JP2013026847A - Antenna impedance matching method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna impedance matching method which can achieve impedance matching in almost the same short time irrespective of the type of antenna to be impedance matched.SOLUTION: First, contacts 5a and 5b of a relay 5 are switched over, and the output of a transmitter is connected to an antenna via a matching circuit 2 and a pre-matching circuit 3 to detect the impedance of the antenna by an error detection circuit 1. Then, a control circuit 4 searches an antenna discrimination table from the detected antenna impedance to determine the type of the antenna, and, on the basis of the result of this determination, impedance characteristics preset in the matching circuit 2 and the pre-matching circuit 3 are selected, whereby the matching of antenna impedance is achieved. Since types of antennas are discriminated in advance, it is made easy to select impedance characteristics preset in the matching circuit 2 and the pre-matching circuit 3.

Description

  The present invention relates to a method for impedance matching between a wireless device and an antenna, and more particularly to an antenna impedance matching method in which impedance matching is automatically provided when an HF band antenna is connected to a wireless device.

When a wireless device such as a transmitter is used, an antenna needs to be connected. At this time, it is necessary to match the impedance of the antenna and the impedance of the wireless device.
For example, in the case of a wireless device such as an HF transmitter, the output impedance I _OUT is normally 50Ω (nominal value), whereas in the case of an HF band (short wave band) antenna, the antenna impedance I _ANT is Generally, the impedance ranges from about 0.1Ω to about 10 kΩ, and the impedance varies depending on the frequency.

  Therefore, conventionally, a method for obtaining impedance matching for each frequency band to be used using an antenna impedance matching device has been used (see, for example, Patent Document 1).

JP-A-11-88201

The prior art has a problem that the time required for impedance matching depends on the type of antenna to be impedance matched.
An object of the present invention is to provide an antenna impedance matching method capable of quickly obtaining impedance matching in substantially the same time regardless of the type of antenna to be impedance matched.

  The object is to use an error detection means connected between the output of the wireless device and the antenna and a matching means with preset matching characteristics, and to perform impedance matching between the output of the wireless device and the antenna. In an antenna impedance matching method in which a matching characteristic of the matching unit is preset based on a detection result of an impedance error by the detection unit, an antenna type determination process is performed to determine the type of the antenna based on the impedance characteristic of the antenna. The presetting of the matching characteristics of the matching means is achieved based on the antenna type discrimination result obtained by the antenna type discrimination process.

According to the present invention, impedance matching can be obtained in a short time even when a plurality of antennas having different characteristics are targeted.
As a result, according to the present invention, the processing load on the control circuit can be suppressed, and therefore the circuit scale of the control circuit does not increase.
In addition, at this time, in the present invention, the maximum value of the time required for the matching process is always the same regardless of the type of the antenna, so there is no great variation in the waiting time until the impedance matching is obtained. As a result, it is possible to quickly respond to the system startup.

It is a block diagram which shows one Embodiment of the apparatus for antenna impedance matching used in the antenna impedance matching method by this invention. 5 is an equivalent circuit for explaining an operation in an embodiment of an antenna impedance matching method according to the present invention. It is an equivalent circuit diagram of an HF antenna. It is the characteristic view which showed the change of the resistance component with respect to the frequency F of an antenna, and the reactance component. 5 is an equivalent circuit for explaining an operation in an embodiment of an antenna impedance matching method according to the present invention. It is a circuit diagram which shows an example of a matching circuit. It is a circuit diagram which shows another example of a matching circuit. It is a circuit diagram which shows an example of a pre-matching circuit. It is a circuit diagram which shows another example of a pre-matching circuit. It is a flowchart which shows an antenna impedance matching process.

Hereinafter, an antenna impedance matching method according to the present invention will be described in detail with reference to illustrated embodiments.
FIG. 1 shows an antenna impedance matching device used in an embodiment of the present invention. As shown, an error detection circuit 1, a matching circuit 2, a pre-matching circuit 3, and a control circuit 4 are shown. A relay 5 having two circuits and two contacts, contacts 5a and 5b of the relay 5, and a connection circuit 6 are provided.
First, the error detection circuit 1, the matching circuit 2, the pre-matching circuit 3, and the control circuit 4 are connected in series between the antenna connection terminal of the transmitter TX and the antenna ANT, thereby the high frequency of the transmitter TX. The output is supplied from the error detection circuit 1 to the antenna ANT antenna via the matching circuit 2 and the pre-matching circuit 3.

At this time, the error detection circuit 1 detects an error (mismatch) between the output impedance of the transmitter TX and the impedance of the antenna ANT as an error signal composed of a resistance component (R) and a reactance component (jX), and detects it as a control circuit 4. And the intensity of the traveling wave (Pf) and the intensity of the reflected wave (Pr) on the path from the transmitter TX to the antenna ANT are detected and input to the control circuit 4.
Here, the matching circuit 2 and the pre-matching circuit 3 will be described later, and the control circuit 4 is composed of, for example, an MPU (microprocessor), and a desired program is stored in the control circuit 4 for the necessary control. Corresponding actions can be obtained.

Therefore, the control circuit 4 relays to the matching circuit 2 and the pre-matching circuit 3 in response to an error signal input from the error detection circuit 1, that is, an error signal composed of a resistance component (R) and a reactance component (jX). The drive signals r ₁ and r ₂ are supplied, the matching characteristics of the matching circuit 2 and the pre-control circuit 3 are changed, and control is performed so that the error between the resistance component (R) and the reactance component (jX) becomes zero. .
The error 0 at this time is an error with respect to 50Ω in the case of the resistance component (R), that is, the resistance component (R) is equal to 50Ω, and it is 0Ω in the case of the reactance component (jX). It is.

When the error becomes 0 (or minimum) in this way, the control circuit 4 calculates the VSWR (voltage standing wave ratio) from the intensity of the traveling wave (Pf) and the reflected wave (Pr) input from the error detection circuit 1 next. If the calculated magnitude of the VSWR is equal to or smaller than a predetermined determination value, the impedance matching is completed.
As shown in FIGS. 6A and 6B, the matching circuit 2 is a so-called “L-type matching circuit” in which a variable capacitance type capacitor 7 and a variable inductance type coil 8 are connected in an L shape. When the relay is operated by the relay drive signal r ₁ supplied from the control circuit 4, the capacitance value of the capacitor 7 and the inductance value of the coil 8 are switched, and the matching characteristics change so that the required matching can be achieved. It is a thing.

By the way, this “L-type matching circuit” is known as a matching circuit that can theoretically obtain the widest matching range.
Therefore, as shown in FIGS. 7A and 7B, a matching circuit in which the connection relationship between the capacitor and the inductance is changed is prepared. As described above, the matching circuit 2 in FIG. If not, the matching circuit 2 of FIG. 7 is selected and used.

  Here, the details of the variable capacitor 7 and the variable inductance coil 8 in FIGS. 6 (a) and 7 (a) are shown in FIGS. 6 (b) and 7 (b). The type capacitor 7 is a circuit in which a relay contact 7P and a unit capacitor element 7C having a capacitance value C connected in series are connected in a plurality of circuits, for example, N circuits, in parallel, and a relay drive signal r1 is supplied and relayed. By closing the contacts 7P one by one, it is possible to digitally change the capacitance value up to the maximum capacitance value NC with the capacitance value C of one unit capacitor element 7C as the minimum unit. Thus, the capacitor 7 functions as a variable capacitance type capacitor 7.

  Further, as shown in the figure, the variable inductance type coil 8 is a circuit in which a relay contact 8P and a unit coil element 8L having an inductance value L are connected in parallel, and a plurality of circuits, for example, M circuits, are connected in series. By closing the contacts 8P one by one, the inductance value L of one unit coil element 8L can be digitally changed up to the maximum inductance value ML with the minimum unit as the variable value type coil 8. It is intended to function.

Next, the pre-matching circuit 3 will be described.
First, FIG. 8 shows a specific example (part 1) of the pre-matching circuit 3. In this case, as shown in the figure, a plurality of series circuits of relay contacts 9 and coils 10 are connected from the matching circuit 2 to the antenna ANT. Connect in parallel between the line and the common potential point (earth), and connect a series circuit of relay contacts 9 and capacitors 11 in parallel between the line from the matching circuit 2 to the antenna ANT and the common potential point. Thus, the pre-matching circuit 3 is formed.

  FIG. 9 shows a specific example (part 2) of the pre-matching circuit 3, which includes a plurality of parallel circuits of the relay contact 9 and the coil 10 and a plurality of parallel circuits of the relay contact 9 and the capacitor 11. The pre-matching circuit 3 is connected in series to a line leading to the antenna ANT.

Therefore, in the case of the pre-matching circuit 3 of FIG. 8, at least one contact is selected and closed by the relay drive signal r _{2 on} each of the capacitor side and the coil side of the plurality of relay contacts 9. Thus, a parallel resonance circuit having a desired resonance frequency can be formed between the line from the matching circuit 2 to the antenna ANT and the common potential point (earth).
Output impedance I _OUT <Antenna impedance I _ANT
This makes it easy to achieve alignment when the state has been reached.

On the other hand, in the case of the pre-matching circuit 3 of FIG. 9, at least one contact is selected and closed by the relay drive signal r _{2 on} each of the capacitor side and the coil side of the plurality of relay contacts 9. A series resonant circuit having a desired resonant frequency can be formed on the line from the matching circuit 2 to the antenna ANT.
Output impedance I _OUT > Antenna impedance I _ANT
In this state, it is possible to facilitate the alignment.

Here, the reason why the pre-matching circuit 3 is provided will be described.
As described above, an L-type matching circuit having the widest matching range is theoretically used for the matching circuit 2. However, the variable capacitance range of the capacitor 7 and the variable inductance range of the coil 8 are nonetheless. Therefore, when the antenna impedance is as wide as about 0.1Ω to about 10 kΩ as in the case of an HF antenna, for example, the matching circuit 2 alone cannot match the antenna. A case will arise.

  Therefore, in this conventional example, the pre-matching circuit 3 is provided, and thereby, roughly matching is first performed over a wide range, thereby narrowing down to a certain range and fine matching is performed by the matching circuit 2 in the narrowed range. I am trying to take it.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG.
As already described, the impedance characteristics of the antenna vary depending on the frequency used. However, in the case of the HF band antenna, the frequency used is particularly wide, for example, from 2.00 MHz to 30.00 MHz. Yes.
On the other hand, there are many combinations of the characteristics of the matching circuit 2 necessary for impedance matching and the characteristics of the pre-matching circuit 3.
Therefore, in the case of a wideband antenna, trying to match it indiscriminately is very inefficient and hardly practically uses.

More specifically, in this case, the control circuit 4 starts matching when the transmitter and the HF antenna are connected to the antenna impedance matching unit and a high frequency output of a desired frequency is supplied from the transmitter. Is activated as the conditions necessary for the above are satisfied, and the matching process is started (step S1).
At this time, first, as an initial setting, the relay contact of the matching circuit 2 and the relay contact of the pre-matching circuit 3 are selected at random (randomly), and the relay drive signals r1 and r2 corresponding to them are selected as the matching circuit. 2 and the pre-matching circuit 3, and the selected relay contacts are combined and closed.

  Thereafter, different relay drive signals r1 and r2 are supplied one after another to the matching circuit 2 and the pre-matching circuit 3 in accordance with the error signal inputted from the error detection circuit 1, and the matching circuit 2 and the pre-matching circuit 3 are preliminarily supplied. The matching characteristics of the control circuit 3 are sequentially changed, and this is repeated until the error between the resistance component (R) and the reactance component (jX) becomes 0 or converges to the minimum value (step S2). ) When the error becomes 0 or converges to the minimum value, the process ends here (step S3).

At this time, there are a plurality of relay contacts of the matching circuit 2 and the pre-matching circuit 3, and therefore, the number of combinations increases geometrically.
And since errors are examined while sequentially testing these many combinations, it is natural that the efficiency deteriorates. Therefore, if it remains as it is, it is not very practical.

Therefore, in this embodiment, according to the type and frequency of the HF antenna assumed to be used in advance, the characteristics of the matching circuit 2 and the pre-matching circuit 3 that are required to be adapted to the characteristics are obtained and necessary to provide them. A combination of relay contacts is determined and stored in the software program of the control circuit 4 as a matching order preset table shown in Table 1.
In the matching process, this matching order preset table is used to search the table based on the frequency and the type of the HF antenna so that a combination of relay contacts of the matching circuit 2 and the pre-matching circuit 3 can be obtained immediately. .

  Here, the matching order preset table shown in Table 1 is an optimum matching for each of the antennas A, B, C,..., N at each of the frequencies F1, F2, F3,. The characteristics a, b, c,..., N are obtained in advance and arranged in order from the antenna A to the antenna N. In this case, the frequencies are arranged in the column direction (vertical direction), and the matching order is set in the row. For the direction (lateral direction), the matching characteristics corresponding to the antennas are arranged in the matching order direction and arranged in the vertical direction for each frequency.

For example, the optimal matching characteristic a1 for the antenna A at the frequency F1 is arranged in the first row of the matching order 1, the optimal matching characteristic a2 at the frequency F2 is the optimal matching for the second row, and the frequency Fm. The characteristic am is arranged in the lowest row (m row) in the matching order 1.
Next, the optimum matching characteristic b1 for the antenna B at the frequency F1 is arranged in the first row of the matching order 2, and the optimum matching characteristic b2 at the frequency F2 is optimum for the second row and the frequency Fm. The matching characteristic bm is arranged in the bottom row of the matching order 2.

  And, for the matching characteristics a, b, c,..., M at this time, whichever of the relay contacts 7P, 8P of the matching circuit 2 and the relay contact 9 of the pre-matching circuit 3 is closed. As data representing whether it is good, information which is obtained in advance and designates the contact points is described.

  Therefore, in this embodiment, when impedance matching is performed by connecting an HF antenna, the control circuit 4 randomly determines the relay contacts 7P and 8P of the matching circuit 2 and the relay contacts 9 of the pre-matching circuit 3. Each time the selection is made, the matching process is executed in accordance with the matching order preset table of Table 1 instead of sequentially checking whether or not the matching can be achieved.

First, the output frequency of the transmitter TX is set to F1, and then the control circuit 4 executes matching processing from matching order 1 to matching order n.
In matching order 1, the matching characteristic is set to a1, and it is determined whether or not the error between the resistance component (R) and the reactance component (jX) converges to the minimum value. Finish the operation. At this time, setting the matching characteristic to a1 means closing the contact necessary for providing the matching characteristic a1 as described above.

If the matching order 1 does not converge to the minimum value, the matching order 2 is executed next. That is, the matching characteristic is set to b1, and it is determined whether or not matching is achieved.
Then, if the matching order 2 does not match, the process of shifting to the matching order 3 is executed sequentially according to the matching order until the matching is achieved.
Thus, if matching is not achieved even when the processing from the matching order 1 to the matching order n is executed at the frequency F1, the frequency is set to F2. Then, the processing from the matching order 1 to the matching order n is executed again at the frequency F2, and it is determined whether or not the matching can be obtained each time, and this is sequentially executed up to the frequency Fm.

  Then, in this process, it can eventually be matched. This is because the characteristics of the matching circuit 2 and the pre-matching circuit 3 required in conformity with the type and frequency of the HF antenna assumed to be used in advance are obtained as shown in Table 1. This is because the combination of relay contacts required to provide it is determined and listed, so that matching should be achieved sooner or later unless an unexpected antenna and frequency are used.

Therefore, according to this embodiment, since the characteristic data of the matching circuit necessary for impedance matching is given from the table, it is not necessary to select at random for each relay contact, and as a result, the time required for impedance matching is eliminated. The load on the control circuit necessary for processing can be reduced.
However, in this case, it cannot be said that consideration is given to the diversification of the types of antennas that are assumed to be impedance matching targets. When a plurality of antennas having different characteristics are targeted, impedance matching is not necessarily performed in a short time. It is not necessarily obtained.

Here, as apparent from the table of Table 1, in this case, the order (matching order) is also arbitrarily or arbitrarily determined from specific antennas arbitrarily or arbitrarily determined from among a plurality of types of antennas. It is determined, and processing for matching in order is advanced accordingly.
For this reason, the time required to start processing for impedance matching differs depending on the order of antennas that require impedance matching at this time, and the time required for impedance matching becomes longer as the antenna is later in order. As a result, impedance matching is not always obtained in a short time.

Therefore, in this embodiment, the relay 5 and the connection circuit 6 are further provided so that impedance matching can be obtained in substantially the same time even if the type of antenna to be impedance-matched is different. This point will be described in detail.
As described above, in this embodiment, impedance matching is performed using the apparatus shown in FIG. 1. At this time, the antenna type discrimination process described above, that is, the antenna type for discriminating the type of the antenna is performed. Perform discrimination processing.
For this purpose, the MPU is programmed in the control circuit 4.

Here, first, the relay 5 is switched and controlled by the relay drive signal r ₅ supplied from the control circuit 4, and the contacts 5 a and 5 b are brought into the illustrated state, that is, the lower circuit in the normal antenna impedance matching process described above. When the antenna type discrimination processing is closed, the contacts 5a and 5b are closed on the upper side in the figure, and the path from the error detection circuit 1 to the antenna ANT is switched to the path by the connection circuit 6.
Next, the connection circuit 6 bypasses the matching circuit 2 and the pre-matching circuit 3 at the time of the antenna type discrimination process, and circuit elements for facilitating the antenna type discrimination as needed are referred to as the error detection circuit 1. It works to connect between the antennas ANT.

In this antenna type determination process, first, the antenna AXT is connected to the apparatus. Then, the control circuit 4 starts processing. At this time, the transmitter TX is operated in advance so that the high-frequency signal having the frequency Fa is input to the error detection circuit 1 and then the control circuit 4 starts processing. .
The high-frequency signal at this time is intended to be used for enabling the error detection circuit 1 to detect the error signal, and thus may be a signal with a low level output (for example, 25 W).

Next, the control circuit 4 supplies the relay driving signal r ₅ to the relay 5 is switched relay contacts 5a, and 5b to connect circuit 6 side. Then, a high-frequency signal having a frequency Fa is supplied from the error detection circuit 1 to the antenna ANT via the circuit element of the connection circuit 6. This state is shown in the equivalent circuit of FIG.
Here, the case where a resistor is used as the circuit element of the connection circuit 6 is shown, however, other circuit elements other than the resistor may be applied to this, as shown in FIG.

For example, when it is difficult to determine the type because the reactance of the antenna is small, a coil having a desired inductance value is used as a circuit element to correct the reactance component in the “+ jX” direction. A series circuit of a coil and a resistor may be used to correct both the reactance component and the resistance component.
Also, if it is easier to determine the type when the reactance is in the "-jX" direction, a capacitor is connected, and if necessary, a series circuit of a capacitor and a resistor is used to correct both the reactance component and the resistance component. You may make it do.
Here, if there is no problem in particular, it may be simply connected with an electric wire.

At this time, the error detection circuit 1 detects the resistance component (R) and reactance component (± jX) of the antenna ANT connected via the connection circuit 6 at this time, as shown in FIG. Supply.
Therefore, the control circuit 4 converts these resistance component (R) and reactance component (± jX) from an analog signal to a digital signal by an A / D converter, and digitized resistance component (R) and reactance component (± jX) is compared with the data in the antenna determination table prepared in advance in software, and the type of antenna currently connected to the apparatus is specified.

Therefore, assuming a plurality of HF antennas to be used in advance, the resistance component (R) and the reactance component (± jX) are individually examined for each of them, and the resistance component (R) and the reactance component for each antenna are examined. A table in which (± jX) values are paired is created and stored in the MPU software of the control circuit 4 as the antenna type discrimination table described above.
For example, if the resistance component (R) is RA and the reactance component (± jX) is + jXA as a result of examining the antenna A, “Antenna A” is written in the “RA: jXA” section, and the resistance component of the antenna B If the resistance component (R) is RB and the reactance component (± jX) is −jXB after examining (R) and the reactance component (± jX), the “RB: −jXB” is written with “antenna B”. The antenna type discrimination table is used.

Here, the antenna type determination at this time will be described together with its principle.
First, as is well known, the equivalent circuit of the antenna is represented as a series circuit of a resistance component (R) and a reactance component (± jX) as shown in FIG. (R ± jX).
Further, the resistance component (R) and reactance component (± jX) of these antennas change depending on the frequency, and the state of change varies depending on the type of antenna.

FIG. 4 is a characteristic diagram showing changes in resistance components (RA, RB, RC) and reactance components (jXA, jXB, jXC) with respect to respective frequencies F of three types of antennas A, B, C as an example. As is apparent from this figure, it can be seen that the resistance component (R) and reactance component (± jX) of the antenna change in different manners for each antenna.
Therefore, by looking at the resistance component (R) and the reactance component (± jX), the type of the antenna ANT connected at this time can be identified, and the type can be determined.

At this time, FIG. 4 shows a state in which the resistance component (R) and the reactance component (± jX) are greatly different between the antenna A, the antenna B, and the antenna C at a specific frequency (frequency Fa). It is shown.
Therefore, the presence of such a specific frequency is examined in advance for the antenna assumed to be used, and the frequency Fa is obtained.
When creating this antenna type discrimination table, the resistance component (R) and reactance component (± jX) of the antenna are detected in a state where a high-frequency signal of frequency Fa is output from the transmitter TX.

At this time, the frequency Fmin and the frequency Fmax on the horizontal axis of FIG. 4 are matched with the minimum frequency and the maximum frequency of the HF band, and the center frequencies in each band at this time are the frequencies F1, F2, F3,. .., Fn.
For example, in the case of the frequency F1, the bandwidth is 2.00 MHz to 2.49 МHz, and in the case of the frequency F2, the bandwidth is 2.50 MHz to 2.99 МHz.

  When the antenna type determination process is executed and the antenna type can be specified, for example, as a result of examining the antenna connected to the apparatus, the resistance component (R) is RA and the reactance component (± jX) is + jXA. Then, by looking at the item “RA: jXA” in the antenna type determination table, it is immediately known that the antenna connected now is “antenna A”, and the type of antenna can be specified.

Here, the control circuit 4 again outputs the relay drive signal r5 to the relay 5, and as shown in FIG. 5, the relay contacts 5a and 5b are switched from the connection circuit 6 side to the matching circuit 2 and the pre-matching circuit 3 side, In this state, the impedance matching process is executed as in the conventional example.
At this time, unlike the conventional example, the matching characteristics are preset by using the antenna order preset table of Table 2 instead of using the matching order preset table of Table 1.

  The antenna order preset table in Table 2 is a vertical arrangement of matching characteristics for each frequency with the type of antenna as a parameter. As shown in the figure, for example, the column of antenna A has a frequency F as a variable (F1). , F2,...) And corresponding matching characteristics a (a1, a2,...) Are arranged from the top to the bottom. .. Are arranged from the top to the bottom. Therefore, if the type of antenna is known in advance, the matching characteristics are sequentially applied to each frequency only for the antenna column. It is only necessary to check whether or not impedance matching is achieved, and by this alone, matching characteristics for matching required for the antenna can be reached.

Here, FIG. 5 shows an equivalent circuit when the antenna type determination process is executed and the antenna type can be specified and then the impedance matching process is performed. In this case, the matching circuit 2 includes the circuit shown in FIG. 9 is applied to the pre-matching circuit 3.
At this time, it is assumed that the type of the antenna ANT connected to the apparatus is specified as A, that is, the antenna A.
Then, in this case, the control circuit 4 proceeds with the processing using the impedance matching characteristic in the term of the antenna A in the antenna order preset table of Table 2.

That is, first, the transmitter TX is turned on, and the output frequency is sequentially switched from F1 to F2,..., Fm, and the matching characteristics are sequentially switched from a1 to a2. When switching, the resistance component (R) and the reactance component (jX) input from the error detection circuit 1 are examined to determine whether or not these errors converge to the minimum value. If it is determined, the matching operation ends there.
Here, the meaning of setting the matching characteristic to a1 is, as described above, the contact necessary for providing the matching characteristic a1, that is, the matching circuit 2 includes the pre-matching circuit 3 among the relay contacts 7P and 8P. In the relay contact 9, each corresponding contact is closed.

If this process is sequentially executed up to the final frequency Fm, the matching characteristic necessary for impedance matching is surely reached.
This is because Table 2 shows the characteristics of the matching circuit 2 and the pre-matching circuit 3 that are necessary in conformity with the type and frequency of the HF antenna assumed to be used in advance as described above. This is because the combination of relay contacts required to provide it is determined and listed, so that matching should be achieved sooner or later unless an unexpected antenna and frequency are used.

Then, in this case, the number of times required to obtain matching characteristics necessary for impedance matching is the maximum number n of antenna types.
This is because in this case, the type of the antenna ANT has already been specified, and it is known in advance that it is the antenna A.
On the other hand, if this antenna type discrimination processing is not performed, the maximum number of times required to obtain matching characteristics necessary for impedance matching is the product of the frequency type m and the antenna type number n (m × n) It will be times. For example, when there are five types of frequencies and eight types of antennas, in the above embodiment, the maximum number of times is eight. However, when the antenna type determination process is not performed, the maximum number is 40 times (5 × 8 = 40 ).

Therefore, according to this embodiment, even when a plurality of antennas having different characteristics are targeted, impedance matching can be obtained in a short time.
As a result, according to the above-described embodiment, the processing load on the control circuit 4 is suppressed, and therefore the circuit scale of the control circuit 4 does not increase.
In addition, at this time, the maximum number is always the same regardless of the type of antenna, so there is no great variation in the waiting time until impedance matching is obtained, and as a result, the system can be started up quickly. Can do.

Here, in the case of the above embodiment, since there is an antenna type determination process, the process is increased accordingly.
However, the time required for the antenna type determination processing is approximately 10 mS to 50 mS, although it depends on the processing speed of the MPU used in the control circuit 4, and therefore, compared with the merit by shortening the impedance matching processing time. It can be said that it hardly becomes a problem.

  The present invention can be widely used for wireless devices of any application as long as they use antennas.

DESCRIPTION OF SYMBOLS 1 Error detection circuit 2 Matching circuit 3 Pre-matching circuit 4 Control circuit 5 Relay 5a, 5b Relay contact

Claims (1)

Using an error detection means connected between the output of the wireless device and the antenna, and a matching means with preset matching characteristics, impedance matching between the output of the wireless device and the antenna is performed by the error detection means. In the antenna impedance matching method of the method performed by presetting the matching characteristics of the matching means based on the error detection result,
An antenna type determination process for determining the type of the antenna based on the impedance characteristic of the antenna is executed, and the matching characteristic preset of the matching unit is executed based on the antenna type determination result by the antenna type determination process. A characteristic antenna impedance matching method.

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