JP7424813B2 - Primary radiator for antenna - Google Patents

Description

The present disclosure relates to a primary radiator for an antenna having an airtight structure and a waterproof structure.

A primary radiator for an antenna having an airtight structure and a waterproof structure is applied to a radar, satellite communication, or microwave line antenna having a horn or a reflector (see Patent Document 1, etc.).

A perspective exploded view and a side sectional view of a prior art primary radiator for an antenna are shown in FIGS. 1 and 2. A prior art primary radiator P for an antenna includes a circular waveguide 1, a cap 2, and a covering member 3.

The circular waveguide 1 has an outer diameter screw 11 cut on the outer periphery of the radiation opening which is the tip portion , and has a choke structure 12 on the outer periphery of the radiation opening. The cap 2 has an inner diameter thread 21 cut on the inner periphery of the insertion opening into which the circular waveguide 1 is inserted, and an end face inside the regulation opening 22 (on the circular waveguide 1 side) that regulates the insertion of the circular waveguide 1. The inner diameter thread 21 is cut until the end. When the circular waveguide 1 is inserted into the cap 2, the outer thread 11 of the circular waveguide 1 is threaded with the inner thread 21 of the cap 2. The covering member 3 is sandwiched between the radiation opening of the circular waveguide 1 and the regulation opening 22 of the cap 2, and covers the hollow region within the radiation opening of the circular waveguide 1 from the outside.

In this manner, in the antenna primary radiator P of the prior art, the degree of freedom in designing the circular waveguide 1 is increased, and the airtight reliability and waterproof reliability of the circular waveguide 1 can be increased.

Japanese Patent Application Publication No. 2009-267672

Here, in the primary antenna radiator P of the prior art, the cap 2 is threaded with an internal thread 21 up to the inner end surface of the regulation opening 22 that regulates the insertion of the circular waveguide 1 . This is because, in the conventional primary antenna radiator P, when processing the internal thread 21 of the cap 2, it is possible to use a specially shaped internal thread cutting tool that can perform thread processing up to the inner end surface of the regulation opening 22. be. However, since the above-mentioned special inner diameter thread cutting tool needs to be specially manufactured according to the shape of the circular waveguide 1 to be processed, there is a problem that the processing cost increases. Therefore, since a general primary radiator P for an antenna uses a general-shaped internal thread cutting tool, the cap 2 has an internal thread 21 cut to the inner end surface of the regulation opening 22 that regulates the insertion of the circular waveguide 1. I can't.

FIG. 3 shows a method for manufacturing a cap of a comparative example. This is an example of using a general-shaped internal thread cutting tool. The internal thread cutting tool 5 has an internal thread cutting section on the front side of the tip of the cutting tool. Therefore, when the tip of the internal thread cutting tool 5 comes into contact with the regulation opening 22 of the cap 2, the internal thread cutting tool 5 will cut the internal thread 21 of the cap 2 up to the inner end surface of the regulation opening 22 of the cap 2 at the internal thread cutting part. I can't cut it. However, if nothing is applied to the inner circumference of the cap 2 up to the inner end surface of the restriction opening 22 that restricts the insertion of the circular waveguide 1, the circular waveguide 1 will be inserted up to the restriction opening 22 of the cap 2. I can't. On the other hand, if the cap 2 is cut with the nip 23 of the inner diameter screw 21 near the inner end surface of the restriction opening 22 that restricts the insertion of the circular waveguide 1, the circular waveguide 1 will be inserted into the restriction opening 22 of the cap 2. can be inserted up to

An exploded perspective view and a side sectional view of a primary radiator for an antenna according to a comparative example are shown in FIGS. 4 and 5. A primary radiator P for an antenna according to a comparative example includes a circular waveguide 1, a cap 2, and a covering member 3. In the following, in comparison with the prior art, points of agreement will be omitted and differences will be explained.

The cap 2 has an inner diameter thread 21 cut on the inner periphery of the insertion opening into which the circular waveguide 1 is inserted, but the inner diameter thread 21 is cut up to the inner end surface of the regulation opening 22 that regulates the insertion of the circular waveguide 1. Since it is not possible to do so, a nip 23 of the internal thread 21 is cut near the inner end surface of the restriction opening 22 that restricts the insertion of the circular waveguide 1. The length of the nip 23 of the internal thread 21 of the cap 2 needs to be 1.5 to 2 pitches or more of the internal thread 21 of the cap 2, which is not a problem at low frequencies, but can be a problem at high frequencies.

FIG. 6 shows the cross-polarization level of the primary antenna radiator of the comparative example. The diameter φD of the inner circumference of the circular waveguide 1 is 0.829λ, and the thickness t of the covering member 3 (Teflon glass fiber sheet) is , 0.012λ.

Here, although the outer diameter thread 11 of the circular waveguide 1 located within the nip 23 of the inner diameter thread 21 of the cap 2 provides non-axis symmetry to the circular waveguide 1, in calculating the cross polarization level, The complicated structure of the outer diameter thread 11 of the circular waveguide 1 was not reflected in the calculation, and a simple structure of the elliptical cross section of the circular waveguide 1 was assumed in the calculation.

Then, as the length L of the nip 23 of the internal thread 21 of the cap 2 increased from about 0λ to 0.1λ, the cross polarization level increased from about -45 dB to about -17 dB. On the other hand, as the length L of the nip 23 of the internal thread 21 of the cap 2 increased from 0.1λ to 0.15λ, the cross polarization level decreased from about -17 dB to about -45 dB. As the length L of the nip 23 of the internal thread 21 of the cap 2 increases, the cross-polarization level repeatedly rises and falls. In particular, when the length L of the nip 23 of the internal thread 21 of the cap 2 was 0.1λ, the cross polarization level did not meet the target specification of −35 dB or less.

FIG. 7 shows the E-plane directivity and H-plane directivity of the primary antenna radiator of the comparative example. The diameter φD of the inner circumference of the circular waveguide 1 is 0.829λ, and the thickness t of the covering member 3 (Teflon glass fiber sheet) is , 0.012λ, the length L of the nip 23 of the internal thread 21 of the cap 2 is 0.1λ, and the width W of the nip 23 of the internal thread 21 of the cap 2 is 0.0167λ. Here, the E-plane directivity and H-plane directivity of the main polarized wave and the cross-polarized wave are calculated in FIG. 7 using the same assumptions as in FIG. 6.

Then, the E-plane directivity of the main polarization caused a beam tilt from the front direction. The cross-polarized E-plane directivity met the target specification of -35 dB or less. On the other hand, the H-plane directivity of the main polarization did not cause beam tilt from the front direction. The H-plane directivity of cross-polarized waves did not meet the target specification of −35 dB or less. The reason for this will be explained in FIGS. 8 and 9.

FIG. 8 shows the effective inner circumferential diameter φD' of the circular waveguide of the primary radiator for an antenna of the comparative example. The electromagnetic waves propagating through the circular waveguide 1 enter the nip 23 of the internal thread 21 of the cap 2 via the covering member 3 in the vicinity of the radiation opening of the circular waveguide 1 . Therefore, the effective diameter φD' of the inner circumference of the circular waveguide 1 is the diameter φD of the inner circumference of the circular waveguide 1, the thickness T of the circular waveguide 1, the width W of the nip 23, and the width W of the nip 23. Using the length L, it becomes φD+2(T+W+L), which is larger than the diameter φD of the inner circumference of the circular waveguide 1.

FIG. 9 shows the generation mode of a circular waveguide of a primary radiator for an antenna in a comparative example. The effective diameter φD' of the inner circumference of the circular waveguide 1 is larger than the diameter φD of the inner circumference of the circular waveguide 1. The outer diameter thread 11 of the circular waveguide 1 provides non-axial symmetry to the circular waveguide 1. Therefore, the TE11 basic mode occurs and the TM01 higher mode occurs. Here, in the TE11 fundamental mode, electric lines of force run approximately in the y-axis direction within the cross section of the circular waveguide 1, and magnetic lines of force run approximately in the x-axis direction within the cross section of the circular waveguide 1. On the other hand, in the TM01 higher-order mode, lines of electric force run in the radial direction within the cross section of the circular waveguide 1, and lines of magnetic force run in the azimuth direction within the cross section of the circular waveguide 1.

Then, the TM01 higher-order mode is superimposed on the TE11 basic mode. Therefore, the directivity of the main polarized wave in the E plane (yz plane) causes a beam tilt from the front direction. On the other hand, the H-plane (xz-plane) directivity of cross-polarized waves does not fall below the target specification.

Therefore, in order to solve the above problems, the present disclosure provides a primary radiator for an antenna having an airtight structure and a waterproof structure, in which an inner diameter screw is provided near the inner end surface of a regulating opening of a cap that regulates the insertion of a circular waveguide. The objective is for the E-plane directivity of the main polarized wave to not cause beam tilt from the front direction even when the polarization is turned off, and for the H-plane directivity of the cross-polarized wave to be below the target specification.

In order to solve the above problem, a ring-shaped shielding member is disposed between the cap's inner diameter thread and the covering member, and the ring-shaped shielding member is arranged between the inner diameter thread of the cap and the covering member to prevent the inner diameter of the cap from blocking the hollow region within the radiation aperture of the circular waveguide. Made it shield against screw damage. Then, the effective diameter of the inner circumference of the circular waveguide becomes smaller by the amount that the inner diameter screw of the cap is shielded, and becomes close to the diameter of the inner circumference of the circular waveguide. Although the TE11 basic mode occurs, the TM01 higher-order mode hardly occurs.

Specifically, the present disclosure provides a circular waveguide having an outer diameter thread cut on the outer periphery of a radiation aperture that is a tip portion , and an inner diameter thread cut on the inner periphery of an insertion opening into which the circular waveguide is inserted. a cap having an inner diameter thread cut near an inner end surface of a regulating opening that regulates insertion of the circular waveguide; and a cap between the radiation opening of the circular waveguide and the regulating opening of the cap. a covering member that is sandwiched between the circular waveguide and covers the hollow region in the radiation opening of the circular waveguide to the outside; The primary radiator for an antenna is characterized in that it is provided with a ring-shaped shielding member that shields from the damage of the inner diameter screw of the cap without blocking the hollow region in the radiation opening of the wave tube.

According to this configuration, even when the inner diameter screw is cut near the inner end surface of the regulating opening of the cap that regulates the insertion of the circular waveguide, the E-plane directivity of the main polarized wave causes a beam tilt from the front direction. This allows the H-plane directivity of cross-polarized waves to fall below the target specifications.

Further, in the present disclosure, the shielding member is sandwiched between the radiation opening of the circular waveguide and the covering member, and the radius of the inner circumference of the shielding member is such that the radiation opening of the circular waveguide is The radius of the inner circumference of the shielding member is equal to or larger than the radius of the inner circumference of the shielding member, and the radius of the outer circumference of the shielding member is equal to the radius of the outer circumference of the inner diameter screw of the cap.

According to this configuration, the shielding member can be stably held between the radiation opening of the circular waveguide and the covering member. Even when the inner diameter screw is cut near the inner end surface of the regulating opening of the cap that regulates the insertion of the circular waveguide, the E-plane directivity of the main polarization ensures that beam tilt does not occur from the front direction. , it is possible to ensure that the H-plane directivity of cross-polarized waves is below the target specification.

Further, in the present disclosure, the shielding member is sandwiched between the radiation opening of the circular waveguide and the covering member, and the radius of the inner circumference of the shielding member is such that the radiation opening of the circular waveguide is The width of the gap between the outer periphery of the shielding member and the outer periphery of the inner diameter screw of the cap, when viewed from the extending direction of the circular waveguide, is equal to or larger than the radius of the inner periphery of the cap. This is a primary radiator for an antenna, characterized in that the width is 20% or less of the width of the inner diameter screw.

According to this configuration, the shielding member can be stably held between the radiation opening of the circular waveguide and the covering member. Even if the outer periphery of the shielding member and the outer periphery of the inner thread of the cap are not in complete electrical contact, the E-plane directivity of the main polarization almost certainly does not cause beam tilt from the front direction. The H-plane directivity of cross-polarized waves can almost certainly be below the target specification.

As described above, the present disclosure provides a primary radiator for an antenna having an airtight structure and a waterproof structure, even when an inner diameter screw is cut near the inner end surface of a regulating opening of a cap that regulates the insertion of a circular waveguide. The E-plane directivity of the main polarized wave does not cause beam tilt from the front direction, and the H-plane directivity of the cross-polarized wave can be below the target specification.

1 is a diagram showing a perspective exploded view of a prior art primary radiator for an antenna; FIG. 1 is a diagram showing a side cross-sectional view of a prior art primary radiator for an antenna; FIG. It is a figure which shows the manufacturing method of the cap of a comparative example and this disclosure. It is a figure which shows the perspective exploded view of the primary radiator for antennas of a comparative example. It is a figure which shows the side sectional view of the primary radiator for antennas of a comparative example. It is a figure which shows the cross polarization level of the primary radiator for antennas of a comparative example. It is a figure which shows the E plane directivity and H plane directivity of the primary radiator for antennas of a comparative example. FIG. 7 is a diagram showing the effective inner circumference diameter of a circular waveguide of a primary radiator for an antenna according to a comparative example. FIG. 7 is a diagram showing a generation mode of a circular waveguide of a primary radiator for an antenna according to a comparative example. 1 is a diagram showing a perspective exploded view of a primary radiator for an antenna of the present disclosure. FIG. FIG. 2 is a diagram illustrating a side cross-sectional view of a primary radiator for an antenna according to the present disclosure. FIG. 3 is a diagram illustrating cross-polarization levels of a primary radiator for an antenna of the present disclosure. It is a figure showing E plane directivity and H plane directivity of the primary radiator for antennas of this indication. FIG. 3 is a diagram showing the effective inner circumference diameter of a circular waveguide of a primary radiator for an antenna according to the present disclosure. FIG. 3 is a diagram illustrating a generation mode of a circular waveguide of a primary radiator for an antenna according to the present disclosure. FIG. 2 is a diagram illustrating a side cross-sectional view of a primary radiator for an antenna according to the present disclosure. It is a figure showing E plane directivity and H plane directivity of the primary radiator for antennas of this indication. It is a figure which shows the side sectional view of the primary radiator for antennas of a modification. It is a figure which shows the side sectional view of the primary radiator for antennas of a modification.

Embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of implementation of the present disclosure, and the present disclosure is not limited to the following embodiments.

A perspective exploded view and a side sectional view of the primary radiator for an antenna of the present disclosure are shown in FIGS. 10 and 11. A primary radiator P for an antenna according to the present disclosure includes a circular waveguide 1, a cap 2, a covering member 3, and a shielding member 4. In the following, in comparison with the prior art, points of agreement will be omitted and differences will be explained.

The cap 2 has an inner diameter thread 21 cut on the inner periphery of the insertion opening into which the circular waveguide 1 is inserted, but the inner diameter thread 21 is cut up to the inner end surface of the regulation opening 22 that regulates the insertion of the circular waveguide 1. Since it is not possible to do so, a nip 23 of the internal thread 21 is cut near the inner end surface of the restriction opening 22 that restricts the insertion of the circular waveguide 1. The length of the nip 23 of the internal thread 21 of the cap 2 needs to be 1.5 to 2 pitches or more of the internal thread 21 of the cap 2, which is not a problem at low frequencies, but can be a problem at high frequencies.

The shielding member 4 has a ring shape and is disposed between the nip 23 of the inner diameter thread 21 of the cap 2 and the covering member 3, and is configured to cover the cap 2 without blocking the hollow region within the radiation opening of the circular waveguide 1. It shields against the nip 23 of the inner diameter screw 21. For this purpose, the shielding member 4 is preferably made of metal, and its thickness is preferably equal to or greater than the skin thickness.

The shielding member 4 is then sandwiched between the radiation opening of the circular waveguide 1 and the covering member 3. Therefore, the shielding member 4 can be stably held. Note that the radius of the inner circumference of the shielding member 4 is equal to the radius of the inner circumference of the radiation opening of the circular waveguide 1. Further, the radius of the outer circumference of the shielding member 4 is equal to the radius of the outer circumference of the nip 23 of the inner diameter screw 21 of the cap 2. In other words, the width of the gap between the outer periphery of the shielding member 4 and the outer periphery of the nip 23 of the internal thread 21 of the cap 2 is equal to It is 0% of the width.

The cross-polarization level of the primary radiator for the antenna of the present disclosure is shown in FIG. For the wavelength λ used in the primary radiator P for an antenna according to the present disclosure, the diameter φD of the inner circumference of the circular waveguide 1 is 0.829λ, and the thickness t of the covering member 3 (Teflon glass fiber sheet) is , 0.012λ.

Here, although the outer diameter thread 11 of the circular waveguide 1 located within the nip 23 of the inner diameter thread 21 of the cap 2 provides non-axial symmetry to the circular waveguide 1, in calculating the cross polarization level, The complicated structure of the outer diameter screw 11 of the circular waveguide 1 was not reflected in the calculation, and a simple structure of the elliptical cross section of the circular waveguide 1 was assumed in the calculation.

The hollow region within the radiation opening of the circular waveguide 1 is shielded by the shielding member 4 from the nip 23 of the internal thread 21 of the cap 2 . Then, the length L of the nip 23 of the internal thread 21 of the cap 2 was substantially the same as the thickness t of the covering member 3, L = 0.012λ, and the cross polarization level was approximately −45 dB. That is, even if the length L of the nip 23 of the internal thread 21 of the cap 2 is increased compared to 0.012λ, it is substantially 0.012λ because it is shielded by the shielding member 4. In particular, even when the length L of the nip 23 of the internal thread 21 of the cap 2 was 0.1λ, the cross polarization level met the target specification of -35 dB or less.

FIG. 13 shows the E-plane directivity and H-plane directivity of the primary radiator for an antenna according to the present disclosure. For the wavelength λ used in the primary radiator P for an antenna according to the present disclosure, the diameter φD of the inner circumference of the circular waveguide 1 is 0.829λ, and the thickness t of the covering member 3 (Teflon glass fiber sheet) is , 0.012λ, the length L of the nip 23 of the internal thread 21 of the cap 2 is 0.1λ, the width W of the nip 23 of the internal thread 21 of the cap 2 is 0.0167λ, and the shielding member The thickness t' of No. 4 (aluminum ring) was 0.002λ. Here, the E-plane directivity and H-plane directivity of the main polarized wave and the cross-polarized wave are calculated in FIG. 13 using the same assumption as in FIG. 12.

Then, the E-plane directivity of the main polarization did not cause beam tilt from the front direction. The cross-polarized E-plane directivity met the target specification of -35 dB or less. On the other hand, the H-plane directivity of the main polarization did not cause beam tilt from the front direction. The H-plane directivity of the cross-polarized waves met the target specification of −35 dB or less (furthermore, in FIG. 13, the H-plane directivity of the cross-polarized waves was suppressed compared to FIG. 17). The reason for this will be explained in FIGS. 14 and 15.

FIG. 14 shows the effective inner diameter φD' of the circular waveguide of the primary radiator for an antenna according to the present disclosure. The electromagnetic waves propagating through the circular waveguide 1 do not enter the nip 23 of the internal thread 21 of the cap 2 due to the presence of the shielding member 4 in the vicinity of the radiation opening of the circular waveguide 1 . Therefore, the effective diameter φD' of the inner circumference of the circular waveguide 1 is determined by the diameter φD of the inner circumference of the circular waveguide 1, the thickness T of the circular waveguide 1, the width W of the nip 23, and the covering member 3. Using the thickness t, it becomes φD+2(T+W+t), which is close to the diameter φD of the inner circumference of the circular waveguide 1.

FIG. 15 shows the generation mode of the circular waveguide of the primary radiator for an antenna of the present disclosure. The effective diameter φD' of the inner circumference of the circular waveguide 1 is approximately equal to the diameter φD of the inner circumference of the circular waveguide 1. Therefore, although the TE11 basic mode occurs, only a small amount of the TM01 higher-order mode occurs. Here, in the TE11 fundamental mode, electric lines of force run approximately in the y-axis direction within the cross section of the circular waveguide 1, and magnetic lines of force run approximately in the x-axis direction within the cross section of the circular waveguide 1. On the other hand, in the TM01 higher-order mode, lines of electric force run in the radial direction within the cross section of the circular waveguide 1, and lines of magnetic force run in the azimuth direction within the cross section of the circular waveguide 1.

Even if the TM01 higher-order mode is superimposed on the TE11 fundamental mode, its influence is small. Therefore, the E plane (yz plane) directivity of the main polarized wave does not cause beam tilt from the front direction. On the other hand, the H-plane (xz-plane) directivity of cross-polarized waves is below the target specification.

In this way, even when the nip 23 of the internal thread 21 is cut near the inner end surface of the restriction opening 22 of the cap 2 that restricts the insertion of the circular waveguide 1, the E-plane directivity of the main polarized wave is ensured in the front direction. Therefore, the H-plane directivity of cross-polarized waves can be reliably kept below the target specification without causing beam tilt.

A side cross-sectional view of another primary radiator for an antenna according to the present disclosure is shown in FIG. Another primary radiator P for an antenna according to the present disclosure includes a circular waveguide 1, a cap 2, a covering member 3, and a shielding member 4. In the following, FIG. 16 will be compared with FIG. 11, and the points of agreement will be omitted and differences will be explained.

The shielding member 4 is sandwiched between the radiation aperture of the circular waveguide 1 and the covering member 3. Therefore, the shielding member 4 can be stably held. Note that the radius of the inner circumference of the shielding member 4 is equal to the radius of the inner circumference of the radiation opening of the circular waveguide 1. Furthermore, when viewed from the extending direction of the circular waveguide 1, the width of the gap between the outer periphery of the shielding member 4 and the outer periphery of the nip 23 of the internal thread 21 of the cap 2 is the width of the gap 23 of the internal thread 21 of the cap 2. It is 20% or less of the width. In other words, the radius of the outer circumference of the shielding member 4 is smaller than the radius of the outer circumference of the nip 23 of the internal thread 21 of the cap 2.

FIG. 17 shows the E-plane directivity and H-plane directivity of another primary radiator for an antenna according to the present disclosure. The diameter φD of the inner circumference of the circular waveguide 1 is 0.829λ, and the thickness of the covering member 3 (Teflon glass fiber sheet) is t is 0.012λ, the length L of the nip 23 of the internal thread 21 of the cap 2 is 0.1λ, the width W of the nip 23 of the internal thread 21 of the cap 2 is 0.0167λ, The thickness t' of the shielding member 4 (aluminum ring) is 0.002λ, and the width g of the gap between the outer periphery of the shielding member 4 and the outer periphery of the nip 23 of the internal thread 21 of the cap 2 is 0.0033λ. Met.

Here, since the width g of the gap is sufficiently small (g/W≦0.2), the electromagnetic waves propagating through the circular waveguide 1 are prevented by the presence of the shielding member 4 in the vicinity of the radiation aperture of the circular waveguide 1. , it hardly penetrates into the nip 23 of the inner diameter screw 21 of the cap 2. Therefore, the effective diameter φD' of the inner circumference of the circular waveguide 1 is determined by the diameter φD of the inner circumference of the circular waveguide 1, the thickness T of the circular waveguide 1, the width W of the nip 23, and the covering member 3. Using the thickness t, it becomes φD+2(T+W+t), which is close to the diameter φD of the inner circumference of the circular waveguide 1. Therefore, although the TE11 basic mode occurs, only a small amount of the TM01 higher-order mode occurs. Even if the TM01 higher-order mode is superimposed on the TE11 fundamental mode, its influence is small.

Then, the E-plane directivity of the main polarization did not cause beam tilt from the front direction. The cross-polarized E-plane directivity met the target specification of -35 dB or less. On the other hand, the H-plane directivity of the main polarization did not cause beam tilt from the front direction. The H-plane directivity of the cross-polarized waves met the target specification of −35 dB or less (however, in FIG. 17, compared to FIG. 13, the gap width g is a finite value, so the cross-polarized waves H-plane directivity is not suppressed).

In this way, even if the outer periphery of the shielding member 4 and the outer periphery of the nip 23 of the inner diameter screw 21 of the cap 2 are not in complete electrical contact, the E-plane directivity of the main polarized wave almost certainly becomes a beam from the front direction. It is possible to almost certainly ensure that the H-plane directivity of cross-polarized waves is below the target specification without causing any tilt.

In this embodiment, when the shielding member 4 is sandwiched between the radiation opening of the circular waveguide 1 and the covering member 3, the radius of the inner circumference of the shielding member 4 is within the radiation opening of the circular waveguide 1. It is set equal to the radius of the circumference. As a modification, when the shielding member 4 is sandwiched between the radiation opening of the circular waveguide 1 and the covering member 3, the radius of the inner circumference of the shielding member 4 is equal to the inner circumference of the radiation opening of the circular waveguide 1. may be larger than the radius of In short, the shielding member 4 only needs to shield the nip 23 of the internal thread 21 of the cap 2 without blocking the hollow region within the radiation opening of the circular waveguide 1.

In FIG. 18, the radius of the inner circumference of the shielding member 4 is larger than the radius of the inner circumference of the radiation aperture of the circular waveguide 1, and similarly to FIG. It is equal to the radius of the outer periphery of the nip 23 of the internal thread 21. In FIG. 19, the radius of the inner circumference of the shielding member 4 is larger than the radius of the inner circumference of the radiation opening of the circular waveguide 1, and as in FIG. 16, when viewed from the extending direction of the circular waveguide 1, The width of the gap between the outer periphery of the shielding member 4 and the outer periphery of the nip 23 of the internal thread 21 of the cap 2 is 20% or less of the width of the nip 23 of the internal thread 21 of the cap 2.

The primary radiator for an antenna having an airtight structure and a waterproof structure according to the present disclosure can be applied to a radar, satellite communication, or microwave line antenna having a horn or a reflector.

P: Primary radiator for antenna 1: Circular waveguide 2: Cap 3: Covering member 4: Shielding member 5: Inner diameter thread cutting tool 11: Outer diameter screw 12: Choke structure 21: Inner diameter screw 22: Regulation opening 23: Nige

Claims (3)

A circular waveguide with an outer diameter thread cut on the outer periphery of the radiation aperture that is the tip part ,
a cap having an inner diameter thread cut on the inner periphery of the insertion opening into which the circular waveguide is inserted, and a cap having the inner diameter thread cut near the inner end surface of the regulation opening that regulates the insertion of the circular waveguide;
a covering member that is sandwiched between the radiation opening of the circular waveguide and the regulation opening of the cap and covers a hollow region within the radiation opening of the circular waveguide from the outside;
The cap is disposed between the inner diameter thread of the cap and the covering member, and is shielded from the inner diameter thread of the cap without blocking the hollow region within the radiation opening of the circular waveguide. a ring-shaped shielding member;
A primary radiator for an antenna, comprising: The shielding member is sandwiched between the radiation opening of the circular waveguide and the covering member,
The radius of the inner circumference of the shielding member is greater than or equal to the radius of the inner circumference of the radiation aperture of the circular waveguide,
The primary radiator for an antenna according to claim 1, wherein the radius of the outer circumference of the shielding member is equal to the radius of the outer circumference of the inner diameter screw of the cap. The shielding member is sandwiched between the radiation opening of the circular waveguide and the covering member,
The radius of the inner circumference of the shielding member is greater than or equal to the radius of the inner circumference of the radiation aperture of the circular waveguide,
When viewed from the extending direction of the circular waveguide, the width of the gap between the outer periphery of the shielding member and the outer periphery of the nip of the internal thread of the cap is 20% of the width of the nip of the internal thread of the cap. The primary radiator for an antenna according to claim 1, characterized in that:

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