radio wave used, and has a resistance value per unit length that is the same as or higher than that of the monopole radiating element, Comprising a longitudinal direction in a direction perpendicular to the longitudinal direction of the monopole radiating element portion, the opposite end of the monopole radiating element portion side being an open end,
Multiband monopole antenna characterized by that. Any of the above matching lines
A first matching line portion having a length of 0.05 to 0.20 times the wavelength of the radio wave used;
Connected in series to the first matching line portion, the resistance value per unit length is the same or higher than that of the first matching line portion, and is 0.05 to 0.15 times the frequency of the radio wave used. A second matched line portion having
2. The multiband monopole antenna according to claim 1, comprising a third matching line portion that connects the first matching line portion and the second matching line portion. The matching line above is
A first matching line portion having a length of 0.05 to 0.20 times the wavelength of the radio wave used;
Branching from the first matching line portion, the resistance value per unit length is the same as or higher than that of the first matching line portion, and the length is 0.05 to 0.15 times the frequency of the radio wave used. A second matching line portion;
2. The multiband monopole antenna according to claim 1, comprising a third matching line portion that connects the first matching line portion and the second matching line portion.   4. The multiband monopole antenna according to claim 1, wherein the monopole radiating element section and the matching line are provided on the same plane or on the same plane obtained by bending the plane.   5. The multiband monopole antenna according to claim 1, wherein the monopole radiating element portion and the matching line are formed using a printed circuit board.   The length of the monopole radiating element portion is in the range of 3 to 15 mm, the matching line connected to the radiating element is in the range of 60 to 80 mm, and the total length of 10 to 25 mm connected to the radiating element. 2. The multiband monopole antenna according to claim 1, wherein the multiband monopole antenna is fed with any one of signals from 800 MHz to 1000 MHz and any signal from 1.9 to 2.2 GHz.

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