Electromagnetic waveguide that can be mounted on a substrate

Description

TECHNICAL FIELD

[0001] The disclosure relates generally to electromagnetic waveguides and more particularly to dielectric waveguide components that are mountable on a substrate.BACKGROUND

[0002] Electromagnetic waveguides generally comprise a metallized conduit that defines boundaries within which the propagation of energy is constrained. Dielectric filled waveguides are often used for higher frequency applications, like microwaves. The geometry of the waveguide affects characteristics of the waveguide like impedance, cutoff frequency and propagation mode. Waveguides can be configured as couplers, polarizers, and filters among other circuit elements in small-scale radio frequency (RF) and microwave systems. These and other waveguide systems often require mounting of a waveguide component on a printed circuit board (PCB) for transitioning to coplanar, microstrip, stripline or other impedance controlled transmission lines. To facilitate such integration, microstrip transmission lines sometimes include a widening apron that forms a transition for interfacing with the waveguide. It's also known to provide a tapered spacing between conductive posts in substrate integrated waveguides (SIW) to form a narrowing transition for interfacing with a coplanar transmission line. The transition interface between waveguide components and impedance controlled transmission lines however tends to be a source of impedance mismatch or reduced bandwidth and may require increased component size.

[0003] EP0859423A1 provides a dielectric filter (21) and a dielectric duplexer. At both ends of an insulating substrate (11), lead electrodes (12b) are formed. TE-mode dielectric resonators (1a and 1b) connected in series with electrically conductive adhesive such as solder are secured to the substrate (11) again with electrically conductive adhesive. An input and output electrode (2b) of the resonators (1a and 1b) is connected to a lead electrode (12b) with electrically conductive adhesive.

[0004] US 2016 / 0308264 A1 describes an RF dielectric waveguide duplexer filter module with antenna and lower and upper Tx and Rx signal transmission blocks of dielectric material attached together in a side-byside and stacked relationship. The blocks are covered with conductive material. Antenna and Tx and Rx input / outputs are defined at opposite ends of the filter module. RF signal transmission windows define direct coupling RF signal transmission paths between the antenna and the Tx and Rx blocks and between the lower and upper Tx and Rx blocks. One or more bridges of dielectric material on the lower Tx and Rx blocks define inductive cross-coupling Tx and Rx signal transmission paths. The Tx signal is transmitted only in the direction of the antenna block or between the upper and lower Tx blocks. The Rx signal is transmitted only in the direction of the Rx RF signal input / output or between the upper and lower Rx blocks.

[0005] JP2003069307A discloses a waveguide type filter where a capacitive window or an inductive window comprising a plurality of through- conductors is formed in a dielectric board 1 and spaces demarcated by the capacitive window or the inductive window respectively act like resonators.

[0006] It is the object of the present invention to provide an improved electromagnetic waveguide and an improved electromagnetic waveguide component.

[0007] The object is solved by the subject matter of the independent claims which define the present invention. Preferred embodiments of the present invention are defined by the dependent claims.

[0008] The objects, features and advantages of the present disclosure will become more fully apparent to those of ordinary skill in the art upon careful consideration of the following Detailed Description and the appended claims in conjunction with the accompanying drawings described below.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a top perspective view of a waveguide. FIG. 2 is a bottom perspective view of the waveguide in FIG. 1. FIGS. 3-7 show various waveguide implementations. FIG. 8 is a perspective view of a waveguide mounted on a host device. FIG. 9 is a perspective view of a portion of a host device. FIG. 10 illustrates electric field strength of a waveguide mounted on a host device. DETAILED DESCRIPTION

[0010] The present disclosure relates generally to electromagnetic waveguides mountable on a substrate like a printed circuit board (PCB) as described further herein. Such waveguides can be configured as a coupler, a polarizer, resonator, or filter among other electrical components for use in small-scale radio frequency (RF) systems or subassemblies. The term "radio frequency" as used herein includes microwaves.

[0011] The waveguide generally comprises a dielectric substrate, also referred to herein as a dielectric, having at least partially conductive portions that define boundaries within which propagating radio frequency energy is confined. The dielectric can comprise a ceramic, glass, or plastic among other materials and compositions having suitable permittivity and other characteristics. The conductive portions can be metallized surfaces of the dielectric substrate formed by selectively applying metal or other conductive material on portions of the dielectric substrate. The metal can be a base metal, precious metal, metal alloy or some other conductive material. Metals can be applied by sputtering, plating or other known or future deposition processes. The conductive material can also be conductive sheet material layered onto the dielectric.

[0012] Characteristics of the waveguide depend on its geometry as well as dielectric material properties. For example the cutoff frequency is a function of spacing between the side conductors, i.e., a width of the waveguide, dielectric constant of the substrate material, and impedance is a function of the spacing or height between the conductors on the upper and lower surfaces of the waveguide.

[0013] One such waveguide is a transverse electric (TE) mode waveguide. In FIGS. 1, 2 and 8, a rectangular waveguide 100 comprises a dielectric 110 having a cuboid shape. More generally however the dielectric substrate and hence the waveguide can have other shapes, like cubic or cylindrical shapes. One of the conductive surfaces of the waveguide can be a ground plane mountable on a printed circuit board (PCB) of a host device as described herein.

[0014] In FIG. 1, the waveguide comprises a conductor 122 adjacent a top surface of the dielectric 110. In FIG. 2, the waveguide includes a conductor 124 adjacent a bottom surface of the dielectric 110. In some implementations, the conductor 124 is a ground plane. Generally, the conductor 122 is electrically coupled to the conductor 124 by a first side conductor adjacent a first side surface portion of the dielectric and by a second side conductor adjacent a second side surface portion of the dielectric. In other implementations, the conductors 122 and 124 can have other shapes or structures, e.g., metallic screens among others, to constrain the radio frequency energy.

[0015] The first and second side conductors of the waveguide can be implemented in any one of many different forms. In FIGS. 1, 2 and 6, the first and second side conductors are metallized surfaces 126 and 128 disposed on and covering substantially all of the outer surfaces of corresponding side wall portions of the dielectric. The conductive surfaces 126 and 128 interconnect the conductor 122 and the ground plane 124. In other implementations, however, the first and second side conductors do not cover the entire side wall portions of the dielectric. In FIG. 3, the first and second side conductors each comprise a metallized slot 131 and 132 disposed on outer surface portions of corresponding dielectric side walls. The conductive slots 131 and 132 interconnect the conductor 122 and the ground plane. In FIG. 4, the first and second side conductors comprise a corresponding plurality of metallized cylindrical vias 133 and 134 extending through openings in the dielectric adjacent corresponding side walls of the dielectric. The conductive vias 133 and 134 interconnect the conductors on the upper and lower surfaces of the dielectric. In FIG. 5, the first and second side conductors comprise a corresponding plurality of metallized semi-cylindrical castellations 135 and 136 formed on an outer surface of the dielectric side walls. The conductive castellations 135 and 136 interconnect the conductors on the upper and lower surface of the dielectric. In other implementations, the first and second side conductors can be other than sheet like conductors to constrain radio frequency energy. For example, the conductive materials can be implemented as metallic screens, or meshes or other structures.

[0016] The waveguide also comprises a conductive excitation member at one or both ends thereof. In some implementations, the signal is introduced at an input of the waveguide and extracted at an output of the waveguide. Generally, the excitation member is electrically coupled to the conductor and is disposed through or across a portion of the dielectric at or near an end surface of the dielectric that is devoid of conductive material, wherein portions of the end surface, on opposite sides of the conductive excitation member, are devoid of conductive material. The excitation member also includes a host interface electrically isolated from the ground plane and connectable to a transmission line on a host device.

[0017] In FIGS. 1 and 2, a conductive excitation member 140 is electrically coupled to the conductor 122 and includes a semi-cylindrical shaped castellation 142 disposed across the first end surface portion 112 of the dielectric. In other embodiments, the castellation 142 can have other shapes and need not be located on the end surface of the dielectric. For example, the castellation can have a cylindrical shape and be located in an opening through the dielectric spaced inwardly from the end surface 112. FIG. 2 shows dielectric portions 111 and 113 on opposite sides of the excitation member 140 devoid of conductive material. In FIG. 2, the excitation member 140 includes a host interface embodied as a flange 144 extending therefrom for integration with the host. The host interface flange is separated and electrically isolated from the ground plane 124 by a dielectric portion 146. An impedance of the transition is a function of the gap exposing the dielectric portion 146 between the outermost portion of the host interface flange 144 and the ground plane 124. In FIG. 2, the host interface flange 144 is coplanar with the ground plane 124. In other implementations however the host interface can have other shapes and spatial orientations and configurations to accommodate a complementary non-planar interface on a host device.

[0018] In some implementations, the waveguide includes one or more lateral conductors interconnecting the conductive member and the ground plane. The one or more lateral conductors are disposed on or near the same end surface portion of the dielectric where the conductive excitation member is located, wherein at least a portion of the first end surface portion of the dielectric is devoid of conductive material between the one or more lateral conductors and the conductive excitation member. An input impedance of the waveguide is a function of the one or more lateral conductors and the size of the excitation member. In implementations including first and second lateral conductor, the conductive excitation member can be located between the first and second lateral conductors. In FIGS. 1-5, the waveguide includes lateral conductive material 150 and 152 disposed on corresponding corners of the waveguide. In FIG. 6, the lateral conductive material corresponds to conductive material 126 and 128 on the side surfaces of the dielectric, wherein the end surface portion 112 of the dielectric is devoid of conductive material. In FIG. 7, the waveguide includes only a single lateral conductive member or material 150 disposed on a corner of the waveguide. In the illustrated embodiments, the lateral conductive material is disposed on an outer surface of the dielectric. In other embodiments, however, the lateral conductive materials may be castellations formed in or on through-holes located inwardly of an outermost surface or surfaces of the dielectric.

[0019] In FIG. 8, a waveguide 100 is mounted on a substrate 200, which may be a printed circuit board (PCB) or other component of a host device or subassembly. FIGS. 8 and 9 show a PCB substrate comprising conductive transmission line portions 202 and 204 and ground plane 206 formed thereon. The transmission line can be a microstrip, stripline, coplanar waveguide trace or other transmission structure. The conductive excitation members of the waveguide are electrically coupled to corresponding transmission lines and the ground plane of the waveguide is electrically coupled to the ground plane of the substrate. In FIG. 8, the conductive excitation member 140 and particularly the host interface flange 144 thereof is electrically coupled to the transmission line 202. The ground plane 124 on the underside of the waveguide is shown coupled to the ground plane 206 of the substrate. The waveguide is a surface-mount component that can be mounted on the substrate by reflow soldering or other known or future affixation processes. Alternatively, the ground plane 124 can have though-hole contacts that are disposed in, and soldered to, corresponding openings in the substrate.

[0020] FIG. 10 illustrates the magnitude of the TE mode electric field inside of a rectangular waveguide mounted on a host substrate with microstrip transmission line feeds.

[0021] While the present disclosure and what is presently considered to be the best mode thereof has been described in a manner establishing possession by the inventors and enabling those of ordinary skill in the art to make and use the same, it will be understood and appreciated that equivalents of the exemplary embodiments disclosed herein exist, and that myriad modifications and variations may be made thereto, within the scope of the appended claims.

Claims

1. An electromagnetic waveguide (100) comprising: a dielectric (110) having an upper surface (122), a lower surface (124), opposite side surfaces (126, 128), a first end surface (112) and a second end surface opposite the first end surface (112), the first end surface (112) and the second end surface located between the opposite side surfaces (126, 128); a conductive material adjacent the upper (122), the lower (124) and the opposite side surfaces (126, 128) of the dielectric (110), wherein the first end surface (112) of the dielectric (110) is devoid of the conductive material; a first conductive excitation member (140) electrically coupled to the conductive material on the upper surface (122) of the dielectric (110) and extending to the lower surface (124) of the dielectric (110) at or near the first end surface (112) of the dielectric (110), the first conductive excitation member (140) having a first host interface (144), the first host interface (144) separated and electrically isolated from the conductive material adjacent the lower surface (124) of the dielectric (110).

2. The waveguide (100) of Claim 1 is a transverse electric, TE, mode waveguide.

3. The waveguide (100) of one of Claims 1 or 2 is a surface-mount component and the conductive material on the lower surface (124) of the dielectric (110) is a ground plane.

4. The waveguide (100) of Claim 3, wherein the first host interface (144) is substantially coplanar with the ground plane.

5. The waveguide (100) of Claim 4, wherein the first host interface (144) is a flange extending from the first conductive excitation member (140), the first host interface flange spaced apart from the ground plane.

6. The waveguide (100) of Claim 2 further comprising a first lateral conductive material (150) interconnecting the conductive materials adjacent the upper and lower surfaces (122, 124) of the dielectric (110), the first lateral conductive material (150) disposed on a first corner of the dielectric (110), the first corner between the first end surface (112) and one of the side surfaces (126, 128) of the dielectric (110).

7. The waveguide (100) of Claim 6 further comprising a second lateral conductive material (152) interconnecting the conductive materials on the upper and lower surfaces (122, 124) of the dielectric (110), the second lateral conductive material (152) disposed on a second corner of the dielectric (110), the second corner between the first end surface (112) and the other one of the side surfaces (126, 128) of the dielectric (110), the first conductive excitation member (140) located between the first and second lateral conductive members (150, 152).

8. The waveguide (100) of one of Claims 1 to 7 further comprising: a second conductive excitation member electrically coupled to the conductive material on the upper surface (122) of the dielectric (110) and extending to the lower surface (124) of the dielectric (110) at or near the second end surface of the dielectric (110), wherein the second end surface of the dielectric is devoid of conductive material, the second conductive excitation member having a second host interface, the second host interface separated and electrically isolated from the conductive material adjacent the lower surface (124) of the dielectric (110).

9. The waveguide (100) of Claim 2, the conductive material adjacent the first side surface (126) of the dielectric interconnecting the conductive material on the upper and lower surfaces (122, 124) of the dielectric (110), and the conductive material adjacent the second side surface (128) of the dielectric (110) interconnecting the conductive material adjacent the upper and lower surfaces (122, 124) of the dielectric (110), the end surface of the dielectric (110) located between the first and second side surfaces (126, 128) of the dielectric (110); and / or the conductive material on the first and second side surfaces (126, 128) of the dielectric (110) comprising any one or more of a metallized slot, a metallized via, a metallized surface, or a metallized castellation.

10. An electromagnetic waveguide component (100) comprising: a dielectric (110); a conductive material (122) on a first surface of the dielectric (110); a ground plane (124) on a second surface of the dielectric (110), the seconad surface opposite the first surface; a conductive material (126) on a first side surface of the dielectric (110) interconnecting the ground plane (124) and the conductive material (122) on the first surface of the dielectric (110); a conductive material (126) on a second side surface of the dielectric (110) interconnecting the ground plane (124) and the conductive material (122) on the first surface of the dielectric (110), the second side surface opposite the first side surface; a first conductive excitation member (140) disposed between the first and second surfaces of the dielectric (110) on or near a first end surface (112) of the dielectric (110), the first conductive excitation member (140) electrically coupled to the conductive material (122) disposed on the first surface of the dielectric (110), the first conductive excitation member (140) having a first flange (144) substantially coplanar with the ground plane (124), the first end surface (112) of the dielectric (110) located between the first side surface (126) and the second side surface of the dielectric (110), and being devoid of conductive material on opposite sides of the first conductive excitation member (140), and a first portion (146) of the dielectric (110) separating and electrically isolating the first flange (144) from the ground plane (124).

11. The waveguide (100) of Claim 10 is a transverse electric mode, TE, waveguide; or further comprising a first lateral conductive material (150) interconnecting the conductive material (122) on the first surface of the dielectric (110) and the ground plane (124), the first lateral conductive material (150) disposed on a first corner of the dielectric (110) between the first end surface (112) and the first side surface of the dielectric (110).

12. The waveguide (100) of Claim 11, further comprising a second lateral conductive material (152) interconnecting the conductive material (122) and the ground plane (124), the second lateral conductive material (152) disposed on a first corner of the dielectric (110) between the first end surface (112) and the second side surface of the dielectric (110), the first conductive excitation member (140) located between the first and second lateral conductive materials (150, 152).

13. The waveguide (100) of Claim 11, wherein the first portion (146) of the dielectric (110) between the first flange (144) and the ground plane (124) is devoid of conductive material.

14. The waveguide (100) of Claim 11, further comprising: a second conductive excitation member disposed between the first and second surfaces of the dielectric (110) on or near a second end surface of the dielectric (110), the second conductive excitation member electrically coupled to the conductive material (122) disposed on the first surface of the dielectric (110), the second conductive excitation member having a second flange substantially coplanar with the ground plane (124), the second end surface of the dielectric (110) devoid of conductive material on opposite sides of the second conductive excitation member, and a second portion of the dielectric (110) separating and electrically isolating the second flange from the ground plane (124).

15. The waveguide (100) of Claim 11, wherein: the waveguide (100) is a surface-mount component; and / or the conductive material on each of the first and second side surfaces of the dielectric (110) comprises one or more of a metallized slot, a metallized via, a metallized surface, or a metallized castellation.