This application is related to Japanese Patent Application NO. 2008-56397 filed on Mar. 6, 2008, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to high frequency devices and, in particular, to a high frequency device provided with a rectangular waveguide tube that is capable of transmitting high frequency signals.
2. Description of the Related Art
Conventionally, a high frequency device that is capable of transmitting high frequency signals using rectangular waveguide tubes is known. For example, Japanese Patent Laid-open publication No. 2004-221718 discloses a high frequency device that is capable of transmitting high frequency signals, in which two metallic plates are joined and a plurality of rectangular waveguide tubes are formed on the joint surface.
In this type of high frequency device, forming a groove on at least one metallic plate is necessary to make a rectangular waveguide tube. In this regard, it is required to process the metallic plate to be a complex shape, which makes manufacturing the device difficult.
In addition, the high frequency device having joined metallic plates has problems such as being heavy, and requiring an additional high frequency circuit board for processing signals being transmitted through the waveguide tube. Furthermore, there can be a problem that thickness of the device is increased when the high frequency board is laminated to the metallic plates.
Since the metallic plates cannot be joined using an adhesive, the metallic plates are joined using screws. Therefore, it is necessary to secure space for the screws, which makes the scale of the device increase.
The present invention has been achieved to solve above described issues. An object of the present invention is to provide a high frequency signal transmitting device having a lightweight and thin body. To achieve above-described object, a high frequency device equipped with a waveguide tube unit that transmits a high frequency signal, the waveguide having a rectangular waveguide passage through which the high frequency signal is transmitted, the waveguide passage extending in a longitudinal direction thereof and having a rectangle section cut perpendicularly to the longitudinal direction, the rectangle section consisting of short side edges and long side edges, the device comprising: a plate having a thickness corresponding to a length of the short side edges of the waveguide passage and having a through hole formed through the mutually-opposite surfaces of the plate in a direction of the thickness, the through hole having a width perpendicular to the longitudinal direction, having an inner wall and openings opened at the surfaces, wherein at least the inner wall and edges of the openings are given electrical conductivity; and a pair of resin-made substrates, each substrate being laminated on each of the mutually-opposite surfaces of the plate and having grounding patterns connected to the ground, the grounding pattern being located at a specified region of a surface of each of the substrates, the specified region positionally corresponding to the waveguide passage formed in the plate, the plate and the pair of substrates composing the waveguide tube unit.
In the accompanying drawings:
Embodiments of a high frequency signal transmitting device of the present invention will hereinafter be described by reference to the accompanying drawings.
Referring to
The high frequency signal transmitting device 1, which serves as the high-frequency device according to the present invention, is applied to a radar device using millimeter waves and microwaves.
As shown in
Among these, the first substrate 20 is a resin-made substrate. High frequency circuits are formed (e.g. printed) on a surface (hereinafter referred to circuit-formed-surface) of the first substrate 20 opposite to the joint surface with the waveguide plate 10. The high frequency circuits are, for example, an oscillator 21 that generates high frequency signals, a high frequency signal line 23 formed by strip lines that transmit an output from the oscillator 21 to rectangular areas 22 serving as an input terminal of the rectangular waveguide passage 3, and transitions 24 that converts electrical signals (output from the oscillator 21) provided via the high frequency signal line 23 into electromagnetic waves and emit the electromagnetic waves towards the rectangular waveguide passage 3. The rectangular areas 22 (22a to 22c) are arranged corresponding to the through holes 11a to 11c respectively. All high frequency signal line 23 which connect the rectangular areas 22 and the oscillator 21 placed on a center of the first substrate 20, are arranged radially such that the lengths of the waveguides are the same.
On the other hand, the second substrate 30 is a resin-made substrate, like the first substrate 20. Antenna sections 31, transitions 33, high frequency signal line 34, are formed (e.g. printed) on a surface (circuit-formed-surface) of the second substrate 30 opposite to the joint surface with the waveguide plate 10, such as to correspond to each of the rectangular waveguide passage 3. The antenna sections 31 are formed by a plurality of patch antennas being arrayed in a single row. The transitions 33 converts the high frequency signals provided via the rectangular waveguide passage 3 into electrical signals at rectangular areas 32 serving as output terminals of the rectangular waveguide passage 3. The rectangular areas 32 (32a to 32c) are arranged in a line along a side of the second substrate 30.
Furthermore, the through hole 11 on the waveguide plate 10 are formed such that a center of a portion facing to the rectangular areas 22 of the first substrate and a center of a portion facing to the rectangular areas 32 of the second substrate each locate λg/2 away from the passage-end of the through holes 11 (λg refers to a guide wave length of the electromagnetic waves to be transmitted in the waveguide 3). In addition, thickness of the waveguide plate 10 is set to avoid forming standing waves of higher harmonics in the thickness-direction (I.e., short-side/electric field direction) of through holes 11.
As shown
Further, the waveguide plate 10, the first substrate 20 and the second substrate 30 are integrally attached by a conductive adhesive. In other words, the substrates 10 and 30, each substrate are laminated on each of the mutually-opposite surfaces of the waveguide plate 10.
Therefore, in the high frequency signal transmitting device 1, the rectangular waveguide passage 3 which can be referred to a rectangular waveguide tube are formed by the through holes 11 and the grounding patterns 25, 35 of the first and second substrate that cover the through holes 11, and E bends for input/output terminals of the rectangular waveguide passage 3 are formed at the rectangular areas 22, 32 surrounded by the via holes 27, 37.
In the high frequency signal transmitting device 1 configured as such, the high frequency signals (electrical signals) generated by the oscillator 21 that is mounted on the circuit-formed-surface of the first substrate 20, are supplied to the transitions 24 via the high frequency signal line 23. The high frequency signals (electric signals) are converted to electromagnetic waves by the transitions 24 and then supplied to the rectangular waveguide passage 3 via rectangular areas 22. Moreover, the electromagnetic waves are transmitted to the transitions 33 that are mounted on the circuit-formed-surface of the second substrate 30 via the rectangular waveguide passage 3 and the rectangular area 32 of the second substrate 30. As a result, the high frequency signals (electromagnetic waves) that are supplied to the transitions 33 are converted to electric signals and supplied to the antenna sections 31 via high frequency signal line 34. The electric signals are again converted to the electromagnetic waves at the antenna sections 31 so as to emit the waves. In
As described above, the high frequency signal transmitting device 1 only requires forming the through holes 11 for processing of the waveguide plate 10 in order to provide the rectangular waveguide passage 3. Therefore, unlike a conventional device, complex processing such as forming a groove is not necessary, the high frequency signal transmitting device 1 can be manufactured easily and with low cost.
Also, the high frequency signal transmitting device 1 has the rectangular waveguide passage 3 formed by a pair of resin-made plates (the first substrate 20 and the second substrate 30) joined to the waveguide plate 10. Besides, a high frequency circuits that generate/process the high frequency signals to be transmitted via the rectangular waveguide passage 3, are formed on the first substrate 20 and the second substrate 30. Accordingly, it is not necessary to use additional configuration for the high frequency circuit (e.g. resin-made plates) so that configuration of the high frequency circuits is accomplished with a lightweight and thin body.
Moreover, in the high frequency signal transmitting device 1, since the waveguide plate 10, the first substrate 20 and the second substrate 30 are joined by a conductive adhesive, it is not necessary to secure a specific configuration and space for the joint. Therefore, the high frequency signal transmitting device 1 can be downsized and simply structured. The high frequency signal transmitting device 1 corresponds to the high frequency device of the present invention.
Next, referring to
In this embodiment, only a configuration of the waveguide plate 10 differs from that of the waveguide plate 10 according to the first embodiment. Therefore, a portion of the configuration that differs will mainly be described.
As shown
This groove 12 (12a to 12c) are formed such that end portions at a side of the through holes 11 are formed to be at portions that are nλg/2 (n is 0 or positive integer number) away from end portions that are facing to rectangular areas 32 (32a to 32c). Apertures of the groove 12 are equal or less than λ/4, where λ refers to “free space wavelength” of electromagnetic waves to be transmitted.
In the high frequency signal transmitting device 1 configured as such, the air passages by grooves 12 are formed when the waveguide plate 10, the first substrate 20 and the second substrate 30 are joined together, thereby the air flow through the rectangular waveguide passage 3. As a result, even if the air in the rectangular waveguide passage 3 fluctuates in its volume (i.e., expansion or contraction) due to temperature variation or other reason, joint portions of the waveguide plate 10, the first substrate 20 and the second substrate 30, or joint portions between the first/second substrates and circuit parts mounted on those substrates 20, 30 do not suffer any extra force. Thus, a structural reliability of the high frequency signal transmitting device 1 can be enhanced.
The grooves 12 forming the air passages are not necessarily arranged on the joint surface of the waveguide plate 10 at which the waveguide plate 10 and the first substrate 20 are joined. However, the grooves 12 may be arranged on the joint surface of the waveguide plate 10 and the second substrate 30.
Also, a configuration to form the air passages (the grooves 1Z in the second embodiment) may be arranged on the joint surface of the first or second substrate (i.e., not the surface of the waveguide plate 10) that are joined to the waveguide plate 10.
In such case, for example, as shown
Besides,
Next, referring to
A high frequency signal transmitting device 5 of the third embodiment is configured as a slot array antenna.
As shown in
Among these, the first substrate 50 is made of resin in which various high frequency circuits are arranged on an opposite side of the joint surface of the waveguide plate 40 (i.e., circuit-formed-surface). The high frequency circuits include an oscillator (not shown) that generates a high frequency signal, a high frequency signal line 53 formed by strip line that transmits an output from the oscillator to rectangular area 52 serving as an input terminal of the rectangular waveguide passage 7, and a transition 54 that converts an electrical signal (output from the oscillator) provided via the high frequency signal line 53 into electromagnetic waves and emit the electromagnetic waves towards the rectangular waveguide passages 7. Further, the grounding pattern 56 is formed on the rest of the area other than those high frequency circuits.
Also, on the joint surface of the first substrate 50 at which the first substrate 50 and the waveguide plate 40 are joined, a portion 58 (having no grounding pattern) as an air passage that allows the air to flow between the rectangular waveguide passage 7 and outside space of the waveguide plate 5. In addition, the grounding pattern 55 is formed on the entire portion of the joint surface except a rectangular area 52. Regarding the portion 58, an end portion corresponding to a side of the rectangular wave guide passage 7 has an aperture at a portion confronting to the rectangular portion 52 of the first substrate 50. The portion 58 is formed to have length of aperture equal to or less than λ/4. Further, plurality of via holes 57 which electrically connect the grounding patterns 55 and 56 are arranged around the rectangular portion 52 with an interval of which length is equal or less than λg/4. Accordingly, an E bend for input terminal of the rectangular waveguide passage 7 is formed at the rectangular area 52 surrounded by the via holes 57.
On the other hand, the second substrate 60 is made of resin as well as the first substrate 50 and on the joint surface of the waveguide plate 40, a grounding pattern 55 is formed to cover almost all area of the joint surface of the waveguide plate 40. However, plurality of slits 62 are formed on a line at a portion that is facing to the through hole 41 (i.e., rectangular waveguide passage 7) of the waveguide plate 40. The plurality of slits 62 are formed along with the through hole 41. The intervals among each slot are set to a predetermined value so as to obtain desired directional characteristics.
In the high frequency signal transmitting device 5 configured such as this, the high frequency signal (electrical signal) generated by the oscillator arranged on the circuit-formed-surface of the first substrate 50 is supplied to the transition 54 via the high frequency signal line 53. Subsequently, the high frequency signal is converted to electromagnetic waves and supplied to the rectangular waveguide passage 7 via the rectangular area 52. Then, the high frequency signal (electromagnetic waves) supplied to the rectangular waveguide passage 7 is emitted to an outside of the device from the each slit 62 formed on the second substrate 60.
As described, in the high frequency signal transmitting device 5, forming the through hole 41 on the waveguide plate 40 is only required to provide the waveguide 7. Also, the rectangular waveguide passage 7 is formed such that pair of resin-made substrates (the first substrate 50 and the second substrate 60) are joined to the waveguide plate 40 by conductive adhesive. Accordingly, the same effect as the first embodiment can be achieved.
Furthermore, according to the high frequency signal transmitting device 5, the electromagnetic waves transmitted in the rectangular waveguide passage 7 can be emitted to outside of the device from the slits 62 without converting the electromagnetic waves into an electrical signal. As a result, the electromagnetic waves can be emitted efficiently. The high frequency signal transmitting device 5 corresponds to the high frequency device of the present invention.
As shown in
As shown
According to the above-described embodiments, metallic plates including through holes are used as waveguide plates 10 and 40. However, as shown in
According to the above-described embodiments, the waveguide plate 10 (40), or the first substrate 20 (50), and the second substrate 30 (60) are processed in order to make the air passage. However, when these plates are laminated on one another using the conductive adhesive, a portion at which there is no conductive adhesive can be used as the air passage.
Furthermore, the air passage may be a through hole (i.e., via hole) that vertically passes through the resin-made substrate, which through hole can be formed as part of circuit wirings. Practically, in the configuration shown in
Here,
As shown in
In addition, at least one substrate can be configured as a multi-layered substrate between the first substrate 20 (50) and the second substrate 30 (60). In
Also, on the circuit-formed-surface of the first substrate 20 (50) or the second substrate 30 (60) (in
Number | Date | Country | Kind |
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2008-056397 | Mar 2008 | JP | national |