JPH0429980B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for connecting to an output circuit of a wireless transmitter,
Load SWR (here SWR stands for Standing Wave)
It relates to an automatic SWR measurement device that automatically measures the standing wave ratio.

[Conventional technology]

Conventionally, high-frequency power sent out from a transmitter is generally consumed by a load such as an antenna via a feeder line, but the transmitter output impedance, feeder line characteristic impedance, and load impedance are different. This causes a phenomenon in which part of the power is reflected from the connected portion. On the other hand, since normal transmitters are adjusted to match the characteristic impedance of the feeder line, this type of reflection is often caused by a mismatch between the feeder line and the load, and is reflected from the connection to the load. Electric power (hereinafter referred to as reflected wave power) travels backwards into the feeder line and interferes with the output power of the transmitter (hereinafter referred to as traveling wave power),
Voltage and current peaks and valleys occur within the feeder line. The greater the degree of mismatch and the greater the reflection, the greater the peak-to-valley ratio, so the SWR value often represents the matching state with the load. In addition, the displayed value of “SWR” can be determined by knowing the values of forward wave power P _F and reflected wave power P _R in a certain state, SWR = √P _F +√P _R /√P _F −√P _R …(1) However, in reality, it is not possible to directly measure high-frequency power without loss, so the traveling wave voltage V _F (hereinafter simply referred to as V _F ) and the reflected wave voltage V _R (hereinafter simply referred to as
Generally, it is calculated by measuring SWR=V _F +V _R /V _F −V _R ( ₂ ).

In addition, FIG. 1 is an example of a circuit of a conventional SWR meter, and the part inside the dotted line constitutes a CM type directional coupler 1 .
Furthermore, if one of the primary sides of the current transformer M is connected to the transmitter output and the other to the load side, each
Since a high-frequency voltage proportional to V _F and V _R is output, by rectifying this with diodes D ₁ and D ₂ , DC outputs E _F and E _R are generated within the rectification range.
(hereinafter simply referred to as E _F or E _R ) is also V _F and
The value is proportional to V _R and can be easily read with a DC voltmeter.

Also, to transform equation (2) above, if both the denominator and numerator terms are divided by V _F , SWR=1+(V _R /V _F )/1−(V _R /V _F )...(3) , it can be seen that the SWR in equation (3) is determined by the ratio of the values of V _R and V _F , regardless of the magnitudes of V _F and V _R. On the other hand, instead of V _R and V _F , E _R and E _F
Since this value is the same even if , SWR can be expressed as (E _R /E _F ). Furthermore, if we add the condition that the denominator E _F is a constant value, the SWR value is determined only by the E _R , so we have been able to directly read the SWR by using the SWR value instead of the E _R.

[Problem to be solved by the invention]

However, in the conventional technology as mentioned above,
It was difficult to quickly and directly read the SWR value due to the calculation time involved in the SWR meter and the need to repeatedly make adjustments by switching various switches.

The present invention was made for the purpose of improving these drawbacks of conventionally known SWR meters.

[Means to solve the problem]

As shown in FIG. 2, the present invention connects diodes D _{1 and} D ₂ inversely to both output terminals a and b of the CM coupling type directional coupler 1 , respectively, and furthermore, the diodes D ₁ and
By providing a bleeder resistor _R0 and a zero potential detector A having an arbitrary tap point between the outputs of _D2 ,
This is an automatic SWR measuring device that can instantly and directly read the SWR value, and solves the problems of the prior art described above.

〔Example〕

Next, the automatic SWR measuring device of the present invention will be explained based on the drawings. In _{FIG .} Since it is set to
The difference is that when E _F , which is rectified V _F , is a (+) voltage, E _F , which is rectified V _R , is a (-) voltage.
Therefore, when a bleeder resistor R ₀ (hereinafter simply referred to as R ₀ ) is connected between both output terminals of diodes D ₁ and D ₂ , the potential across R ₀ becomes (+) as described above.
and (-), so there is always a zero potential point at any point of this R ₀ . The position of this zero potential point is determined by the ratio of V _F and _VR ,
Next, this will be proven using a graphical solution method based on FIG.

In Figure 3, the voltages E _F and E _R across R ₀ are R ₀
is expressed by a vector in the opposite direction at right angles to , and
The potential distribution at an arbitrary point of R ₀ is shown by a straight line connecting the tips of both vectors E _F and E _R , and the intersection point N of this straight line and R ₀ is the zero potential point. and,
Triangle ΔF on the left and triangle ΔR on the right from the intersection N
are similar because all interior angles are the same. Therefore, the resistance on the E _F side from the intersection N is R _F ,
If the resistance on the E _R side is R _R , then E _R /E _F = R _R /R _F (4), and from equation (3), SWR is determined as (E _R /E _F ), so (4 ), the intersection point N determined by R _R and R _F indicates the SWR value.

On the other hand, SWR and intersection point N when perfectly matched (no reflection)
Since E _R = 0, the positional relationship with
SWR=1 and R _R = R _F , i.e. the intersection N is R ₀
Located in the middle. On the other hand, when misaligned (total internal reflection)
The positional relationship between SWR and intersection N is E _R = E _F , so (3)
From the equation and equation (4), it can be seen that SWR=∞ and R _R =0, that is, the intersection N is located at the E _R end of R ₀ .
In this way, the zero potential point on R ₀ is determined by SWR, and the CM type directional coupler 1 and diodes D ₁ and D ₂
Within the linear operating range of , it is not affected by transmit power or frequency, and by omitting any adjustment operations, we have made it possible to directly read the SWR at all times, and we would like to display it on R ₀ . A detection circuit is connected to the point where the SWR has zero potential, and the detection result is further supplied to a blinking indicator L such as a light emitting diode, so that when the detected potential is zero, negative potential, or positive potential, the blinking indicator L is Configure the light to turn on or off, and request such a display.
SWR value (e.g. SWR=1, 1.2, 1.5, 2.0, 2.5,
If connected to the R ₀ tap point corresponding to 3.0, 5.0…∞), the SWR indicated by the lit display closest to the off display
The value represents the operating state of the measurement circuit. The closer the SWR is to 1, the more desirable it is, and in practice up to about 3 is acceptable, but conversely, it can be said that displaying 3 or more is unnecessary. In addition, there is almost no major difference in functionality between SWR1.1 and SWR1.2, and therefore there is often no need for detailed reading, so usually a 5 to 8 point display is sufficient for practical use. be.

Next, an example of the configuration of the zero potential detector A and the blinking indicator L is shown in FIG. A detection potential is applied to the phase input, and a blinking indicator L such as a light emitting diode is loaded to the output. Furthermore, if it is desired to reverse the blinking state of the display, an inverter may be inserted or the polarities of the second diodes D ₁ and D ₂ may be reversely connected.

In addition, in the zero potential detector A, there is a problem that all detection points become zero potential when there is no input, so in the present invention, when E _F becomes below a predetermined value, the operation of the blinking indicator L is controlled. By providing a stopping means (described in detail later), it is possible to prevent incorrect use when no input is made or malfunction when the value is below a predetermined value.

_Next , Fig. 5 shows a detection/display section which is an example of a circuit according to the present invention.
The blinking indicator L ₁ connected to the zero potential detector A ₁ via D ₂ is configured via a control relay RL to turn on when SWR = 1 or more, and the blinking indicators L ₂ , L ₃ …L _o is SWR=1.2, 1.5, respectively…
It is configured to light up sequentially in the ∞ state, and for example, the lights are displayed in the arrangement order shown in Figure 6.
1.5 is the SWR value of this measurement circuit.

However, when there is no input, zero potential detector A ₁ ~
All the inputs of A _o become zero potential, causing a malfunction in which all the flashing indicators L ₁ to L _o light up. Therefore, while V _F is applied to the base of transistor Q to operate control relay RL of the collector circuit, when the base potential of transistor Q falls below a predetermined value, the collector-emitter of transistor Q is in a cut-off state. Become. As a result, since the control relay RL does not operate only in the no-input state, the blinking indicators L ₁ to L _o also do not operate, which shows that the above-mentioned malfunction in the no-input state can be prevented.

Note that although the control relay RL is shown as a mechanical relay in the figure, it may of course be one that uses an electronic relay or other control means.

〔Effect of the invention〕

As explained above, the present invention has the effect of enabling quick and continuous measurement without requiring any adjustment operations, and is not affected by the amplitude, frequency, etc. of the wave to be measured, so it can be modulated. It has the feature of being able to measure even waves.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of a conventional SWR measuring device, Figure 2 is a circuit diagram of the present invention, Figure 3 is an explanatory diagram of the operating principle of the present invention, and Figure 4 is a zero potential detector and blinking display. FIG. 5 is a circuit diagram based on FIG. 4, and FIG. 6 is a diagram showing an embodiment of the flashing indicator. 1 ...CM type directional coupler, A, A ₁ ~ _{A o} ...
Zero potential detector, D ₁ , D ₂ ...diode, L,
L ₁ ~L _o ...Flashing indicator, Q...Transistor,
R ₀ , R ₁ to R _o , R _F , R _R ...resistance, RL...control relay.

Claims (1)

[Claims] 1 Transmission power is passed through the primary side, a high frequency voltage proportional to the square root of the traveling wave power is transmitted to one output terminal of the secondary side, and a high frequency voltage proportional to the square root of the reflected wave power is transmitted to the other output terminal of the secondary side. Generates a high frequency voltage proportional to
In a CM-coupled directional coupler, diodes are connected in reverse to both output ends of the CM-coupled directional coupler, and a bleeder resistor and potential detection means are further provided with an arbitrary tap point between the outputs of the diodes. is connected to the blinking indicator, while the potential at the tap point of the bleeder resistor is connected to the CM
The blinking display is configured to turn on or off in a state of zero, negative potential, or positive potential with respect to the return path of the coupled type directional coupler, and further, when the output voltage of the traveling wave side diode falls below a predetermined value. An automatic SWR measuring device that is equipped with a means to prevent malfunction of the device.