JPH1065562A - Tuner circuit for antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable tuning without supplying transmission power to an antenna by operating the number of steps from the frequency of a main point between the frequencies of main points to the frequency of use frequency data and switching a capacitor group based on this number of steps. SOLUTION: The use frequency data set by radio equipment 1 are applied to a control circuit 11 and based on these frequency data, tuning is performed. A memory, to which the capacitance of a capacitor at the time of tuning is preset, is built in the control circuit 11 and when the frequency to be used is a frequency between the frequencies of main points, a tuning capacitor capacitance value is found by linear interpolation with the capacitor capacitances at these respective main points as a reference. Therefore, when the use frequency data are applied from the radio equipment, the control circuit 11 calculates the capacitance value of any tuning capacitor corresponding to these frequency data through a microprocessor, operates the group of switching relays 12 and selectively connects the combination of respective capacitors in the capacitor group 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna tuning circuit.

[0002]

2. Description of the Related Art Hitherto, when a variable capacitor or a variable coil is connected to an antenna element to perform tuning in a wide frequency range, the following circuit configuration is used. One of them, as shown in FIG. 5, is to supply a low-power transmission power from a radio 1 to an antenna (loop antenna element) 2, and to provide a traveling-wave power (Pf) and a reflected-wave power ( These powers are detected by the meter 4 by the detection circuit 3 of Pr).
The variable capacitor 5 or a variable coil (not shown) provided at the place where the variable capacitor 5 is arranged is manually adjusted while monitoring the instruction of the meter 4 to perform tuning. In addition, 6 is a coupling transformer. The two are
As shown in FIG. 6, a low transmission power is supplied from the wireless device 1 to the antenna 2, and the traveling wave power (P
f) and the reflected wave power (Pr) detection circuit 3 detects the respective powers, and the control circuit 7 compares and determines these detection signals, and automatically controls the variable capacitor 5 by servo control or control by a microprocessor. Alternatively, tuning is performed by changing a variable coil (not shown) by the motor 8.

[0003]

However, the conventional tuning circuit has the following disadvantages. That is,
(A) Since both circuits need to supply transmission power to the antenna 2 during tuning, unnecessary radio waves are emitted during tuning. (B) In order to perform tuning, a detection circuit 3 for traveling wave power (Pf) and reflected wave power (Pr) is required in the antenna input section. In the latter case, in particular, the variable capacitor 5 or a variable coil (not shown) Since the variable motor 8 is required, there is a problem that the tuning circuit is complicated, the volume is large, and the mass is large. The present invention provides an antenna tuning circuit which eliminates unnecessary radio waves during tuning of the antenna 2, which is a problem of the prior art, and which can reduce the size and weight of equipment or equipment for tuning adjustment. Things.

[0004]

SUMMARY OF THE INVENTION A first invention of an antenna tuning circuit according to the present invention is an antenna connected to a radio device and adapted to tune with a working frequency by changing a capacitance value of a capacitor of an antenna element. in the tuning circuit, previously memory means to be preset in a memory a plurality of the capacitance value at the tuning at the frequency of the main points defined, 2 ⁿ the capacitance value of the capacitor in use frequency帶域
A capacitor group in which a plurality of capacitors each set to a binary step value are connected in parallel via a switch, means for detecting use frequency data transmitted from the wireless device, and the main unit including the use frequency data. A microprocessor for calculating the number of steps at a predetermined switching frequency from the frequency of one main point between the frequencies of points to the frequency of the used frequency data, and switching the capacitor based on the number of steps; And a control means for switching in a binary step, whereby tuning is performed by selectively connecting one or more capacitors from the capacitor group according to the used frequency data.

A second invention of an antenna tuning circuit according to the present invention is used in an antenna tuning circuit which is connected to a radio and varies the inductance value of a coil of an antenna element so as to tune with a working frequency. A memory means for presetting an inductance value at the time of tuning at a frequency of a plurality of predetermined main points in a frequency band in a memory, and a plurality of coils each having a coil inductance value set to a binary step value of 2 ^n. A switch group is connected in parallel, and a coil group in which the coils are connected in series, means for detecting use frequency data sent from the wireless device, and a frequency between the main points including the use frequency data, From the frequency of one main point to the frequency of the used frequency data,
A microprocessor for calculating the number of steps at a predetermined switching frequency, and control means for switching the coil in a binary step by the switch based on the number of steps; Tuning is achieved by selectively connecting two or more coils.

[0006]

FIG. 1 shows an antenna tuning circuit according to the present invention applied to a loop antenna.
This will be described below. In FIG. 1, the same symbols as those in FIG. 5 or FIG. 6 indicate the same parts or the same circuits. In FIG.
11 is a control circuit using a microprocessor, 12 is a relay group, and 13 is a capacitor group composed of a plurality of capacitors. When the wireless device 1 is in use, the transmission power input is supplied to the loop antenna element 2 via the coupling transformer 6, but when tuning in switching the operating frequency, the transmission power input from the wireless device 1 is reduced. It is not supplied to the antenna 2. That is, when the operating frequency is set in the wireless device 1, the operating frequency data is given to a control circuit 11 using a microprocessor, and tuning is performed based on the operating frequency data.

The control circuit 11 has, for example, 3 MHz to 13 MHz.
The frequency of the main point in the operating frequency band of MHz, for example, the capacitance value of the capacitor at the time of tuning at intervals of 1 MHz of 3 MHz, 4 MHz, 5 MHz,.
It has a memory that is preset in advance. And
At frequencies where the operating frequency is between the frequencies of the main points (between the preset frequencies), there is a built-in software program that can obtain the capacitance value of the tuning capacitor by linear interpolation based on the capacitor value of each main point. I have. Therefore, when the use frequency data is given from the wireless device, the control circuit 11 calculates the capacitance value of the tuning capacitor corresponding to the frequency data by the microprocessor, operates the group of switching relays 12, and sets the capacitor indicated as 13. The combination of each capacitor in the group is selectively connected to obtain a tunable capacitance value.

As shown in FIG. 2, the capacitor group 13 includes a plurality of capacitors C0, C1, C3, C4,.
n and the relay contacts S of the relay group 12
, Sn, S1, S3, S4,... Sn are formed in series with each other and connected in parallel with each other. Further, each capacitance value of the plurality of capacitors C0, C1, C3, C4,.
, And the relay contacts S0 to Sn of the relay group 12 are appropriately switched to set the capacitors C0 to
By selecting Cn, an arbitrary value is set. The capacitance value of each capacitor is, for example, 1 pF for C0, 2 pF for C1, 4 pF for C3, 8 pF for C4,.
Is set as 2 ⁿ pF.

An example of the operation of the control circuit 11 will be described. As described above, the used frequency is, for example, 3 MHz to 13 MHz.
When the main point is provided in 1 MHz steps as z, the wireless device 1 sets the minimum step of the normally used frequency to 100
Since the frequency can be set in Hz, 10,000 kinds of frequencies can be designated during this period, and the frequencies during this period are linearly complemented. This linear interpolation will be described with reference to a graph of frequency versus capacitance shown in FIG. The operating frequency is shown on the horizontal axis and the capacitance value on the vertical axis in the graph of FIG.
And preset values of the capacitor capacitance at 4 MHz (f2) are prepared in advance in the table as A or B, respectively. Here, when the use frequency fx is designated by the wireless device 1, a preset value of x is obtained by linear interpolation. That is, since a is a straight line between a and b between the main points, the following equation (1) is established.

[0010]

(Equation 1)

Here, N is the number of steps between a and b. As described above, when the minimum frequency switching step interval of the wireless device 1 is 100 Hz, N = N
It will be 10,000. M is the number of steps from f1 to fx. When the use frequency fx is specified, from the frequency table of the frequencies f1 and f2 before and after that,
The preset values of the capacitor capacities of A and B are read, and the difference between the previous frequency f1 (3 MHz in this example) and fx is obtained from the value of the used frequency fx, and the number of steps M is obtained from the following equation (2). .

[0012]

(Equation 2)

Here, fmin is the above-mentioned minimum frequency switching step interval, which is 100 Hz in this example. Accordingly, x, which is the capacitance value of the capacitor tuned to the operating frequency, is obtained from the above equation 1, and is set as a preset value. This capacitance value x is based on the number of steps M from the main point A or B, and the capacitor C0 is set to a binary step value.
ＣCn are formed by selectively connecting one or more of them through relay contacts S0 Sn, and tuning is achieved.

[0014]

Although the above embodiment has been described with respect to an example in which tuning is performed by a capacitor, tuning may be performed by a coil instead of a capacitor. In this case, tuning can be performed by a similar operation in place of the coil group 14 shown in FIG. That is, the coil group 14
Is composed of a series circuit of a plurality of coils L0, L1, L2, L3,... Ln, and each coil is connected in parallel with relay contacts S0, S1, S3, S4,. I have. The use frequency data is supplied from the wireless device 1 to the control circuit 11, and the microprocessor calculates the inductance value of the tuning coil corresponding to the frequency data, operates the switching relays 12, and sets each coil of the coil group 14. Are selectively connected to obtain an inductance value that can be tuned. Since the operation of the microprocessor of the control circuit 11 is almost the same as the case where tuning is performed using a capacitor, the description thereof is omitted.

The control circuit 11 according to the present invention may be installed in a case where the antenna group 2 is mounted with the tuning capacitor group 13 or the coil group 14 for tuning.
It may be installed inside, and the selection data of the capacitor group 13 or the coil group 14 may be sent to the mounting case. Further, although the embodiment of the present invention has been described with respect to an example in which the present invention is applied to a loop antenna, the present invention can be applied to all antennas (antennas) of a system that tunes with a capacitor or a coil, in addition to a whip antenna. In addition, although an example has been described in which the selective connection of each element of the capacitor group 13 or the coil group 14 is performed by switching the contacts of the relay group, an electronic switch such as a switching transistor may be used.

[0016]

The present invention has the following effects. (1) Since there is no need to input transmission power when tuning the antenna, unnecessary radio waves are not emitted during tuning. When tuning the antenna to the operating frequency, since the radio can tune only from the operating frequency data,
Unlike the conventional case, transmission power is not required, and emission of unnecessary radio waves during tuning can be avoided. (2) The antenna input section does not require the Pf / Pr detection circuit conventionally required for tuning, and does not require a tuning motor or the like for changing a tuning variable capacitor or a variable coil. Lighter weight can be achieved. (3) Since the tuning variable capacitor or variable coil is switched in a binary step using a switch such as a relay, tuning can be performed instantaneously.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating an embodiment of a loop antenna tuning circuit according to the present invention.

FIG. 2 is a circuit diagram showing an example of a capacitor group and a switch group according to the present invention.

FIG. 3 is a graph for explaining a tuning circuit of the present invention.

FIG. 4 is a circuit diagram showing an example of a coil group and a switch group according to the present invention.

FIG. 5 is a circuit diagram illustrating an example of a conventional loop-type antenna manual tuning circuit.

FIG. 6 is a circuit diagram illustrating an example of a conventional loop-type antenna automatic tuning circuit.

[Explanation of symbols]

 Reference Signs List 1 radio 2 loop antenna element 3 Pf, pr power detection circuit 4 Pf, pr power meter 5 variable capacitor 6 coupling transformer 7 control circuit 8 motor 11 microprocessor-based control circuit 12 relay group 13 capacitor group 14 coil group

Claims (3)

[Claims] An antenna tuning circuit connected to a radio device and adapted to tune with a working frequency by changing a capacitance value of a capacitor of an antenna element, a plurality of predetermined main points in a working frequency band. A memory means for presetting the capacitance value of the capacitor at the time of tuning at a frequency in a memory; and a capacitor group in which a plurality of capacitors each having a capacitance value set to a binary step value of 2 ⁿ are connected in parallel via a switch. Means for detecting use frequency data transmitted from the wireless device, and from one main point frequency between the main point frequencies including the use frequency data to a frequency of the use frequency data And a microprocessor for calculating the number of steps at a predetermined switching frequency. Control means for switching the capacitor in a binary step by the switch based on the number of capacitors, and tuning is performed by selectively connecting one or more capacitors from the group of capacitors according to the used frequency data. A tuning circuit for an antenna. 2. A plurality of predetermined main points in an operating frequency band in an antenna tuning circuit connected to a radio device and adapted to tune with an operating frequency by changing an inductance value of a coil of an antenna element. A memory means for presetting the inductance value at the time of tuning at the frequency of the memory in a memory; and a switch connected in parallel to each of a plurality of coils in which the inductance value of the coil is set to a binary step value of 2 ⁿ , and A coil group connected in series, means for detecting use frequency data transmitted from the wireless device, and a frequency of one of the main points between the frequencies of the main points including the use frequency data, the use frequency data Microprocessor that calculates the number of steps at a predetermined switching frequency up to the frequency of Control means for switching the coil in a binary step by the switch based on the number of steps, and tuned by selectively connecting one or more coils from the coil group according to the used frequency data. A tuning circuit for an antenna. 3. The antenna tuning circuit according to claim 1, wherein the switch is formed by a contact of a relay.