Radio frequency device

Abstract

A transition unit of a radio frequency device provides a transition between a planar differential pair transmission line and a hollow radio frequency waveguide. It comprises a substrate layer arrangement with a planar differential pair transmission line arranged on one or more surfaces of at least one substrate layer, whereby an end section of the differential pair transmission line is configured as a radio frequency signal transition pattern. It further comprises an end section of a waveguide that is attached to the substrate layer arrangement and that superposes the radio frequency signal transition pattern. The waveguide is directed perpendicular to the substrate layer arrangement. An open end of the end section of the waveguide is attached to a first outer surface or a second outer surface of the substrate layer arrangement. The transition pattern comprises open loop shaped end sections of a first and second transmission line segment.

Claims

1. A radio frequency device (1), comprising: a substrate layer arrangement (3) with a planar differential pair transmission line (7) arranged on one or more surfaces (10, 11) of at least one substrate layer (4, 5) of the substrate layer arrangement (3); and a transition unit (2) providing a transition between the planar differential pair transmission line (7) and a hollow radio frequency waveguide (15), comprising an end section (12) of the planar differential pair transmission line (7) that is configured as a radio frequency signal transition pattern (13), an end section (14) of the waveguide (15) for radio frequency electromagnetic waves that is attached to the substrate layer arrangement (3) and that superposes the radio frequency signal transition pattern (13), wherein the end section (14) of the waveguide (15) is directed perpendicular to the one or more surfaces (10, 11) of the substrate layer arrangement (3) with the planar differential pair transmission line (7), wherein an open end (17) of the end section (14) of the waveguide (15) is attached to a first outer surface (16) or a second outer surface (19) of the substrate layer arrangement (3), wherein the end section (12) of the planar differential pair transmission line (7) comprises a first end section (24) of a first transmission line segment (8) and a second end section (25) of a second transmission line segment (9) that are arranged at a distance towards each other in a direction perpendicular to the one or more surfaces (10, 11) of the substrate layer arrangement (3), and wherein the first end section (24) of the first transmission line segment (8) overlaps the second end section (25) of the second transmission line segment (9) across an overlapping section to form a capacitive coupling of the first and second end section (24, 25) that enhances an inductive coupling between the radio frequency electromagnetic wave within the waveguide (15) and the end section (12) of the planar differential pair transmission line (7).

2. The radio frequency device (1) according to claim 1, wherein the first and second transmission line segment (8, 9) each have a course which is curved at least in sections and runs towards each other to form the overlapping first and second end section (24, 25).

3. The radio frequency device (1) according to claim 1, wherein the first and second end sections (24, 25) of the first and second transmission line segments (8, 9) each form an open loop, wherein both open loops overlap each other to form the transition pattern (13).

4. The radio frequency device (1) according to claim 1, wherein a length of the overlapping first and second end section (24, 25) is less than ¼λ with λ being the wavelength of a radio frequency signal that is transmitted within the radio frequency device (1).

5. The radio frequency device (1) according to claim 1, wherein a length of the overlapping first and second end section (24, 25) is less than 1/10λ with λ being the wavelength of a radio frequency signal that is transmitted within the radio frequency device (1).

6. The radio frequency device (1) according to claim 1, wherein the first and second end section (24, 25) of the first and second transmission line segment (8, 9) is electroconductively connected to a bias voltage source.

7. The radio frequency device (1) according to claim 6, wherein the first and second end section (24, 25) of the first and second transmission line segment (8, 9) form a symmetric pattern with respect to a cross-section of the end section (14) of the waveguide (15), and wherein the electroconductive connection is positioned in a symmetry plane (28) with respect to the cross-section of the end section (14) of the waveguide (15) and perpendicular to the one or more surfaces (10, 11) of the substrate layer arrangement (3).

8. The radio frequency device (1) according to claim 1, wherein opposite to the end section (14) of the waveguide (15) a back cavity (18) is attached with an open end (21) of the back cavity (18) to the substrate layer arrangement (3), wherein the back cavity (18) prevents a part of a radio frequency signal emission that is emitted from the transition pattern (13) from leaking outside of the end section (14) of the waveguide (15).

9. The radio frequency device (1) according to claim 1, wherein the radio frequency device (1) comprises several transition units (2) arranged adjacent to each other.

10. The radio frequency device (1) according to claim 9, wherein opposite to the end section (14) of the waveguides (15) of the several transition units (2) a common back cavity (29) that extends along the several transition units (2) is arranged next to the substrate layer arrangement (3) with an open end (30) of the common back cavity (29) facing the substrate layer arrangement (3).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be more fully understood, and further features will become apparent, when reference is made to the following detailed description and the accompanying drawings. The drawings are merely representative and are not intended to limit the scope of the claims. In fact, those of ordinary skill in the art may appreciate upon reading the following specification and viewing the present drawings that various modifications and variations can be made thereto without deviating from the innovative concepts of the invention. Like parts depicted in the drawings are referred to by the same reference numerals.

[0023] FIG. 1 illustrates a perspective sectional view of a transition unit of a radio frequency device with an arrangement of two substrate layers with a planar differential pair transmission line arranged between facing surfaces of the substrate layers, with an end section of a hollow waveguide positioned at a top surface of a substrate layer arrangement comprising the two substrate layers, whereby an end section of the hollow waveguide superposes the radio frequency signal transition pattern of the planar differential pair transmission line, and with a back cavity opposingly attached to a back surface of the substrate layer arrangement,

[0024] FIG. 2 illustrates a sectional view along the line II-II of the transition unit shown in FIG. 1,

[0025] FIG. 3 illustrates a top view of an embodiment of the transition unit, whereby the end section of the respective differential pair transmission line is configured as an oval radio frequency signal transition pattern,

[0026] FIG. 4 illustrates a sectional view along the line IV-IV shown in FIG. 3,

[0027] FIG. 5 illustrates a top view of another embodiment of the transition unit, whereby the end section of the respective differential pair transmission line is configured as a rectangular radio frequency signal transition pattern,

[0028] FIG. 6 illustrates a sectional view along the line VI-VI shown in FIG. 5,

[0029] FIG. 7 illustrates a top view of yet another embodiment of the transition unit, whereby the end section of the respective differential pair transmission line is configured as a circular radio frequency signal transition pattern,

[0030] FIG. 8 illustrates a sectional view along the line VIII-VIII shown in FIG. 7,

[0031] FIG. 9 illustrates a perspective view of another embodiment of a radio frequency device with several transition units, whereby several hollow waveguides are arranged along a row and a common back cavity is arranged on the opposing side of the substrate layer arrangement, and

[0032] FIG. 10 illustrates a schematic top view of the embodiment shown in FIG. 9.

DETAILED DESCRIPTION

[0033] In FIGS. 1 and 2 a perspective sectional view of an exemplary part of a radio frequency device 1 with a transition unit 2 according to the present invention is shown. The radio frequency device 1 comprises a substrate layer arrangement 3 that comprises a first substrate layer 4 and a second substrate layer 5, each made of an electrically non-conducting material like e.g. glass. The first and second substrate layer 4, 5 are arranged parallel and at a distance towards each other. The volume between the first and second substrate layer 4, 5 is filled with a tunable dielectric material 6 like e.g. a liquid crystal material with variable and controllable dielectric properties. The volume between the first and second substrate layer 4, 5 can be segmented to allow for many small segments or chambers that are filled with the tunable dielectric material 6. The dielectric properties of the tunable dielectric material 6 can be controlled e.g. by applying a bias voltage to bias electrodes on opposite sides of the volume or of a small segment for which the dielectric properties of the tunable dielectric material are to be preset or modified.

[0034] A planar differential pair transmission line 7 with two parallel transmission line segments 8, 9 of an electrically conducting material is arranged on a first surface 10 of the first substrate layer 4 and on a second surface 11 of the second surface 5 of the substrate layer arrangement 3. The first surface 10 and the second surface 11 are facing each other and confine the volume between the first and second substrate layer 4, 5. The planar differential pair transmission line 7 runs into an end section 12 that is configured as a radio frequency signal transition pattern 13. The transition pattern 13 as viewed from a top view perpendicular to the first and second surface 10, 11 of the substrate layer arrangement 3 forms an open loop structure that is oval shaped within this embodiment. In FIG. 1 the first transmission line segment 8 is represented by a dashed line and the second transmission line segment 9 is represented by a dotted line. Both transmission line segments 8, 9 run parallel and with a distance towards each other into the end section 12 forming an overlapping transition pattern. A small deviation parallel to the first and second surface 10, 11 is shown for clarification only, as both transmission line segments 8, 9 exactly overlap within the end section 12.

[0035] An end section 14 of a hollow waveguide 15 made from an electroconductive material is also arranged on a first outer surface 16 of the substrate layer arrangement 3. An open end 17 of the end section 14 of the hollow waveguide 15 superposes the radio frequency signal transition pattern 13 of the end section 12 of the planar differential pair transmission line 7, as can be seen in FIG. 2. Thus, a radio frequency signal that is transmitted along the planar differential pair transmission line 7 towards the end section 12 will be emitted from the frequency signal transition pattern 13. A part of the emitted signal power will be directed through the open end 17 and into the hollow waveguide 15. Another part of the emitted signal power will be directed into an opposite direction.

[0036] Opposite to the end section 14 of the hollow waveguide 15 there is a back cavity 18 that is mounted onto a second outer surface 19 of the substrate layer arrangement 3, whereby the second outer surface 19 is opposite to the first outer surface 16 of the substrate layer arrangement 3. A distance between the second outer surface 19 of the substrate layer arrangement 3 and a back side 20 of the back cavity 18 that opposes the second outer surface 19 is larger than the distance between opposing parts of the circumferential line of a cross-section of an open end 21 of the back cavity 18, i.e. larger than a distance between opposing wall sections 22, 23 around the open end 21 of the back cavity 18.

[0037] A shape of the open end 21 of the back cavity 18 equals the shape of the open end 17 of the hollow waveguide 15. Furthermore, the open end 21 of the back cavity 18 is positioned opposing to the end section 14 of the hollow waveguide 15 in a manner as to fully superimpose the open end 17 of the hollow waveguide 15. A large part of the signal power that is directed into the direction of the back cavity 18 will be reflected and fed into the hollow waveguide 15. By adding the back cavity 18 to the transition unit 2, an unwanted leakage of radio frequency signal emission from the transition unit 2 can be significantly reduced.

[0038] FIGS. 3 to 8 show a part of a top view and a respective sectional view of three different embodiments of a transition unit 2 of the radio frequency device 1 that is designed according to the invention. FIGS. 3 and 4 illustrate an end section 12 of the planar differential pair transmission line 7 that forms an oval-shaped open loop transition pattern 13. A first end section 24 of the first transmission line segment 8 is shown with solid lines, whereas a second end section 25 of the second transmission line segment 9 is shown with dashed lines. A small deviation in a direction parallel to the first outer surface 16 is only for clarification purposes, as both first and second end section 24 and 25 exactly overlap each other within the transition pattern 13.

[0039] FIGS. 5 and 6 illustrate another embodiment of the transition unit 2 of a radio frequency device 1. The first and second end section 24, 25 of the respective first and second transmission line segment 8, 9 form a rectangular shaped open loop transition pattern 13. The distance between the first and second transmission line segment 8, 9 is larger than with the embodiment that is illustrated in FIGS. 3 and 4. However, it is also possible to arrange both the first and second transmission line segment 8, 9 in such a manner that they run with a smaller distance towards each other into the end section 12 of the planar differential pair transmission line 7 and the transition pattern 13 that is formed by the overlapping first and second end sections 24, 25.

[0040] FIGS. 7 and 8 illustrate yet another embodiment of the transition unit 2 with first and second end sections 24, 25 that form a circular shaped open loop transition pattern 13. Each of the first and second end section 24, 25 is electroconductively connected by a electroconductive line segment 26, 27 to a bias voltage source that is not shown in FIGS. 7 and 8. The electroconductive line segments 26, 27 are arranged along a symmetry plane 28 with respect to the cross-section of the end section 14 of the waveguide 15 and perpendicular to the one or more surfaces 10, 11, 16, 19 of the substrate layer arrangement 3. The open loop transition pattern 13 formed by the first and second end sections 24, 25 is also designed and arranged to be symmetric with respect to the symmetry plane 28.

[0041] FIGS. 9 and 10 illustrate yet another aspect of the radio frequency device 1 with several transition units 2 arranged along a straight line. Three hollow waveguides 15 are shown that represent a row of transition units 2 which might comprise more than three hollow waveguides 15. At an opposite side of the substrate layer arrangement 3 there is a common back cavity 29 that partially overlaps with the end sections 14 of the hollow waveguides 15, but extends over many or all end sections 14 of the hollow waveguides 15 that are aligned along the row. An open end 30 of the common back cavity 29 faces the substrate layer arrangement 3 and thus the several hollow waveguides 15 arranged at an opposite side of the substrate layer arrangement 3. Most part of a radio frequency signal emission that is emitted by the frequency signal transition pattern 13 of the planar differential pair transmission line 7 will be directed either into the first hollow waveguide 15 that is arranged on the first outer surface 16 of the substrate layer arrangement 3 or into the common hollow waveguide 29 that is arranged on the second outer surface 19 of the substrate layer arrangement 3 opposing the first hollow waveguide 15. The undesired leakage of radio frequency signal emission from the transition unit 2 will be significantly reduced.