Waveguide filter with electronically controllable variable dielectric material

Abstract

A waveguide filter may include a waveguide conduit through which electromagnetic waves propagate. The waveguide filter may include a resonant cavity comprising at least a portion of the waveguide conduit. The waveguide filter may include a variable dielectric material disposed adjacent to the resonant cavity. The waveguide filter may include a tuning electrode for applying an electric field through the variable dielectric material to modify the permittivity of the variable dielectric material.

Description

[Background technology]

[0001] A waveguide filter is an electronic filter that removes unwanted components from electromagnetic waves. Typically, a waveguide filter comprises a waveguide conduit that may contain coupled resonant cavities. The geometry of the coupled resonant cavities allows certain frequencies to pass through the waveguide conduit while rejecting other frequencies.

[0002] U.S. Patent No. 5,459,123 A1 relates to a cylindrical cavity loaded with ferroelectric rods, which resonates in the fundamental mode. EP Patent No. 3,240,102 A1 relates to an improved resonator, particularly a high-frequency resonator. U.S. Patent No. 5,934,910 relates to a high-power bandpass filter consisting of sections of circular waveguide resonator and sections of waveguide between them. CN Patent No. 104,319,447 relates to a multilayer coplanar waveguide transmission line based on graphene and its manufacturing method, belonging to the field of communication electronic components. CN Patent No. 112,952,326 relates to an X-band CT structure spherical cavity waveguide bandpass filter by 3D printing and its manufacturing method. Summary of the Invention

[0003] In some aspects, the technology described herein relates to a waveguide filter comprising an electronically controlled variable dielectric material. The waveguide filter includes a waveguide conduit and a resonant cavity that includes at least a portion of the waveguide conduit. The variable dielectric material is disposed adjacent to the resonant cavity. A tuning electrode applies an electric field through the variable dielectric material to modify the permittivity of the variable dielectric material.

[0004] In some aspects, the technology described herein relates to a method of operating a waveguide filter comprising an electronically controlled variable dielectric material. The method includes applying an electric field through a variable dielectric material disposed adjacent to a resonant cavity in a waveguide conduit using a tuning electrode. The method also includes modifying the permittivity of the variable dielectric material in response to the electric field. The permittivity of the variable dielectric material affects the performance of the waveguide filter.

[0005] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0006] Other implementations are also described and listed herein. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 illustrates an example of a waveguide filter with an electronically controlled variable dielectric material. [Figure 2] FIG. 2 illustrates a cross-sectional side view of an example of a waveguide filter having multiple resonant cavities containing variable dielectric materials. [Figure 3] FIG. 3 illustrates a cross-sectional top view of an example of a waveguide filter having multiple resonant cavities containing variable dielectric material. [Figure 4] FIG. 4 illustrates a cross-sectional side view of an example of a resonant cavity with a variable dielectric material. [Figure 5] FIG. 5 illustrates example plots of the performance of an optimal waveguide filter, a waveguide filter with physical dimensions that deviate from the nominal values, and a waveguide filter with physical dimensions that deviate from the nominal values ​​where the performance has been corrected using an electronically controlled variable dielectric material. [Figure 6] FIG. 6 illustrates an example plot showing an example shift in performance of an example waveguide filter as a function of different electric field magnitudes applied to a variable dielectric material. [Figure 7] FIG. 7 illustrates an example of a method of operating a waveguide filter with electronically controlled variable dielectric material. [Figure 8] FIG. 8 illustrates an example method for fabricating a waveguide filter with electronically controlled variable dielectric material. DETAILED DESCRIPTION OF THE INVENTION

[0008] While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It is to be understood, however, that it is not intended to limit the invention to the particular forms disclosed, but rather the invention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the claims.

[0009] The performance of a waveguide filter may correspond to the frequency of the signal filtered through and / or passing through the waveguide filter, as well as the quality of the passed signal upon exiting the waveguide filter (i.e., the amount of loss associated with the passed and filtered signals). For example, desired signals passing through the waveguide filter should experience little or no degradation, while undesired signals are attenuated. The performance of a waveguide filter may depend, at least in part, on the physical dimensions of the waveguide filter. Therefore, tight tolerances may be imposed on the manufacturing process for the waveguide filter to ensure acceptable performance. Regardless of the method used to manufacture the waveguide filter, tight tolerances are required for the physical dimensions of the waveguide filter. For example, waveguide filters are commonly manufactured using milling or casting processes. However, both processes suffer from the susceptibility of deviations in physical dimensions from design specifications. For example, wear of cutter bits during milling and wear of molds during casting are both sources of deviations in physical dimensions from design specifications that can result in errors in the manufacturing process. Deviations from design specifications in physical dimensions result in changes in the performance of the waveguide filter that may exceed acceptable limits.

[0010] To combat such undesirable variations in waveguide filter performance, manufacturing processes may be tightly controlled using tight tolerances to reduce deviations in the waveguide filter's physical dimensions from design specifications. However, such tight tolerances may add cost to the manufacturing process because they require highly accurate manufacturing techniques and / or skilled manufacturing personnel to manufacture the waveguide filter to the exact specifications. In addition, manufacturing waveguide filters may result in significant waste in the form of unacceptable waveguide filters that exceed acceptable tolerances for the waveguide filter's physical dimensions relative to the design specifications. In either case, the result may be an undesirable increase in manufacturing costs for the waveguide filter.

[0011] The present disclosure relates to a waveguide filter whose performance can be adjusted through the use of an electronically controlled variable dielectric material. An example waveguide filter according to the present disclosure may utilize a variable dielectric material whose permittivity can be changed by applying an electric field to the variable dielectric material. As a result, when placed within or adjacent to a waveguide conduit of a waveguide filter (e.g., adjacent to a resonant cavity of the waveguide conduit), the permittivity of the variable dielectric material may be controlled to control the performance of the waveguide filter. For example, controlling the permittivity of the variable dielectric material may be used to correct the performance of a waveguide filter when the performance of the waveguide filter deviates from the design performance due to imperfections in the physical dimensions of the waveguide filter from the design specifications. That is, because changes in the permittivity of the variable dielectric material change the scattering parameters of the waveguide filter, controlling the permittivity of the variable dielectric material may be used to compensate for the performance of the waveguide that deviates from the desired response. This ability to control the performance of the waveguide filter may allow for relaxed tolerances on the physical dimensions of the waveguide filter, while potentially compensating for the performance of the waveguide filter if the physical dimensions of the waveguide filter vary from the design specifications due to manufacturing process variations, wear, etc.

[0012] Relaxing the tolerances on the physical dimensions of a waveguide filter can significantly reduce the manufacturing cost and time of the waveguide filter by reducing waste while enabling the waveguide filter to be manufactured using less precise manufacturing processes. Moreover, some applications may benefit from controllable scattering parameters of the waveguide filter for signal processing approaches. For example, certain applications may benefit from the ability to modify the scattering parameters of a waveguide filter (e.g., while the waveguide filter is in operation) to achieve different signal processing objectives.

[0013] FIG. 1 schematically illustrates an example of a waveguide filter 100. The waveguide filter 100 may include a waveguide conduit 108. The waveguide conduit 108 may comprise a hollow passageway through a body 102 of the waveguide filter 100. The body 102 of the waveguide filter 100 may include a metal or other conductive material. In some examples, the body 102 of the waveguide filter 100 may include aluminum. An electromagnetic wave 104 may be introduced into the waveguide conduit 108 at an input port 106 of the waveguide conduit 108. The electromagnetic wave 104 may propagate through the waveguide conduit 108 through at least one resonant cavity 110 and exit through an output port 112 of the waveguide conduit 108. The physical size and / or characteristics of the waveguide conduit 108, including the resonant cavity 110, affect the ability of certain frequencies of the electromagnetic wave 104 to pass through the waveguide conduit 108. For example, waveguide filter 100 may be used as a bandpass filter, allowing frequencies within a particular band to pass through waveguide filter 100 while rejecting frequencies outside the band.

[0014] Various characteristics of the resonant cavity 110, such as the size and shape, determine the effect of the waveguide filter 100 on the electromagnetic wave 104. While FIG. 1 shows a single resonant cavity 110 for ease of explanation, as described in more detail below, a waveguide filter may include multiple resonant cavities (having identical, similar, or different sizes and shapes) that may be combined to collectively provide the desired performance of the waveguide filter. Various types or configurations of waveguide filters may utilize electronically controlled variable dielectric materials. For example, waveguide filters employing the techniques described herein may include, but are not limited to, cavity resonator waveguides, iris waveguides, iris-coupled waveguides, post waveguides, post-wall waveguides, insert filter waveguides, fin-line filter waveguides, or other suitable configurations.

[0015] In either case, the variable dielectric material 116 may be disposed adjacent to the resonant cavity 110. The variable dielectric material 116 may be subjected to an electric field to change the permittivity of the variable dielectric material 116. The permittivity of the variable dielectric material 116 adjacent to the resonant cavity 110 affects the performance (e.g., scattering parameters) of the waveguide filter 100. Consequently, the performance of the waveguide filter 100 may be controlled by changing the permittivity of the variable dielectric material 116.

[0016] While specific layout examples for placing the variable dielectric material 116 relative to the waveguide conduit 108 are described herein, it will be understood that the variable dielectric material 116 may be positioned in any suitable manner within the waveguide filter 100 such that a change in the dielectric constant of the variable dielectric material 116 modifies the performance of the waveguide filter 100. Thus, while non-limiting examples are described herein in which the variable dielectric material 116 is disposed within the sidewalls of the waveguide conduit 108, other layouts may be provided. For example, the variable dielectric material 116 may be located within the volume of the resonant cavity 110 or otherwise positioned to significantly affect the scattering parameters of the waveguide filter 100. When used with a waveguide filter having features (e.g., irises, posts, walls, or other features) that extend into the waveguide conduit 108, the features extending relative to the waveguide conduit 108 may include the variable dielectric material 116. That is, such features may be made from or otherwise include the variable dielectric material 116 .

[0017] As described above, any variable dielectric material 116 whose permittivity can be modified (e.g., via electronic control or other means) can be used in the waveguide filter 100. As a non-limiting example, the variable dielectric material 116 can include a graphene material. Other materials whose permittivity changes in response to an applied electric field can be used without limitation. Other variable dielectric materials can include liquid crystals or other bandgap crystalline structures. Applying an electric field to a graphene material can affect the arrangement of carbon atoms in the graphene material, resulting in a change in the permittivity of the graphene material. The resulting change in permittivity in the graphene material can be at least partially maintained even after the electric field is removed from the variable dielectric material 116. In this regard, an electric field can be applied to set the permittivity of the variable dielectric material 116 to a desired value and then discontinued so that the permittivity of the variable dielectric material 116 remains at the desired value. In another example, an electric field can be applied continuously or periodically to the variable dielectric material 116 to maintain the desired value of the permittivity of the variable dielectric material 116.

[0018] In one specific example, the variable dielectric material 116 may include an aqueous graphene oxide paste. Such a paste may include approximately 50% graphene oxide (by mass or volume) and approximately 50% water (by mass or volume). Such a paste may be sufficiently viscous to allow for easy handling of the aqueous graphene oxide paste and to allow the aqueous graphene oxide paste to be sufficiently malleable to allow it to be contained within the recesses 114 in the sidewalls of the waveguide conduit 108. Additionally, the aqueous graphene oxide paste may be relatively easily incorporated without having to consider potential leakage of the lower viscous variable dielectric material 116. However, other configurations of graphene, including different relative proportions of water and graphene in the aqueous graphene oxide paste, may be used without limitation.

[0019] 1, a recess 114 containing the variable dielectric material 116 may be disposed in a sidewall of the waveguide conduit 108 adjacent the resonant cavity 110. The recess 114 may define a depression that receives the variable dielectric material 116. The variable dielectric material 116 may fill the recess 114 such that the variable dielectric material 116 is approximately flush with the sidewall of the waveguide conduit 108. Further details regarding possible layouts of the variable dielectric material 116 within the recess 114 of the resonant cavity 110 are provided below in the examples of FIGS. 2-4.

[0020] Modifying the permittivity of the variable dielectric material 116 disposed adjacent to the resonant cavity 110 can result in a change in the scattering parameters of the resonant cavity 110. As a result, the performance of the waveguide filter 100 can change, and this change can be used to compensate for performance deviations from design specifications. The application of an electric field to the variable dielectric material 116 can be achieved through the use of a tuning electrode 120. Additionally, a ground electrode 122 can be provided. A voltage control device 118 can apply a voltage to the tuning electrode 120, which results in the application of an electric field through the variable dielectric material 116 between the tuning electrode 120 and the ground electrode 122. In some examples, the ground electrode 122 can comprise the body 102 of the waveguide filter 100 if the body 102 is conductive or includes a conductive path to ground. One or both of the tuning electrode 120 and the ground electrode 122 can be in conductive contact with the variable dielectric material 116. That is, the tuning electrode 120 may be in physical contact with the variable dielectric material 116. In other examples, an electric field may be induced in the variable dielectric material 116 without being in physical conductive contact with the variable dielectric material 116. In this latter example, the electric field may be induced in multiple portions of the variable dielectric material 116, which may be laid out relative to multiple resonant cavities 110, as described in more detail below.

[0021] As one example, an electric field may be applied to the variable dielectric material 116 and then the application of the electric field may be discontinued. That is, the permittivity of the variable dielectric material 116 may change in response to the electric field such that the change (or at least a portion of it) is maintained when the application of the electric field through the variable dielectric material 116 is discontinued. In other examples, an electric field may be applied continuously or periodically to the variable dielectric material to achieve a change in permittivity in the variable dielectric material.

[0022] In instances where the change in permittivity is maintained upon discontinuation of the applied electric field, it may be desirable to modify the permittivity of the variable dielectric material 116 to "reset" or otherwise reconfigure the permittivity of the variable dielectric material 116. Consequently, the voltage controller 118 may also be capable of applying a voltage to the reset electrode 124. The reset electrode 124 may be used to modify or reset the permittivity of the variable dielectric material 116 to a second state different from the permittivity resulting from the application of an electric field through the variable dielectric material 116 by the tuning electrode 120. The reset electrode 124 may utilize a common ground electrode 122 with the tuning electrode 120 or may use a dedicated reset ground electrode (not shown).

[0023] The reset electrode 124 may comprise a discrete electrode provided in combination with one of the tuning electrode 120 and the ground electrode 122 to apply an electric field in a different direction than the tuning electrode 120. In other examples, the reset electrode 124 may comprise the tuning electrode 120 such that the permittivity of the variable dielectric material 116 is modified or reset by application of an electric field different from that originally used to modify the permittivity of the variable dielectric material 116 (e.g., an electric field of a different magnitude or opposite polarity using the tuning electrode 120). In either case, the reset electrode 124 may apply a reset field that is of a different magnitude and / or direction than the field applied by the tuning electrode 120. The different magnitude and / or direction of the reset field applied by the reset electrode 124 may result in a change in the permittivity of the variable dielectric material 116 that is different from that set by application of the electric field applied by the tuning electrode 120. In examples where an electric field is applied continuously to achieve a change in permittivity, resetting the material may include removing the applied electric field. That is, in instances where an applied electric field is applied continuously or periodically to maintain a desired change in the permittivity of the variable dielectric material, a reset electrode may not be provided, as cessation of application of the electric field may result in a "reset" of the permittivity of the variable dielectric material.

[0024] With further reference to Figure 2, a cross-sectional side view of an example of a waveguide filter 200 is shown. In Figure 2, the waveguide filter 200 is shown in a side view with the cross section taken along the major axis of propagation of the electromagnetic wave 204 through the waveguide conduit 208, as represented by the arrows in Figure 2. In Figure 3, the waveguide filter 200 is shown in a cross-sectional top view with the cross section taken along the major axis of propagation of the electromagnetic wave 204. Figure 4 illustrates a detailed cross-sectional side view of a portion of the resonant cavity 210a.

[0025] Waveguide filter 200 includes an input port 206 and an output port 212 at opposite ends of a waveguide conduit 208. Consequently, waveguide conduit 208 may define a passageway through body 202 of waveguide filter 200. Waveguide conduit 208 may be a hollow passageway through body 202, may be filled with a dielectric material or with air, or may be a vacuum.

[0026] An example of a waveguide filter 200 may include multiple resonant cavities 210a-210h. The multiple resonant cavities may be laid out relative to one another and may have respective sizes and shapes to achieve a desired performance of the waveguide filter 200. As a result, the waveguide filter 200 may be used to filter electromagnetic waves 204 propagating through a waveguide conduit 208. As can be appreciated, the multiple resonant cavities 210a-210h may have relatively complex shapes and may be particularly difficult to manufacture with acceptable tolerances for their physical dimensions if tight tolerances are imposed. Therefore, using a variable dielectric material with one or more of the resonant cavities 210a-210h may enable tuning the performance of the waveguide filter 200 to accommodate the physical dimensions of the waveguide filter 200 with wider acceptable tolerances.

[0027] Waveguide filter 200 may include resonant cavity 210a. At least one other resonant cavity may be provided along the length of waveguide conduit 208. The other resonant cavity may be referred to as coupled resonant cavity 210b because coupled resonant cavity 210b may cooperate with resonant cavity 210a to achieve the performance of waveguide filter 200. In other words, the scattering parameters of waveguide filter 200 may be established by the interaction of coupled resonant cavity 210b with resonant cavity 210a to provide the overall performance of waveguide filter 200. That is, the physical properties of the two cavities, both individually and when laid out relative to one another, may be considered to interact. The geometry of one resonant cavity may affect how the other operates. The resonant cavities may not independently affect the performance of waveguide filter 200, but rather work together to achieve the performance of waveguide filter 200.

[0028] While a single additional coupled resonant cavity 210b is described in detail, waveguide filter 200 may include multiple coupled resonant cavities that cooperate to define the overall performance of waveguide filter 200. Also, while each coupled resonant cavity is shown with a variable dielectric material and a tuning electrode, not all resonant cavities of a waveguide filter need include variable dielectric material; different resonant cavities may include different amounts of variable dielectric material, different resonant cavities may include different variable dielectric materials, and so on. Moreover, the presence of variable dielectric material, the amount of variable dielectric material, and / or the type of variable dielectric material may be varied for different ones of the resonant cavities to control the performance of waveguide filter 200.

[0029] As shown in FIGS. 2-4, resonant cavity 210a may include first variable dielectric material 216a. First variable dielectric material 216a may be disposed within first recess 214a adjacent to resonant cavity 210a. First tuning electrode 220a may be configured to be in conductive contact with first variable dielectric material 216a. Specifically, first tuning electrode 220a may extend through first sealing portion 222a. First sealing portion 222a may prevent first variable dielectric material 216a from leaking or otherwise being expelled from first recess 214a.

[0030] The coupled resonant cavity 210b may include a second variable dielectric material 216b disposed within a second recess 214b adjacent to the coupled resonant cavity 210b. The second recess 214b may also have a second sealing portion 222b that helps maintain the second variable dielectric material 216b within the second recess 214b. The second tuning electrode 220b may extend through the second sealing portion 222b and into the second variable dielectric material 216b.

[0031] The circuit board 218 may be disposed outside the body 202. The circuit board 218 may include a conductive element that establishes electrical communication with the first tuning electrode 220a. The circuit board 218 may be used to establish a connection between a voltage controller and the first tuning electrode 220a so that a voltage may be applied to the first tuning electrode 220a, thereby generating a first electric field through the first variable dielectric material 216a to change the permittivity of the first variable dielectric material 216a. In the example shown in FIG. 2, the body 202 may include a conductive material such that the body 202 surrounding the first variable dielectric material 216a may function as a ground electrode that couples with the first tuning electrode 220a to realize an electric field within the first variable dielectric material 216a upon application of a voltage to the first tuning electrode 220a.

[0032] The second tuning electrode 220b may also be in conductive communication with the circuit board 218. As a result, the circuit board 218 may be used to establish a connection between a voltage controller and the second tuning electrode 220b such that a voltage may be applied to the second tuning electrode 220b, thereby generating a second electric field through the second variable dielectric material 216b to change the permittivity of the second variable dielectric material 216b.

[0033] The circuit board 218 may include independent control of the first tuning electrode 220a and the second tuning electrode 220b to enable application of different voltages to the first tuning electrode 220a and the second tuning electrode 220b. This may result in different field strengths for the first electric field applied through the first variable dielectric material 216a and the second electric field applied through the second variable dielectric material 216b. As a result, the dielectric constants of the first variable dielectric material 216a and the second variable dielectric material 216b may be independently controllable for the resonant cavity 210a and the coupled resonant cavity 210b. In other examples, the first tuning electrode 220a and the second tuning electrode 220b may have the same voltage applied thereto, whether independently controlled or coupled to a common voltage source.

[0034] Although not described in detail herein for brevity, a number of additional coupled resonant cavities may be provided, including coupled resonant cavity 210c, coupled resonant cavity 210d, coupled resonant cavity 210e, coupled resonant cavity 210f, coupled resonant cavity 210g, and coupled resonant cavity 210h. Although each of these additional coupled resonant cavities 210c-210h is not described in detail, each coupled resonant cavity 210c-210h may include a structure similar to that described in connection with resonant cavity 210a and coupled resonant cavity 210b. In addition, each tuning electrode of coupled resonant cavities 210c-210h may be independent of one another such that a unique voltage may be applied to each, thus resulting in an independently controlled change in the permittivity of the respective variable dielectric material for each coupled resonant cavity. While eight coupled resonant cavities are shown in FIGS. 2-3, it will be understood that any number of resonant cavities may be provided without limitation. Moreover, in some examples, each tuning electrode of the various coupled resonant cavities may be independently controlled, while in other examples, some of the tuning electrodes may be commonly controlled to receive the same voltage.

[0035] As discussed above, varying the permittivity of a variable dielectric material adjacent to a resonant cavity can affect the performance of a waveguide filter by modifying the scattering parameters of the waveguide filter. To further illustrate this, FIG. 5 includes plots 500, 520, and 550, each illustrating the scattering parameters of a waveguide filter. The vertical axis of plot 500 may represent the scattering parameters, and the horizontal axis may represent frequency. The traces of plot 500 represent the frequency response of an optimized waveguide filter according to the present disclosure. That is, plot 500 illustrates a waveguide filter having idealized physical dimensions and operating according to its designed specifications.

[0036] Typically, waveguides can operate in frequency bands as low as 0.32 GHz and as high as 1100 GHz, with the percentage of the normalized waveguide bandwidth typically being about 40%. As shown in FIG. 5, by way of example, the performance of a waveguide filter can be in the frequency range of about 25 GHz to about 34 GHz. In another example, the performance of a waveguide filter can be in the frequency range of 14 GHz to about 70 GHz. In another example, the performance of a waveguide filter can be in the frequency range of 15 GHz to about 50 GHz. Thus, a waveguide filter can operate in the microwave portion of the electromagnetic spectrum. This portion of the electromagnetic spectrum is often used for communications purposes, such as satellite communications, where waveguide filters can be utilized.

[0037] Plot 500 illustrates the scattering parameter S11 performance of a waveguide filter. The waveguide filter includes a resonant cavity with cavity geometry tuned for optimized performance. The optimized waveguide filter achieves scattering parameter S11 performance of better than -25 dB from 27 GHz to 31 GHz. Plot 520 illustrates degraded performance compared to the optimized waveguide filter. The degradation in performance can result from modeled deviations in the waveguide filter's physical dimensions from design specifications. Specifically, plot 520 illustrates the dimensions of a structural model using a Gaussian distribution with a range of plus or minus two thousandths of an inch, with random replicates performed to mimic the results of a typical manufacturing process. Plot 520 illustrates that the scattering parameter of a degraded waveguide filter can degrade by more than 10 dB compared to the optimized waveguide filter, even with tight dimensional tolerances, resulting in rejection of the manufactured part.

[0038] As an example of the ability to compensate for a degraded waveguide filter using an electronically controlled variable dielectric material, plot 550 represents the results of a dielectrically tuned waveguide filter in which the degraded filter was corrected by optimizing the permittivity of the variable dielectric material adjacent to the resonant cavity, as described in the previous section. The permittivity values ​​of the variable dielectric material in the simulation matched typical values ​​for water-based graphene oxide paste and were individually optimized between plus and minus 25% of the standard permittivity value, as needed. As a result, the dielectrically tuned filter improved its response by nearly 4 dB, thereby correcting the performance of an otherwise out-of-tolerance waveguide filter and making it an acceptable part for field operation.

[0039] In FIG. 6 , plot 600 includes multiple traces representing the scattering parameters of a waveguide filter with different electric field strengths applied to the waveguide filter's variable dielectric material. Plot 650 shows a detailed view of plot 600 in the frequency range of 29 GHz to 34 GHz. As can be better seen in plot 650, the effect of different electric field strengths applied through the variable dielectric material is that higher voltages generally correspond to a shift in the waveguide filter's scattering parameter S21, which shifts the waveguide filter's frequency response to a lower frequency (i.e., the corresponding waveguide filter's frequency response shifts to the left relative to plot 650). This shift in the waveguide's scattering parameter S21 can be attributed to a change in the permittivity of the variable dielectric material resulting from the application of an electric field to the variable dielectric material. This shift in the waveguide filter's performance can be used to tune the waveguide filter's performance, for example, to eliminate unwanted signal components that may be significant at a particular operating frequency. As will be described in more detail below, control of the electric field applied to the variable dielectric material may be based on the monitored performance of the waveguide filter such that the scattering parameters are modified to achieve the desired performance for the waveguide filter.

[0040] With further reference to FIG. 7 , an example of a method 700 for operation of a waveguide filter according to the present disclosure is illustrated. Method 700 may include a monitoring step 702. Monitoring step 702 may include observing (e.g., measuring) the performance of the waveguide filter. In one example, the performance of the waveguide filter may be characterized through measured scattering parameters such as those described above in FIGS. 5 and 6 . Monitoring step 702 may occur at any time during operation of the waveguide filter, whether prior to any application of an electric field to the variable dielectric material or any time after applying an electric field to the variable dielectric material to modify the permittivity of the variable dielectric material. In this regard, monitoring step 702 may be performed during an initialization process for the waveguide filter to tune the waveguide filter to a nominal or designed performance. Additionally or alternatively, monitoring step 702 may be performed after an initialization adjustment of the waveguide filter to achieve a desired change in performance.

[0041] Method 700 may also include a determining step 704 for determining a desired change in the performance of the waveguide filter. Determining step 704 may be performed based on the observed performance of the waveguide filter in monitoring step 702. For example, the waveguide filter may have undesirable or off-nominal performance resulting from variations in one or more physical dimensions of the waveguide conduits of the waveguide filter. Such variations in dimensions may result from variations in the manufacturing process. Monitoring step 702 may be used to observe deviations in the performance of the waveguide filter from nominal or designed performance. Consequently, determining step 704 may be utilized to determine a desired change in the performance of the waveguide filter to achieve the nominal design performance. Determining step 704 may include the use of an algorithm, lookup table, or other quantitative approach to determine the desired change in the performance of the waveguide filter. In another example, determining step 704 may be based on an empirical study of the effects of changes in the permittivity of a variable dielectric material in a waveguide filter.

[0042] Method 700 may include an applying step 706 of applying an electric field through a variable dielectric material disposed adjacent to a resonant cavity of the waveguide filter. As described above, the electric field applied through the variable dielectric material may be applied using a tuning electrode, which may be in conductive contact with the variable dielectric material to apply a voltage between the tuning electrode and a ground electrode. As a result, an electric field may be established across the variable dielectric material. As a result, the permittivity of the variable dielectric material may be modified in response to the application of the electric field in applying step 706. Applying step 706 and the resulting modification of the permittivity of the variable dielectric material may occur for a single resonant cavity of the waveguide filter, or applying step 706 may include applying the electric field to multiple resonant cavities and modifying the permittivity of the variable dielectric material for the multiple resonant cavities. If applying step 706 includes multiple resonant cavities, applying step 706 and the resulting modification of the permittivity of the variable dielectric material may be performed independently for each resonant cavity, as described above.

[0043] In some examples, applying 706 may include modifying the variable dielectric material in ways other than applying an electric field. For example, applying 706 may include physical changes to the variable dielectric material, such as adding material, removing material, or modifying the type of material used. This may include different relative changes for different resonant cavities if multiple resonant cavities are provided.

[0044] Additionally, method 700 may include a propagating step 708, in which the electromagnetic wave is propagated through the waveguide filter. Because a change in the permittivity of the variable dielectric material may have been altered in applying step 706, the scattering parameters for the resulting waveguide filter may also be modified from those measured in monitoring step 702. Thus, method 700 may be used to control the scattering parameters of the waveguide filter to achieve the performance of the waveguide filter (e.g., to correct for deviations from design specifications). As a result, propagating step 708 may result in the waveguide filter affecting the electromagnetic wave with a filtering step using the altered scattering parameters. Such filtering may occur to condition the electromagnetic wave signal for purposes such as communications. Propagating step 708 may occur after applying step 706, in which the permittivity of the variable dielectric material is modified.

[0045] In one example, method 700 may be performed to achieve a desired performance of the waveguide filter, which may require a single execution of method 700. Although not shown in FIG. 7 , in other examples, method 700 may repeat back to monitoring step 702 such that the process of method 700 may be performed iteratively (e.g., while the waveguide filter is in operation). Such iteration of method 700 may allow a control loop feedback to be established for continuous control of the waveguide filter to achieve the desired performance of the waveguide filter. Such a control loop may be used to achieve a design performance for the waveguide filter, or the performance of the waveguide filter may be tunable to control the waveguide filter to operate with different scattering parameters for different operating conditions that may be tailored to a given application of the waveguide filter.

[0046] FIG. 8 illustrates an example method 800 for manufacturing a waveguide filter. Method 800 may include a forming step 802 in which a waveguide conduit is formed. Forming step 802 may include any suitable manufacturing technique, such as casting, forging, milling, stamping, additive manufacturing (3D printing), etc. Forming step 802 may include forming the waveguide conduit into a body (e.g., a milling step, etc.) such that the waveguide conduit is formed by removing material from the body. Alternatively, the body may be formed to create the waveguide conduit (e.g., in a casting, forging, stamping, or additive manufacturing step). In some examples, the waveguide conduit is partially formed into two portions of the body, which are integrated to define the waveguide conduit. Forming step 802 may also include forming one or more resonant cavities of the waveguide conduit in any of the ways described above.

[0047] Method 800 may further include a fabricating step 804 of fabricating a recess adjacent the resonant cavity of the waveguide conduit. Fabricating step 804 may occur after forming step 802 or substantially simultaneously with forming step 802. For example, in examples where forming step 802 includes a milling or other material removal step to form the waveguide conduit, fabricating step 804 may include a subsequent manufacturing step to create a recess for the resonant cavity of the waveguide conduit. In examples where the waveguide conduit is formed in a casting, forging, stamping, additive manufacturing, or other process in which a body is formed to create the waveguide conduit, the recess may be formed during the same manufacturing step used to form the waveguide conduit.

[0048] Method 800 may also include a depositing step 806, in which a variable dielectric material is deposited within the recess. Depositing step 806 may include filling the recess with an aqueous graphene oxide paste. Method 800 may also include an establishing step 808, in which contact is established between the tuning electrode and the variable dielectric material. Establishing step 808 may occur after depositing step 806 or substantially simultaneously with depositing step 806. That is, the tuning electrode may be positioned relative to the recess before depositing step 806 such that contact is established between the variable dielectric material and the tuning electrode during depositing step 806. In other examples, deposition step 806 may occur, after which the tuning electrode may contact the variable dielectric material.

[0049] While this specification includes many specific implementation details, these should not be construed as limitations on the scope of any technology or the scope that may be claimed, but rather as descriptions of features inherent to particular implementations of the particular described technology. Certain features described herein in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation can also be implemented separately in multiple implementations or in any suitable subcombination. Moreover, while features may be described above as working in a particular combination, and even initially claimed as such, one or more features from a claimed combination can, in some cases, be deleted from the combination, and a claimed combination may be directed to a subcombination or a variation of a subcombination.

[0050] Similarly, although steps are depicted in the figures in a particular order, this should not be understood as requiring that such steps be performed in the particular order shown or sequential order, or that all of the depicted steps be performed, to achieve desirable results. In certain situations, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the above-described implementations should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems may generally be integrated together in a single software product or packaged into multiple software products.

[0051] Thus, particular implementations of the subject matter have been described. Other implementations are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In certain implementations, multitasking and parallel processing may be advantageous.

[0052] Although several implementations of the described technology have been illustrated, it will be understood that various modifications can be made without departing from the spirit and scope of the recited claims.

Claims

1. 1. A waveguide filter comprising an electronically controlled variable dielectric material, a waveguide conduit; a resonant cavity including at least a portion of the waveguide conduit; a variable dielectric material disposed adjacent to the resonant cavity; a tuning electrode for applying an electric field through said variable dielectric material to modify the permittivity of said variable dielectric material.

2. a coupled resonant cavity positioned relative to the resonant cavity along the waveguide conduit; a second variable dielectric material disposed adjacent to the coupled resonant cavity; 10. The waveguide filter of claim 1, further comprising: a second tuning electrode for applying a second electric field through said second variable dielectric material to modify a second dielectric constant of said second variable dielectric material.

3. 3. The waveguide filter of claim 2, wherein the tuning electrode and the second tuning electrode are independently controllable to independently apply the electric field in the variable dielectric material and the second electric field in the second variable dielectric material.

4. 4. The waveguide filter of claim 3, wherein the magnitude of the electric field is different from the magnitude of the second electric field.

5. The waveguide filter of claim 1 , wherein the variable dielectric material comprises a water-based graphene oxide paste.

6. 2. The waveguide filter of claim 1, wherein the tuning electrode is in conductive communication with the variable dielectric material.

7. 10. The waveguide filter of claim 1, further comprising a recess in a sidewall of the waveguide conduit adjacent to the resonant cavity, the resonant cavity being defined by the sidewall of the waveguide conduit, and the variable dielectric material being located within the recess.

8. 8. The waveguide filter of claim 7, wherein the tuning electrode extends into the recess and is in contact with the variable dielectric material to apply the electric field through the variable dielectric material.

9. The waveguide filter of claim 8 , wherein the sidewall comprises a ground electrode.

10. 10. The waveguide filter of claim 1, further comprising a voltage control device that controls the electric field applied by the tuning electrode through the variable dielectric material to control the permittivity of the variable dielectric material and correspondingly, scattering parameters of the waveguide filter.

11. 10. The waveguide filter of claim 1, further comprising a reset electrode for applying a reset field through the variable dielectric material, the reset field being in a different direction than the field relative to the variable dielectric material.

12. 12. The waveguide filter of claim 11, wherein the reset electrode comprises the tuning electrode of opposite polarity.

13. 12. The waveguide filter of claim 11, wherein the reset electrode comprises a discrete electrode different from the tuning electrode and disposed in a different physical orientation relative to the variable dielectric material than the tuning electrode.

14. 10. The waveguide filter of claim 1, wherein the resonant cavity and the variable dielectric material are configured to allow electromagnetic waves including frequencies greater than or equal to about 26 GHz and less than or equal to about 40 GHz to propagate through the waveguide conduit.

15. 1. A method of operating a waveguide filter with an electronically controlled variable dielectric material, said method comprising: applying an electric field through a variable dielectric material disposed adjacent to a resonant cavity of the waveguide conduit using a tuning electrode; modifying a permittivity of the variable dielectric material in response to the electric field, the permittivity of the variable dielectric material affecting performance of the waveguide filter.

16. applying a second electric field through a second variable dielectric material disposed adjacent the coupled resonant cavity of the waveguide conduit, the coupled resonant cavity being positioned relative to the resonant cavity along the waveguide conduit, using a second tuning electrode; 16. The method of claim 15, further comprising modifying a second dielectric constant of the second variable dielectric material in response to the second electric field.

17. 17. The method of claim 16, wherein the electric field and the second electric field are applied independently to the tuning electrode and the second tuning electrode, respectively.

18. 18. The method of claim 17, wherein the magnitude of the electric field is different from the second electric field.

19. 16. The method of claim 15, wherein the variable dielectric material comprises a water-based graphene oxide paste.

20. The method of claim 15 , wherein the tuning electrode is in conductive communication with the variable dielectric material.

21. 16. The method of claim 15, wherein the variable dielectric material is located in a recess in a sidewall of the waveguide conduit adjacent the resonant cavity, the resonant cavity being defined by the sidewall of the waveguide conduit.

22. 22. The method of claim 21, wherein the tuning electrode extends into the recess and is in contact with the variable dielectric material to apply the electric field through the variable dielectric material.

23. The method of claim 22 , wherein the sidewall comprises a ground electrode.

24. monitoring the performance of the waveguide filter; The method of claim 15 , further comprising: determining a magnitude of the electric field applied by the tuning electrode in response to the performance.

25. 16. The method of claim 15, further comprising applying a reset field to the variable dielectric material with a reset electrode, the reset field being in a different direction relative to the variable dielectric material than the electric field.

26. 26. The method of claim 25, wherein the reset electrode comprises the tuning electrode of opposite polarity.

27. 26. The method of claim 25, wherein the reset electrode comprises a discrete electrode different from the tuning electrode and disposed in a different physical orientation relative to the variable dielectric material than the tuning electrode.

28. 16. The method of claim 15, wherein the resonant cavity and the variable dielectric material are configured to allow electromagnetic waves including frequencies greater than or equal to about 26 GHz and less than or equal to about 40 GHz to propagate through the waveguide conduit.

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