JP2628214B2 - Antenna matching method and antenna matching device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna matching method and an antenna matching apparatus for matching the impedance of an antenna to the impedance of a wireless device main body.

[Conventional technology]

Generally, an antenna matching device for matching the impedance of both the wireless transmitter body and the antenna is connected.

 A conventional antenna matching device 50 is shown in FIG.

In the figure, Po and Zo are the output power and the equivalent output impedance of the radio transmitter main body, and AT is an antenna for connecting to the radio transmitter main body via the antenna matching device 50.
Reference numeral 51 denotes an LC network formed of a π-shaped circuit, which includes a coil unit 52 and capacitor units 53 and 54 connected to the input side and the output side of the coil unit 52, respectively. The input side of the coil section 52 is connected to the output terminal of the wireless transmitter main body via the standing wave measuring device 55, and the circumferential side of the coil section 52 is connected to the antenna AT.
Connect to The other ends of the nuclear condenser units 53 and 54 are grounded.

The coil unit 52 is formed by connecting a plurality of coils 52a, 52b... 52n having different inductances in series, and short-circuit relay switches 56a, 56b. Furthermore, each of the capacitor units 53 and 54 also has a different capacitance 53a, 5
3b ... 53n, 54a, 54b ... 54n are connected in parallel, and each of the capacitors 53a ..., 54a ... is provided with an open relay switch 57a, 57b.
... 57n, 58a, 58b ... 58n are connected in series.

On the other hand, a detection function unit 59 having a computer function is provided. The detection function unit 59 is connected to a standing wave measuring device 55 via an analog-to-digital converter 60, and each of the relay switches 56a ..., 57a ..., 58a ... Is connected to a driver 61 for controlling the opening and closing of.

An antenna matching method using such an antenna matching device 50 is performed as follows.

First, an upper limit value (set value) of the standing wave ratio for detecting a matching point is set in the detection function unit 59.

Next, the detection function unit 59 detects a matching point according to a preset sequence program. For example, the capacitance of the capacitor section 54 on the output side is
The standing wave ratio to be measured is monitored while changing the inductance of the coil unit 52 and the capacitance of the capacitor unit 53 on the input side while increasing stepwise by the opening / closing control of a... The integers of the capacitor units 53 and 54 and the coil unit 52 are set as matching points.

[Problems to be solved by the invention]

By the way, when matching is performed using the LC network 51 of the π-shaped circuit, if the inductance of the coil unit 52 and the capacitance of the capacitor units 53 and 54 on the input side and the output side are respectively varied, there are countless optimal matching points. .

However, the conventional matching method merely performs impedance conversion between the wireless transmitter main body and the antenna AT, and does not consider the loss of the LC network 51 at all. For this reason, even if an arbitrary matching point is detected from a plurality of matching points, it is unknown whether or not the loss is in a minimum state.
The loss of the LC network 51 and the amount of heat generated based on the loss may be unnecessarily large, and particularly when the current is large, the loss (copper loss) of the coil section 52 also becomes large and the efficiency deteriorates. There is a problem to be solved in that it becomes difficult to take measures against heat radiation to the coil portion 52 and the like.

An object of the present invention is to provide an antenna matching method and an antenna matching device which solve the problems existing in such conventional techniques.

[Means for solving the problem]

The antenna matching method according to the present invention varies the capacitances of the capacitor units 5 and 6 and the inductance of the coil unit 7 of the π-type LC network 4 connected between the radio unit 2 and the antenna 3 so that the radio unit 2 When matching the impedance of the antenna 3 to the impedance of the antenna, the standing wave ratio between the radio unit (radio transmitter or radio receiver) 2 and the antenna 3, the input current Ii to the LC network 4 and the coil flowing through the coil unit 7 By measuring the current Ic and sequentially varying the capacitance and the inductance according to a sequence program, a process of detecting a quasi-matching point at which the standing wave ratio is equal to or less than a set value is performed. The program is stopped and the ratio (current ratio) of the coil current Ic to the input current Ii at the detected quasi-matching point is calculated. When the current ratio is equal to or less than the set value, the matching process is terminated, and when the current ratio exceeds the set value, another quasi-matching point is detected by continuously executing the stopped sequence program, The processing for determining the current ratio is repeated.

Further, the antenna matching device 1 according to the present invention includes a standing wave-side constant device 8 for measuring a standing wave ratio between the wireless device main body 2 and the antenna 3, and a high-frequency current for measuring a coil current Ic flowing through the coil unit 7. And a second high-frequency ammeter 10 for measuring the input current Ii to the LC network 4, and by sequentially varying the capacitance and the inductance according to a sequence program, the standing wave ratio becomes equal to or less than the set value. A process for detecting a matching point is performed. If a quasi-matching point is detected, the sequence program is periodically performed, and a ratio (current ratio) of the coil current Ic to the input current Ii at the detected quasi-matching point is determined. When the value is equal to or less than the set value, the matching process is terminated, and when the value exceeds the set value, the halted sequence program is continuously executed to execute another semi-matching. Detects, characterized by comprising a detection function unit 11 to repeat the process of determining the current ratio.

[Action]

According to the antenna matching method and the antenna matching device 1 according to the present invention, the standing wave measuring device 8 varies the capacitance of the capacitor portions 5 and 6 and the inductance of the coil portion 7 in the LC network 4 while changing the radio device main body 2.
By measuring the standing wave ratio between the antenna and the antenna 3, it is possible to detect a matching point (quasi-matching point) where the value of the standing wave ratio is equal to or less than the set value.

Further, the ratio (current ratio) of the coil current Ic to the input current Ii can be obtained by measuring the input current Ii to the LC network 4 and the coil current Ic flowing through the coil unit 7 by the high-frequency ammeters 9 and 10, respectively. Therefore, at the quasi-matching point, a normal matching point at which the current ratio becomes equal to or less than the set value can be detected.

In this case, when the current ratio at an arbitrary quasi-matching point does not become equal to or less than the set value, the inductance of the coil unit 7 and the capacitance of the capacitor units 5 and 6 are varied again to detect another quasi-matching point, By obtaining the current ratio at that time and repeating the determination of both, a normal matching point can be detected.

The reason why the coil current Ic is used as a determination factor is as follows.

In general, if the inductance of the coil unit 7 and the capacitance of the capacitor unit 5 on one (input side) in the LC network 4 are varied, a matching point with the antenna 3 can be detected. However, when a plurality of different capacitors 5a... And coils 7a... Are selectively combined and changed, as the number increases, the matching time becomes longer, and the minimum value is limited from the viewpoint of component manufacturing.

Therefore, there is a mismatch region where matching cannot be achieved depending on the case where the operating frequency is high or the state of the antenna impedance. Therefore, as in the present invention, the LC comprising the π-type circuit is used.
Matching points are detected by using the network 4. In this case, it is necessary to use all the capacitors in each of the capacitor units 5 and 6 and all the coils in the coil unit 7, and there are many matching points. become.

On the other hand, in the case of matching, in FIG. 1, the pure resistance component Ra of the impedance when the antenna 3 and the capacitor 6 are viewed from the point S needs to be smaller than the pure resistance component of the wireless transmitter main body 2. In this case, the relationship of the input current Ii <the coil current Ic is established, and the coil current Ic increases as the pure resistance component Ra decreases. When the coil current Ic increases, the copper loss increases, and the efficiency decreases. In this case, the capacitance of the capacitor portions 5 and 6 also increases, the current flowing through the capacitor portions 5 and 6 increases, the loss in the coil portion 7 increases, and the dielectric loss tangent having the capacitor portions 5 and 6 further increases. Losses also increase. As described above, the smaller the pure resistance component of the impedance of the antenna 3 and the capacitor 6 from the point S is, the larger the coil current Ic becomes,
In addition, the loss increases.

Therefore, by bringing the pure resistance component Ra closer to the resistance component of the impedance in the wireless transmitter main body 2, that is, by bringing the coil current Ic closer to the input current Ii, it is possible to detect a matching point at which the efficiency becomes maximum.

〔Example〕

Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the drawings.

First, the configuration of the antenna matching device 1 will be described with reference to FIG.

In the figure, Po and Zo indicate the output power and the equivalent output impedance of the wireless transmitter main body, and 3 indicates an antenna connected to the wireless transmitter main body 2 via the antenna matching device 1. Reference numeral 4 denotes an LC network composed of a π-shaped circuit,
And capacitor units 5 and 6 connected to the input side and the output side of the coil unit 7, respectively. The input side of the coil unit 7 is a high-frequency ammeter 9 and a second high-frequency ammeter connected in series.
10, the radio transmitter main unit 2 via the standing wave measuring device 8 respectively
And the output side of the coil section 7 is connected to the antenna 3. Note that each of the capacitor units 5, 6
Are grounded.

The coil unit 7 is configured by connecting a plurality of coils 7a, 7b... 7n having different inductances in series.
7a are connected in parallel with short-circuit relay switches 21, 21b... 21n. Furthermore, each of the capacitor sections 5 and 6 also has a different capacitance 5a, 5b... 5n,
6a, 6b ... 6n are connected in parallel, and each capacitor 5a ...,
6a ... are open relay switches 22a, 22b ... 22n, 23a,
23b ... 23n are connected in series.

On the other hand, a detection function unit 11 having a computer function is provided, and the detection function unit 11 includes an analog-digital converter.
24, the high-frequency ammeters 9 and 10 are connected via analog-to-digital converters 25 and 26, respectively.
, 22a ..., 23a ... are connected with a driver 27 for selectively opening and closing.

Next, an antenna matching method using the antenna matching device 1 will be described with reference to FIG. 1 and FIG.

First, a setting value (upper limit value) for detecting a quasi-matching point where the standing wave ratio is equal to or less than a certain value is set in the detection function unit 11. In addition, a set value (upper limit value) for detecting a normal matching point at which the current ratio is equal to or less than a certain value at the quasi-matching point is set.

Next, the detection function unit 11 is operated to start execution of a sequence program for detecting a matching point (step 31).
As an example of the program, for example, a relay switch 23
The opening / closing control of a ... gradually increases the capacitance of the capacitor unit 6 on the output side in a stepwise manner. At this time, the inductance of the coil unit 7 and the capacitance of the capacitor unit 5 on the input side are changed at each stage by relay switches 21a ... 22a. .. Can be used in a sequential manner by selective opening / closing control. on the other hand,
The standing wave ratio measured during execution of the sequence program is monitored (step 32). Then, if a state where the standing wave ratio has become equal to or less than a preset set value (quasi-matching point) is detected (step 33), the sequence program is stopped (step 34), and the current ratio at this time is detected. Then, a determination is made for the detected current ratio (steps 35 and 36).
The current ratio measures the coil current Ic flowing through the coil unit 7 with the high-frequency ammeter 9, measures the input current Ii to the LC network 4 with the second high-frequency ammeter 10, and detects the input current Ii with the detection function unit 11. The ratio of the coil current Ic (= Ic / Ii) is calculated. Thus, if the current ratio is equal to or less than a preset value, the sequence control operation is terminated as a normal matching point, and if the current ratio exceeds the set value,
The sequence program is stopped and executed again from the part again to detect another quasi-matching point and repeat the process of determining the current ratio at that time (steps 37, 37-).

The sequence program for detecting a matching point is not limited to such an example. For example, first, a quasi-matching point is detected by a current ratio, and a standing wave ratio at this time is determined to detect a normal matching point. Alternatively, any program can be set. Also, the method of measuring the input current Ii using the second high-frequency ammeter 10 and improving the accuracy has been exemplified.
Ii may be calculated from the impedance Zo and the output power Po of the radio transmitter main body 2 which are known in advance, and may be set in the detection function unit 11. In this case, the second high-frequency ammeter 10
Is unnecessary. Further, although the LC network 4 of the π-type circuit has been illustrated, the invention is also applicable to other types of LC networks and variable variable capacitors and variable inductance systems controlled by motors. In addition, the detection function unit 11 performs an automatic detection operation under computer control. In addition, it is possible to arbitrarily change the detailed configuration, method, and the like without departing from the gist of the present invention.

〔The invention's effect〕

As described above, the antenna matching method and the antenna matching device according to the present invention measure the standing wave ratio between the radio device body and the antenna, the input current to the LC network and the coil current flowing through the coil unit, and measure the coil current in the LC network. By sequentially varying the capacitance of the capacitor unit and the inductance of the coil unit in accordance with the sequence program, a process of detecting a quasi-matching point at which the standing wave ratio is equal to or less than a set value is performed. In addition to stopping, the ratio (current ratio) of the coil current to the input current at the detected quasi-matching point is determined. If the current ratio is equal to or less than the set value, the matching process is terminated. The other quasi-matching points are detected by continuously executing the stopped sequence program, and the current ratio is determined. Since it repeats the that process, a marked effect as follows.

Since the loss due to the copper loss of the coil portion and the loss due to the dielectric loss tangent of the capacitor portion in the LC network can be reduced, the efficiency of the matching device can be improved.

The current flowing in the coil part is reduced, and the amount of heat dissipation is reduced, so that heat dissipation measures are facilitated. In addition, the size and cost of the entire matching device can be reduced by downsizing the components used in the LC network.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of an antenna matching device according to the present invention, FIG. 2 is a flowchart showing an antenna matching method according to the present invention, and FIG. 3 is a block circuit diagram of an antenna matching device according to a conventional technique. In the drawings, 1: antenna matching device, 2: radio unit 3: antenna, 4: LC network 5, 6: capacitor unit, 7: coil unit 8, standing wave measuring instrument 9, 10: high-frequency ammeter 11: Detection function section, Ii: input current Ic: coil current

Claims (2)

(57) [Claims] 1. A π-shaped antenna connected between a radio unit and an antenna.
In the antenna matching method that changes the capacitance of the capacitor part of the LC network and the inductance of the coil part to match the impedance of the antenna to the impedance of the radio unit, the ratio of the standing wave between the radio unit and the antenna to the LC network By measuring the input current and the coil current flowing through the coil unit, and sequentially changing the capacitance and the inductance according to a sequence program, a process of detecting a quasi-matching point at which the standing wave ratio is equal to or less than a set value is performed. When a matching point is detected, the sequence program is stopped, and a ratio (current ratio) of the coil current to the input current at the detected quasi-matching point is determined. When the current ratio is equal to or less than a set value, matching processing is performed. If the operation is terminated and the set value is exceeded, the stopped Antenna methods consistent characterized by detecting the other quasi-aligned points by execution continues with Ken scan program repeats the process of determining the current ratio. 2. A π-shaped matching antenna between a radio unit and an antenna.
In an antenna matching device that changes the capacitance of the capacitor part of the LC network and the inductance of the coil part to match the impedance of the antenna to the impedance of the radio unit, it measures the standing wave ratio between the radio unit and the antenna. Wave measuring device, a high-frequency ammeter for measuring the coil current flowing through the coil unit, a second high-frequency ammeter for measuring the input current to the LC network, and by sequentially varying the capacitance and the inductance according to a sequence program Performing a process of detecting a quasi-matching point at which the standing wave ratio is equal to or less than a set value, stopping the sequence program if the quasi-matching point is detected, and detecting the coil current with respect to the input current at the detected quasi-matching point. Judge the ratio (current ratio) and when the current ratio is below the set value Is a detection function unit that terminates the matching process, and when the set value is exceeded, continuously executes the stopped sequence program to detect another quasi-matching point and repeat the process of determining the current ratio. An antenna matching device comprising: