JP3398211B2 - Auto antenna tuner and control method therefor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for an automatic antenna tuner, which is inserted and connected between a transmitter and an antenna system (antenna including a feeder) to automatically perform impedance matching.

[0002]

2. Description of the Related Art The input impedance of an antenna system changes depending on the transmission frequency. Therefore, in a transmitter that uses multiple frequency bands or has large frequency changes, an auto antenna tuner is installed between the transmitter and the antenna system to prevent the reflected wave from occurring in the transmitter automatically. The input impedance of and the output impedance of the transmitter are matched. The auto antenna tuner detects the SWR value and
The matching circuit is controlled so that the value becomes the minimum, and when the SWR value becomes equal to or less than the predetermined value, the matching is completed. The voltage standing wave ratio (VSWR value) is used as the SWR value. Here, in the above-mentioned auto antenna tuner, the matching circuit is controlled so that the SWR value is always minimized, so that the input impedance of the antenna system is extremely mismatched with the output impedance of the transmitter (SWR).
(If the value is large), if you perform the automatic matching control as described above and send as it is, high voltage or large current is applied to the matching circuit regardless of whether the matching is completed or not, and the matching circuit generates heat. Cause damage. In other words, by using the auto antenna tuner as described above,
Reducing the R value puts a heavy burden on the matching circuit, and the burden also increases in proportion to the decrease in the SWR value. Normally, in the matching circuit of the auto antenna tuner, the range of ability in which matching can be completed by automatic matching control (for the output impedance of the transmitter
Since there is a range of the input impedance of the antenna system in which the matching can be completed), the matching cannot be completed when the input impedance of the antenna system is extremely mismatched with the output impedance of the transmitter as described above. Therefore, as a solution to the above problem, when the matching cannot be completed, the matching circuit is cut off, and the transmitter is directly connected to the antenna system by the through circuit to protect the matching circuit. There is an auto antenna tuner that protects the matching circuit by limiting the transmission output on the transmitter side when it cannot be completed.

[0003]

However, the actual range of the matching circuit as described above is not a constant SWR value, but it depends on the position when the input impedance of the antenna system is represented on the Smith chart or the transmission frequency. It depends on FIG. 3 shows an example of a specific range of actual ability (it does not become a pure circle although it varies depending on the elements constituting the matching circuit) on the Smith chart. In FIG. 3, [S-1] indicated by a solid line indicates an example of the actual range when the transmission frequency is 24.4 MHz, and [S-2] indicated by a broken line indicates an example of an actual range in the case where the transmission frequency is 30 MHz. It is shown. Generally, when obtaining the SWR value from the Smith chart, the center 0 is “1”
And the size will increase in concentric circles.
It can be seen that the WR value changes depending on the position and that the higher the transmission frequency, the wider the range of ability. Therefore, according to the above-described auto antenna tuner, when the input impedance of the antenna is out of the actual range (for example, point C), the matching cannot be completed, so that the protection function works. At the point A or at the point B when the transmission frequency is high, the matching can be completed even though the SWR value is large. Therefore, the protection function does not work and the matching circuit is large. It causes a burden and causes damage due to heat generation as described above.

Here, since the matching circuit is composed of a combination of a coil and a capacitor, power consumption (heat generation) is not ideally performed. However, when the SWR value is extremely lowered as described above, matching is performed. The matching circuit has an extremely low impedance or high impedance part in order to match the input impedance of the antenna system,
High voltage or large current is supplied. When a high voltage is supplied, power is consumed due to the leakage conductance of the capacitor, and when a large current is supplied, power is consumed due to the resistance component of the coil and the like, both of which cause heat generation. Such heat generation causes damage to the matching circuit.

The present invention has been proposed in view of the above problems, and when the input impedance of the antenna system is extremely mismatched with the output impedance of the transmitter, automatic matching control is not performed, and the matching circuit generates heat. It is an object of the present invention to provide a control method for an auto antenna tuner that can prevent damage due to damage.

In order to solve the above-mentioned problems, the invention of claim 1 is an auto antenna tuner inserted and connected between a transmitter and an antenna system, and an SWR detection circuit for detecting an SWR value on an input side, A matching operation in an automatic antenna tuner including a matching circuit controlled to minimize the SWR value, a through circuit that directly connects a transmitter and an antenna system, and a switching circuit that switches the matching circuit and the through circuit. When the switching circuit is switched to the through circuit side at the start of
The SWR value detected by the detection circuit is compared with a predetermined set value, and when the SWR value is equal to or less than the set value, the switching circuit is switched to the matching circuit side so that the SWR value becomes the minimum. There is provided a control circuit for controlling the matching circuit to perform a matching operation, and for terminating the matching operation when the SWR value exceeds the set value. The invention according to claim 2 is an auto antenna tuner which is inserted and connected between a transmitter and an antenna system, wherein the SWR value on the input side is detected.
An automatic system including a WR detection circuit, a matching circuit controlled to minimize the SWR value, a through circuit for directly connecting a transmitter and an antenna system, and a switching circuit for switching between the matching circuit and the through circuit. In the antenna tuner control method, at the time of starting the matching operation, the switching circuit is switched to the through circuit side, and the SWR is set.
The SWR value detected by the detection circuit is compared with a predetermined set value, and when the SWR value is equal to or less than the set value, the switching circuit is switched to the matching circuit side so that the SWR value becomes the minimum. The matching circuit is controlled to perform a matching operation, and when the SWR value exceeds the set value, the matching operation is terminated as it is.

[0007]

In the above structure, when the matching operation is started, first, the switching circuit is switched to the through circuit side, and the transmitter and the antenna system are directly connected. In this state, the SWR value is detected by the SWR detection circuit, and if this SWR value exceeds a predetermined set value, the matching operation is terminated with the connection to the through circuit side being maintained. Therefore, excessive heat generation does not occur in the matching circuit. However, if the SWR value is less than or equal to the set value, the switching circuit is switched to the matching circuit side. Then, this matching circuit is automatically matched as in the conventional case, and is controlled so that the SWR value is minimized.

[0008]

The present invention will be described with reference to FIG. FIG. 1 is a block diagram showing an embodiment of an auto antenna tuner according to the present invention. In FIG. 1, reference numeral 1 is an auto antenna tuner in which a transmitter 2 and an antenna system 3 are inserted and connected, and a matching circuit 4 for adjusting impedance,
A through circuit 5 for directly connecting the transmitter 2 and the antenna system 3,
Switching circuits 6A and 6B for switching to either the matching circuit 4 or the through circuit 5 and S for detecting the SWR value.
A WR detection path 7, an impedance detection circuit 8 for detecting impedance, a reactance detection circuit 9 for detecting reactance, a control circuit 10 by a microcomputer, and a necessary buffer circuit and driver circuit are provided between the circuits. ing.

The matching circuit 4 includes two variable capacitors 41.
A T-shaped circuit is composed of A and 41B and the coil 42. The variable capacitors 41A and 41B are provided with driving motors 43A and 43B, respectively, and the series capacitor C1 is connected or short-circuited by the capacitor relay circuits 44A and 44B, and among the parallel capacitors C2, C3, and C4. A maximum of three are selected and connected in parallel to change the capacitance. The coil 42 is provided with a plurality of taps, and the reactance is changed by selecting the taps by the coil relay circuit 45 and short-circuiting or grounding.

Reference numeral 11 denotes a memory in which data such as various set values is stored. The control circuit 10 has a control program as shown in FIG. When is input, it operates as follows. First, the matching start signal a from the transmitter 2 is sent to the control circuit 10
Is input to start the control program of FIG.
First, in step 1, the through switching signal b1 is output to switch the switching circuits 6A and 6B to the through circuit side. Next, in step 2, the SWR value c output from the SWR detection circuit 7 is compared with the set value d (for example, 2.5) stored in the memory 11.

When the SWR value c exceeds the set value d in step 3, the switching circuits 6A and 6B are left in the through state and the operation is terminated. Therefore, even if transmission is performed in this state, the auto antenna tuner 1 will not be damaged. Further, since the transmission output is controlled by an APC (automatic output control) circuit (not shown) provided at the final stage of the transmitter 2, the transmitter 2 will not be heated and damaged.

However, when the SWR value c is equal to or less than the set value d, the matching switching signal b2 is output in step 4 to switch the switching circuits 6A and 6B to the matching circuit side. In step 5, automatic matching control for the matching circuit 4 is started. Here, when the SWR value c becomes equal to or less than the matching judgment value read from the memory 11, it is judged that the matching is completed. In step 6, the matching completion signal is output and the matching completion lamp 12 is turned on to indicate that the matching is completed.

The automatic matching control in step 5 will be described in detail below. When the impedance of the antenna and the characteristic impedance of the coaxial cable (50Ω) are mismatched, a standing wave is generated on the coaxial cable, and the input impedance of the antenna system 3 seen from the point A is equal to the output impedance of the transmitter 2 (50Ω). It becomes a mismatch state.
Therefore, in the matching circuit 4, automatic impedance matching is performed so that a reflected wave does not occur in the transmitter 2.
Specifically, the impedance detection circuit 8 detects the voltage and current input to the auto antenna tuner 1,
The absolute value of impedance is detected by the ratio of the values.

The reactance detection circuit 9 detects the reactance component value from the phase difference between the voltage and the current. The absolute value of the impedance and the reactance component value thus detected are input to the control circuit 10 via the buffer. The control circuit 10 adjusts the variable capacitors 41A and 41B of the matching circuit 4 by rotating the motors 43A and 43B forward and backward so that the reactance component value is 0 and the absolute value of the impedance is 50Ω. In addition, when the bands are switched, it may not be possible to achieve matching only by adjusting the variable capacitors 41A and 41B. Therefore, the band data output from the transmitter 2 in accordance with the switched band may be used for the matching. By referring to the switching data table of the memory 11 and setting the operation start angles of the capacitor relay circuits 44A and 44B, the coil relay circuit 45, and the variable capacitors 41A and 41B according to the obtained switching data. , A quick matching operation can be obtained.

The switching data table of the memory 11 is rewritten based on the respective states such as the angles of the capacitor relay circuits 44A and 44B, the coil relay circuit 45, and the capacitors 41A and 41B at the time of completion of matching. , May be referred to in the next automatic matching control. The variable condenser 41 in the above matching operation
The rotation speeds of A and 41B may not be constant and may be controlled to rotate at a high speed when the SWR value is large, and to rotate at a low speed when the SWR value approaches 1.

In this way, when the matching is completed,
Since a large amount of heat is not generated inside the auto antenna tuner 1 by the transmission power, the auto antenna tuner is not damaged. The set value d
May be determined based on usage conditions, elements used for the matching circuit 4, and the like. For example, the SWR value may be set so that the auto antenna tuner is not damaged when 100 W of power is supplied in the HF band. S of the set value d
The range of the WR value is a circle centered on the point 0 on the Smith chart. For example, it becomes a circle like [S-3] shown by the chain double-dashed line in FIG. In this case, point A
As in point B and point B, automatic matching control is not performed even within the actual range of the matching circuit, so that the matching circuit is prevented from being damaged by excessive heat generation.

Further, the automatic impedance matching method in the control circuit 10 is not limited to the above, and any method may be used as long as it is controlled to minimize the SWR value.

[0018]

As described above, according to the present invention, at the start of the control operation, first, the SWR value is detected in the state of being switched to the through circuit, and only when the SWR value is equal to or less than the predetermined set value, Switch to the matching circuit side for automatic matching control,
When the SWR value exceeds the predetermined set value, the matching operation is terminated while being connected to the through circuit side, so that the matching circuit can be prevented from being damaged by excessive heat generation.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of an auto antenna tuner according to an embodiment of a method for controlling an auto antenna tuner according to the present invention.

FIG. 2 is a control flowchart of a control method of the auto antenna tuner.

FIG. 3 is a diagram showing an example of an actual range on a Smith chart.

[Explanation of symbols]

1 Auto antenna tuner 2 transmitter 3 antenna system 4 Matching circuit 5 through circuit 6A, 6B switching circuit 7 SWR detection circuit 8 Impedance detection circuit 9 Reactance detection circuit 10 control circuit 11 memories c SWR value d Set value (predetermined set value)

Claims (2)

(57) [Claims] 1. An auto antenna tuner inserted and connected between a transmitter and an antenna system, wherein an S on the input side is provided.
A SWR detection circuit that detects a WR value, a matching circuit that is controlled to minimize the SWR value, a through circuit that directly connects a transmitter and an antenna system, and a switching circuit that switches the matching circuit and the through circuit. In the auto antenna tuner provided with, at the start of the matching operation, the SWR value detected by the SWR detection circuit is compared with a predetermined set value while the switching circuit is switched to the through circuit side. When it is less than the set value, the switching circuit is switched to the matching circuit side, and the matching operation is performed to control the matching circuit so that the SWR value becomes the minimum, and the SWR value is set to the setting value. If the value exceeds the value , the automatic antenna tuner is equipped with a control circuit for controlling the matching operation to end as it is. 2. An auto antenna tuner inserted and connected between a transmitter and an antenna system, wherein an S on the input side is provided.
A SWR detection circuit that detects a WR value, a matching circuit that is controlled to minimize the SWR value, a through circuit that directly connects a transmitter and an antenna system, and a switching circuit that switches the matching circuit and the through circuit. In the control method of the auto antenna tuner including and, at the time of starting the matching operation, in a state where the switching circuit is switched to the through circuit side, the SWR value detected by the SWR detection circuit is compared with a predetermined set value, If the SWR value is less than or equal to the set value, the switching circuit is switched to the matching circuit side, and the matching operation is performed to control the matching circuit so that the SWR value becomes the minimum. Is above the set value , the control method is to control so as to end the matching operation as it is.