JPS6057725B2 - frequency discriminator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION There is a discriminator that uses one or two magic T's to discriminate the frequency of microwaves such as SHF signals.

In this case, if the magic T is configured with a waveguide, the discriminator can be realized relatively easily, but it becomes impossible to integrate it into an integrated circuit.

In this respect, if the Magic T is configured with a microstrip line, it can be integrated into an integrated circuit, but it is extremely difficult to configure the Magic T with a microstrip line, and the configuration becomes complicated.

In view of these points, it is an object of the present invention to provide a frequency discriminator for microwaves that has an extremely simple configuration and is easy to integrate into an integrated circuit.

An example will be explained below.

In this example, the local oscillation frequency of the SHF receiver is stabilized, that is, it is configured as a frequency discriminator for AFC. In FIG. 1, 1 designates a frequency discriminator according to the invention, which corresponds to circuit 2 in FIG.
, 3 and 5 are excluded.

And 10 is a dielectric substrate made of alumina, for example.
On the lower surface (back surface in the figure), a ground side conductor is provided in a predetermined pattern.In addition, on the upper surface (front surface in the figure) of the board 10, an input conductor layer made of a conductor layer of uniform width is provided. A microstrip line 11 is provided in a straight line.

One end of this line 11 is connected to the local oscillation circuit 2, and the other end is connected to the mixer circuit (frequency conversion circuit) 3, and the local oscillation signal 5 from the oscillation circuit 2 is connected to the mixer circuit (frequency conversion circuit) 3.
0 is supplied to mixer circuit 3 via line 11.
In this case, the circuits 2 and 3 are not included in the frequency discriminator, but when used in the AFC circuit, they are provided on the substrate 10 as shown in the figure. Further, on the upper surface of the substrate 10, microstrip lines 12 to 14 made of a conductor layer having a uniform width are arranged in a straight line, and the line 11
They are provided parallel to each other so as to be perpendicular to each other on the same side.

In this case, among both ends of lines 12 to 14, line 1
The end of the line 11 is bent at right angles to the direction of the oscillation circuit 2 so as to be close to and parallel to the side edge of the line 11, and these ends and the line 11 form a directional coupler (distributor). )22
~24 are respectively configured. Also, the center frequency of the local oscillation signal SO is F.

, whose wavelength is λ. Then, the interval between lines 12 to 14 is
That is, the spacing between the couplers 22 to 24 is set to λo (or an integral multiple thereof). Furthermore, for example, the length of line 12 (length from line 11) is an arbitrary length [x+y]
However, line 13 is λ more than line 12. /8, and line 14 is longer than line 12 by λ. It has been lengthened by /4. Note that 12A to 14A are line 1
2 to 14 open ends. Furthermore, a cylindrical dielectric resonator 33 is provided on the upper surface of the substrate 10 in contact with the line 13 .

In this case, the resonant frequency of the resonator 33 is frequency F. The circumferential surface of the resonator 33 is line 1.
3, a length λ from the open end 13A of the line 13. /
4, so that they touch at point 13C. Also, the board 10
On the upper surface, between the lines 12 and 13, there are microstrip lines 15 and 1 made of a conductive layer of uniform width.
6 are provided in a V-shape or Y-shape as a whole.

That is, line 15 has one end connected to line 1.
The directional coupler 25 is configured to be close to the line 12 at a point of length x (x is arbitrary) from the line 1 and to move away from the line 12 toward the other end. In addition, line 16 is also considered to be one, and line 16
A directional coupler 2 is connected between one end of the line 13 and the line 13.
6 are configured. The other ends of the lines 15 and 16 are gradually brought close together and integrated to form a coupler 31. In this case, the lines 15 and 16 are symmetrical about a straight line that is orthogonal to the line 11 and passes through the coupler 31. Further, on the upper surface of the substrate 10, lines 17 and 18 are provided between lines 13 and 14 in the same manner as lines 15 and 16, and couplers 25 and 26 are provided.
, 31 are constructed.

Note that in lines 12 to 14, the points where couplers 25 to 28 are formed are 12B to 14B. Diodes 41 and 42 are connected to the output ends of the couplers 31 and 32 with the same polarity, and the output ends of the diodes 41 and 42 are connected to capacitors 51 and 52 and resistors 61 and 62. It is connected to output terminals 71 and 72.

In this case, the elements 41 to 61 are configured or arranged, for example, as shown in FIGS. 2 and 3. That is, the diode 41 has a cylindrical shape as a whole, and has the upper and lower surfaces of the diode 41.
It has a disk-shaped cathode terminal 41K and an anode terminal 41A, and the terminal 41A is soldered to the top surface of the output end of the coupler 31.

Further, in the vicinity of the output end of the coupler 31, a through hole 10H is formed in the substrate 10, and a cylindrical dielectric material 56 is formed in the through hole 10H.
is buried so that its lower surface is in contact with the ground conductor 19 on the lower surface of the substrate 10, and is fixed with adhesive.

Furthermore, an electrode 56E is formed on the upper surface of the dielectric 56. In this case, the dielectric constant of the dielectric 56 is about 103,
Q is considered to be 10 or less. The cathode terminal 41K of the diode 41, the electrode 56E, and the terminal 71 are connected by a lead wire 67.

Therefore, the capacitor 51 is constituted by the electrode 56E, the dielectric 56, and the ground conductor 19, and the dielectric 56
Since Q of 6 is small, resistor 61 is also configured at the same time, and these have the connection relationship shown in FIG.

Note that the elements 42 to 62 are also similar to the elements 41 to 61.

The output signals of the terminals 71 and 72 are then supplied to the differential amplifier 4 to configure the frequency discriminator 1, and the output signal is
The signal is supplied to the oscillation circuit 2 through the low-pass filter 5 as a control signal (AFC signal) for its oscillation frequency.

According to such a configuration, the local oscillation signal S is supplied from the oscillation circuit 2 to the line 11.

are provided as signals S2-S, on lines 12-14 through couplers 22-24. The signal S2 supplied to line 12 then passes through point 12B, is reflected at open end 12A of line 12, reaches point 12B again, and is supplied to line 15 through coupler 25. Also line 14
The signal S4 supplied to line 1 also passes through point 14B and
After being reflected at the open end 14A of 4, it reaches the point 14B again,
It is fed into line 18 through a coupler 28 . moreover,
The signal S3 applied to line 13 should be applied to lines 16 and 17 in the same way.

But now, signal S.

is the center frequency F. Suppose that Then, due to the resonance of the resonator 33, the point 13C where the resonator 33 is in contact acts as an open end, so the signal S3 supplied to the line 13 is reflected at the point 13C and reaches the point 13B, where it is coupled. Vessel 2
6, 27 to the lines 16, 17. The signal S2 therefore has a length [x+? ] and is supplied to line 15, and the signal S3 is supplied to line 13
The signal S4 travels the length [x+2(y-λo/8)]=[x+ki-λo/4] at the line 14 and is supplied to the lines 16 and 17.
+λ.

/4)]=[x+ki+λo/2] to line 18
supplied to And in this case, the spacing between the couplers 22-24 is equal to the signal S.

(S2-S4) wavelength λ. , so that when signals S2-S4 are applied to lines 12-14,
This means that the signals S2 to S4 are supplied in phase with each other. Therefore, the phase of the signal S2 supplied to line 15 is θ
Then, the phase of the signal S3 supplied to the lines 16 and 17 becomes [θ-π/2], and the phase of the signal S, supplied to the line 18 becomes [0+π].

That is, in lines 15-18, signals S2-S
As shown in FIG. 4, the phases of the signals S2 and S4 are sequentially different by π/2, and the levels of the signals S2 and S4 are equal. However, since the signal S3 supplied to lines 16 and 17 causes loss due to the unloaded Q value of the resonator 33 and the strength of the coupling between the resonator 33 and the line 13, the signal S3 supplied to lines 15 and 18 The level is somewhat lower than that of signals S2 and S4 (
This level reduction is not important for the frequency discrimination operation; the phase of signal S3 is important. and line 15,1
Since the signals S2 and S3 of 6 are combined in the combiner 31, the combined signal 2 of the signals S2 and S3 is taken out from the combiner 31 as shown in FIG.

Furthermore, since the signals S3 and S4 on the lines 17 and 18 are supplied to the coupler 32, a composite signal S6 of the signals S3 and S4 is taken out from the coupler 32, as shown in FIG. In this case, the levels of signals S2 and S4 are equal to each other, so
The levels of the signals S5 and S6 are also equal to each other. Then, these signals S5, S6 are detected by diodes 41, 42 and output as signals 1S51, IS61 to terminals 71, 72, and these signals 1S51, :S6l are supplied to the differential amplifier 4. , the output voltage E5 of the filter 5 becomes zero.

That is, the signal S. is the center frequency F. When , the seventh
As shown in the figure, the voltage E5 becomes zero. On the other hand, signal S.
The frequency is the center frequency F. If the resonator 33 is sufficiently lower or higher than , the resonator 33 will not resonate.
A is an open end, and the signal S3 supplied to the line 13 is reflected at the end 13A and then supplied to the lines 16 and 17 through couplers 26 and 27. Therefore, in this case the signal S3 has a length [x+2(y+λ
o/8)]=[x+ki+λo/4] to line 1
6 and 17, the phase of the signal S3 on the lines 16 and 17 becomes [0+π/2], and the vector diagram of the signals S2 to S6 is as shown in FIG.

Therefore the signal S. The frequency is the center frequency F. The output voltage E5 becomes zero when it is sufficiently lower than and also when it is higher than. Also signal S.

The frequency is the center frequency F. If it is slightly lower than
The change in level and phase of the force signals S2, S4 supplied to line 13 is small, so that the signals S2, S4 are similar to those in FIG.
The signal S reflected from C and fed into lines 16, 17
3 varies greatly around the resonant frequency FO. Therefore, the vector diagram of the signals 1 to S6 becomes as shown in FIG. 6, and since 1S51>IS6l, the output voltage E5 becomes positive. Therefore, for the frequency of the signal SO, the output voltage E
5 changes as shown in FIG.
Frequency discrimination is performed.

Also on this phone, signal S.

The frequency of is controlled, ie M°C. Thus, according to the present invention, it is possible to discriminate the frequency of microwaves such as the S8 signal, but in this case, since the entire structure is made up of microstrip lines, it is possible to implement integrated circuits.

In addition, there are no complicated parts, and the design is easy.
A frequency discrimination circuit with excellent performance can be obtained. Note that in the above description, a cavity resonator can also be used as the resonator 33, and in this case, the resonator 33 is connected to the coupling hole 33.
It may be coupled to line 13 through H. Alternatively, the resonator 33 may be a magnetic resonator. In addition, couplers 22-2
The signals S2 to S, each having a phase shift of π/2, are sequentially supplied to the lines 12 to 14 with the intervals of λo/4 (or an odd multiple thereof), and between the points 12A and 12B,
The lengths of the lines 12 to 14 between the points 13C and 113B and between the points 14A and 14B may be any equal length.

Furthermore, when the diodes 41 and 42 have opposite polarities, the signal 1S51<51S61 may be added in the amplifier 4.

[Brief explanation of drawings]

FIG. 1 is a plan view of an example of the present invention, FIG. 2 is a plan view of a part of the invention, FIG. 3 is a sectional view thereof, FIGS. 4 to 7 are illustrations for explaining the invention, and FIG. The figure is a plan view of another example of a part of the present invention. 11 to 18 are microstrip lines, and 33 is a dielectric resonator.

Claims (1)

[Claims] 1. An input microstrip line is connected to the first to third input microstrip lines.
a resonator is coupled to the second microstrip line, the first and second microstrip lines are coupled by a first coupler, and the second and second microstrip lines are coupled by a first coupler; 3 microstrip lines are coupled by a second coupler, and when the frequency of the input signal is the center frequency, the signals supplied to the first coupler have a phase difference of π/2 from each other, and The length of the input microstrip line or the first to third microstrip lines is selected so that the signals supplied to the second coupler also have a phase difference of π/2, and The output signals of the first and second couplers are supplied to first and second detectors, and the first and second
A frequency discriminator in which the detection outputs of the detectors are added or subtracted to obtain a frequency discrimination output of the input signal. 2. The frequency discriminator according to claim 1, wherein the resonator is a dielectric resonator.