Mode engineered loop gap resonator enclosure for sensing atom

Abstract

To improve isolation of electromagnetic resonance modes generated in a loop gap resonator (LGR).SOLUTION: A housing 100 for coupling to an LGR includes an interior cavity in which the LGR112 is disposed therein. The LGR is attached to the housing by at least one mounting bracket 106 designed to fix the LGR in the interior cavity. Additionally, the interior cavity includes a separation region 110 between a cavity wall and the LGR. A width of each mounting bracket and a width of the separation region are determined in order to support a uniform electromagnetic field inside the LGR.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with government support under N00014-22-C-1043 awarded by the Navy. The government has certain rights in this invention. [Background technology]

[0002] Miniature atomic sensors, such as atomic clocks, require atoms to interact with microwave fields with highly uniform spatial phase profiles to ensure accuracy in critical sensing applications, one of which is timing holdover in environments lacking global navigation satellite systems (GNSS). However, small spatial gradients in phase can result in substantial clock errors, thereby degrading sensor performance. One advantageous mechanism for generating microwave fields in laser-cooled atomic clocks is the loop gap resonator (LGR). Nevertheless, LGRs are not immune to spatial gradients relative to their favored electromagnetic resonant modes. For example, the electromagnetic resonant modes in an LGR can be detrimentally altered by the LGR's structure or its surrounding environment. Even coupling an LGR within an external housing designed to isolate it can introduce perturbations to the resonant modes, potentially destabilizing the LGR.

[0003] Therefore, it is necessary to improve the isolation of electromagnetic resonance modes occurring in LGRs. Summary of the Invention

[0004] Details of one or more embodiments are set forth in the Summary and Description below. Features shown or described in connection with one exemplary embodiment may be combined with features of other embodiments. Accordingly, any of the various embodiments described herein may be combined to provide further embodiments. Aspects of the embodiments may be modified, as necessary, to employ concepts from the various patents, applications, and publications identified herein to provide further embodiments.

[0005] In one embodiment, a device is disclosed. The device includes a housing coupled to a loop gap resonator (LGR). The LGR includes an inner cavity and is configured to support an electromagnetic field within the inner cavity. The housing includes an exterior and an interior. The interior includes an internal cavity in which the LGR is disposed. The housing includes at least one mounting bracket protruding into the internal cavity. The at least one mounting bracket has a first width and is configured to secure the LGR to the internal cavity of the housing. The LGR is secured by the at least one mounting bracket such that a separation region exists between an outer edge of the LGR and an inner edge of the housing. The separation region has a second width. Based on the first width of the at least one mounting bracket and the second width of the separation region, an electromagnetic field of substantially uniform phase and amplitude is provided within the internal cavity of the LGR.

[0006] In another embodiment, a system is disclosed. The system includes a signal generator configured to couple an electromagnetic signal to a loop gap resonator (LGR). The LGR includes an inner cavity and is configured to receive the electromagnetic signal and generate an electromagnetic field within the inner cavity. The system includes a housing coupled to the LGR. The housing includes an exterior and an interior. The interior includes an internal cavity in which the LGR is disposed. The housing includes at least one mounting bracket protruding into the internal cavity. The at least one mounting bracket has a first width and is configured to secure the LGR to the internal cavity of the housing. The LGR is secured by the at least one mounting bracket such that a separation region exists between an outer edge of the LGR and an inner edge of the housing. The separation region has a second width. Based on the first width of the at least one mounting bracket and the second width of the separation region, an electromagnetic field of substantially uniform phase and amplitude is provided within the internal cavity of the LGR.

[0007] According to yet another embodiment, a method is disclosed. The method includes determining dimensions of at least one mounting bracket and an isolation region. The dimensions of the at least one mounting bracket include a first width and the dimensions of the isolation region include a second width. The method includes manufacturing the at least one mounting bracket, wherein the at least one mounting bracket is coupled to a housing and protrudes into an internal cavity of the housing. The method includes coupling a loop gap resonator (LGR) to the at least one mounting bracket. The LGR includes an internal cavity and is configured to generate an electromagnetic field in a free space region within the internal cavity. The LGR is positioned within the internal cavity of the housing such that the second width of the isolation region separates the LGR from the housing. The method includes inputting an electromagnetic signal to the LGR. The method includes exciting a desired electromagnetic mode at a resonant frequency within the internal cavity of the LGR from the electromagnetic signal. [Brief explanation of the drawings]

[0008] The exemplary embodiments will be described with additional specificity and detail using the accompanying drawings and in conjunction with the detailed description, as hereinafter explained, with the understanding that the drawings depict exemplary embodiments only and therefore should not be considered limiting of scope. [Figure 1] 1 illustrates a top view of an LGR enclosed in a housing as described in one or more embodiments. [Figure 2A] 2A, 2B, and 2C show various isometric views of the LGR (FIG. 2A), housing (FIG. 2B), and enclosure (FIG. 2C), as described in one or more embodiments. [Figure 2B] 2A, 2B, and 2C show various isometric views of the LGR (FIG. 2A), housing (FIG. 2B), and enclosure (FIG. 2C), as described in one or more embodiments. [Figure 2C] 2A, 2B, and 2C show various isometric views of the LGR (FIG. 2A), housing (FIG. 2B), and enclosure (FIG. 2C), as described in one or more embodiments. [Figure 3] FIG. 3 shows a block diagram of a sensing circuit incorporating the enclosure of FIGS. 1-2, as described in one or more embodiments. [Figure 4] 1 illustrates a flow diagram of a method for manufacturing an electromagnetic device, as described in one or more embodiments.

[0009] In accordance with common practice, the various depicted features are not drawn to scale but are drawn to emphasize features relevant to the exemplary embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0010] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific exemplary embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and logical, mechanical, and electrical changes may be made without departing from the scope of the invention. Accordingly, the following detailed description is not to be construed in a limiting sense.

[0011] FIG. 1 shows a top view of an LGR 112 enclosed in a housing 100, which may form part of an atomic sensor, such as a miniature atomic clock, as will be described further. The housing 100 is defined by a base 102 and an interior cavity that surrounds the LGR 112. In the embodiment of FIG. 1, the base 102 has a rectangular length and width such that the housing 100 is approximately cubic in three-dimensional space (see FIGS. 2A-2C). Typically, the housing comprises a metal or other conductor. In some atomic sensing applications, the LGR 112 has an electromagnetic mode in the microwave region of the electromagnetic spectrum; therefore, the base 102 may comprise a material that alters the propagating electromagnetic field and corresponding resonant mode of the LGR 112. Depending on its material composition, the base 102 may function as an electromagnetic insulator, preventing electromagnetic fields from propagating within the base 102.

[0012] The interior cavity of the housing 100 includes a volume designed to enclose the LGR 112. In the embodiment of FIG. 1, the interior cavity is cylindrical, with its radius defined by the inner surface of the inner wall 104 (which may be made of the same material as the surrounding base 102). The interior cavity may be made of other shapes, depending on the geometry of the LGR 112 and the desired electromagnetic resonant modes supported therein. In addition to the LGR 112, in various embodiments, the interior cavity is filled with a gas or vacuum. However, the interior cavity may also be filled with an insulating material, such as a dielectric glass or dielectric ceramic.

[0013] In the embodiment of FIG. 1 , the LGR 112 is disposed within the interior cavity of the housing 100 so as to be concentric with the interior wall 104 that defines the interior cavity. The LGR 112 is generally configured to support electromagnetic field modes at one or more resonant frequencies (resonant modes). Although not shown in FIG. 1 , the LGR 112 (and the housing 100) are coupled to an electromagnetic energy source via a transmission line, thereby exciting one or more electromagnetic modes of the LGR 112. Specifically, the LGR 112 includes an inner cavity 116 that may be filled with a gas, vacuum, or dielectric insulating material. In some embodiments, one or more resonant modes of the LGR 112 have a large amplitude in the volume of the inner cavity 116. In some applications, it is important to excite only one mode and suppress excitation of other modes that have a large amplitude within the inner cavity 116. The housing 100 is designed to promote excitation of one desired mode within the inner cavity 116 and suppress excitation of undesired modes. The electromagnetic modes resonating within the inner cavity 116 preferably have substantially uniform phase and amplitude to improve the accuracy of atomic sensing measurements utilizing signals generated from these modes.

[0014] As shown in FIG. 1 , the LGR 112 consists of at least one or more axial (into-page) through-holes 114 connected by at least one or more axial (into-page) through-gap. These holes 114 act as the outer cavity of the LGR 112, and electromagnetic signals received by the LGR 112 can be coupled to the inner cavity 116 (e.g., through a conductive coil around the holes 114). Additionally, the LGR 112 can have pits, depressions, axial blind holes, radial blind holes, radial through-holes, or other surface features. The number, shape, and dimensions of the holes and gaps, along with other aspects of the LGR's geometry, determine the spectrum of resonant modes. Detailed operation and functionality of the LGR 112 have been omitted for brevity and are well known to those skilled in the art.

[0015] When coupled to a signal generator, the LGR 112 may support electromagnetic modes within the inner cavity 116. Some of the modes supported by the LGR 112 have energy that allows them to propagate outside the walls of the inner cavity 116. As a result, the desired electromagnetic modes supported by the LGR may not be adequately isolated from other electromagnetic fields.

[0016] The LGR 112 is physically coupled to the housing 100 via one or more mounting brackets 106 (three of which are shown in FIG. 1 ). Each mounting bracket 106 projects outward from the interior wall 104 and leads to a respective contact 108 on the surface of the LGR 112. In some embodiments, each mounting bracket 106 includes one or more male contacts that physically couple to a respective female contact 108 on the LGR 112. However, the contacts 108 on the LGR 112 may also include male contacts for coupling to the female contacts on the mounting bracket 106. Each mounting bracket 106 may physically couple to the LGR 112 via screws, bolts, nuts, and other couplers. In the embodiment of FIG. 1 , the LGR 112 includes respective grooves on its upper outer surface in which the contacts 108 are located. The grooves match the spatial dimensions of the protruding end of each corresponding mounting bracket 106 so that the respective mounting bracket 106 "fits" into the groove. Each mounting bracket 106 may be attached to a surface of the LGR 112 (i.e., the top surface shown in FIG. 1), but in some embodiments, the mounting bracket 106 may have a volume (extending into the page of FIG. 1) that couples to one or more contacts 108 located on a suitable receiving surface of the LGR 112.

[0017] Each mounting bracket 106 can be made of the same material as the interior wall 104 and / or base 102. When multiple mounting brackets 106 are used, they can extend azimuthally equidistant from one another to the LGR 112, as shown in FIG. 1. Each mounting bracket 106 protrudes from the interior wall 104 into the interior cavity a sufficient length to physically couple to the LGR 112. Additionally, each mounting bracket 106 includes a width w1, as shown in FIG. 1. While the width of each mounting bracket 106 is instructionally described as being the same (w1), in general, the width of each mounting bracket 106 can vary in particular embodiments.

[0018] The LGR 112 is coupled by a mounting bracket 106 and mounted within the inner cavity 116 such that it is separated from the inner wall 104. This forms an isolation region 110 (alternatively, a "guard ring 110" or "gap 110") having a width w2 between the inner wall 104 and the LGR 112. The isolation region 110 includes a width w2 that is independent of the width w1 of the mounting bracket 106 (although w1 may be equal to w2). The isolation region 110 can be filled with a vacuum, gas, and / or a dielectric material such as glass, ceramic, or plastic. In some embodiments, electromagnetic waves can propagate within the isolation region 110. These electromagnetic waves are considered to be complementary to the electromagnetic waves within the inner cavity 116 in the resonant modes of the LGR 112.

[0019] Certain implementations of the housing 100 are driven by the advantage of suppressing excitation of electromagnetic modes other than the desired mode within the internal cavity 116. Accordingly, certain spatial parameters of the housing 100, including the geometry of the internal cavity, the width w2 of the isolation region 110, the width w1 of each mounting bracket 106, etc., are modeled to establish a configuration that promotes excitation of the desired electromagnetic mode within the internal cavity 116. For example, one or more processors, processing circuits, etc. (not shown) may be configured to execute a modeling application that predicts characteristic profiles of resonant modes of an electromagnetically coupled system comprising the LGR 112 and the housing 100, including modeling the spatial characteristics of the electromagnetic field within the internal cavity 116. Exemplary modeling applications that may be used include numerical approximation techniques for solving Maxwell's equations, such as finite element modeling. A processor implementing the modeling application may then generate a model of the resonant modes based on parameters including the number, size, and location of the through-holes and perforations in the LGR 112, the number, location, and width w1 of each mounting bracket 106 coupled to the LGR 112, and the width w2 of the isolation region between the LGR 112 and the interior wall 104. In modeling the resonant modes, the width w1 of each mounting bracket 106 and the width w2 of the isolation region 110 may be designed to achieve an electromagnetic field within the inner cavity 116 at a particular resonant frequency that exhibits substantially uniform phase and amplitude. Stated another way, the width w1 of the mounting bracket 106 and the width w2 of the isolation region 110 may be modeled to optimize the electromagnetic field within the inner cavity 116 by suppressing excitation of undesired modes. Once the number, location, and widths w1 and w2 of each mounting bracket are determined, the housing 100 may be manufactured based on these parameters using conventional techniques.

[0020] Figures 2A-2C show various isometric views of components of an atomic sensing circuit. Specifically, Figure 2A shows an isometric view of an embodiment of the LGR 112 shown in Figure 1, Figure 2B shows an isometric view of an embodiment of the housing 100 shown in Figure 1 (without the LGR 112), and Figure 2C shows an isometric view of an embodiment of an enclosure with the housing 100 and the LGR 112 disposed therein. The LGR 112 shown in Figures 2A-2C is exemplary and may have different dimensions and cavity characteristics than those shown in these figures.

[0021] 2A, the LGR 112 is cylindrical with a bottom surface having a plurality of holes 114 fabricated therethrough and one or more grooves that may be etched on the surface. The LGR 112 may be fabricated using conventional fabrication techniques.

[0022] 2B, the housing 100 occupies a cubic shape with a central cylindrical interior cavity. Three mounting brackets 106 protrude into the interior cavity. Each mounting bracket 106 physically couples to a contact point (not shown) on the LGR 112 via a screw, bolt, or other connector.

[0023] In FIG. 2C , the LGR 112 is coupled to the interior cavity of the housing 100 by three mounting brackets 106 (not shown). Coupling the LGR 112 to the mounting brackets 106 in this manner creates an isolation region 110, which can be filled with gas, vacuum, or, in some embodiments, an electromagnetic dielectric material. In some embodiments, the spatial dimensions of the housing 100 are 3 centimeters by 3 centimeters by 1 centimeter. Although not shown in FIG. 2C , the housing 100 may be covered on the top and bottom. When coupled to an electromagnetic field generator (see FIG. 3 ), the LGR 112 supports an electromagnetic field of uniform phase and magnitude within the central inner cavity 116. This is the desired field. However, depending on the implementation, other undesired electromagnetic modes may be supported not only in the central inner cavity 116, but also in the spaces surrounding the interior cavities, such as the isolation region 110, and in the surrounding environment in which the housing 100 resides. Based on the width of the mounting bracket 106 used to couple the LGR 112 to the housing and the width of the isolation region 110, the housing 100 is designed to keep the phase and amplitude of the electromagnetic field uniform within the central inner cavity 116. For example, the design of the housing 100 can shift the frequency or spatial structure or quality factor of undesired modes to reduce the effect of these undesired modes on the field within the inner cavity 116.

[0024] FIG. 3 shows a block diagram of a sensing circuit 300 incorporating the enclosure of FIGS. 1-2. The sensing circuit 300 may be implemented as an atomic clock, or more generally, as an atomic sensor. The sensing circuit 300 generally includes a housing 100 containing the LGR 112, a signal generator 302 that provides electromagnetic energy in the RF to microwave frequency range, and a photodetector circuit 304 coupled to one or more processors 306. The sensing circuit 300 may include other components than those explicitly shown in FIG. 3.

[0025] The signal generator 302 generates an electromagnetic signal that is input into the housing 100 and directed into the inner cavity 116 of the LGR 112 via coupling to the outer cavity 114 of the LGR 112. For example, the signal generator 302 may include a synthesizer or other signal source that generates an electromagnetic signal in the RF to microwave range of the electromagnetic spectrum. The signal emitted by the signal generator 302 is coupled to the LGR 112 via a transmission line or other electromagnetic waveguide to one or more conductive loops that encase the outer cavity 114 of the LGR 112. The so-coupled signal excites one or more electromagnetic resonant modes in the LGR 112, and in doing so, the LGR 112 generates an electromagnetic field within the volume of the inner cavity 116. As previously mentioned, the LGR 112 is physically attached to the housing 100 by one or more mounting brackets 106, and the LGR 112 is separated from the walls of the housing 100 by an isolation region 110. Based on the width of the mounting bracket 106 and the width of the isolation region 110, the electromagnetic field excited in the LGR 112 is one of the desired modes, and undesired modes are substantially suppressed. Numerical models (e.g., finite element analysis models) can be used to determine the widths of the mounting bracket 106 and the isolation region 110 before manufacture that satisfy the desired condition that the desired resonant mode of the LGR 112 is excited and the undesired modes are not excited.

[0026] To operate as an atomic clock, an atomic source such as rubidium may be deposited within the inner cavity 116 of the LGR. Upon interaction with a desired isolated electromagnetic field within the inner cavity 116, the rubidium atoms may be excited at a resonant frequency. This frequency may serve as the basis for an atomic clock reference signal. To detect the resonant frequency of the rubidium atoms, the photodetector circuit 304 monitors the LGR 112 and receives an electromagnetic signal at the resonant frequency. One or more processors 306 may use the detected electromagnetic signal at the resonant frequency to serve as a reference clock measurement.

[0027] 4 illustrates a flow diagram of a method 400 for manufacturing an electromagnetic device including the housing 100 and LGR 112 described in connection with FIGS. 1-3. The method 400 may be implemented by the techniques described in connection with FIGS. 1-3, but may also be implemented by other techniques. The blocks of the flow diagram are arranged generally sequentially for ease of explanation. However, it should be understood that this organization is merely exemplary, and that the processing associated with the methods described herein (and the blocks illustrated in the figures) may occur in a different order (e.g., at least some of the processing associated with the blocks may be performed in a parallel and / or event-driven manner).

[0028] Method 400 includes, at block 402, determining dimensions of an LGR having a desired mode at a resonant frequency. The dimensions of the LGR may be determined using finite element modeling or other numerical analysis based on the desired mode to be supported within the LGR's internal cavity. In an atomic clock embodiment, this desired mode is used to excite atoms at the resonant frequency. Block 402 may be performed by one or more processors executing a modeling application. At block 404, the LGR is fabricated based on the analysis performed in block 402 such that the LGR has dimensions that support the desired mode. Block 404 may be performed by conventional fabrication techniques.

[0029] At block 406, method 400 determines the dimensions of the mounting brackets and isolation regions comprising the housing. For example, one or more processors may execute a finite element model or other numerical scheme using various characteristics of the LGR and housing to determine the width w1 of each mounting bracket and the width w2 of the isolation region for the desired electromagnetic field supported by the LGR. In some embodiments, the number and dimensions of the mounting brackets may vary, which may be advantageous in generating desired electromagnetic modes from the LGR that are uniform in phase and amplitude. Additionally, the dimensions of the LGR and / or the housing's internal cavity may be known, and these quantities may also be used in determining the appropriate width w2 of the isolation region. However, if the housing composite has not yet been manufactured, only the dimensions of the LGR may be known. In this case, the housing's internal cavity may be manufactured to achieve the isolation gap width w2 determined at block 402.

[0030] At block 408, the method 400 proceeds by manufacturing at least one mounting bracket for the housing. At this point, the width w1 of each mounting bracket is known from the numerical analysis performed in block 406, and the mounting brackets may then be fabricated based on those widths. Conventional manufacturing processes may be used to couple the mounting brackets to the base of the housing such that each mounting bracket protrudes into the interior cavity, as shown in FIG. 1 .

[0031] Proceeding to block 410, method 400 mechanically attaches the LGR to the housing's mounting brackets. As shown in FIG. 1, the LGR is positioned within the housing's interior cavity and separated from the interior wall of the cavity by a separation gap, the width of which is determined from block 406. The LGR may be mechanically attached to the end of each mounting bracket by one or more contact points, as shown in FIG. 1. In various examples, screws, nuts, bolts, and other connectors may be used to couple the mounting brackets to the LGR. In some embodiments, the separation region may then be filled with an insulating material that shields the LGR from electromagnetic or vibration effects.

[0032] The housing composite, including the housing and enclosed LGR, can then be used in a sensing circuit such as that described in FIG. 3 . Accordingly, method 400 proceeds to block 412, where electromagnetic energy is coupled to the LGR, e.g., by a signal generator coupled to the LGR via one or more transmission lines. Such energy induces a resonant mode in the LGR, exciting an electromagnetic field at a desired frequency consistent with the numerical analysis performed in block 414. The resonant mode generated in the LGR is a substantially uniform electromagnetic field. For example, such an electromagnetic field may be uniform in both phase and amplitude. The uniformity of the electromagnetic field within the LGR's inner cavity is due at least in part to the geometry of the LGR, i.e., the dimensions of the LGR's through-holes and gaps, and in part to the geometry of the housing, i.e., the dimensions of the mounting bracket and the isolation region separating the LGR from the wall of the inner cavity. More specifically, the width w1 of the mounting bracket and the width w2 of the isolation region help create electromagnetic boundary conditions that suppress the excitation of undesired electromagnetic modes having non-uniform spatial modes. In some embodiments, undesired modes are shifted to lower frequencies or have a reduced quality (Q) factor as a result of the geometry and dimensions of the housing, guard gap, and mounting bracket of the housing.

[0033] The uniform electromagnetic field can then be used in a desired application, for example, in an atomic clock, the uniform electromagnetic field is used to serve as the basis for exciting atoms into an excited state at a resonant frequency, which serves as the reference for the clock signal.

[0034] The methods and techniques described herein may be implemented in part in digital electronic circuitry, or in a programmable processor (e.g., a special-purpose processor or a general-purpose processor such as a computer), firmware, software, or various combinations of each. Apparatus embodying these techniques may include suitable input and output devices, a programmable processor, and a storage medium tangibly embodying program instructions for execution by the programmable processor. Processes embodying these techniques may be performed by the programmable processor executing a program of instructions to perform the desired function by operating on input data and generating appropriate output. The techniques may advantageously be implemented in one or more programs executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and transmit data and instructions to, a data storage system, at least one input device, and at least one output device. Generally, the processor receives instructions and data from a read-only memory and / or a random-access memory. Suitable storage devices for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including, for example, semiconductor memory devices such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory devices, magnetic disks (internal or removable), magneto-optical disks, etc. Any of the foregoing may be supplemented by, or incorporated in, specially-designed application-specific integrated circuits (ASICs).

[0035] Illustrative Embodiments Example 1 includes a device comprising: a housing coupled to a loop gap resonator (LGR), the LGR including an inner cavity and configured to support an electromagnetic field within the inner cavity; the housing including an exterior and an interior including the inner cavity in which the LGR is disposed; the housing including at least one mounting bracket protruding into the inner cavity, the at least one mounting bracket having a first width and configured to secure the LGR within the inner cavity of the housing; the LGR secured by the at least one mounting bracket such that a separation region exists between an outer edge of the LGR and an inner edge of the housing, the separation region having a second width; and an electromagnetic field of substantially uniform phase and amplitude is provided within the inner cavity of the LGR based on the first width of the at least one mounting bracket and the second width of the separation region.

[0036] Example 2 includes the device of example 1, wherein the separation region comprises free space, gas, and / or insulating material.

[0037] Example 3 includes the device of any of Examples 1-2, wherein the at least one mounting bracket includes a plurality of mounting brackets, each of the plurality of mounting brackets having the second width.

[0038] Example 4 includes the device of example 3, wherein each of the plurality of mounting brackets is azimuthally equidistant to adjacent mounting brackets.

[0039] Example 5 includes the device of any of examples 1-4, wherein at least one mounting bracket includes a connector that mates with a contact on the LGR.

[0040] Example 6 includes the device of any of Examples 1-5, wherein the interior cavity comprises a cylindrical volume.

[0041] Example 7 includes the device of any of examples 1-6, wherein the device forms part of an atomic clock sensor.

[0042] Example 8 includes the device of any of Examples 1-7, wherein the first width and the second width are determined from a finite element model.

[0043] Example 9 includes the device of any of Examples 1-8, wherein the LGR is configured to receive an electromagnetic signal from the signal generator at a first frequency and establish an electromagnetic field of substantially uniform phase and amplitude within the inner cavity of the LGR from the electromagnetic signal.

[0044] Example 10 includes the device of any of Examples 1-9, wherein the at least one mounting bracket is coupled to the LGR via one or more screws, nuts, or bolts.

[0045] Example 11 includes a system comprising: a signal generator configured to couple an electromagnetic signal into a loop gap resonator (LGR), the LGR including an internal cavity, the signal generator configured to receive the electromagnetic signal and generate an electromagnetic field within the internal cavity; and a housing coupled to the LGR, the housing including an exterior and an interior including the internal cavity in which the LGR is disposed, the housing including at least one mounting bracket protruding into the internal cavity, the at least one mounting bracket having a first width and configured to secure the LGR within the internal cavity of the housing, the LGR being secured by the at least one mounting bracket such that a separation region exists between an outer edge of the LGR and an inner edge of the housing, the separation region having a second width, and an electromagnetic field of substantially uniform phase and amplitude is provided within the internal cavity of the LGR based on the first width of the at least one mounting bracket and the second width of the separation region.

[0046] Example 12 includes the system of example 11, wherein the isolation region includes free space, gas, and / or insulating material.

[0047] Example 13 includes the system of any of Examples 11-12, wherein the at least one mounting bracket includes a plurality of mounting brackets, each of the plurality of mounting brackets having the second width.

[0048] Example 14 includes the system of example 13, wherein each of the plurality of mounting brackets is azimuthally equidistant to adjacent mounting brackets.

[0049] Example 15 includes the system of any of examples 11-14, wherein at least one mounting bracket includes a connector that mates with a contact on the LGR.

[0050] Example 16 includes the system of any of Examples 11-15, wherein the internal cavity comprises a cylindrical volume.

[0051] Example 17 includes the system of any of Examples 11-16, further comprising a photodetection circuit coupled to the one or more processors, the photodetection circuit receiving an electromagnetic signal indicative of atomic excitation at a resonant frequency of the LGR, and the one or more processors configured to determine a reference clock signal from the electromagnetic signal.

[0052] Example 18 includes the system of any of examples 11-17, wherein the first width and the second width are determined from a finite element model.

[0053] Example 19 includes a method including: determining dimensions of at least one mounting bracket and isolation region, wherein the dimensions of the at least one mounting bracket include a first width and the dimensions of the isolation region include a second width; manufacturing the at least one mounting bracket, wherein the at least one mounting bracket is coupled to a housing and protrudes into an internal cavity of the housing; coupling a loop gap resonator (LGR) to the at least one mounting bracket, wherein the LGR includes an internal cavity and is configured to generate an electromagnetic field within a region of free space within the internal cavity, the LGR being positioned within the internal cavity of the housing such that the second width of the isolation region separates the LGR from the housing; inputting an electromagnetic signal to the LGR; and exciting a desired electromagnetic mode at a resonant frequency within the internal cavity of the LGR from the electromagnetic signal.

[0054] Example 20 includes the method of example 19, wherein the isolation region includes free space, gas, and / or insulating material.

[0055] Although specific embodiments have been shown and described herein, those skilled in the art will recognize that any configuration that is expected to achieve the same purpose may be substituted for the specific embodiments shown. Therefore, it is manifestly intended that the claimed invention be limited only by the claims and the equivalents thereof.

Claims

1. A device, a housing coupled to a loop gap resonator (LGR), the LGR including an inner cavity, the housing configured to support an electromagnetic field within the inner cavity; The housing includes: With the outside, an interior including an interior cavity in which the LGR is disposed; the housing includes at least one mounting bracket protruding into the internal cavity, the at least one mounting bracket having a first width and configured to secure the LGR within the internal cavity of the housing; the LGR is secured by the at least one mounting bracket such that a separation region exists between an outer edge of the LGR and an inner edge of the housing, the separation region having a second width; A device comprising a housing, wherein an electromagnetic field of substantially uniform phase and amplitude is provided within the inner cavity of the LGR based on the first width of the at least one mounting bracket and the second width of the separation region.

2. The device of claim 1 , wherein the at least one mounting bracket comprises a plurality of mounting brackets, each of the plurality of mounting brackets having the second width.

3. The device of claim 2 , wherein each of the plurality of mounting brackets is azimuthally equidistant to adjacent mounting brackets.

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