JPH09148808A - Input structure of lnb - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an input structure in which the leakage of electromagnetic waves and loss is low even if the contact of the ground surface around a pickup probe and a casing is insufficient. SOLUTION: On the casing having a waveguide input part, a circuit board 2 exists, and an input radio wave signal is fetched into the circuit board 2 and is received by the pickup probe 1 protected by an insulated body 1b through the casing from the circuit board 2. in the outer peripheral part of the pickup probe part 1 under the circuit board 2 of the casing, a cylindrical recessed part 5 is formed. The value L1 that the radius of the opening of the casing is subtracted from the radius of the cylindrical recessed part 5 is made the half of the wavelength λg in the line of input radio waves and the depth D of the cylindrical recessed part 5 is made smaller than the wavelength λg in the line. The equivalent circuit at the surrounding part becomes (B) and the input impedance viewing the outer peripheral part b point of the cylindrical recessed part 5 from the outer peripheral part a point of the opening part of the casing becomes equal to λg/2 line of tip short circuit and becomes a short circuit state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reduces the loss of conversion between the coaxial mode and the waveguide mode of an LNB having a waveguide input or feed horn input structure, which is used in the input section of a BS / CS antenna. It relates to the input structure of the LNB.

[0002]

2. Description of the Related Art FIGS. 3A and 3B are a front view and a side sectional view of an example of an input structure of an LNB. Conventional LNB
The basic structure of the input unit is a housing 33 having a waveguide input unit 34, a circuit board 32, a pickup probe 31 for coaxial-waveguide mode conversion, and a cylindrical insulator covering the tip of the probe 31. It is composed of a jacket 31b and a shield case (not shown) for preventing the emission of electromagnetic waves from the circuit board 32, and the radio wave incident from the waveguide input section 34 is taken into the circuit board 32 by the probe 31.
In such a structure, the back surface conductor pattern of the circuit board 33 around the pickup probe needs to be completely adhered to the housing 33 as a ground surface, and if a slight gap is generated, a part of the input signal is input from that portion. Leaks out and becomes a loss, which causes deterioration of the noise figure of the LNB. However, in order to improve the contact of this portion, it is necessary to take measures such as screwing around the pickup of the circuit board or pressing it with a shield case. However, there was a problem that it was difficult to apply this measure.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is a low-loss LNB that does not worry about electromagnetic wave leakage even if the contact between the ground surface around the pickup probe and the housing is insufficient. To provide an input structure for.

[0004]

[MEANS FOR SOLVING THE PROBLEMS] A housing having a waveguide input section or a feed horn input section and a pickup means for an input radio wave signal are provided, and a radio wave input from the waveguide input section or the feed horn input section is provided. In an LNB (low noise block down converter) that takes in a signal to a circuit board, a choke structure is provided at the contact portion between the pickup means and the casing to reduce the loss at the input portion.

The choke structure provided at the contact portion between the pickup means and the housing is a cylindrical recess centered on the center of the pickup means formed between the housing and the circuit board.

The value obtained by subtracting the radius of the opening for the pick-up means of the housing from the radius of the cylindrical shape is half the wavelength in the line of the input radio wave signal, and the depth of the cylindrical shape is the input radio wave. One-tenth to one-hundredth of the wavelength of the signal in the line
And the wavelength is sufficiently smaller than the wavelength in the line.

The choke structure provided at the contact portion between the pickup means and the casing has a cylindrical recess formed around the center of the pickup means formed between the casing and the circuit board and a cylindrical shape formed on the outer periphery of the same cylindrical shape. To be a concave part.

The value obtained by subtracting the radius of the opening for the pickup means of the casing from the cylindrical radius and the depth from the surface of the cylindrical circuit board are set to 1/4 of the in-line wavelength of the input radio signal. In addition, the depth of the cylindrical shape and the thickness of the cylindrical shape are sufficiently smaller than the wavelength of the input radio signal.

The pickup means is a pickup probe inserted from the circuit board into the waveguide input section of the housing, a pattern formed on the circuit board, a slot antenna feeding through the transmission line, a patch antenna feeding through the transmission line, or feeding through the slot. Use as a patch antenna.

[0010]

[Function] A housing having a waveguide input section or a feed horn input section and a pickup means for input radio signal are provided,
In the LNB that takes in the radio signal input from the same waveguide input section or feed horn input section to the circuit board,
By providing the choke structure at the contact portion between the pickup means and the casing, the ground plane of the circuit board around the pickup can be effectively short-circuited to the casing, and the loss of the input portion can be reduced.

The choke structure provided at the contact portion between the pick-up means and the housing is a cylindrical structure centered on the center of the pick-up means formed between the housing and the circuit board. The purpose can be achieved.

The radius obtained by subtracting the opening for the pickup means of the cylindrical casing is one half of the wavelength in the line of the input radio signal, and the depth of the column is the line of the input radio signal. By making the structure sufficiently smaller than the internal wavelength, the ground plane in the peripheral portion of the pickup means is effectively short-circuited with the housing.

The choke structure provided at the contact portion between the pickup means and the casing has a cylindrical recess formed around the center of the pickup means formed between the casing and the circuit board and a cylindrical shape formed on the outer periphery of the same cylindrical shape. By forming the concave portion, the adhesion between the ground surface of the circuit board and the housing is not required even in the outer peripheral portion of the cylindrical concave portion.

The radius from which the opening for the pick-up means of the cylindrical housing is subtracted and the depth from the surface of the cylindrical circuit board are set to ¼ of the in-line wavelength of the input radio signal, and the cylindrical shape. By making the depth of the shape and the thickness of the cylindrical tube sufficiently smaller than the wavelength of the input radio signal, the ground plane in the peripheral portion of the pickup means is effectively short-circuited with the housing.

The pickup means is a pickup probe inserted from the circuit board into the waveguide input section of the housing, a pattern formed on the circuit board, a slot antenna feeding through the transmission line, a patch antenna feeding through the transmission line, or feeding through the slot. By using one of the patch antennas,
A pickup means that can realize the above-mentioned low loss input can be obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The LNB input structure according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a side sectional view of a peripheral portion of a pickup probe (A) of an embodiment of an LNB input structure according to the present invention, and (B) an equivalent circuit thereof. There is a circuit board 2 on a housing 3 made of a conductor having a waveguide input part similar to that shown in FIG.
The pickup probe 1 protected by the insulator 1b is inserted therethrough to convert the input radio wave signal from the waveguide input section from the waveguide mode to the coaxial mode and take it into the circuit board 2 to receive the input radio wave. A cylindrical recess 5 is formed on the outer peripheral portion of the pickup probe 1 below the circuit board 2 of the housing 3. A value L1 obtained by subtracting the radius of the insulator 1b, which is the opening of the housing for the pickup probe of the housing, from the radius of the cylindrical shape 5 is 2 of the wavelength λg in the line of the input radio wave.
It is one-third. The depth D of the cylindrical recess 5 is about 1/10 to 1/100 of the in-line wavelength λg, which is sufficiently smaller than λg. At this time, the equivalent circuit around the pickup probe is as shown in FIG.
The input impedance from the outer peripheral portion a point of the opening of the housing for the pickup probe of the cylindrical concave portion 5 to the outer peripheral portion b point of the cylindrical concave portion 5 becomes equal to the tip short-circuited λg / 2 line and short-circuited. It becomes a state.

FIG. 2 is a side sectional view of a peripheral portion of a pickup probe of another embodiment of the input structure of the LNB according to the present invention, and (B) an equivalent circuit thereof. Similar to the above, FIG.
There is a circuit board 22 on a housing 23 made of a conductor having a waveguide input part similar to that shown in FIG. 2, and the pickup probe 21 protected by an insulator 21b is inserted from the circuit board 22 through the housing 23. The input radio wave signal from the waveguide input section is converted from the waveguide mode to the coaxial mode and taken into the circuit board 22 to receive the input radio wave. A cylindrical concave portion 25 is formed on the outer peripheral portion of the pickup probe 21 below the circuit board 22 of the housing 23, and a cylindrical concave portion 26 is formed on the outer peripheral portion of the cylindrical concave portion 25. A value L2 obtained by subtracting the radius of the insulator 21b, which is the opening of the housing for the pickup probe of the housing, from the radius of the cylindrical shape 25 is assumed to be a quarter of the in-line wavelength λg of the input radio wave. Further, the depth L3 of the cylindrical shape 26 is also set to be a quarter of the in-line wavelength λg of the input radio wave. Further, the depth D of the cylindrical recess 25 and the thickness D of the cylinder of the cylindrical shape 26 are 10 of the in-line wavelength λg.
It is assumed to be 1/100 to 1/100, which is sufficiently smaller than λg. At this time, the equivalent circuit of the peripheral portion of the pickup probe is as shown in FIG. 7B, and the point e from the outer peripheral portion c of the opening of the housing for the pickup probe of the cylindrical concave portion 25 to the bottom point e of the cylindrical concave portion 26. The input impedance seen is equal to the λg / 2 line of which the tip is short-circuited, and the short-circuited state occurs. However, since the point d on the outer peripheral portion of the cylindrical portion 25 corresponds to the node of the current, even if the contact between the substrate 22 and the housing 23 is insufficient at this point, it does not affect the above operation.

4 (A) is a front view and FIG. 4 (B) is a side sectional view of another embodiment of the LNB input structure according to the present invention.
A circuit board 42 is provided behind a housing 43 having a feed horn input section 44, and a circuit for input radio signals input to the feed horn input section 44 by the pickup means 41 through an opening 44b of the housing 43 for the pickup means. It is received on the substrate 42 by being received.

FIG. 5 is a side sectional view (A) and a rear view (B) of a main part of an embodiment using a pattern formed on a circuit board as the pickup means 41. The pattern 51 formed on the circuit board 52 arranged on the back surface of the housing 53 passes through the opening 54b for the pickup means of the housing 53 having the feed horn input portion, and the input radio signal input to the feed horn is fed to the circuit board 52. And receive it. Behind the pattern 51, the short surface 5
7 is arranged. On the surface of the housing 53 that contacts the circuit board 52, a cylindrical recess 55 is formed, as in the above case.
A value L1 obtained by subtracting the radius of the opening 54b from the radius of the cylindrical shape 55 is set to one half of the in-line wavelength λg of the input radio wave.

FIG. 6 is a side sectional view (A) and a rear view (B) of a main part of an embodiment using a slot antenna feeding by a transmission line as the pickup means 41. Input to the feed horn through a slot 61 and a transmission line 61a formed on a ground surface of a circuit board 62 arranged on the back surface of the housing 63 through an opening 64b for a pickup means of the housing 63 having a feed horn input portion. The input radio wave signal is received by the circuit board 62. Case 6
On the surface of the No. 3 contacting the circuit board 62, a cylindrical recess 65 is formed as in the above. A value L1 obtained by subtracting the radius of the opening 64b from the radius of the cylindrical shape 65 is set to half of the in-line wavelength λg of the input radio wave.

FIG. 7 is a side sectional view (A) and a rear view (B) of the main part of an embodiment using a patch antenna fed by a transmission line as the pickup means 41. Input to the feed horn is made through a patch 71 and a transmission line 71a formed on the ground surface of a circuit board 72 arranged on the back surface of the housing 73 through an opening 74b for a pickup means of the housing 73 having a feed horn input portion. The input radio signal is received by the circuit board 72. A cylindrical recess 75 is formed on the surface of the casing 73 that contacts the circuit board 72, as described above. From the radius of the cylindrical shape 75 to the opening 7
The value L1 obtained by subtracting the radius of 4b is one half of the in-line wavelength λg of the input radio wave.

FIG. 8 is a side sectional view (A) and a rear view (B) of a main part of an embodiment using a patch antenna feeding a slot as the pickup means 41. A patch 81 formed on an insulating plate 81c placed on a ground surface of a circuit board 82 arranged on the back surface of the housing 83 and a slot of the ground surface through an opening 84b for a pickup means of the housing 83 having a feed horn input portion. The input radio signal input to the feed horn is received by the circuit board 82 by 81b and the transmission line 81a. A cylindrical recess 85 is formed on the surface of the housing 83 that contacts the circuit board 82, as in the above case. From the radius of the cylindrical shape 85 to the opening 84
The value L1 obtained by subtracting the radius of b is set to one half of the in-line wavelength λg of the input radio wave.

In the above embodiments, the combination of the waveguide input section, the Ford horn input section, the pickup means, the choke structure, etc. is limitedly described, but the present invention is not limited to this, and other combinations between them. Needless to say, it is possible in the same manner as above. Further, in the above-mentioned embodiment, the explanation was made on the assumption that the input radio wave is received, but the present invention is not limited to reception but can be similarly applied to the case of transmission. In addition, the radio waves handled may be circularly polarized waves or linearly polarized waves.

[0024]

As described above, at the contact portion between the pickup means for taking the radio signal input from the waveguide input section or the feed horn input section into the circuit board and the waveguide or the feed horn housing. By providing the choke structure, loss due to leakage of electromagnetic waves from the coaxial-waveguide conversion unit can be eliminated, and deterioration of the noise figure of the LNB can be prevented.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a pickup probe peripheral portion of an embodiment of an input structure of an LNB according to the present invention;
(B) The equivalent circuit.

FIG. 2 is a side sectional view of (A) a pickup probe peripheral portion of another embodiment of the LNB input structure according to the present invention;
(B) The equivalent circuit.

FIG. 3A is a front view of an example of an input structure of an LNB,
(B) It is a side sectional view.

4 (A) is a front view and FIG. 4 (B) is a side sectional view of another embodiment of the LNB input structure according to the present invention.

FIG. 5 is a side sectional view (A) of a main part of an embodiment using a pattern formed on a circuit board as a pickup means,
(B) It is a rear view.

FIG. 6 is a side sectional view (A) and a rear view (B) of a main part of an embodiment in which a slot antenna that feeds by a transmission line is used as a pickup means.

7 (A) is a side sectional view and FIG. 7 (B) is a rear view of a main part of an embodiment using a patch antenna fed by a transmission line as a pickup means.

FIG. 8 is a side sectional view (A) and a rear view (B) of a main part of an embodiment using a patch antenna that feeds power through a slot as the pickup means.

[Explanation of symbols]

 1 Pick-up probe 1b Insulator 2 Circuit board 3 Case 5 Cylindrical recess 21 Pick-up probe 21b Insulator 22 Circuit board 23 Casing 25 Cylindrical recess 26 Cylindrical recess 31 Pick-up probe 31b Insulator 32 Circuit board 33 Casing Body 34 Waveguide input section 41 Pickup means 42 Circuit board 43 Housing 44 Feed horn input section 51 Pattern 52 Circuit board 53 Housing 54b Housing opening 55 Cylindrical recess 57 Short surface 61 Slot 61b Transmission line 62 Circuit board 63 housing 64b housing opening 65 cylindrical recess 71 patch 71a transmission line 72 circuit board 73 housing 74b housing opening 75 cylindrical recess 81 patch 81a transmission line 81b slot 81c insulating plate 82 circuit board 83 housing 84b housing opening 8 The recess of the cylindrical

Claims (10)

[Claims] 1. A circuit board comprising: a housing having a waveguide input section or a feed horn input section; and an input radio wave signal pickup means, and a radio wave signal inputted from the waveguide input section or the feed horn input section. In the LNB (low noise block down converter) to be taken into, the input structure of the LNB is characterized by reducing the loss of the input part by providing a choke structure at the contact part between the pickup means and the casing. 2. The choke structure provided at the contact portion between the pickup means and the housing is a cylindrical recess centered on the center of the pickup means formed between the housing and the circuit board. Input structure of the described LNB. 3. A value obtained by subtracting the radius of the opening for the pick-up means of the housing from the radius of the cylindrical shape is one half of the in-line wavelength of the input radio signal and the depth of the cylindrical shape. Is 1/10 to 10 of the wavelength of the input radio signal in the line
The L according to claim 2, which is about 1/0.
Input structure of NB. 4. The choke structure provided at the contact portion between the pickup means and the casing is formed in a cylindrical concave portion centered on the center of the pickup means formed between the casing and the circuit board and in the same cylindrical outer peripheral portion. The LNB input structure according to claim 1, wherein the input structure is a cylindrical recess. 5. The value obtained by subtracting the radius of the opening for the pick-up means of the casing from the radius of the cylindrical shape and the depth from the surface of the cylindrical circuit board are 4 minutes of the in-line wavelength of the input radio signal. 3. The LNB according to claim 2, wherein the depth of the cylindrical shape and the thickness of the cylindrical shape are about 1/10 to 1/100 of the wavelength of the input radio signal. Input structure. 6. The pickup probe as claimed in claim 1, wherein the pickup means is a pickup probe inserted from a circuit board into a waveguide input portion of a housing. The input structure of LNB described in 5. 7. The LNB input structure according to claim 1, 2, 3, 4, or 5, wherein the pickup means is a pattern formed on a circuit board. 8. The pick-up means is a slot antenna fed by a transmission line.
LN according to claim 2, claim 3, claim 4 or claim 5
Input structure of B. 9. The LNB according to claim 1, claim 2, claim 3, claim 4, or claim 5, wherein the pickup means is a patch antenna that is fed by a transmission line.
Input structure. 10. The pick-up means is a patch antenna that feeds power through a slot.
LN according to claim 2, claim 3, claim 4 or claim 5
Input structure of B.