Dielectric line intersection

Abstract: An intersect-line apparatus has two conductor plates (1, 2). An HE-mode dielectric resonator (4) and four dielectric strips (3a to 3d) to be coupled to the resonator (4) are disposed between the two conductor plates. The adjacent four dielectric strips (3a to 3d) are spaced from each other substantially at 90 degrees. Accordingly, signals propagating in two strip lines (3a to 3d) positioned substantially at 180 degrees and signals propagating in the remaining two strip lines cross each other within the dielectric resonator (4) without interfering with each other.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric line apparatus and, more particularly, to an intersect-dielectric line apparatus in which a dielectric resonator is disposed at the intersecting portion of the lines. 2. Description of the Related Art Dielectric lines through which electromagnetic waves propagate along dielectric strips inserted between two parallel conductors are used in a dielectric line apparatus in a microwave or a millimetric band. The above type of dielectric line apparatus is configured by, for example, the following manner. Components, such as an oscillator, a circulator, and a mixer, are formed into modules, which are then disposed at predetermined positions, thereby forming an integrated circuit. Alternatively, several circuit elements are integrally provided between two conductor plates, thereby forming an integrated circuit. Whichever structure the dielectric line apparatus has, in order to miniaturize the overall apparatus, it is important to design the apparatus to achieve the optimal routing of the dielectric lines by suitably locating the individual modules, since the dielectric lines are disposed substantially in the same plane. This may be achieved by designing the arrangement of electronic components and wiring patterns on a circuit board in the following manner. Wiring patterns are positioned to cross each other if necessary. Dielectric lines through which electromagnetic waves propagate in different directions are also located to intersect each other, thereby efficiently integrating the components in a limited space. For example, an intersect-line apparatus may be formed, as shown in Fig. 12, by using a cross-shaped dielectric strip. In Fig. 12, a cross-shaped dielectric strip 3 is inserted between conductor plates 1 and 2 so that electromagnetic waves propagate through the dielectric strip 3 in two intersecting directions. However, by merely using a cross-shaped dielectric strip in the above manner, non-continuous portions are generated in the dielectric lines, thereby failing to achieve matching and increasing the reflection on the intersecting portion. Accordingly, the above type of dielectric line apparatus is not suitable for use where low reflection-characteristics are demanded. Further, by merely using a cross-shaped dielectric strip, mode conversion disadvantageously occurs in the intersecting portion, and signals are transmitted in different modes at the intersecting portion of the dielectric strip from one line to the other line. NALLO DI C ET AL: "EXPERIMENTAL INVESTIGATION ON NRD-GUIDE DUAL-MODE FILTERS" IEEE MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM DIGEST, US, NEW YORK, IEEE, 1994, pages 237-240 discloses a non-radiative dielectric waveguide component including an input waveguide, an output waveguide and a dielectric resonator for coupling the input and output waveguides with each other. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an intersect-line apparatus using intersecting dielectric lines in which reflection of signals at the intersecting portion of the lines is inhibited and intersecting lines do not influence each other. In order to achieve the above object, according to the present invention, there is provided an intersect-line apparatus comprising two conductor plates disposed substantially parallel to each other. One HE-mode dielectric resonator or a plurality of HE-mode dielectric resonators connected to each other are disposed between the two conductor plates. Four dielectric strips with end portions facing the HE-mode dielectric resonator or a predetermined dielectric resonator of the plurality of dielectric resonators are provided. The adjacent dielectric resonators are spaced from each other at an angle of substantially 90 degrees. With this arrangement, the HE-mode dielectric resonator is disposed between one pair of dielectric strips positioned substantially at 180 degrees. An LSM-mode electromagnetic wave propagating in one of the pair of dielectric strips excites the dielectric resonator in the HE mode and further propagates in the other dielectric strip. Similarly, the HE-mode dielectric resonator is disposed between the other pair of dielectric strips positioned substantially at 180 degrees. An LSM-mode electromagnetic wave propagating in one of the pair of dielectric strips excites the dielectric resonator in the HE mode and further propagates in the other dielectric strip. Accordingly, each of the dielectric strips is coupled to the dielectric resonator, thereby forming an intersect-line apparatus in which two dielectric lines intersect each other with low reflection-characteristics. Moreover, in the foregoing intersect-line apparatus, an LSE-mode suppressor may be provided for each of the four dielectric strips. This makes it possible to inhibit an LSE-mode signal from propagating in the 90°-spaced intersecting lines, thereby preventing mode conversion between the two intersecting dielectric lines. As a consequence, the two lines are used as independent (isolated) lines. Further, in the foregoing intersect-line apparatus, a spacing h1 between the two conductor plates in a propagating region where the dielectric strips are disposed, a spacing h2 between the two conductor plates in a non-propagating region outside the propagating region, a dielectric constant ε1 of the propagating region, and a dielectric constant ε2 of the non-propagating region may be determined under conditions that the cut-off frequency of an LSM 01 -mode signal propagating in the propagating region may be lower than the cut-off frequency of an LSE 01 -mode signal, and that electromagnetic waves in the LSM 01 mode and the LSE 01 mode may be interrupted. In the above dielectric lines, only a single-mode signal, i.e., an LSM 01 -mode signal, propagates. Accordingly, mode conversion between the two intersecting dielectric lines can be prevented without needing to provide LSE-mode suppressors, thereby ensuring isolation between the two dielectric lines. As a consequence, the two lines are used as independent (isolated) lines. BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1A and 1B are respectively a partial perspective view and a sectional view illustrating the configuration of dielectric lines used in an intersect-line apparatus according to a first embodiment of the present invention; Fig. 2A and 2B illustrate two modes used in the dielectric lines shown in Figs. 1A and 1B; Figs. 3A and 3B are respectively a perspective view and a sectional view illustrating the configuration of the intersect-line apparatus shown in Figs. 1A and 1B; Fig. 4 illustrates an example of excitation modes of a dielectric resonator used in the intersect-line apparatus shown in Figs. 1A and 1B; Fig. 5 is a perspective view illustrating the coupling state between dielectric strips and the dielectric resonator used in the intersect-line apparatus illustrated in Figs. 1A and 1B; Figs. 6A and 6B are plan views illustrating the coupling state between the dielectric strips and the dielectric resonator used in the intersect-line apparatus shown in Figs. 1A and 1B; Fig. 7 is an exploded perspective view illustrating the configuration of an intersect-line apparatus according to a second embodiment of the present invention; Fig. 8 is a plan view illustrating the configuration of an intersect-line apparatus according to a third embodiment of the present invention; Figs. 9A and 9B illustrate the coupling state between dielectric strips and a dielectric resonator used in the intersect-line apparatus shown in Fig. 8; Fig. 10 is a plan view illustrating the configuration of an intersect-line apparatus according to a fourth embodiment of the present invention; Fig. 11 is a plan view illustrating the configuration of an intersect-line apparatus according to a fifth embodiment of the present invention; and Fig. 12 is an exploded perspective view illustrating an example of the configuration of a known intersect-line apparatus. DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an intersect-line apparatus according to a first embodiment of the present invention is described below with reference to Figs. 1 through 6. Fig. 1A is a partial perspective view illustrating dielectric lines used in an intersect-line apparatus, and Fig. 1B is a sectional view of the dielectric lines shown in Fig. 1A. In Figs. 1A and 1B, the intersect-line apparatus has two conductor plates 1 and 2 and a dielectric strip 3 inserted between the two plates 1 and 2. Fig. 2A illustrates the electromagnetic distribution in the LSM 01 mode, while Fig. 2B illustrates the electromagnetic distribution in the LSE 01 mode. In Figs. 2A and 2B, the solid lines indicate the electric-field distribution, while the broken lines indicate the magnetic-field distribution. Fig. 3A is a partial perspective view of the essential portion of the intersect-line apparatus (upper and lower conductor plates 1 and 2 are not shown), and Fig. 3B is a sectional view of the essential portion shown in Fig. 3A. A dielectric resonator 4 resonating in the HE 111 mode is provided between the conductor plates 1 and 2, and four dielectric strips 3a through 3d are disposed around the dielectric resonator 4 in such a manner that the adjacent dielectric strips are spaced from each other at 90°. Moreover, a mode suppressor 5 for suppressing the propagation of the LSE 01 mode is provided at the end of each of the dielectric strips 3a through 3d that is closer to the dielectric resonator 4. The mode suppressor 5 is formed, as shown in Fig. 3B, by providing a conductor member within each of the dielectric strips 3a through 3d in directions parallel to the dielectric strips 3a through 3d and perpendicular to the conductor plates 1 and 2, and inhibits the LSE mode signals from propagating in the dielectric strips 3a through 3d. Fig. 4 illustrates an example of excitation modes of the dielectric resonator 4. In Fig. 4, the solid lines indicate the electric field, while the broken lines represent the magnetic field. In this example, the dielectric resonator 4 is excited in the HE 111 mode, and the resonant frequency is tuned to a frequency band of an electromagnetic wave to propagate in the dielectric lines. Accordingly, the dielectric resonator 4 is magnetically coupled to the LSM 01 mode or electrically coupled to the LSE 01 mode of an adjacent dielectric line. In this embodiment, however, the LSE 01 mode is treated as an unwanted mode, as described below. The dielectric resonator 4 is designed with the following conditions in order to resonate in the HE 111 mode at a frequency of 60 GHz. More specifically, in forming a dielectric material having a relative dielectric constant εr of 2.04 into a cylindrical dielectric resonator, the dimensions of the dielectric resonator are determined as follows. The height of the dielectric material shall be indicated by h, and the diameter shall be represented by D. When the height h is 2.25 mm, the diameter D is set to be 2.8 mm. Moreover, when the height h is 2.2 mm, the diameter D is set to be 3.0 mm. If the diameter D is determined to be 4.9 mm when the height h is 2.25 mm, the dielectric resonator 4 resonates in the TE 011 mode. If the diameter D is determined to be 5.2 mm when the height h is 2.2 mm, the dielectric resonator 4 resonates in the TE 011 mode. Fig. 5 illustrates the coupling state between the individual dielectric strips 3a through 3d and the dielectric resonator 4. Fig. 6 illustrates the coupling state between the dielectric strips 3a through 3d and the dielectric resonator 4 particularly by referring to the electric-field components. An electromagnetic wave in the LSM 01 mode is incident on the dielectric strip 3a from a port #1, as illustrated in Figs. 5 and 6A, so that the dielectric strip 3a is magnetically coupled to the dielectric resonator 4, which is then excited in the HE 111 mode. The dielectric resonator 4 is then magnetically coupled to the dielectric strip 3c, thereby outputting an electromagnetic wave in the LSM 01 mode from a port #3. At this time, an electromagnetic wave in the LSE 01 mode is induced to propagate in the dielectric strips 3b and 3d. As illustrated in Fig. 6A, however, the LSE mode suppressors 5 provided for the dielectric strips 3b and 3d suppress the LSE 01 mode signals from reaching ports #2 and #4, respectively. Conversely, when an electromagnetic wave in the LSM 01 mode is incident on the dielectric strip 3b from the port #2, as shown in Fig. 6B, the dielectric strip 3b is magnetically coupled to the dielectric resonator 4, which is then excited in the HE 111 mode. The dielectric resonator 4 is then magnetically coupled to the dielectric strip 3d, thereby outputting an electromagnetic wave in the LSM 01 mode from the port #4. At this time, an electromagnetic wave in the LSE 01 mode is induced to propagate in the dielectric strips 3a and 3c. The LSE mode suppressors 5 provided for the dielectric strips 3a and 3c inhibit the LSE 01 mode signals, as illustrated in Fig. 6B, from reaching the ports #1 and #3, respectively. In the embodiment shown in Fig. 6A and 6B, the adjacent dielectric strips 3a through 3d are spaced from each other at 90°. Even a slight amount of displacement of the angle between the adjacent dielectric strips from 90° causes leakage of the LEM 01 mode into the intersecting line, thereby lowering the isolation between the intersecting lines. However, the angle between the adjacent dielectric strips 3a through 3d may be displaced from 90° as long as the resulting isolation is negligible. Moreover, a tubular HE 111 -mode dielectric resonator may be used, which is operated in a manner similar to the above cylindrical HE 111 -mode dielectric resonator. Further, the end faces of the dielectric strips should be placed symmetrically with respect to the direction in which electromagnetic waves propagating in the dielectric strips are headed. Namely, the end faces of the dielectric strips may be configured in any shape as long as signals are effectively transmitted from the dielectric strip 3a to the dielectric strip 3c via the dielectric resonator 4 (or in the reverse direction) and from the dielectric strip 3b to the dielectric strip 3d via the dielectric resonator 4 (or in the reverse direction). The dielectric strips may be bent as required. In short, it is only essential that the end faces of the dielectric strips 3a, 3b, 3c and 3d opposedly face the dielectric resonator 4 in such a manner that the signals propagating in the dielectric strips 3a and 3c do not interfere with the signals propagating in the dielectric strips 3b and 3d. The configuration of an intersect-line apparatus according to a second embodiment of the present invention is explained below with reference to the exploded perspective view of Fig. 7. The second embodiment differs from the first embodiment in that the intersect-line apparatus is formed by dielectric lines in which signals are transmitted only in a single mode, i.e., in the LSM 01 mode, thereby eliminating the need to provide LSE-mode suppressors. More specifically, grooves 6 for receiving the dielectric strips 3a through 3d are formed, as illustrated in Fig. 7, in the internal surfaces of the upper and lower conductor plates 1 and 2. Thus, the spacing between the conductor plates 1 and 2 in a non-propagating region outside the area where the dielectric strips 3a through 3d are provided is made narrower than the. spacing between the conductor plates 1 and 2 in a propagating region where the dielectric strips 3a through 3d are placed. The spacing in the non-propagating region is indicated by h1, while the spacing in the propagating region is represented by h2. The dielectric constant of the dielectric strips 3a through 3d is indicated by ε1, while the dielectric constant of a dielectric member (normally air) between the conductor plates 1 and 2 in the non-propagating region is represented by ε2. Then, the respective spacings h1 and h2 and the respective dielectric constants ε1 and ε2 are determined so that the cut-off frequency of the LSM 01 mode propagating in the propagating region is lower than the cut-off frequency of the LSE 01 mode, and that the LSM 01 mode and the LSE 01 mode electromagnetic waves are blocked in the non-propagating region. Thus, dielectric lines in which only single-mode electromagnetic waves, i.e., the LSM 01 -mode electromagnetic waves, propagate are constructed. Accordingly, in Fig. 7, when an LSM 01 -mode electromagnetic wave propagates in the dielectric strips 3a and 3c via the dielectric resonator 4, an LSE 01 -mode electromagnetic wave does not propagate in the dielectric strips 3b and 3d. Similarly, when an LSM 01 -mode electromagnetic wave propagates in the dielectric strips 3b and 3d, an LSE 01 -mode electromagnetic wave does not propagate in the dielectric strips 3a and 3c. In the foregoing embodiments, the dielectric strips with end faces opposing the dielectric resonator are disposed linearly. It is only essential, however, that at least opposing portions of adjacent dielectric strips are spaced from each other substantially at 90°, and the portions other than the opposing portions may be bent to lead the dielectric strips to the exterior in any direction. Particularly in the second embodiment shown in Fig. 7, since only the single mode electromagnetic waves, the LSM 01 -mode electromagnetic waves, propagate in the dielectric lines, the mode conversion from the LSM 01 mode to the LSE 01 mode is prevented even though the radius of curvature of the bent portion is made small, thereby enabling transmission with only small losses. Fig. 8 is a plan view of an intersect-line apparatus according to a third embodiment of the present invention (the upper and lower conductor plates are not shown). Although in the foregoing embodiments, only a single dielectric resonator is used, a plurality of dielectric resonators may be used to form an intersect-line apparatus. In the third embodiment illustrated in Fig. 8, dielectric resonators 4a and 4b resonating in the HE mode are used. Dielectric strips 3b and 3d are disposed in the direction in which the dielectric resonators 4a and 4b are arranged, and dielectric strips 3a and 3c are located at 90° in the above direction to opposedly face the dielectric resonators 4a and 4b, respectively. Fig. 9 illustrates the coupling state between the dielectric strips 3a through 3d and the dielectric resonators 4a and 4b in the intersect-line apparatus shown in Fig. 8. For example, when an LSM 01 -mode electromagnetic wave is incident on the dielectric strip 3a from a port #1, as illustrated in Fig. 9A, the dielectric resonator 4a is excited in the HE 111 mode, which is magnetically coupled to the dielectric resonator 4b, thereby also exciting the dielectric resonator 4b in the HE 111 mode. The dielectric resonator 4b is then magnetically coupled to the dielectric strip 3c, thereby outputting an LSM 01 -mode electromagnetic wave to a port #3. At this time, LSE-mode suppressors 5 provided for the dielectric strips 3b and 3d suppress the LSE-mode signals from propagating in the dielectric strips 3b and 3d. Conversely, when an LSM 01 -mode electromagnetic wave is incident on the dielectric strip 3b from a port #2, as shown in Fig. 9B, the dielectric resonator 4a is excited in the HE 111 mode, which is magnetically coupled to the dielectric resonator 4b, thereby also exciting the dielectric resonator 4b in the HE 111 mode. The dielectric resonator 4b is magnetically coupled to the dielectric strip 3d, thereby outputting an LSM 01 -mode electromagnetic wave to a port #4. At this time, LSE-mode suppressors 5 provided for the dielectric strips 3a and 3c prevent the LSE 01 -mode signals from propagating in the dielectric strips 3a and 3c. In this manner, two-stage dielectric resonators intervene between the dielectric lines in each intersecting direction, thereby increasing the pass bandwidth characteristics. Fig. 10 is a plan view illustrating an intersect-line apparatus according to a fourth embodiment of the present invention (the upper and lower conductor plates are not shown). The fourth embodiment is different from the third embodiment illustrated in Figs. 8 and 9 in that the dielectric strip 3c faces the dielectric strip 3a with the dielectric resonator 4a therebetween. In the fourth embodiment, only a single dielectric resonator 4a is interposed between the ports #1 and #3, while the two dielectric resonators 4a and 4b are interposed between the ports #2 and #4. It is thus possible to differentiate the pass bandwidth characteristics of the dielectric lines in the intersecting directions. Fig. 11 is a plan view illustrating the configuration of an intersect-line apparatus according to a fifth embodiment of the present invention (the upper and lower conductor plates are not shown). Unlike the foregoing embodiments, in the fifth embodiment, a dielectric resonator 4 formed in an elliptical prism shape, which is not rotationally symmetrical, is used, and dielectric strips 3a and 3c are located along the longer axis, while dielectric strips 3b and 3d are positioned along the shorter axis. In this case, the resonant frequency generated when an electromagnetic wave is excited from the port #1 or #3 is different from the resonant frequency produced when an electromagnetic wave is excited from the port #2 or #4. By utilizing the above different resonant frequencies, transmission characteristics with only small losses can be obtained even though there is a comparatively great difference between the frequencies of the signals transmitted in the two intersecting lines. By using a cylindrical or tubular HE-mode dielectric resonator, as well as by the dielectric resonator formed in an elliptical prism shape in the fifth embodiment, the characteristics of the two intersecting lines may be differentiated by providing different gaps between the end faces of the dielectric strips and the dielectric resonator. For example, relatively large gaps are provided to deliberately increase transmission losses of the dielectric lines in either direction. As is seen from the foregoing description, the present invention offers the following advantages. An intersect-line apparatus having good isolation characteristics and small losses is constructed in the same plane with a simple structure. Moreover, by providing LSE-mode suppressors, the propagation of an LSE-mode signal in the 90°-spaced intersecting dielectric strips can be suppressed, thereby preventing mode conversion between the two intersecting dielectric lines. Thus, the two intersecting dielectric lines are used as independent (isolated) lines. Additionally, it is possible to prevent mode conversion between two intersecting dielectric lines without requiring to provide LSE-mode suppressors under certain conditions. Thus, the two intersecting dielectric lines are used as independent (isolated) lines.

Claims: An intersect-line apparatus comprising: two conductor plates (1, 2) disposed substantially parallel to each other; one HE-mode dielectric resonator (4; 4a, 4b) or a plurality of HE-mode dielectric resonators connected to each other disposed between said two conductor plates (1, 2); and four dielectric strips (3a to 3d) with end portions facing said HE-mode dielectric resonator (4; 4a, 4b) or a predetermined dielectric resonator of said plurality of dielectric resonators, the adjacent dielectric strips (3a to 3d) being spaced from each other at an angle of substantially 90 degrees. An intersect-line apparatus according to claim 1, wherein an LSE-mode suppressor (5) is provided for each of said four dielectric strips (3a to 3d). An intersect-line apparatus according to claim 1, wherein a spacing (h1) between said two conductor plates (1, 2) in a propagating region where said dielectric strips (3a to 3d) are disposed, a spacing (h2) between said two conductor plates (1, 2) in a non-propagating region outside the propagating region, a dielectric constant (ε1) of the propagating region, and a dielectric constant (ε2) of the non-propagating region are determined under conditions that a cut-off frequency of an LSM 01 -mode signal propagating in the propagating region is lower than a cut-off frequency of an LSE 01 -mode signal, and that electromagnetic waves in the LSM 01 mode and the LSE 01 mode are interrupted in the non-propagating region.

Inventors: NISHIDA HIROSHI, SAITOH ATSUSHI, TANIZAKI TORU, NISHIDA, HIROSHI, SAITOH, ATSUSHI, TANIZAKI, TORU
Applicants: MURATA MANUFACTURING CO, MURATA MANUFACTURING CO., LTD.
Application year: 1998
Main classification: H01P1
IPC codes: H01P7, H01P1, H01P3, H01P5