JPS642250B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in an automatic antenna tuner in which a motor automatically adjusts a matching tuning circuit that matches a transmitter output stage and an antenna circuit.

[Conventional technology]

Currently, antenna circuits for the HF band or VHF band are 50 ohm or 75 ohm, depending on the impedance of the coaxial feeder used. Therefore, it is desirable that the input/output impedance of the communication device used in conjunction with this also matches this. Particularly in the case of a transmitter, since loss due to mismatching causes a drop in output power, an impedance matching section with the load is provided at the output section of the final stage power amplifier to adjust the output power to obtain the maximum output. Furthermore, since many transistor output stages have fixed impedance, an impedance matching device may be inserted between the transmitter output and the antenna.

Since these output matching devices or antenna matching devices require a lot of effort to readjust when changing the transmission frequency, various automatic adjustment methods have been proposed and put into practical use to compensate for this. Most of them use the SWR (standing wave ratio) of the antenna circuit as an index, and
automatically adjusts to the best condition. this
Since the best SWR condition also means the best matching between the transmitter and antenna, it is suitable as an index for automatic adjustment, but the SWR detection device itself is complex.

[Problems to be Solved by the Invention] Therefore, in the present invention, the output power is adjusted to the maximum value using the output power as an index. In order to measure the output power without loss, a pass-through wattmeter is required, which is simpler than an SWR meter, but for the purpose of automatic adjustment it is not necessary to know the absolute value of the power. , it is sufficient to be able to compare the magnitude, so in the present invention, if the output power voltage is E and the load resistance (impedance) is R, the power P = E ² /R, so if R is constant, the previous Since P and E in the equation are in a proportional relationship, it is clear that even if E is measured instead of P, the magnitude and maximum point of P can be detected. In general, there is a concept that the maximum voltage point is not necessarily the maximum power point due to the problem of standing waves in high frequency transmission lines, so output voltage detection instead of output power detection is considered incomplete. However, under the conditions that the load (in this case the antenna) and the transmission frequency are constant, a proportional relationship between P and E holds true, so there is no problem in using the output high-frequency voltage as an index. Since voltage detection can be easily performed with a diode, it is extremely advantageous in terms of practical economic value.

Next, the adjustment of the circuit constants in an automatic matching box is usually carried out by adjusting the capacitor that is easily variable among the coil and capacitor that make up the circuit. Since this part is a power circuit, electronic tuning using capacitance diodes is not possible, so the variable capacitor must be rotated by a servo motor. Due to the large inertia, even if the control power is turned off at the stopping point, it will overrun, and the see-saw movement of stopping, reversing, and overshooting and reversing will be repeated several times, so there will be unexpected problems before the adjustment is completed. It takes time. If the rotation speed is lowered, the adjustment can be completed in one go, but it also takes time to complete.

[Means to solve the problem]

A servo circuit of a drive motor that adjusts the tuning of a matching tuning circuit that matches the transmitter output stage and the antenna circuit changes the power supply current that drives the motor in the direction of increasing the output power sent to the antenna circuit to the maximum output power point. Until then, DC drive is used, but once the maximum output point has been reached, the drive is switched to pulse drive to shorten the time until the maximum output power is reached, and during the overrun period, the motor control speed is reduced to reduce the amount of overrun. This is an automatic antenna matching tuner characterized by reducing the time required to complete tuning by reducing the number of antennas.

〔Example〕

Figure 1 is a block diagram showing the outline of an automatic matching device (sometimes included in the transmitter) inserted between the transmitter output stage and the antenna circuit, and the output provided on the output side of the antenna matching device. Power detector (In the present invention, it detects the output voltage, so it can be easily configured with a diode rectifier. Also, a voltage of about 1 Vrms is appropriate for the diode, and the voltage of the output circuit is set to 1 Vrms at a transmission power of 10 W. When the impedance is 50Ω, the output is about 22Vrms, so it is supplied to the diode through a divider or multiplier of 1/20 or more, so the load effect on the output circuit can be ignored) is added to the motor rotation control circuit. The servo motor M is rotated to rotate the variable capacitor VC of the antenna matching device in the matching direction, and the operation is stopped at the best matching point. Further, in the present invention, the motor rotation control circuit is characterized in that the power supply current for driving the motor is DC driven until the maximum output point is reached, and then converted to pulsed drive after the maximum output point is reached. A circuit device suitable for performing such an operation is disclosed in claim 2 and will be described below.

FIG. 2 shows an outline of the configuration of a motor rotation control circuit as an embodiment of the present invention, and FIG. 3 shows an example of a wiring diagram.
The configuration shown in FIG. 2 is roughly divided into [start/stop circuit], [motor rotation direction detection circuit], [pulse drive circuit], [rotation direction command circuit], and [power supply control circuit]. To start a stopped circuit, turn on the start circuit, and the positive power supply +V _cc passes through diode D ₃ to voltage detection comparators Q ₁ and Q ₂
In addition, the output of comparator _Q1 for + detection is set to H.
This causes the output of the start/stop circuit to become H through diodes D ₇ and D ₉ , making the power supply control circuit ready for operation.

At the start, the rotation direction command circuit issues a preset rotation direction command, applies either the positive or negative power source to the motor, and rotates the variable capacitor VC in the matching circuit.

Changes in the output voltage due to the rotation of the variable capacitor VC occur through the differentiator circuit of C ₁ and R ₂ in Figure 3,
Only the increase/decrease value is supplied to comparators Q ₁ and Q ₂ regardless of the absolute value of the detected voltage. Diode _D1 , _D2
is an amplitude limiter and is used to prevent damage due to excessive input. If the detected voltage is in the increasing direction, the differential output is +, so the same state as at the start is maintained.

If the detected voltage is in the decreasing direction, the differential output is -, so comparator Q ₁ is stopped, and the output of comparator Q ₂ changes from L to H, so this is added to semiconductor Q ₁₃ of the rotation direction command circuit. Reverse the direction of rotation. The semiconductor _Q13 is composed of a JK flip-flop, and the outputs Q and Q are both inverted according to the clock input of CK, so the comparator _Q2
The rotation direction of the motor M is determined by the output level of the motor M. J/K is close to H level in the diagram,
If this is set to L level, it will be opposite to Q, which is convenient for setting the rotation direction of the motor.

In FIG. 4, when the output decreases as it rotates in the direction from the origin a, the output increases in the reverse direction at point b, and the differential output becomes zero at the maximum point c. Therefore, the outputs of comparators Q ₁ and Q ₂ also become L.

When the AND gate _Q4 of the pulse drive circuit starts, the A and B inputs are both H through the diodes _D4 and _D7 , so the output is also H, and the H level of the output is added to the A input to change the H level of the output. Hold. The L level reversed by inverter Q ₃ is Q ₆ , Q ₇
In addition to one input of the NAND gate of the multivibrator consisting of , oscillation is stopped. The differential output disappears near the maximum output point, and the comparator Q ₁ ,
The output of Q ₂ becomes L, and the B input of AND gate Q ₄ also becomes L. The output of AND gate Q ₄ becomes L, and the inverter
When the output of _Q5 becomes H, multivibrator _Q6 ,
_Q7 oscillates, and comparator _Q8 is switched to intermittent motor power to perform pulse drive.

After passing the maximum point c, the pulse drive overruns at a lower speed, reverses at point d, and stops at point c as shown.

The instantaneous differential output disappears at points b and d in Figure 4, but in order to prevent this from disturbing the operation of the pulse drive circuit, a time constant circuit of c ₄ and R ₇ is provided to detect the point near point c, where the change is gradual. It is designed to work only with. Further, the start/stop circuit is provided with time constant circuits c ₃ and R ₆ having larger time constants in order to ensure that the power is maintained when passing point c.

FIG. 5 corresponds to each operation in FIG. 4. Motor M
This figure shows the drive current of .

Since the rotational speed is slower in the period than in the period, the time for the differential output to disappear when passing point c is longer. Therefore, the time constant circuit c ₄ , R ₇ of the pulse drive circuit
By appropriately setting the time constant of , it is held at the H level during overrun, and becomes the L level when passing through point c, thereby stopping the oscillation of the multivibrators Q ₆ and Q ₇ .

When the differential output disappears and the holding time of c ₃ and R ₆ has elapsed, the output level of the start/stop circuit becomes L, fixing the power supply control circuit to be inoperative.

With the above steps, automatic matching is completed and the stopped state is maintained until the start switch is pressed again.

〔Effect of the invention〕

According to the present invention, there is an advantage that automatic antenna matching tuning of a transmitter can be achieved by shortening the adjustment completion time with a relatively simple circuit configuration.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the outline of the configuration of the automatic antenna matching tuner of the present invention, Figure 2 is a block diagram showing the outline of the configuration of the motor control circuit, Figure 3 is the motor control circuit, and Figure 4 is the control circuit. FIG. 5, which is a diagram showing the relationship between motor rotation and output power, is a diagram showing changes in motor current during control. Q ₁ , Q ₂ ... Voltage detection comparator, Q ₄ ...
AND gate, Q ₅ ... Inverter, Q ₆ , Q ₇ ... Multivibrator, V _c ... Variable capacitor, D ₁ , D ₂ ... Amplitude limiter, C ₃ , R ₆ ... Time constant circuit.

Claims (1)

[Claims] 1. A servo circuit of a drive motor that adjusts the tuning of an antenna matching circuit that matches the transmitter output stage and the antenna circuit rectifies the high frequency voltage on the output side of the antenna matching circuit. By detecting the differential output of the change and driving the motor in the direction of increasing the output voltage, the power supply current is driven by DC drive until the maximum output power point, and then converted to pulse drive after the maximum output point. An automatic antenna matching tuner characterized by shortening the time required to reach the maximum point and reducing the amount of overrun to complete tuning. 2. The servo circuit of the drive motor, which adjusts the tuning of the antenna matching circuit that matches the transmitter output stage and the antenna circuit, outputs the differential output of the change in the DC voltage obtained by rectifying the high-frequency voltage on the output side of the matching tuning circuit. , determine the polarity using a positive polarity comparator and a negative polarity comparator, and add the result to the clock input of the J-K flip-flop.The forward output controls the motor's forward rotation power supply, and its reverse output controls the motor reverse rotation power supply. is controlled, the rotation of the motor is maintained in the direction of increasing the output high frequency voltage, the multivibrator is oscillated as the polarity of the differential output is reversed, and the power output of the motor is intermittent according to the output waveform. 2. The automatic antenna matching tuner according to claim 1, wherein the power to the motor is turned off and the rotation of the motor is stopped when the output disappears.