Phased antenna arrays use multiple phase shifting elements when receiving and emitting electromagnetic energy. The different phase shifting elements shift the phase of signals passing through the phase shifting elements by different magnitudes to form and steer at least one antenna beam of the phased antenna array. In certain implementations, to provide adequate gain, the antenna arrays can include thousands of phase shifting elements to adequately steer the beam over a desired frequency range. The amount of power travelling through the many phase shifting elements can cause thermal management issues. To thermally manage the system, passive elements like ferrite phase shifters can be used because ferrite phase shifters offer a low insertion loss and low design complexity. Also, waveguide non-reciprocal ferrite phase shifters offer a lower complexity and lower insertion loss than other ferrite phase shifter types. However, ferrite phase shifters mounted within housings designed to fit within a phased array are fabricated according to tight tolerances which make the ferrite phase shifters expensive to fabricate. Also, Broadband ferrite phase shifters are mounted within housings that are too large for the spacing of elements in a phased antenna array
Systems and methods for an injection molded phase shifter are provided. In at least one embodiment, a method for fabricating a phase shifter comprises fabricating a ferrite element with a first end and a second end, wherein electromagnetic energy propagating through the ferrite element propagates between the first end and the second end; placing the ferrite element within a waveguide mold; and injecting a liquefied dielectric into the waveguide mold, wherein the liquefied dielectric hardens to form a first solid dielectric layer and a second solid dielectric layer that abut against out-of-plane surfaces of the ferrite element, wherein the first solid dielectric layer and the second solid dielectric layer have a first dielectric end that corresponds to the first end and a second dielectric end that corresponds to the second end. The method further comprises exposing in-plane surfaces of the ferrite element, wherein the in-plane surfaces extend longitudinally between the first end and the second end and are orthogonal to the out-of-plane surfaces that extend longitudinally between the first end and the second end; masking surfaces through which electromagnetic energy is emitted into and transmitted from the phase shifter; and plating the exposed surfaces of the phase shifter.
Understanding that the drawings depict only exemplary embodiments and are not therefore to be considered limiting in scope, the exemplary embodiments will be described with additional specificity and detail through the use of the accompanying drawings, in which:
In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize specific features relevant to the exemplary embodiments.
In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific illustrative embodiments. However, it is to be understood that other embodiments may be utilized and that logical, mechanical, and electrical changes may be made. Furthermore, the method presented in the drawing figures and the specification is not to be construed as limiting the order in which the individual steps may be performed. The following detailed description is, therefore, not to e taken in a limiting sense.
Embodiments of the present invention address the problems posed by the size and expense of phase shifters using ferrite elements. As disclosed herein, phase shifters containing ferrite elements can be fabricated using an injection molding process that results in a ferrite element that is both smaller and less expensive to fabricate. For example, a ferrite element is placed within a mold, the mold is injected with a dielectric and when the dielectric is sufficiently hardened, the mold is removed. The ferrite element and the dielectric are then shaped to expose surfaces of the ferrite element and the ferrite element and dielectric are coated in a metal layer, which metal layer forms a waveguide enclosure, where the waveguide enclosure is in contact with the exposed surfaces of the ferrite element.
As electromagnetic energy propagates through the waveguide enclosure 108, the electromagnetic energy propagates longitudinally through the ferrite element 102 between a first end 110 and a second end 112 of the ferrite element 102. During the propagation, magnetic fields aligned with an H-plane 114 and electric fields aligned with an E-plane 116 propagate within the ferrite element 102 within the waveguide enclosure 108. The H-plane 114 and the E-plane 116 are orthogonal to one another. Further, the H-plane 114 is aligned with the longitudinal direction of propagation within the waveguide enclosure 108. As described below, the surfaces of the components within the phase shifter segment 100 are referred to as in-plane surfaces or out-of-plane surfaces. An in-plane surface is a surface of a component that is parallel to the H-plane 114. An out-of-plane surface is a surface of a component that is perpendicular to the H-plane 114 but aligned with the direction of propagation
As stated earlier, the ferrite element 102 is layered between a first solid dielectric layer 104 and a second solid dielectric layer 105. The first solid dielectric layer 104 and the second solid dielectric layer 105 are formed against surfaces of the ferrite element 102 in a manner that inhibits the formation of air gaps between the first solid dielectric layer 104 and the second solid dielectric layer 105. In certain implementations, the ferrite element 102 has a rectangular (e.g., square) cross-section and consists of four surfaces that extend longitudinally between the first end 110 and the second end 112 of the ferrite element 102. The four surfaces include two in-plane surfaces that are opposite one another and two out-of-plane surfaces that are opposite one another and orthogonal to the in-plane surfaces. The in-plane surfaces of the ferrite element 102 are the two surfaces that abut against the inner surface of the waveguide enclosure 108 and the out-of-plane surfaces are the two surfaces that abut against the first solid dielectric layer 104 and the second solid dielectric layer 105. Accordingly, the first solid dielectric layer 104 and the second solid dielectric layer 105 abut against the out-of-plane surfaces of the ferrite element 102, where the in-plane surfaces of the ferrite element 102 are in contact with an inner surface of the waveguide enclosure 108. The first solid dielectric layer 104 and the second solid dielectric layer 105 are layers of solid dielectric that allow a greater bandwidth of signals to propagate within the ferrite element 102. Further, because the out-of-plane surfaces of the ferrite element 102 are bounded by material having a larger dielectric constant than air, the cross-sectional size of the phase shifter segment 100 can be smaller. For example, in certain implementations, the first solid dielectric layer 104 and the second solid dielectric layer 105 are formed from a solid material having a dielectric constant of 4 as opposed to the dielectric constant of air.
As described herein, the surfaces of the first solid dielectric layer 104 and the second solid dielectric layer 105 that are not in contact with the out-of-plane surfaces of the ferrite element 102 are in contact with the inner surface of the waveguide enclosure 108. The waveguide enclosure is formed around the first solid dielectric layer 104, the second solid dielectric layer 105, and the ferrite element 102 such that there are no air gaps between the inner surface of the waveguide enclosure and the first solid dielectric layer 104, the second solid dielectric layer 105, and the ferrite element 102. The waveguide enclosure 108 is formed around the first solid dielectric layer 104, the second solid dielectric layer 105, and the ferrite element 102 without air gaps to prevent the propagation and/or formation of signals having non-desired modes within the waveguide enclosure 108. Further, the waveguide enclosure 108 is a continuous layer of metal that encapsulates the combination of the ferrite element 102, the first solid dielectric layer 104, and the second solid dielectric layer 105.
In at least one embodiment, the ferrite element 102 includes a magnetizing winding 106 that extends from a first end 110 of the phase shifter segment 100 to a second end 112 of the phase shifter segment. The magnetizing winding 106 can be used to change the phase of a signal propagating through the ferrite element 102 by adjusting a current sent through the magnetizing winding to adjust the magnetization of the ferrite element 102. When an electrical pulse or electrical signal is conducted through the magnetizing winding 106, the current passing through the magnetizing winding 106 creates electric and magnetic fields within the waveguide enclosure 108. The strength of the electrical signal conducting through the magnetizing winding 106, determines the magnetic field of the ferrite element 102. In certain implementations, when only an electrical pulse or other electrical signal of short duration is conducted through the magnetizing winding, the ferrite element 102 is latched to a particular magnetization value. For example, an electrical pulse through the magnetizing winding 106 can produce a magnetization value that saturates the magnetization of the ferrite element 102. When the electrical pulse subsides, the ferrite element 102 remains magnetized at a remnant magnetization value. Values of magnetization lower than full remnance can be achieved by applying an electrical pulse of lower value, the remance can be controled from zero to full remnance by adjusting the value of the electrical pulse. Alternatively, a continuous electrical signal is passed through the ferrite element 102 where the magnetic field produced by the electrical signal determines the magnetization value of the ferrite element 102. In a further alternative implementation, when there is no magnetizing winding, the ferrite element 102 is magnetized by an external magnetic field.
In certain embodiments, when the ferrite element 102 is magnetized by a current or pulse conducted through the magnetizing winding 106, or an external magnetic field, the ferrite element 102 will shift the phase of electromagnetic waves propagating through the ferrite element 102. For example, a magnetized ferrite element 102 shifts the phase of electromagnetic signals as they propagate through the ferrite element 102 between the first end 110 and the second end 112 of the ferrite element 102. The amount that the ferrite element 102 is magnetized in conjunction with the length of the ferrite element 102 determines the amount of phase shift for the electromagnetic signals propagating within the ferrite element 102.
As described above, the phase shifter segment 100 is formed such that there are no air gaps between the ferrite element 102, the first solid dielectric layer 104, the second solid dielectric layer 105, and the waveguide enclosure 108. To form the components of the phase shifter segment 100 without the air gaps while limiting the cost of the phase shifter segment 100, the phase shifter segment 100 is formed using an injection molded process.
In a further implementation, a first mode suppressor 220 and a second mode suppressor 222 can be placed at opposite ends of the ferrite element 202. The first mode suppressor 220 and the second mode suppressor 222 are dielectric sections that prevent the development of higher order modes within the ferrite element 202. For example, the first mode suppressor 220 and the second mode suppressor 222 include portions of dielectric film that absorb RF energy that propagates at higher order modes within the ferrite element 202. In an alternative implementation, the shape of the ferrite element 202 can be altered to prevent the propagation of higher order modes such that the first mode suppressor 220 and the second mode suppressor 222 are not necessary.
In certain implementations, the phase shifter 200 includes a first coupling section 224 and a second coupling section 226, where the first coupling section 224 and the second coupling section 226 allow the phase shifter 200 to connect to other waveguide elements. For example, the first coupling section 224 and the second coupling section 226 allow the phase shifter 200 to connect to double ridge waveguides, rectangular waveguides, circular waveguides, and the like. coupling sections 224 and 226 further include coupling faces that are masked by masks 232 and 234 during the metallic plating. A coupling face is the face of a coupling section that is orthogonal to the direction of propagation for electromagnetic energy either away or towards the phase shifter. The coupling faces are masked by masks 232 and 234 to prevent the metallic plating from interfering with the propagation of electromagnetic waves either away or towards the phase shifter 200. Because the ferrite element 202 is exposed before metal plating, the metal plating bonds to the ferrite element 202 in such a way that there are no air gaps between the metal plating and the ferrite element 202. The lack of air gaps between the metal plating and the ferrite element 202 inhibits the propagation of higher order modes through the phase shifter 202 and also aids in obtaining consistent impedance matching thus not requiring external tuning elements to counteract inconsistent air gap effects.
When the phase shifter 200 is metal plated, the masks 232 and 234 are removed and, as shown in
Method 700 proceeds at 704 where the ferrite element is placed within a waveguide mold. As described in
When the dielectric has been injected into the waveguide mold, the waveguide mold is removed and method 700 proceeds to 708, where in-plane surfaces of the ferrite element are exposed. For example, the in-plane surfaces of the phase shifter are cut to remove dielectric material that has formed on the in-plane surfaces of the phase shifter during the injection molding process. When the in-plane surfaces of the ferrite element are exposed, method 700 proceeds at 710, where surfaces through which electromagnetic energy is emitted into and transmitted from the phase shifter are masked. When the surfaces through which electromagnetic energy is emitted into and transmitted from the phase shifter is masked, method 700 proceeds at 712, where the exposed surfaces of the phase shifter are plated. As illustrated in
Example 1 includes a phase shifting segment, the phase shifting segment comprising: a ferrite element configured to propagate electromagnetic energy longitudinally between a first end and a second end, wherein the ferrite element has two in-plane surfaces and two out-of-plane surfaces, wherein the in-plane surfaces are opposite one another and extend longitudinally between the first end and the second end, and the out-of-plane surfaces are opposite one another and extend longitudinally between the first end and the second end, wherein the out-of-plane surfaces are orthogonal to the in-plane surfaces; a first solid dielectric layer that abuts against one of the out-of-plane surfaces of the ferrite element; a second solid dielectric layer that abuts against one of the out-of-plane surfaces of the ferrite element, wherein the first solid dielectric layer and the second solid dielectric layer abut against different out-of-plane surfaces, wherein the first solid dielectric layer and the second solid dielectric layer have a first dielectric end that corresponds to the first end and a second dielectric end that corresponds to the second end; and a metal layer encapsulating the ferrite element, the first solid dielectric layer, and the second solid dielectric layer, wherein the metal layer is in contact with the two in-plane surfaces of the ferrite element.
Example 2 includes the phase shifting segment of Example 1, further comprising a magnetizing winding that extends between the first end and the second end in parallel with the in-plane surfaces, wherein current applied to the magnetizing winding changes the magnetization of the ferrite element.
Example 3 includes the phase shifting segment of Example 2, wherein the magnetizing winding further extends from both the first end and the second end of the ferrite element through the metal layer in parallel with the in-plane surfaces.
Example 4 includes the phase shifting segment of any of Examples 1-3, further comprising: a first mode suppressor coupled to the first end of the ferrite element; and a second mode suppressor coupled to the second end of the ferrite element, wherein the first mode suppressor and the second mode suppressor are configured to suppress the propagation of electromagnetic energy having high order modes within the ferrite element, wherein the first mode suppressor and the second mode suppressor also abut against the first solid dielectric layer and the second solid dielectric layer and are encapsulated by the metal layer.
Example 5 includes the phase shifting segment of any of Examples 1-4, further comprising: a first coupling section; and a second coupling section, wherein the first coupling section and the second coupling section are respectively connected to the first dielectric end and the second dielectric end, wherein the first coupling section and the second coupling section are configured to couple the phase shifting segment to at least one waveguide element.
Example 6 includes the phase shifting segment of Example 5, wherein the first coupling section and the second coupling section is composed of the same material as the first solid dielectric layer and the second solid dielectric layer.
Example 7 includes the phase shifting segment of any of Examples 5-6, wherein the first coupling section and the second coupling section couple the phase shifting segment to at least one double ridge waveguide.
Example 8 includes the phase shifting segment of any of Examples 5-7, wherein the metal layer encloses the surfaces of the first coupling section and the second coupling section that are not coupled to the phase shifting segment or to the at least one waveguide element.
Example 9 includes the phase shifting segment of any of Examples 5-8, wherein the waveguide element is a radiation element.
Example 10 includes the phase shifting segment of any of Examples 1-9, wherein the phase shifting segment is part of a phased antenna array.
Example 11 includes a method for fabricating a phase shifter, the method comprising: fabricating a ferrite element with a first end and a second end, wherein electromagnetic energy propagating through the ferrite element propagates between the first end and the second end; placing the ferrite element within a waveguide mold; injecting a liquefied dielectric into the waveguide mold, wherein the liquefied dielectric hardens to form a first solid dielectric layer and a second solid dielectric layer that abut against out-of-plane surfaces of the ferrite element, wherein the first solid dielectric layer and the second solid dielectric layer have a first dielectric end that corresponds to the first end and a second dielectric end that corresponds to the second end; exposing in-plane surfaces of the ferrite element, wherein the in-plane surfaces extend longitudinally between the first end and the second end and are orthogonal to the out-of-plane surfaces that extend longitudinally between the first end and the second end; masking surfaces through which electromagnetic energy is emitted into and transmitted from the phase shifter; and plating the exposed surfaces of the phase shifter.
Example 12 includes the method of Example 11, wherein the waveguide mold comprises a first coupling section mold and a second coupling section mold, wherein the injected dielectric forms: a first coupling section; and a second coupling section, wherein the first coupling section and the second coupling section are respectively connected to the first dielectric end and the second dielectric end, wherein the first coupling section and the second coupling section are configured to couple the phase shifting segment to at least one waveguide element.
Example 13 includes the method of Example 12, wherein the at least one waveguide element is a double ridge waveguide.
Example 14 includes the method of any of Examples 11-13, wherein fabricating the ferrite element further comprises: coupling a first mode suppressor to the first end; and coupling a second mode suppressor to the second end.
Example 15 includes the method of any of Examples 11-14, wherein exposing in-plane surfaces of the ferrite element comprises: removing the waveguide mold; and removing the dielectric in contact with the in-plane surfaces of the ferrite element.
Example 16 includes the method of Example 15, wherein the dielectric is removed by fly-cutting at least one in-plane surface of the phase shifter.
Example 17 includes the method of any of Examples 11-16, wherein plating the exposed surfaces of the ferrite element comprises: plating the phase shifter; and removing masks from the masked surfaces.
Example 18 includes the method of any of Examples 11-17, further comprising coupling the phase shifter to at least one waveguide element.
Example 19 includes a phased array antenna system, the system comprising: a plurality of waveguide elements configured to emit electromagnetic radiation; a plurality of phase shifters, a phase shifter in the plurality of phase shifters coupled to an associated waveguide element in the plurality of waveguide elements, wherein the phase shifter changes the phase of the electromagnetic radiation to steer an antenna beam, the phase shifter comprising: a ferrite element configured to propagate electromagnetic energy between a first end and a second end, wherein the ferrite element has two in-plane surfaces and two out-of-plane surfaces, wherein the in-plane surfaces are opposite one another and extend longitudinally between the first end and the second end, and the out-of-plane surfaces are opposite one another and extend longitudinally between the first end and the second end, wherein the out-of-plane surfaces are orthogonal to the in-plane surfaces; a first solid dielectric layer that abuts against one of the out-of-plane surfaces of the ferrite element; a second solid dielectric layer that abuts against one of the out-of-plane surfaces of the ferrite element, wherein the first solid dielectric layer and the second solid dielectric layer abut against opposite surfaces of the ferrite element; and a metal layer encapsulating the ferrite element, the first solid dielectric layer, and the second solid dielectric layer, wherein the metal layer is in contact with the two in-plane surfaces of the ferrite element; and a plurality of magnetizing windings, wherein each magnetizing winding in the plurality of magnetizing windings changes the magnetization of the ferrite element in an associated phase shifter.
Example 20 includes the phased array antenna system of Example 19, wherein the phase shifter further comprises: a first mode suppressor coupled to the first end of the ferrite element; and a second mode suppressor coupled to the second end of the ferrite element, wherein the first mode suppressor and the second mode suppressor are configured to suppress the propagation of electromagnetic energy having high order modes within the ferrite element, wherein the first mode suppressor and the second mode suppressor also abut against the first solid dielectric layer and the second solid dielectric layer and are encapsulated by the metal layer.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiments shown. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.
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Number | Date | Country | |
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20140104130 A1 | Apr 2014 | US |