Patent Application
20200373677
This disclosure is related to the field of using waveguides to transmit signals to a stripline antenna in a first signal direction and receive signals from a stripline antenna in a second signal direction.
Waveguides are used in many radio frequency (RF) applications for low-loss signal propagation. For high frequency applications in particular, waveguides may be preferred over coaxial transmission lines. In some applications, it may be desirable to use waveguides to transition to a stripline antenna. Stripline antennas may be used, individually or in antenna arrays, for various applications, such as high frequency radio communication.
In order for a waveguide to transition to a typical stripline feed for an antenna, multiple adapters are typically required. First, a waveguide-to-coax adapter transitions a waveguide to a coax. Second, a coax-to-microstrip adapter transitions a coax to a microstrip. Finally, the microstrip line may be transitioned to a stripline on an RF board for connection to a stripline antenna. Adapters associated with these transitions can be cost prohibitive at higher frequencies because such adapters are small and may be formed using high precision machining. Also, the size and weight of existing waveguide-to-coax transitions make them non-ideal for many applications.
In this disclosure, a low-loss waveguide fed stripline antenna apparatus is described. In an embodiment, a low-loss waveguide fed stripline antenna apparatus includes a substrate assembly having a first side and a second side. The apparatus further includes a waveguide antenna element positioned on the first side of the substrate assembly. The apparatus also includes a first reference ground plane positioned on the first side of the substrate assembly. The apparatus includes a microstrip line positioned within the substrate assembly and a stripline positioned within the substrate assembly and electrically connected to the microstrip line, the first reference ground plane overlapping the stripline. The apparatus further includes a second reference ground plane positioned on the second side of the substrate assembly and overlapping both the microstrip line and the stripline. The second reference ground plane is electrically shorted to the first reference ground plane. The apparatus also includes a stripline antenna element positioned on the second side of the substrate assembly and enclosed by the second reference ground plane.
In some embodiments, the apparatus includes a waveguide attached to the first side of the substrate assembly and enclosing the waveguide antenna element. In some embodiments, the waveguide is a circular waveguide. In some embodiments, the apparatus includes one or more substrates positioned between the waveguide antenna element and the microstrip line, where the microstrip line is proximity coupled to the waveguide antenna element. In some embodiments, the apparatus includes one or more substrates positioned between the stripline antenna element and the stripline, where the stripline is proximity coupled to the stripline antenna element. In some embodiments, the apparatus includes a slot defined within the waveguide antenna element. In some embodiments, the apparatus includes a slot defined within the stripline antenna element. In some embodiments, the apparatus includes one or more vias electrically shorting the first reference ground plane to the second reference ground plane. In some embodiments, the apparatus includes one or more electrical vias placed in proximity to the microstrip to stripline transition to perform impedance matching. In some embodiments, the waveguide antenna element and the first reference ground plane are positioned on a first substrate of the substrate assembly, the microstrip line and the stripline are positioned on a second substrate of the substrate assembly, and the second reference ground plane and the stripline antenna element are positioned on a third substrate of the substrate assembly.
In an embodiment, a method includes providing a waveguide antenna element and a first reference ground plane on a first substrate. The method further includes providing a microstrip line and a stripline on a second substrate, where the stripline is electrically connected to the microstrip line. The method also includes providing a second reference ground plane and a stripline antenna element on a third substrate. The method includes bonding the first substrate, second substrate, and third substrate together to form a substrate assembly having a first side and a second side, where the waveguide antenna element and the first reference ground plane are positioned on the first side, and where the second reference ground plane and the stripline antenna element are positioned on the second side.
In some embodiments, the method includes attaching a waveguide to the first side of the substrate assembly, the waveguide enclosing the waveguide antenna element. In some embodiments, the method includes positioning one or more additional substrates between the waveguide antenna element and the microstrip line, where the microstrip line is proximity coupled to the waveguide antenna element. In some embodiments, the method includes positioning one or more additional substrates between the stripline antenna element and the stripline, wherein the stripline is proximity coupled to the stripline antenna element. In some embodiments, the method includes providing one or more vias electrically shorting the first reference ground plane to the second reference ground plane. In some embodiments, the method includes providing one or more electrical vias placed in proximity to the microstrip to stripline transition to perform impedance matching. In some embodiments, providing the waveguide antenna element, the first reference ground plane, the microstrip line, the stripline, the second reference ground plane, and the stripline antenna element may include forming them using a subtractive process, an additive process, or a combination thereof. In some embodiments, the subtractive process includes laser etching, milling, wet etching, or a combination thereof, and the additive process includes printing, deposition, or a combination thereof.
In an embodiment, a method includes receiving a first time-varying electric field signal at a waveguide antenna element positioned on a first side of a substrate assembly, where the first time-varying electric field signal induces a current signal with circular behavior within the waveguide antenna element. The method further includes generating a current signal at a microstrip line via proximity coupling with to the waveguide antenna element. The method also includes generating a current signal at the stripline via electrically connecting to the microstrip line. The method includes generating a current signal at a stripline antenna element via proximity coupling to the stripline, where the current signal induces a second time-varying electric field signal.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the intention is to cover all modifications, equivalents and alternatives falling within the scope of the disclosure as defined by the appended claims.
As used herein, the terms “top,” “bottom,” “first,” and “second” can refer to relative directions or positions of features in the apparatus shown in the Figures. These terms, however, should be construed broadly to include apparatus having other orientations, such as inverted or inclined orientations where top/bottom, over/under, above/below, up/down, and left/right can be interchanged depending on the orientation.
Referring to
Referring to
The apparatus 100 may include a microstrip line 116 within the substrate assembly 102. The microstrip line 116 may be proximity coupled to the waveguide antenna element 110. In other words, the microstrip line 116 may be capacitively coupled with the waveguide antenna element 110 such that an electrical current within the waveguide antenna element 110 may induce an electrical current within the microstrip line 116.
Referring to
The first reference ground plane 114 and the second reference ground plane 134 may overlap along a portion of the substrate assembly 102. A stripline 118 may be positioned between the first reference ground plane 114 and the second reference ground plane 134 where they overlap. Thus, the first reference ground plane 114 and the second reference ground plane 134 may provide reference ground functions in order to enable the stripline 118 to perform.
The microstrip line 116 may be electrically connected to the stripline 118. A set of electrical vias 124 may be positioned proximate to a transition 126 between the microstrip line 116 and the stripline 118. The transition 126 may correspond to a region where the first reference ground plane 114 and the second reference ground plane 134 begin to overlap. The electrical vias 124 may be placed in proximity to and perform impedance matching functions between the microstrip line 116 and the stripline 118.
A stripline antenna element 130 may be positioned on the second side 106 of the substrate assembly 102. The stripline antenna element 130 may be a circular stripline antenna element and may include a slot 132 defined therein. The slot 132 may enable a current with circular behavior to be induced within the stripline antenna element 130 in response to a current at the stripline 118. The second reference ground plane 134 may enclose the stripline antenna element 130. By enclosing the stripline antenna element 130, the second reference ground plane 134 may capacitively couple with the stripline antenna element 130.
Referring to
As shown in
The second reference ground plane 134 and the stripline antenna element 130 may be positioned on the third substrate 206. The optional fourth substrate 208 may be for spacing purposes. Although not shown, additional substrates may also be included for spacing purposes. The electrical vias 122 may pass through each of the substrates 202-208 to electrically short the first reference ground plane 114 to the second reference ground plane 134. The substrates 202-208 may be joined together by one or more joining layers 210 (e.g., adhesive layers).
Operation of the apparatus 100 is described with reference to
Referring to
A benefit of the apparatus 100 is that the apparatus 100 may have a reduced size, weight, and cost in comparison to existing waveguide-to-coax adapters and further coax-to-stripline adapters. Further, the substrate assembly 102 may exhibit a lower profile as compared to existing adapters. In some embodiments, the apparatus 100 may operate when the first time-varying electric fields 402, 502 have frequencies of about 20 GHz. Other advantages may exist.
Referring to
The method 800 may further include providing a microstrip line and a stripline on a second substrate, where the stripline is electrically connected to the microstrip line, at 804. For example, the microstrip line 116 and the stripline 118 may be formed on the second substrate 204.
The method 800 may also include providing a second reference ground plane and a stripline antenna element on a third substrate, at 806. For example, the second reference ground plane 134 and a stripline antenna element 130 may be formed on the third substrate 206.
The method 800 may include bonding the first substrate, the second substrate, and the third substrate together to form a substrate assembly having a first side and a second side, where the waveguide antenna element and the first reference ground plane are positioned on the first side, and where the second reference ground plane and the stripline antenna element are positioned on the second side, at 808. For example, the first substrate 202, the second substrate 204, and the third substrate 206 may be bonded together to form the substrate assembly 102.
The method 800 may also optionally include positioning one or more additional substrates between the waveguide antenna element and the microstrip line, where the microstrip line is proximity coupled to the waveguide antenna element, at 810. For example, the one or more additional substrates 702 may be positioned between the waveguide antenna element 110 and the microstrip line 116.
The method 800 may also optionally include positioning one or more additional substrates between the stripline antenna element and the stripline, where the stripline is proximity coupled to the stripline antenna element, at 812. For example, the one or more additional substrates 704 may be positioned between the stripline antenna element 130 and the stripline 118.
The method 800 may include providing one or more vias electrically shorting the first reference ground plane to the second reference ground plane, at 814. For example, the one or more vias 122 may be formed and may electrically short the first reference ground plane 114 to the second reference ground plane 134.
The method 800 may further include attaching a waveguide to the first side of the substrate assembly, the waveguide enclosing the waveguide antenna element, at 816. For example, the waveguide 120 may be attached to the first side 104 of the substrate assembly 102.
The method 800 may further include providing one or more electrical vias placed in proximity to the microstrip to stripline transition to perform impedance matching functions between the microstrip line and the stripline, at 818. For example, the one or more vias 124 may be formed and may be electrically short the first reference ground plane 114 to the second reference ground plane 134.
In some embodiments of the method 800, providing the waveguide antenna element, the first reference ground plane, the microstrip line, the stripline, the second reference ground plane, and the stripline antenna element is performed using a subtractive process, an additive process, or a combination thereof. Further, the subtractive process may include laser etching, milling, wet etching, or a combination thereof, and the additive process may include printing, deposition, or a combination thereof.
Referring to
The method 900 may further include generating a current signal at a microstrip line proximity coupled to the waveguide antenna element, at 904. For example, the current signal 406 may be generated at the microstrip line 116, which may be proximity coupled to the waveguide antenna element 110.
The method 900 may also include receiving the current signal at a stripline electrically connected to the microstrip line, at 906. For example, the current signal 406 may be received at the stripline 118 electrically connected to the microstrip line 116.
The method 900 may include generating a current signal with circular behavior at a stripline antenna element proximity coupled to the stripline, where the current signal induces a second time-varying electric field, at 908. For example, the current signal 422 may be generated at the stripline antenna element 130, which may be proximity coupled to the stripline 118, and the current signal 422 may induce the second time-varying electric field 412. Thus, the method 900 may be used for transmitting signals to the stripline antenna element 130 with the waveguide 120.
The method 1000 may further include generating a current signal at a stripline proximity coupled to the stripline antenna element, at 1004. For example, the current signal 506 may be generated at the stripline 118, which may be proximity coupled to the stripline antenna element 130.
The method 1000 may also include receiving the current signal at a microstrip line electrically connected to the stripline, at 1006. For example, the current signal 506 may be received at the microstrip line 116, which may be electrically connected to the stripline 118.
The method 1000 may include generating a current signal with circular behavior at a waveguide antenna element proximity coupled to the microstrip line, where the current signal induces a second time-varying electric field for use within a waveguide, at 1008. For example, the current signal 522 may be generated at the waveguide antenna element 110, which may be proximity coupled to the microstrip line 116, and the current signal 522 may induce the second time-varying electric field 512 for use within the waveguide 120.
Although this disclosure has been described in terms of certain embodiments, other embodiments that are apparent to those of ordinary skill in the art, including embodiments that do not provide all of the features and advantages set forth herein, are also within the scope of this disclosure. Accordingly, the scope of the present disclosure is defined only by reference to the appended claims and equivalents thereof.
