JPH0555944A - Antenna matching equipment - Google Patents

Abstract

PURPOSE:To realize an excellent VSWR over a wide band in the antenna matching equipment. CONSTITUTION:An antenna matching circuit 12 is provided between an antenna element 11 and a feeding cable 13 and a high frequency switch 14 varying an electric length of a pattern is provided to a pattern 17 of the antenna matching circuit 12. When a transmission frequency from a high frequency circuit 18 is lower than a center frequency of a transmission frequency band, the high frequency switch 14 is opened to allow the pattern 17 to tune with a low frequency and when the transmission frequency from the high frequency circuit 18 is higher than the center frequency of the transmission frequency band, the high frequency switch 14 is closed to allow the pattern 17 to tune with a high frequency thereby selecting an excellent VSWR characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna matching device for feeding an antenna in a mobile device such as a mobile phone.

[0002]

2. Description of the Related Art FIG. 3 shows the structure of an antenna matching device in a conventional mobile phone. In FIG. 3, 31 is an antenna element and 32 is a ground metal conductor. Further, 33 is a feeding cable, 34 is a high frequency circuit, and 35 is an antenna matching circuit.

Next, the operation of the above conventional example will be described.
The high frequency energy emitted from the high frequency circuit 34 is sent to the antenna element 31 through the antenna matching circuit configured by the pattern of the printed circuit board so that the high frequency energy is efficiently radiated from the antenna through the power feeding cable 33.

As described above, in the above-described conventional antenna matching device, the pattern of the printed circuit board is determined in advance so that the antenna is tuned to the target frequency, so that high frequency energy can be efficiently transmitted in a certain frequency bandwidth. It was

[0005]

However, since the pattern on the antenna matching circuit 35 is predetermined in the above-described conventional matching device, a good VSWR (voltage standing wave ratio) can be obtained near the tuning frequency. However, there is a problem that VSWR deteriorates as the distance from the tuning frequency increases, and high-frequency energy cannot be efficiently transmitted at the end of the target frequency band.

The present invention is to solve such a conventional problem, and an object thereof is to provide an excellent antenna matching device capable of efficiently radiating high frequency energy from an antenna in a wide frequency band. Is.

[0007]

In order to achieve the above-mentioned object, the present invention provides a high-frequency switch in a pattern on an antenna matching circuit, and a part of the pattern is short-circuited to restore the electrical pattern of the whole pattern. The length is changed.

[0008]

Therefore, according to the present invention, by opening and closing the high frequency switch, the length of the pattern is electrically changed and the antenna has two tuning frequencies.
It is possible to obtain a good VSWR in a wide frequency band and efficiently radiate high frequency energy from the antenna.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, 11 is an antenna element for transmitting and receiving electromagnetic waves, which is connected to an antenna matching circuit 12. The antenna matching circuit 12 is composed of a printed board in which a pattern 17 is formed of a conductor on an insulating board 16. Since the length of the pattern 17 is related to the tuning frequency, it is usually formed in a rectangular wave shape as shown in the figure, but the pattern 17 is not limited thereto. Reference numeral 13 is a power supply cable for sending the high frequency energy from the high frequency circuit 18 to the antenna matching circuit 12. Reference numeral 14 is a high frequency switch for changing the electrical length of the pattern 17 of the antenna matching circuit 12, and is provided so as to short-circuit a part of the pattern 17. Reference numeral 15 is a feeding point.

Next, the operation of the above embodiment will be described.
The high frequency energy supplied from the high frequency circuit 18 via the power supply cable 13 is supplied from the power supply point 15 to the antenna matching circuit 12. Antenna matching circuit 12 has pattern 1
7 has a resonance frequency corresponding to the length of the antenna element 7, thereby efficiently transmitting high frequency energy to the antenna element 11
Supply to. As a result, the radiation from the antenna is performed with high efficiency.

The signal received by the antenna element 11 also passes through the power feeding cable 13 by the reverse path and the high frequency circuit 1
Received at 8.

The high frequency switch 14 is arranged so as to short-circuit a part of the pattern 17, and when it is closed, it serves to shorten the electrical length of the pattern 17 to increase the resonance frequency, and when it is opened. Does not change the electrical length of the pattern 17 and lowers the resonance frequency. VS at this time
The WR characteristics are shown in FIG. That is, the high frequency switch 14
When the power is turned off, VSWR at the feeding point 15
The characteristic curve is as shown by the curve 21 in FIG. Further, the VSWR characteristic curve when the high frequency switch 14 is turned on is as shown by the curve 22 in FIG. In FIG. 2, T _XL , T _XC , and T _XH
Represents the lower limit frequency, center frequency, and upper limit frequency of the transmission frequency band, and R _XL , R _{X C} , and R _XH represent the lower limit frequency, center frequency, and upper limit frequency of the reception frequency band, respectively.

Now, when the transmission frequency from the high frequency circuit 18 is lower than the center frequency T _XC of the transmission frequency band, that is, when the transmission frequency is between T _XL and T _XC , the curve 2 is obtained.
Set the high frequency switch 14 to OF so that the characteristics such as 1 appear.
Set to F and tune to a lower frequency. On the other hand, high frequency circuit 1
The transmission frequency from 8 is the center frequency T _{X C} of the transmission frequency band.
When the transmission frequency is higher, that is, when the transmission frequency is between T _XC and T _XH , the high frequency switch 14 is turned on to tune to a high frequency so that the characteristic shown by the curve 22 appears.
As a result, a good VSWR can be obtained in a wide frequency band, and high-frequency energy can be efficiently supplied to the antenna.

As described above, according to the above-described embodiment, when the frequency of the electromagnetic wave sent from the high frequency circuit 18 is set or switched, the high frequency switch 14 is switched according to the frequency so that a wide frequency band is obtained. Since a good VSWR can be obtained throughout, high frequency energy can be efficiently radiated from the antenna.

Similarly, when the reception frequency of the high frequency signal received by the antenna element 11 is lower than the center frequency R _XC of the reception frequency band, that is, the reception frequencies are R _XL and R
_When it is between _XC, the high-frequency switch 14 is turned off to tune to a low frequency, and when the reception frequency of the high-frequency signal is higher than the center frequency R _XC of the reception frequency band, that is, when the reception frequency is between R _XC and R _XH. In case 1), the high frequency switch 14 is turned on and tuned to a high frequency, so that a good VSWR can be obtained in a wide frequency band even during reception and efficient reception can be performed.

[0016]

As is apparent from the above-described embodiment, the present invention provides two types of VSW by electrically changing the length of the pattern on the printed circuit board which is the antenna matching circuit.
Since the R characteristic can be obtained, a good VSWR characteristic can be obtained over a wide frequency bandwidth, so that high frequency energy can be efficiently transferred to and from the antenna.

[Brief description of drawings]

FIG. 1 is a perspective view showing an outline of an antenna matching device in an embodiment of the present invention.

FIG. 2 is a VSWR characteristic diagram when a high frequency switch is switched.

FIG. 3 is a perspective view showing an outline of a conventional antenna matching device.

[Explanation of symbols]

 11 antenna element 12 antenna matching circuit 13 power cable 14 high-frequency switch 15 feeding point 17 pattern

Claims (1)

[Claims] 1. An antenna element, a power supply cable, an antenna matching circuit connected between the antenna element and the power supply cable and having a conductor pattern formed on an insulating substrate, and a switch for adjusting the electrical length of the conductor pattern. And an antenna matching device having.