JPH0722249B2 - Diode limiter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide type diode limiter used for, for example, a pulse radar.

[0002]

2. Description of the Related Art In a pulse radar, as shown in FIG. 7, a microwave signal (hereinafter referred to as an RF signal) output from a magnetron 1 is guided to an antenna 3 via a circulator 2 and radiated from the antenna 3. . An RF signal from the outside is received by the antenna 3 and guided to the limiter 4 and the receiving module 5 via the circulator 2. When transmitting and receiving such a signal, the limiter 4 serves to protect the receiving module 5 from an excessive RF signal input to the receiving module 5 because the RF signal from the magnetron 1 directly leaks at the circulator 2. As such a limiter 4, a diode limiter has been used that limits the leakage power to the receiving module by turning on the diode when an excessive RF signal is input.

Further, in the above diode limiter, since the magnetron 1 may oscillate at another unnecessary frequency higher than f0 other than the fundamental frequency f0, these outputs (hereinafter referred to as spurious signals) are generated. In order to prevent this, a filter is arranged so as to sandwich the front and rear of the diode.

FIG. 8 shows such a conventional diode limiter, in which a low-pass comb-teeth waveguide 10 is used, and two convex portions (capacitive gap) inside the waveguide 10 are used. The PIN diode 11 is disposed so as to be sandwiched between the parts 10a and 10b so as to provide a filter characteristic for blocking a spurious signal having a frequency of f0 or higher. In this low-pass comb tooth-shaped waveguide 10, for example, as shown in FIG. 9, convex portions 20a, 20b, 20c and concave portions 20d, 20e are alternately provided on the upper and lower inner walls along the propagation direction of radio waves. Then, the convex portions 20a, 20b, 20c
Represents a capacitance component, and the recesses 20d and 20e operate as an induction component. This waveguide 10 has a convex portion 20 as shown in an equivalent circuit of FIG.
a corresponds to the capacitance C1, the convex portion 20b corresponds to the capacitance C2, the convex portion 20c corresponds to the capacitance C3, the concave portion 20d corresponds to the inductance L1, and the concave portion 20e corresponds to the inductance L2. Further, in the case of forming a comb-tooth low-pass filter, when the fundamental frequency to be used is determined, the length dimension per stage is determined, and the higher the number of stages, the higher the performance. Normally, as shown in FIG. 8, the inner two-stage comb tooth portions 10a and 10b (capacitance gap portions) provided with the PIN diode 11 and the front and rear two-stage comb tooth portions 10c and 10d ( It is often composed of four stages (capacity gap part).

Here, in the conventional diode limiter, the comb tooth portions 10a and 10b of the waveguide 10 are provided.
To the PIN diode 1 via the coaxial circuits 12a and 12b.
1 is disposed and formed, and has an equivalent circuit shown in FIG. In this case, in the waveguide, the convex portion 10c has a capacitance C1, the convex portion 10d has a capacitance C2, the coaxial circuit 12a has an inductance L4, the coaxial circuit 12b has an inductance L5, the concave portion 10e has an inductance L1, and the concave portion 10f has an inductance L2. 10 g corresponds to the inductance L3.

However, in the above diode limiter, the low pass filter is formed by using the comb-toothed waveguide 10 in which the concavo-convex portion is formed along the propagation direction of the radio wave. Since it has to be divided into upper and lower parts to be manufactured and each part must be reassembled and formed, there are problems that there are many constituent parts, the assembling work is troublesome, and highly accurate assembling is difficult. In addition, as a low-pass filter, if the number of stages is increased in order to improve its performance, the overall length becomes twice the number of stages, and the size is increased, which is a constraint for improving its performance. Had the problem of having.

[0007]

As described above, the conventional diode limiter has a problem that the assembling work is troublesome, it is difficult to assemble with high precision, and the size is increased when the performance is improved. Was.

The present invention has been made in view of the above circumstances, and provides a diode limiter having a simple structure, a simple assembling work, a high precision, and a miniaturization. The purpose is to provide.

[0009]

According to the present invention, a screw hole for forming a coaxial outer conductor is provided in a ridge portion provided on one of wide wall surfaces of a substantially rectangular opening, and the screw is provided on the other of the wide wall surfaces. A ridge waveguide provided with a recess having the same center line as the hole, and a first metal screw member provided with a screw hole which is screwed into the screw hole of the ridge waveguide and faces the recess. And a PIN diode in which one electrode is inserted into and connected to the recess of the ridge waveguide, and the other electrode is arranged to face a screw hole of the first metal screw member, and the first metal screw member. Screwed into a screw hole of the ridge waveguide, and a tip end thereof is loosely inserted into the screw hole of the ridge waveguide to form a coaxial inner conductor connected to the other electrode of the PIN diode inserted in the recess. And a second metal screw member for Tsu is obtained by configuring the data.

[0010]

According to the above structure, in the ridge waveguide, the screw portion of the screw hole forms a coaxial outer conductor, and the second metal screw is loosely inserted into the screw hole through the first metal screw member. A coaxial portion is formed by forming the coaxial inner conductor by the member, and by combining the coaxial portion and the PIN diode, RF
As a band elimination filter that keeps the PIN diode off (connected) when the signal is small (transmitting), passes the fundamental frequency component with low loss, and blocks the band above a predetermined level with high insertion loss. Operate. In this band elimination filter, when the RF signal becomes large in power and the PIN diode is switched to the ON state (separation state), the cutoff frequency of the band elimination filter becomes equal to or lower than the fundamental wave frequency, and the cutoff frequency including the fundamental wave frequency is cut off. To do.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a diode limiter according to an embodiment of the present invention. In a single-ridge rectangular waveguide 20, one ridge portion 20a of a wide wall surface (E surface) is screwed at a predetermined interval. Holes 21a and 21b are formed. Recesses 22a and 22b for inserting PIN diodes are formed on the other of the wide wall surfaces of the rectangular waveguide 20 on the same line as the center lines of the screw holes 21a and 21b.
One electrode of the PIN diode 23 is connected to.

The screw holes 21a and 21b form a coaxial outer conductor, and the plate-shaped first metal screw members 24a and 24b are screwed together so that they can be screwed together. This first metal screw member 24
Screw holes 25a and 25b are formed in a and 24b corresponding to the recesses 22a and 22b of the ridge waveguide, and the rod-shaped second metal screw member 26 is formed in the screw holes 25a and 25b.
a and 26b are screwed together so that screwing can be adjusted. Second
The metal screw members 26a and 26b of the ridge waveguide 20 are
To form a coaxial inner conductor by being loosely inserted into the screw holes 21a and 21b of the pin, and the tip end thereof is connected to the other electrode of the PIN diode 23 inserted into the recesses 22a and 22b.

The ridge waveguide 20 is a single ridge type ridge waveguide 10 as shown in FIG. 2, for example.
0 is produced by the well-known drawing technique or die casting technique. Next, as shown in FIG. 3, in the ridge waveguide 100, two screw holes 102 are formed in one ridge portion 101 of the wide wall surface with a predetermined interval. At the same time, a concave portion 103 is formed on the other side of the wide wall surface so as to have the same center line as the screw hole 102.

That is, the ridge waveguide 20 has a screw hole 2
1a and 21b are sandwiched between the ridge portion and the first and second metal screw members 24a and 24b and 26a and 26b, and the PIN diode 23 sandwiched between the recessed portions 22a and 22b. The number of stages is set, and is represented by the equivalent circuit shown in FIG. That is, in FIG. 4, F1, F3, F
Reference numeral 5 is a wall portion formed by forming the screw holes 21a and 21b, and L10 is an inductance due to the metal column of the wall portion. L20 is a narrow wall surface of the ridge waveguide 20 (H
C10 is a capacitor due to the gap between the wide wall surface of the ridge waveguide and the remaining ridge portion, thereby forming a band elimination filter.

Further, in FIG. 4, F2 and F4 are screw holes 21a,
21b, the coaxial portion formed by the first and second metal screw members 24a, 24b and 26a, 26b and the PIN diode 23, L20 of which is the inductance due to the narrow wall surface of the ridge waveguide 20, and L30 and L31 are The inductances D1 and D2 due to the transmission line in the coaxial portion are PIN diodes 23.

In the above structure, the PIN diode 23
Operates as capacitive when the RF signal is small, so F
The overall characteristics of the filter of 1 to F5 at the fundamental frequency f0,
By defining L10, L20, L30, L31 and C10 so as to resonate in parallel, a low loss circuit is formed at f0. As a result, when the RF signal is small (during transmission), the PIN is
The diode is kept in the OFF state (connection state), passes the fundamental wave frequency component with low loss, and operates as a band elimination filter that blocks a band equal to or higher than a predetermined frequency with high insertion loss.
Then, in this band-stop filter, when the RF signal has a large power and the PIN diode 23 is switched to the ON state (during separation), the cutoff frequency becomes equal to or lower than the fundamental wave frequency, and the cutoff is performed including the fundamental wave frequency.

That is, when the frequency characteristics of the pass coefficient are measured, the insertion loss with respect to the frequency when the RF signal is small and at the time of low input (transmission) becomes the minimum at the fundamental wave frequency f0 as shown in FIG. As the bandwidth increases,
It has been confirmed that the loss increases and exhibits the desired band-stop filter characteristics.

Further, as shown in FIG. 5B, the loss with respect to the frequency when the RF signal is at a high input (at the time of separation) increases up to the frequency band including the fundamental frequency f0, and when the input is excessive, the loss is It serves to protect the receiving module 5 (see FIG. 7).

As described above, the diode limiter is
A screw hole 21a, 21b forming one coaxial outer conductor of the wide wall surface on which the ridge portion is formed is provided, and a recess 22 having the same center line as the screw holes 21a, 21b is provided on the other of the wide wall surface.
The ridge waveguide 20 provided with a and 22b is provided, and the second metal screw members 26a and 26b forming the coaxial inner conductor are loosely inserted into the screw holes 21a and 21b of the ridge waveguide 20, respectively. The PIN diode 23 is sandwiched between the second metal screw members 26a, 26b and the recesses 22a, 22b of the ridge waveguide 20. When the RF signal is small (during transmission), the PIN diode 23 is turned off. When the RF signal is large (when separated), the PIN diode 23 is in the ON state, which is maintained and operates as a band-stop filter that passes the fundamental frequency component with low loss and blocks a predetermined band or more with high insertion loss. By switching to, the cutoff frequency becomes equal to or lower than the fundamental wave frequency, and the cutoff is performed including the fundamental wave frequency. According to this, for example, as described above, the recess 22 is formed via the first and second metal screw members 24a, 24b and 26a, 26b.
Since a filter structure having five stages is formed by the PIN diode 23 sandwiched between a and 22b, compared with the conventional comb-tooth waveguide, Since the number of stages can be increased without increasing the size, the performance can be promoted as much as possible. Also,
According to this, since the ridge waveguide 20 can be manufactured by, for example, a drawing technique or a die casting technique without separately forming the ridge waveguide 20 as described above, the assembling work can be simplified and the assembling accuracy can be easily improved. It has the effect of being able to achieve it.

Further, the present invention is not limited to the above-mentioned embodiment, and for example, the double-ridge type ridge waveguide 3 shown in FIG.
It is also possible to configure using 0. In this case,
Screw holes 31a and 31b are formed in one ridge portion 30a of the wide wall surface of the ridge waveguide 30, and the other ridge portion 30b of the wide wall surface is trimmed with the same diameter as the screw holes 31a and 31b to match the wide wall surface. The recesses 32a, 3
2b is formed so as to have the same center line as the screw holes 31a, 31b, and similarly the PIN diode 23 uses the first and second metal screw members 24a, 24b and 26a, 26b to form the recesses 32a, 32b. It is sandwiched between them. Therefore, the present invention is not limited to the above embodiment,
It goes without saying that various modifications can be made without departing from the scope of the invention.

[0022]

As described above in detail, according to the present invention, the diode limiter has a simplified structure, simplifies the assembling work, achieves high precision, and promotes miniaturization. Can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a diode limiter according to an embodiment of the present invention.

2A to 2D are views for explaining a manufacturing process of the ridge waveguide of FIG.

3A to 3D are views for explaining a manufacturing process of the ridge waveguide of FIG.

FIG. 4 is a diagram showing an equivalent circuit of FIG.

5 is a diagram showing frequency characteristics of the pass coefficient of FIG.

FIG. 6 is a diagram showing another embodiment of the present invention.

FIG. 7 is a diagram showing a pulse radar to which the present invention is applied.

FIG. 8 is a diagram showing a conventional diode limiter.

FIG. 9 is a diagram shown for explaining the conventional problem of FIG. 8;

10 is a diagram showing an equivalent circuit of FIG.

11 is a diagram showing an equivalent circuit of FIG.

[Explanation of symbols]

20, 30 ... Ridge waveguide, 20a, 30a, 30b ...
Ridge portion, 21a, 21b, 31a, 31b ... Screw hole,
22a, 22b, 32a. 32b ... recessed portion, 23 ... PIN
Diodes, 24a, 24b ... First metal member, 25
a, 25b ... screw holes, 26a, 26b ... second metal screw members.

Claims (3)

[Claims] 1. A recess having a screw hole for forming a coaxial outer conductor is provided in a ridge portion provided on one of the wide wall surfaces of the substantially rectangular opening, and a recess having the same center line as the screw hole on the other of the wide wall surfaces. Of the ridge waveguide, a first metal screw member screwed into the screw hole of the ridge waveguide and provided with a screw hole facing the recess, A PIN diode in which one electrode is inserted into and connected to the recess and the other electrode is arranged to face the screw hole of the first metal screw member, and screw adjustment is possible in the screw hole of the first metal screw member. A second metal screw member that is screwed to the end of the ridge waveguide and that is loosely inserted into the screw hole of the ridge waveguide to form a coaxial inner conductor connected to the other electrode of the PIN diode inserted into the recess. A diode limiter comprising: 2. The diode limiter according to claim 1, wherein the ridge waveguide is a single ridge waveguide. 3. The diode limiter according to claim 1, wherein the ridge waveguide is a double ridge waveguide.