JPS6235284B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a frequency discriminator using a dielectric resonator, especially for microwave signals, and in particular, it is an object of the present invention to provide a frequency discriminator that is simple and compact in structure and easy to adjust. be.

As a frequency discriminator using a dielectric resonator,
The following are considered.

Figure 1 shows an example in which two dielectric resonators are used. 1 is a dielectric substrate with a ground conductor formed on the back side, and 2 is a microstripe to which an input microwave high-frequency signal is supplied and propagated. It's a lip line.

On both sides of this microstrip line 2, dielectric resonators 3 and 4 for frequency discrimination are provided on a dielectric substrate 1 and electromagnetically coupled to the line 2, respectively. Further, sub-microstrip lines 5 and 6 are connected to these dielectric resonators 3 and 4, respectively. One ends of the sub lines 5 and 6 are each made open, the other end of the sub line 5 is connected to the cathode of a diode 7, the anode of this diode 7 is connected to a ground conductor, and the other end of the sub line 6 is connected to a diode. 8, and the cathode of this diode 8 is connected to a ground conductor.

In this case, the resonant frequency of dielectric resonators 3 and 4
₁ and ₂ are ₁ ≠ ₂ , and the target center frequency
The relationship is chosen to be ₁ < ₀ < ₂ with respect to ₀ .

Therefore, a high frequency signal is extracted from the sub lines 5 and 6 according to the resonance characteristics (bandpass characteristics) of the dielectric resonators 3 and 4, and this is taken out from the diode 7.
Since diodes 7 and 8 are connected with opposite polarities, the cathode of diode 7 receives a positive DC output that reaches its maximum level at frequency ₁ , and the anode of diode 8 receives a positive DC output at frequency 1.
A minimum negative DC output of ₂ is obtained, respectively.

In this example, the cathode of diode 7 and the anode of diode 8 are connected to each other so that their outputs are combined. That is, at the connection point P of the diodes 7 and 8, a composite output having an inverted S-shaped characteristic as shown in FIG. 2 is obtained. In this case, the composite output is selected to be at zero level at frequency ₀ .

Then, a terminal 9a is led out from the connection point P,
A discrimination output having characteristics as shown in FIG. 2 is obtained between this terminal 9a and the grounded terminal 9b.

However, the device shown in FIG. 1 has the disadvantage that two expensive dielectric resonators are required. Furthermore, in order to obtain a discrimination output with desired characteristics, the resonant frequency of each dielectric resonator must be matched with extremely high precision, making adjustment difficult. moreover,
There is a drawback that it is necessary to take measures to eliminate the electromagnetic coupling between the two dielectric resonators or to avoid its influence.

Therefore, it has been considered to configure a frequency discriminator using one dielectric resonator.

FIG. 3 shows an example of the configuration. Similar to the example in FIG. 1, a conductive layer with a uniform width is formed on a dielectric substrate 10 with a ground conductor attached to the back side, forming a microstrip line. 11 is provided, a dielectric resonator 12 is provided coupled to this line 11, and a sub-microstrip line 13 is provided coupled to this dielectric resonator 12. One end of this sub-line 13 is an open end, the other end is connected to the cathode of a diode 14, and the anode of this diode 14 is connected to a ground conductor.

In this case, the resonant frequency ₃ of the dielectric resonator 12
is different from the desired center frequency ₀ , e.g.
₃ < ₀ .

Therefore, when the high frequency SHF signal Si is applied to the microstrip line 11, the sub line 13
To the side, the dielectric resonator 12 exhibits a bandpass characteristic, and according to this characteristic, the high frequency signal is transmitted to the sub line 1.
It is extracted from 3. Then, this high frequency signal is detected by the diode 14, and the diode 14
As shown in Figure 4, frequency ₃ is applied to the cathode side of the
The maximum positive DC output is obtained at 0, and the voltage is E _B at the target center frequency ₀ .

In this example, the output is connected to the terminal 15a derived from the cathode of the diode 14 and the voltage E _B
It is taken out from between the terminal 15b which is grounded via the DC power supply of the
A voltage, that is, a frequency discrimination output, is obtained between a and 15b, which is zero when the target center frequency is ₀ , negative when it is higher than it, and positive when it is lower than it.

However, in the case of the example shown in Fig. 3, only one dielectric resonator is required, but the bias power supply 16 is required because the shoulder part of the characteristic curve due to this one dielectric resonator is used. There is a drawback that.
In addition, in this example, the frequency discrimination output fluctuates as shown by the broken line in the figure as the amplitude of the input signal changes, so it is difficult to distinguish between voltage changes due to amplitude fluctuations and voltage changes due to frequency changes. There is.

In view of the above-mentioned disadvantages, the present invention aims to provide a frequency discriminator that does not suffer from the above-mentioned disadvantages, although it includes only one dielectric resonator.

Below, a fifth example of the frequency discriminator according to the present invention will be described.
Let me explain with reference to the figure below.

Note that in the following example, the dielectric substrate is omitted to simplify the explanation.

In FIG. 5, 17 is a microstrip line to which a high frequency signal Si is supplied, and a dielectric resonator 18 whose resonance frequency is equal to the target center frequency ₀ is coupled to this line 17. Then, the sub microstrip line 1 is connected to the dielectric resonator 18.
9 are coupled together, and a signal through this sub line 19 is supplied to a 90 degree hybrid coupler 22.

On the other end side of each of the microstrip lines 17 and 19, there are two lines 2 between these lines.
2a and 22b, and the extensions of lines 17 and 19, respectively, between these two lines are widened, thereby forming a 90 degree hybrid coupler 22. The ends of the coupler 22 in the extending direction of the lines 17 and 19 are connected to a ground conductor via diodes 23 and 24 that are oriented in opposite directions. And this coupler 22
The connection points between the ends of these diodes 23 and 24 are connected to each other and connected to a terminal 25a, and an output is taken out between this terminal 25a and a grounded terminal 25b.

Here, when the dielectric resonator M is coupled to the microstripline L as shown in FIG.
A band cutoff filter is configured for the signal passing through this coupling section. If the input signal on line L is a and the signal passing through the coupling part is b, then [Q ₀ : Unloaded Q of resonator M k ² _t : Coupling coefficient between resonator M and line L ω ₀ : 2π ₀ , where ₀ is the resonant frequency φ(ω) : Phase corresponding to the length of line L Amount of change] As shown by the broken line in FIG. 7, the phase of the signal b suddenly changes around the resonance frequency ₀ of the resonator m.

In this case, the coupling part between the line 17 and the resonator 18 acts as a band-cut filter for the signal passing through the line 17, and the phase of the signal obtained on the line 17 has a change characteristic as shown by the broken line in FIG. However, the coupling portion between the line 19 and the resonator 18 acts as a bandpass filter, and the phase of the signal extracted from the line 19 is the same as that of the signal obtained on the line 17 side with respect to the input signal Si, as shown by the solid line in FIG. It has the opposite characteristics.

Then, a phase detector 26 consisting of a hybrid coupler 22 and diodes 23 and 24 outputs a DC output corresponding to the phase difference between the signals obtained on lines 17 and 19, that is, _{0 at resonance frequency 0} .
In this case, a frequency discrimination output is obtained in which a positive DC output is obtained at a frequency lower than that, and a negative DC output is obtained at a frequency higher than that, but in this example, the phase characteristics of both signals are completely opposite, so there is a difference between terminals 25a and 25b. The frequency discrimination output obtained is as shown in the example in FIG. 8, and a frequency discrimination output with good sensitivity can be obtained.

As described above, according to the present invention, a frequency discriminator can be configured using one dielectric resonator,
Furthermore, unlike the conventional example shown in FIG. 3, there is no problem that the frequency at which the discrimination output becomes 0 changes when the amplitude of the input signal fluctuates.

Therefore, according to the present invention, it is possible to obtain an excellent frequency discriminator that has a simple structure because only one resonator is required, allows easy frequency adjustment, and is not affected by level fluctuations of an input high frequency signal. Can be done.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of an example of a conventional frequency discriminator, Fig. 2 is a diagram showing its output characteristics, Fig. 3 is a diagram showing the configuration of another example of the conventional frequency discriminator, and Fig. 4 5 is a diagram showing the configuration of an example of the frequency discriminator according to the present invention, and FIG. 6 is a diagram showing the output characteristics thereof.
Figures 8 through 8 are diagrams for explaining the same. 17 is a microstrip line, 18 is a dielectric resonator, 19 is a sub microstrip line,
20 is a directional coupler, 22 is a 90 degree hybrid coupler, 26 is this coupler 22 and a diode 23,
This is a phase detector consisting of 24 components.

Claims (1)

[Claims] 1. A dielectric resonator is electromagnetically coupled and provided near a first microstripline through which a high frequency signal is propagated, and is substantially parallel to the first microstripline and is connected to the dielectric resonator. A second microstrip line is provided on the opposite side, one end of the second microstrip line is an open end, and each of the first microstrip line and the second microstrip line The outputs are respectively supplied to a pair of input terminals of a hybrid coupler, and a pair of diodes are connected in opposite directions to the pair of output terminals of this hybrid coupler to constitute a phase detector. The signals having opposite phases of each other, that is, the signal that has passed through the first microstrip line and the signal that has come through the second microstrip line, are phase-detected, and the phase detection output is used to detect the high-frequency signal. a frequency discriminator configured to form a frequency discriminator signal;