JP4089605B2 - Radio wave lens - Google Patents

Description

  The present invention relates to a radio wave lens configured by combining a hemispherical Luneberg lens and a reflector, and a geostationary satellite configured by combining the radio wave lens and a primary radiator such as an LNB (low noise block). The present invention relates to a lens antenna device suitable for transmitting and receiving radio waves between the two.

  As a radio wave lens for an antenna device, one configured by combining a hemispherical Luneberg lens and a reflector is known. In this type of radio wave lens, a resin lens cover is placed on the outer side of the lens to protect the hemispherical Luneberg lens.

  There is an antenna in which the lens cover (radome) is joined to the end of a reflector (for example, Patent Document 1). However, since this antenna is large in size and hollow, the lens cover has to be thick, and there is a problem in terms of electrical characteristics.

  In some cases, a hemispherical lens cover adapted to the lens size is disposed on a reflector having a diameter larger than the lens diameter (for example, Patent Documents 2 to 4).

  As a method for protecting the hemispherical lens, a technique for covering the entire lens by integrally molding the lens and the lens cover or assembling the divided lens cover has been proposed. Since the size is larger than that of the lens, it is impossible to seal the entire surface in this way.

  For this reason, as in Patent Documents 2 to 4, a hemispherical lens cover is arranged on the reflector. This structure is compact, and the lens cover can be made thin to enhance the electrical characteristics of the antenna.

  However, in the structure in which the hemispherical lens cover is arranged on the reflecting plate, it is necessary to perform sealing between the opening edge of the lens cover and the reflecting plate over the entire circumference of the lens. was difficult. For example, the lens cover may be deformed or bent due to a strong wind or a sudden change in environmental temperature. In such a case, the sealing effect of the seal portion may be reduced and rainwater may flow into the lens cover. there were.

  As a countermeasure, a flange was provided on the opening edge of the lens cover, and this flange was fixed on the reflector with a bolt or adhesive. However, in this structure, a part of the reflecting surface (radio wave reflecting surface) The electrical characteristics of the antenna deteriorated due to the cover ring being covered.

In addition, we tried to tighten the flange without using an adhesive with resin bolts that transmit radio waves, but tightening with only bolts caused differences in the tightening pressure of each part of the flange, and parts that could not be tightened directly on the bolt As a result, problems such as lifting of the flange from the surface of the reflector occurred and stable sealing could not be achieved.
Japanese Patent Laid-Open No. 2002-232230 Japanese Patent Laid-Open No. 2003-110349 JP 2003-110350 A JP 2003-110352 A

  If water enters the lens cover, the performance of the antenna is significantly reduced. Accordingly, an object of the present invention is to improve the sealing performance between the lens cover and the reflecting plate without degrading the electric performance of the antenna.

  In order to solve the above-mentioned problems, in the present invention, a hemispherical Luneberg lens, a reflector having a larger diameter than a lens diameter that reflects radio waves in combination with the Luneberg lens, and a lens that covers the Luneberg lens In the radio wave lens configured by combining the cover, the opening edge of the lens cover is inserted into the reflection plate, and a seal portion between the lens cover and the reflection plate is provided inside or on the back side of the reflection plate.

  The radio wave lens includes a first reflector on which the Luneberg lens is mounted, a second reflector having a hole having a diameter substantially the same as the outer diameter of the lens cover that overlaps the first reflector around the Luneberg lens. It is preferable that the seal portion is configured by sandwiching a flange provided in the opening of the lens cover between the first reflector and the second reflector.

  Further, the seal portion formed between the reflecting plate and the lens cover is preferably sealed by using a seal material such as an O-ring, packing, sealant, or adhesive.

  In the present invention, the overlapping portion of the two reflecting plates is also regarded as the inside of the reflecting plate.

  The lens antenna device of the present invention can be obtained by combining these radio wave lenses, a primary radiator disposed at the focal point of radio waves of the radio wave lens, and a holder for holding the primary radiator.

  In the radio wave lens of the present invention and the lens antenna device using the radio wave lens, since the seal between the lens cover and the reflection plate is sealed inside the reflection plate, no member that affects the reflection of the radio wave is provided on the reflection surface of the reflection plate. I'm sorry. Therefore, radio waves are normally reflected over the entire reflection surface, and the electrical performance of the antenna does not deteriorate.

  Further, when sealing is performed inside the reflecting plate, the stability of the sealing can be improved by eliminating the lifting of the antenna cover from the reflecting plate and the nonuniformity of the sealing pressure of the seal portion.

  Since a flange is provided at the opening edge of the antenna cover and the flange is sandwiched between the first and second reflectors, sealing can be provided by sandwiching the flange, so that manufacture and assembly are facilitated.

  Furthermore, in the case of a structure in which a flange provided at the opening edge of the lens cover is arranged on the reflecting surface for sealing, there is unevenness due to a step or a hole (for example, a hole for draining water) in the flange overlapping portion of the reflecting plate. A gap due to unevenness is formed between the flange and the reflector, making it difficult to achieve a good seal, but this problem can also be solved by sealing inside the reflector.

  If a sealing material is used in combination, the reliability of the sealing portion increases, and a more stable sealing can be performed.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a radio wave lens according to the present invention will be described below with reference to FIGS.

  The illustrated radio wave lens includes a first reflector 1 and a second reflector 2 shown in FIG. 2, a hemispherical Luneberg lens 3, and a flange 4 a at a resin opening edge that fits the lens 3. A hemispherical lens cover 4 is combined.

  The first reflector 1 is larger in size than the Luneberg lens 3. The first reflecting plate 1 is provided with a circular groove 1a for fitting the flange 4a of the lens cover 4, and the inner surface of the groove 1a is used as a radio wave reflecting surface 1b, on the reflecting surface 1b. The Luneberg lens 3 is set.

  The second reflecting plate 2 has a shape that fits and overlaps with a region outside the reflecting surface 1 b of the first reflecting plate 1, and has a circular hole 2 a that is substantially the same diameter as the outer diameter of the lens cover 4. . The entire surface of the second reflecting plate 2 is used as a reflecting surface.

  At least a portion of the reflecting surface 1b of the first reflecting plate 1 has a flatness that does not hinder radio wave reflection. The first reflecting plate 1 is preferably formed of light and inexpensive aluminum, but the reflecting surface 1b may be configured by applying metal plating to the surface of the resin base plate. Further, it may be a metal plate having a small diameter hole (for example, a hole having a diameter of 1 mm or less) that does not hinder radio wave reflection, or a metal mesh plate having a small interval between eyes (for example, 1 mm or less). The material other than the reflection surface 1b is not particularly limited as long as the flatness of the reflection surface can be maintained after the radio wave lens is assembled.

  Similarly to the first reflector 1, the second reflector 2 is preferably formed of light and inexpensive aluminum, but it is sufficient that at least the surface to be a reflective surface is formed of metal. The second reflector 2 can also be formed of a metal plate having a small diameter hole that does not interfere with radio wave reflection, or a metal mesh plate with a small interval between eyes.

  The Luneberg lens 3 uses a lens whose dielectric constant is changed by 2 to 1 or an approximate value from the center toward the outer periphery.

  The material of the lens cover 4 may basically be anything as long as it has a low dielectric loss and weather resistance, but it is inexpensive and easy to process a synthetic resin, especially polyethylene, polystyrene, polypropylene, etc. in terms of low dielectric loss. It is desirable that the thickness of the lens cover 4 is 1 mm or less from the viewpoint of low dielectric loss.

  The exemplary radio wave lens is assembled as follows. That is, as shown in FIG. 1, the Luneberg lens 3 is placed on the reflecting surface 1b of the first reflecting plate 1, and the lens cover 4 is put on the surface of the lens. At this time, it is preferable to apply a sealing agent 5 for watertight sealing to the surface of the flange 4a to be inserted into the groove 1a or the inner surface of the groove 1a, and then insert the flange 4a into the groove 1a. The sealant 5 may be, for example, only a silicon-based coating agent or sealant, or may be used in combination with a rubber packing, an O-ring, or the like. The sealing agent 5 may also be disposed between the flange 4a and the second reflecting plate 2.

  When the flange 4a is inserted into the groove 1a, the second reflector 2 is overlapped on the first reflector 1 and joined. The first reflector 1 and the second reflector 2 may be joined by either adhesion or welding. Even when fastened with a resin bolt, the flange 4a does not lift from the reflector, so that the sealing performance can be improved more than before.

  After the above process, the seal portion 6 as shown in FIG. 3 is formed.

  In addition, it is not an essential matter to form the groove 1 a in the first reflecting plate 1. Since the step formed on the reflecting surface affects the reflection of radio waves, it is necessary to keep it within an allowable range (for example, 1 mm or less). In order to satisfy the requirement, a groove is provided in the first reflecting plate 1 if necessary. Or as shown in FIG. 4, the level | step difference for aligning the height position of a reflecting plate in both of the reflecting plates 1 and 2 is made beforehand.

  Also, as shown in the figure, when the reflector is divided into the first reflector 1 and the second reflector 2 and assembled, it becomes easy to process the reflector and assemble the radio wave lens, but the reflector is divided into two. This is not an essential matter.

  Further, as shown in FIG. 5, an O-ring 7 is disposed between the lens cover 4 and the first reflector 1 for sealing, and as shown in FIG. 6, the flange 4a of the lens cover 4 is made of a reflector. You may arrange | position on the back side and may implement the seal | sticker between the flange 4a and a reflecting plate on the back side of a reflecting plate. The radio wave lens shown in FIG. 6 has a structure in which the first reflecting plate 1 and the second reflecting plate 2 are connected by a connecting ring 8 on the back side, and the sealing portion 6 is covered and protected by the connecting ring 8. The connection between the first reflecting plate 1 and the second reflecting plate 2 may be performed using a plurality of (for example, about 12) connecting members arranged at intervals in the circumferential direction, and the connecting member is a ring. Is not essential.

  As shown in FIGS. 7 and 8, the flange 4 a of the lens cover 4 can be fixed to either the first or second reflecting plate 1 or 2 with a bolt 9. Thus, it is possible to further increase the reliability of the seal portion 6 by tightening the flange 4a with the bolt 9 that does not appear on the reflection surface. The radio wave lens shown in FIG. 7 has a structure in which a bolt operation hole 1c that passes through the groove 1a is provided in the first reflector 1 and the bolt operation hole 1c is filled with a sealant 5 after the bolt 9 is tightened.

  Instead of the flange 4a of the lens cover 4, a screw part 4b is formed as shown in FIG. 9, and the screw part 4b is screwed into a screw hole provided in the reflection plate. In this case, the first, first, It is possible to form two reflectors integrally.

  The results of the effect confirmation test are shown below. The test was performed using the radio wave lens (invention) having the structure shown in FIG. 1 and the radio wave lens (comparative example) having the structure shown in FIGS. A Luneberg lens 3 having an outer diameter of 370 mm was used. The Luneberg lens 3 and the lens cover 4 are the same for the invention and the comparative example.

  The invented product has a lens cover flange 4a in which the first and second reflecting plates 1 and 2 are bonded and integrated, and a silicon coating agent is applied to the abutting surface with the first reflecting plate 1, and the first and second reflecting plates 1 and 2 are provided. 2 is sandwiched between the reflectors 1 and 2.

  The radio wave lens of FIG. 10 (Comparative Example 1) is obtained by fixing a flange 4a of a lens cover with a total of twelve metal bolts 11 to a reflecting plate 10 having a flat upper surface. A sealant 5 is provided between the flange 4a and the reflector 10.

  A radio wave lens (Comparative Example 2) in which the metal bolt 11 in FIG. 10 was replaced with a resin bolt was also prepared.

  The metal bolt 11 of the radio wave lens in FIG. 10 is replaced with a resin bolt 12, and a presser ring 13 (thickness of 2, 5, and 10 mm) made of resin is provided and the flange 4 a is added by the presser ring 13. The pressed radio wave lens of FIG. 11 (Comparative Example 3) and the radio wave lens of FIG. 12 (Comparative Example 4) in which the flange 4a is simply bonded to the reflector 10 with the adhesive 14 were also prepared.

  The antenna device is configured by combining the radio wave lens of the present invention with a primary radiator (LNB) that arranges the radio wave lens of the comparative example at the focal point of the lens and a holder H (see FIG. 1) that holds the primary radiator, The gain (dBi) of each antenna device was measured.

  As a result, the gain of the product of the invention was 31.7 dBi, which was not different from that using a single flat reflector (the lens cover was simply placed on the reflector without sealing). .

  In contrast, the radio wave lens of FIG. 10 using the metal bolt 11 (Comparative Example 1) has a gain of 31.2 dBi, and the radio wave lens of FIG. 11 using the resin retaining ring 13 (Comparative Example 3) is When the holding ring thickness was 2 mm, the gain was 31.5 dBi, when the holding ring thickness was 5 mm, the gain was 31.4 dBi, and when the holding ring thickness was 10 mm, the gain was 31.2 dBi.

  A radio wave lens (Comparative Example 2) in which the flange 4a of the lens cover is fixed to the reflection plate with a resin bolt, and a radio wave lens (Comparative Example 4) in which the flange 4a of the lens cover is fixed to the reflection plate only with an adhesive. ) Has a gain of 31.7 dBi, which is not different from the invention.

  Next, with respect to Comparative Example 2 (in which the metal bolt 11 in FIG. 10 is replaced with a resin bolt) and the Comparative Example 4 in FIG. A rainproof performance test according to rain type) was conducted.

  The test was carried out by spraying water under conditions of about 10 liters / min and exposing the antenna device to it, and after 5 minutes of watering, the water droplets on the surface of the device were wiped clean and the gains before and after the test were compared.

  As a result, the gain of the invention product was 31.7 dBi before and after the test, and it was confirmed that the waterproofness was maintained.

  On the other hand, it was confirmed that both Comparative Example 2 and Comparative Example 4 were immersed in the antenna cover by visual observation. The gain after water immersion was 31.5 dBi, and a decrease in electrical performance due to water immersion was observed.

  In the structures of Comparative Examples 2 and 4, the interface between the reflecting plate and the reflector cannot be reliably sealed due to the bending of the flange portion or the like, and the structure shown in FIG. In order to increase the performance, even if the holding ring is made of resin, the gain is lowered due to the ring, and in the structure of the comparative example, it is not possible to ensure both electrical performance and seal reliability.

  On the other hand, the radio wave lens according to the present invention can ensure both electrical performance and seal reliability. The above experimental results prove it.

Sectional drawing which shows embodiment of the radio wave lens of this invention 1 is an exploded perspective view showing components of the radio wave lens of FIG. 1 is an enlarged cross-sectional view of the seal portion of FIG. Sectional drawing which shows the principal part of other embodiment Sectional drawing which shows the principal part of other embodiment Sectional drawing which shows the principal part of other embodiment Sectional drawing which shows the principal part of other embodiment Sectional drawing which shows the principal part of other embodiment Sectional drawing which shows the principal part of other embodiment Sectional drawing of the radio wave lens of the comparative example 1 Sectional drawing of the radio wave lens of the comparative example 3 Sectional drawing of the radio wave lens of the comparative example 4

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st reflecting plate 1a Groove 1b Reflecting surface 1c Operation hole 2 2nd reflecting plate 2a Circular hole 3 Luneberg lens 4 Lens cover 4a Flange 4b Screw part 5 Sealing agent 6 Sealing part 7 O-ring 8 Connecting ring 9 Bolt

Claims (4)

  It consists of a hemispherical Luneberg lens, a reflector that is larger than the lens diameter that reflects radio waves in combination with this Luneberg lens, and a lens cover that covers the Luneberg lens, and reflects the opening edge of the lens cover. A radio wave lens that enters the inside of the plate and has a seal portion between the lens cover and the reflecting plate provided inside or behind the reflecting plate.   The reflector is composed of a first reflector on which a Luneberg lens is placed, and a second reflector having a hole having a diameter substantially the same as the outer diameter of the lens cover that is superimposed on the first reflector around the Luneberg lens, The radio wave lens according to claim 1, wherein the seal portion is configured by sandwiching a flange provided in an opening of the lens cover between the first reflector and the second reflector.   The radio wave lens according to claim 1 or 2, wherein sealing of the seal portion is performed using a sealant such as an O-ring, packing, sealant, or adhesive.   A lens antenna device comprising a combination of the radio wave lens according to any one of claims 1 to 3, a primary radiator disposed at a radio wave focal point of the radio wave lens, and a holder for holding the primary radiator.

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