The present application is based on and claims priority from Japanese Patent Application 2006-134091, filed May 12, 2006, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a dielectric substrate and a device that utilizes the electric substrate, such as a waveguide or a transmission line transition.
2. Description of the Related Art
Usually, a waveguide tube is formed of a plural dielectric substrates (only one illustrated in
On the other hand, an array of plural via holes or through holes may be formed as a peripheral wall of the hole instead of the conductor film, as disclosed in JP-P2001-196815A. The array of via holes must be formed on the dielectric substrate at a certain distance (e.g. 0.5 mm) from the edge or the peripheral wall of the hole in order to secure the mechanical strength thereof. However, this distance may also degrade the performance of the waveguide tube.
Therefore, an object of the invention is to provide an improved dielectric substrate for a waveguide tube and a transmission line transition.
Another object is to omit a step of forming a flat conductive layer on the through hole.
According to a feature of the invention of a dielectric substrate used for a waveguide tube to transmit an electromagnetic wave whose wave length is λg, the dielectric substrate has a hole and a plurality of via holes disposed to surround the hole at a distance δ that is equal to an integer n×the wave length λg/2 from the peripheral wall of the hole.
Therefore, a waveguide tube of good performance and mechanical strength can be provided without any additional step.
Preferably, the via holes are disposed at equal intervals each of which is less than λg/4.
Another object of the invention is to provide an improved waveguide tube that includes a stack of a plurality of dielectric substrates constructed as above.
Another object of the invention is to provide a transmission line transition, which includes a waveguide tube section having a waveguide tube formed of at least the above dielectric substrate and a line transition section formed of at least the above dielectric substrate disposed adjacent the waveguide tube section to cover the hole, a transmission line for transmitting the electromagnetic wave, and an antenna pattern that is disposed in the hole to be electromagnetically coupled with the transmission line.
Other objects, features and characteristics of the present invention as well as the functions of related parts of the present invention will become clear from a study of the following detailed description, the appended claims and the drawings. In the drawings:
The present invention will be described with reference to the appended drawings.
A dielectric substrate 1 according to the first embodiment of the invention will be described with reference to
The dielectric substrate 1 has conductive layers 3, 5 (
Plural via holes 7 are formed at equal intervals W (
Because the dielectric substrate 1 does not have a conductive layer on the peripheral wall 9 of the hole H, the dielectric substrate 1 and a waveguide tube can be manufactured at a lower cost than a dielectric substrate having a conductive layer on the peripheral wall 9.
The hole H of the dielectric substrate 1 can be used for a waveguide tube by grounding the conductive layers 3, 5 that are connected with the via holes 7. The wall 9 of the hole H, which is distant from the grounded via holes at λg/2, can be treated as being virtually short-circuited. Because the via holes are formed at intervals of W that is shorter than λg/4, a waveguide tube of a low loss can be provided.
As shown in
As shown in
Therefore, a dielectric substrate 10 may be formed of a stack of plural dielectric substrates, as shown in
A transmission line transition 20 according to the second embodiment of the invention will be described with reference to
The transmission line transition 20 is constructed of three dielectric substrate P1, P2 and P3 and four pattern layers L1, L2, L3 and L4 that are interleaved with each other, so that the dielectric substrate P1 and the pattern layers L1, L2 form a line transition section 20a (
The transmission line transition 20 has a rectangular cavity 21 that extends along the center axis of the waveguide tube section 20b to be connected to a waveguide tube G, which is fixed to the waveguide tube section 20b. The waveguide tube G has a rectangular hole of 2.54 mm×1.27 mm to transmit an electromagnetic wave of a frequency between 75 GHz and 110 GHz (e.g. 76.5 GHz).
The waveguide tube section 20b has plural via holes 23 (
The pattern layers L1, L2, L3 and L4 are shown in
The pattern layer L3, which is formed between the dielectric substrates P2 and P3, has a ground pattern GP3 that covers the entire surfaces of the dielectric substrates P2, P3 confronting each other except for the surfaces inside the via holes 23, and the pattern layer L2, which is formed between the dielectric substrates P1 and P2 or between the line transition section 20a and the waveguide tube section 20b, has a ground pattern GP2 that covers the entire surfaces of the dielectric substrates P1, P2 confronting each other except for the surface inside the via holes 23 and an antenna pattern AP disposed at the bottom of the cavity 21.
Referring to
The via holes 23 and 25 are respectively formed to align at intervals W that is equal to λg/4 or smaller. In other words, in the transmission line transition 20, the waveguide tube section 20b is substantially the same in construction as the dielectric substrate according to the first embodiment. Another array of via holes 23a (
Referring to
Thus, the peripheral wall of the cavity 21 of the transmission line transition 20 that is formed in the dielectric substrates P1 and P2 is distant from the via holes 23 by a via-shift δ (λg/2) so that it can be treated as being short-circuited. Therefore, the loss of the waveguide tube section 20b can be minimized.
As described above, because the dielectric loss does not increase much even if the thickness of the dielectric substrate increases by a certain degree, the thickness of the dielectric substrates P1, P2 and P3 can be changed under various conditions.
A transmission line transition 30 according to the third embodiment of the invention will be described with reference to
The transmission line transition 30 is constructed of three dielectric substrates P1, P2 and P3 and four pattern layers L1, L2, L3 and L4 that are interleaved with each other, so that the dielectric substrate P1 and the pattern layers L1, L2 form a line transition section 30a (
The line transition section 30a is formed of the dielectric substrate P1 and the pattern layers L1 and L2. The pattern layer L2 has a ground pattern GP2 that covers the entire surfaces of the dielectric substrates P1, P2 confronting each other except for the surface inside the via holes 23. The antenna pattern AP, which is disposed at the bottom of the cavity 21 in the second embodiment, is omitted.
The pattern layer L1, which is formed on the outside surface of the dielectric substrate P1, includes the transmission line SP and the ground pattern GP1 that is disposed to be electrically separated from the transmission line SP and to cover the circumference of the cavity 21. A short-circuiting waveguide tube GT is fixed to the ground pattern GP1 so as to short circuit one end of the waveguide tube. The transmission line SP is about λg/4 distant from the short-circuiting end of the waveguide tube GT. The distance may be ±20% shorter or longer than the distance λg/4.
The above transmission line transition 30 is the same in construction as the transmission line transition 20 according to the second embodiment except for the line transition section 30a. Incidentally, the arrangement, in which the inside surface of the short-circuiting waveguide tube GT is formed on the same plane of the inside surface of the waveguide tube, the via holes 23 (
According to the invention, the following variations of the above embodiments can be made: the via-shift δ may be an integral multiple of λ/2, that is n×λ/2; the dielectric substrate P1 may be formed of plural dielectric substrates P11, P12, as shown in
In the foregoing description of the present invention, the invention has been disclosed with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made to the specific embodiments of the present invention without departing from the scope of the invention as set forth in the appended claims. Accordingly, the description of the present invention is to be regarded in an illustrative, rather than a restrictive, sense.
Number | Date | Country | Kind |
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2006-134091 | May 2006 | JP | national |
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Number | Date | Country |
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10-190317 | Jul 1998 | JP |
2001-196815 | Jul 2001 | JP |
Number | Date | Country | |
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20070262828 A1 | Nov 2007 | US |