JPH0413855Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a matching circuit between a radio transmitter and an antenna, and more particularly to an automatic adjustment circuit for an output tuner.

[Conventional technology]

The purpose of the output tuner of the transmitter is to match the final stage amplification element and the antenna circuit to supply maximum high-frequency power to the antenna. It is also used to improve circuit matching and reduce spurious radio waves by inserting it between the broadband output section and the antenna. A π-type matching circuit, which has a large harmonic reduction effect, is often used as a circuit, but this consists of a series element coil L and parallel element capacitors on the input and output sides, and band switching is determined by the number of turns of coil L. Normally, fine adjustment within the band is performed by adjusting the input-side variable capacitor VC ₁ and the output-side variable capacitor VC ₂ . By the way, the operations of these two variable capacitors are related to each other and influence each other, so
Adjusting both parts little by little to achieve the best condition requires skill and time. For this reason, automatic tuning control using servo control has conventionally been performed, but this has the following problems. In the conventional method, the transmitter output section is used to detect the optimal point.
Although we try to keep the SWR (standing wave ratio) close to 1.0, SWR detection in the transmitting state is relatively difficult to calculate by calculating the transmitter output (traveling wave power) and the reflected wave power from the antenna side. It's easy. but,
In order to use the SWR value as a standard for servo control, the SWR value must be automatically measured, which is particularly difficult in applications where the frequency range is wide and the output changes. Due to problems with the characteristics of the directional coupler, implementing this method requires a great deal of effort and expense.

[The problem that the idea aims to solve]

Conventionally, changing the tuning of the transmitter changes the standing wave mode of the antenna circuit, so the high frequency voltage at the transmitter output section and the effective output are not necessarily proportional to each other, and therefore the output voltage is proportional to the output power. The SWR value was used as a standard based on the idea that it could not be used as a standard. However, if the antenna and feeder are constant and the transmission frequency is also constant, the shape of the standing wave in the antenna circuit is determined and does not include elements controlled by voltage or current values, so any SWR Since the proportional relationship between power and voltage at the transmitter output section is maintained even in this state, voltage detection is sufficient if simply finding the maximum point of output power.

[Means to try to solve the problem]

π consisting of an SWR detection circuit, a coil, and two variable capacitors VC ₁ and VC ₂ from the output side of the wireless transmitter.
A shape matching circuit, an output detection circuit, and an antenna are connected in series, and the output of the SWR detection circuit is compared with a reference voltage by a comparator, and the output is supplied to the CPU.
The output of the output detection circuit is supplied to the CPU via an A/D converter, and the π
The configuration is such that the two variable capacitors VC ₁ and VC ₂ of the shape matching device are connected to respective drivers M ₁ and M ₂ connected to each other so as to alternately change and match them.

〔Example〕

FIG. 3 shows an embodiment of an automatic adjustment circuit for a transmitter according to the present invention, which will be explained with reference to FIG. 1 in the diagram
is the transmitter output section, the π-type matching circuit 2 is installed between the transmitter output section and the antenna, and the transmission output detection circuit 3 is installed between the antenna and the π-type matching circuit 2.
is provided, and its output side is connected to the A/D converter 4, and the output side of the A/D converter 4 is connected to the input port of the CPU 5. An SWR detection circuit 10 is provided between the transmitter output section 1 and the π-type matching box 2 , a reference voltage is applied to its output side and the other input terminal of the comparator 9, and the output side is connected to the input port of the CPU 5. .
Variable capacitor from CPU5 to π-type matching circuit 2
Output 51 of CPU 5 to driver M ₁ 6 connected to VC ₁
and connect the variable capacitor VC ₂ of the π-type matching circuit 2 .
The output signal 52 is sent to the driver M ₂ 7 which connects and drives the
It is configured to input.

As shown in the details of the transmission output circuit 3 in FIG. 1, the transmission output voltage 21 is connected to capacitors C ₁ and C ₂
The divided voltage is output by the diodes D ₁ and D ₂ and rectified to obtain the output. This transmission output detection voltage 31 is input to the A/D converter 4. This A/D
An example of a practical circuit of the converter 4 is shown in FIG. A/D
The output digital value 41 of the converter 4 is input to the CPU 5.

CPU5 is a variable capacitor of π-type matching circuit 2
Driver 6 of VC ₁ and driver 7 of variable capacitor VC ₂
Drive control signals 51 and 52 are output to.

The control signals 51 and 52 were output from the CPU according to the flowchart of FIG. 4 to alternately operate the driver M ₁ 6 and the driver M ₂ 7 and connect them to each driver. Variable capacitor VC ₁ and
Vary VC ₂ . On the other hand, a change in the output power is determined by checking the digital output 41 of the A/D converter 4, and the driver is operated in a direction in which the digital value 41 input to the CPU increases. This series of operations will be explained according to the flowchart of FIG. First, the configuration is such that when the output voltage 11 of the SWR detector 10 is higher than the reference voltage 91 of the comparator 9, the output 92 of the comparator 9 is input to the CPU 5. That is,
It is determined whether the SWR is equal to or greater than 2, and if it is equal to or greater than 2, the CPU 5 outputs a control signal 51 to the driver M ₁ 6, and the driver M ₁ 6 changes the variable capacitor VC ₁ . If the digital signal 41 from the A/D converter 4 becomes large, it continues to output the control signal 51, and if the digital signal 41 becomes small, the signal supplied to the driver M ₁ 6 is changed to a signal that moves in the opposite direction and is output. . Next, the control signal 51 is stopped and the control signal 52 is outputted to operate the driver M ₂ 7 and change the connected variable capacitor VC ₂ . Check the digital signal 41 and if it becomes small, the control signal 52 is sent to the driver M ₂
7 into a signal that moves in the opposite direction and outputs it. When the variable capacitor VC ₂ is adjusted, the control signal 52 is stopped and the control signal 51 is outputted to adjust the variable capacitor VC ₁ again. These control signals 51 and 52 are alternately and repeatedly outputted until the adjustment is completed to adjust the π-type matching device. This adjustment ends when the output voltage 11 of the SWR detection circuit 10 reaches the lowest voltage and becomes less than the reference voltage 91 of the comparator 9, that is, when the SWR becomes less than 1.5 in the flowchart of FIG. The driving voltage 92 disappears, and the CPU control signals 51 and 52 stop.

[Effect of idea]

This invention uses the SWR signal to automatically start and stop the adjustment of the π-type matching circuit, uses the output signal to compare the matching state, and automatically adjusts the two variable capacitors alternately, just as if a person were performing the matching. Since the alignment is configured to be performed using the same method as the above, there is an effect that alignment can be automatically adjusted reliably and quickly.

[Brief explanation of drawings]

Fig. 1 is a basic circuit diagram, Fig. 2 is an A/D conversion circuit diagram for checking the output level, Fig. 3 is an automatic adjustment circuit diagram of a transmitter showing an embodiment of the present invention, and Fig. 4 is a diagram of an automatic adjustment circuit of a transmitter showing an embodiment of the present invention.
The figure is a flowchart for operating the CPU. 1 ...Transmitter output section, 2 ...π-type matching circuit, 3
...Output detection circuit, 4...A/D converter, 5...
CPU, 6, 7...Driver _M1 , _M2 , 8...Start button, 9...Comparator, 10...SWR
Detection circuit, L...coil, _VC1 , _VC2 ...capacitor.

Claims (1)

[Scope of utility model registration request] An SWR detection circuit, a π-type matching circuit consisting of a coil and two variable capacitors VC ₁ and VC ₂ , an output detection circuit, and an antenna are connected in series from the output side of the transmitter, and the output of the SWR detection circuit is connected to a reference voltage by a comparator. a driver that compares and supplies an output to a CPU, converts the output of the output detection circuit with an A/D converter and supplies it to the CPU as an output level, and connects the output of the CPU to the variable capacitor _VC1 ;
_M1 and a driver _M2 connected to a variable capacitor _VC2 are configured to tune the π-type matching circuit to match the transmission frequency, and while the SWR signal is at a level exceeding the reference value, the CPU supplies the signal to the driver M2 connected to the variable capacitor VC2. driver
a matching signal output means for operating M ₁ and M ₂ to output a matching signal that tunes the π-type matching circuit to the transmission frequency; and supplying the matching signal to one of the drivers M ₁ or M ₂ to adjust the output level. When the output level reaches the maximum, the matching signal switches to the other driver for matching, and when the output level reaches the maximum, the matching signal switches to one driver again.
An automatic adjustment circuit for a transmitter, comprising repeating matching means for alternately repeating matching and stopping and restoring matching when the SWR signal becomes less than a reference value.