The present disclosure is related to radio frequency connectors.
A spacecraft includes numerous radio frequency (“RF”) systems. These RF systems generally utilize numerous sub-systems that are electrically connected to each other utilizing a plurality of RF connectors. For modern space applications, threaded Neill-Concelman (“TNC”) and TNC wedge connectors are the standard type of RF connectors utilized in these RF systems for RF high power applications.
In general, the TNC connector is a threaded version of a bayonet Neill-Concelman (“BNC”) connector that is a miniature quick connect and disconnect RF connector utilized for coaxial cables where the RF connector is designed to maintain the shielding that the design of the coaxial cable offers. These RF connectors include a female connector and a male connector that are electrically connected by pressing both the female connector and male connector together and holding them together either with two bayonet lugs (e.g., BNC) or via a threaded interface (e.g., TNC). Generally, TNC connectors operate at higher frequencies than BNC connectors and have better performance in the microwave frequencies.
The problem with known TNC and BNC connectors is when mated (i.e., physically and electrically connected), the male, female, or both connectors are susceptible to RF breakdown issues known generally as multipactor and ionization breakdown because of the formation of air gaps within the connector interface. These problems increase when higher power RF signals are transmitted through these types of RF connectors and/or these RF connectors are utilized in environments that have very cold temperatures because the dielectrics in the RF connectors typically contract with colder temperatures increasing the presence or size of the gaps. As such, there is a need for an improved RF connector that solves these problems.
Coaxial radio frequency (“RF”) connectors for high-power handling are disclosed. Specifically, a high-power male coaxial connector (“HPMC”) is disclosed. The HPMC includes a center conductor, an outer conductor disposed around the center conductor, an insulating layer positioned between the center conductor and the outer conductor, and a first elastomer. The outer conductor has an outer conductor front-end (“OCFE”) and the insulating layer has an insulating layer front-end (“ILFE”). The first elastomer is positioned between the center conductor and the insulating layer. The insulating layer may include an insulating layer cavity (“ILC”) extending inward into the insulating layer from the ILFE and the first elastomer may be within the ILC.
Other devices, apparatus, systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims.
The invention may be better understood by referring to the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the figures, like reference numerals designate corresponding parts throughout the different views.
Disclosed are coaxial radio frequency (“RF”) connectors for high-power handling. Specifically, a high-power male coaxial connector (“HPMC”) is disclosed. The HPMC includes a center conductor, an outer conductor disposed around the center conductor, an insulating layer positioned between the center conductor and the outer conductor, and a first elastomer. The outer conductor has an outer conductor front-end (“OCFE”) and the insulating layer has an insulating layer front-end (“ILFE”). The first elastomer is positioned between the center conductor and the insulating layer. The insulating layer may include an insulating layer cavity (“ILC”) extending inward into the insulating layer from the ILFE and the first elastomer may be within the ILC.
In
In this example, the center conductor 102 includes an attachment-portion 122 of the center conductor 102, a center-portion 124 of the center conductor 102, and a front-portion 126 (generally known as a “pin”) of the center conductor 102. The attachment-portion 122 may be a part of the center conductor 102 that is electrically and physically connected to a center conductor (not shown) of a coaxial cable (not shown). In this example, the HPMC 100 may include a back cavity 128 within the housing 116 to properly accommodate the physical attachment of the coaxial cable. The center-portion 124 may be a solid cylindrical portion of the center conductor 102 that extends out from attachment-portion 122 to the front-portion 126. In this example, the diameters of the attachment-portion 122, center-portion 124, and front-portion 126 may be equal to varying in size based on the desired design of the HPMC 100 and corresponding HPFC. Similar to the outer conductor 104, the center conductor 102 may include any conductive material capable of electrically conducting a current such as, for example, a metal material (such as, for example, copper, silver, gold, aluminum, steel, or any similar conductive alloy). The insulating layer 106 may be any dielectric material utilized for radio-frequency (“RF”) coaxial cable applications that may include, for example, fluorocarbon materials such as, for example, polytetrafluoroethylene (“PTFE”).
In this example, the first elastomer 108 is located adjacent to a bottom surface 130 and a wall 132 of the ILC 114. The first elastomer 108 is also located adjacent to a surface 134 of the center-portion 124 of the center conductor 102; however, the first elastomer 108 is constructed of an elastomer material formed of a ring (i.e., a ring-shaped washer gasket) having an opening that surrounds the center-portion 124 of the center conductor 102. In some situations, the opening of the ring of the first elastomer 108 may have a diameter that does not cause the first elastomer 108 to physically press against both the wall 132 of the ILC 114 and the surface 134 of the center-portion 124 creating a small radial air-gap 136 between the inner surface of the opening of the ring of the first elastomer 108 and the surface 134 of the center-portion 124 of the center conductor 102. In other words, the first elastomer 108 may be positioned between the center conductor 102 and the insulating layer 106 within the ILC 114 in a way that creates the radial air-gap 136 between the first elastomer 108 and the center conductor 102. Moreover, the first elastomer 108 may have a height (i.e., a thickness in the direction that is perpendicular to the direction of the diameter of the ring) that extends out from the bottom surface 130 of the ILC 114 further than a transition 138 from the center-portion 124 to the front-portion 126 of the center conductor 102. In general, if there is a radial air-gap 136 present, once the HPMC 100 is physically connected to the HPFC, the HPMC 100 is designed to allow the first elastomer 108 to approximately fill in the radial air-gap 136 with the material of the first elastomer 108 when the first elastomer 108 is compressed in a normal direction towards the bottom surface 130 of the ILC 114. In this example, the compression of the first elastomer 108 is the result of physically connecting the HPMC 100 to the HPFC since the height (i.e., thickness) of the first elastomer 108 will be slightly oversized as compared to the material that would be present in a standard known RF connector. The first elastomer 108 may be natural rubber or a polymer material with viscoelasticity (i.e., having both viscosity and elasticity) that is relatively soft and deformable. Examples of the first elastomer 108 may include natural rubber or polyisoprene, polybutadiene, polyisobutylene, polyurethanes, vulcanizing (“RTV”) silicone, and other similar materials. In the case of RTV silicone, the first elastomer 108 may be constructed of CV-2289 material produced by NUSIL™ Technology LLC of Carpinteria, Calif.
The HPMC 100 may also include a second elastomer 140 positioned between the center conductor 102 and the outer conductor 104. In this example, the second elastomer 140 is positioned adjacent to the ILFE 112 outside of the ILC 114. Similar to the first elastomer 108, the second elastomer 140 may be natural rubber or a polymer material with viscoelasticity (i.e., having both viscosity and elasticity) that is relatively soft and deformable. Examples of the first elastomer 108 may include nature rubber or polyisoprene, polybutadiene, polyisobutylene, polyurethanes, RTV silicone, and other similar materials. In the case of RTV silicone, the second elastomer 140 may also be constructed of CV-2289 material produced by NUSIL™ Technology LLC of Carpinteria, Calif. In this example, the second elastomer 140 is also constructed as a ring having an opening that surrounds the front-portion 126 of the center conductor 102. The opening of the ring on the second elastomer 140 will have an inner diameter that is approximately equal to an ILC diameter 142 of the opening of the ILC 114. The second elastomer 140 has a height (i.e., thickness) that is approximately equal to or greater than the difference between the OCFE 110 and ILFE 112 such that the when the second elastomer 140 is placed adjacent to the ILFE 112 the outer surface 144 of the second elastomer 140 is approximately coplanar with the OCFE 110 or slightly protrudes out past the plane of the OCFE 110. Similar to the first elastomer 108, the second elastomer 140 is configured to be compressed as the result of physically connecting the HPMC 100 to the HPFC and may be slightly oversized as compared to the material that would be present in a standard known RF connector.
In these examples, the first elastomer 108 and second elastomer 140 are compressible dielectric rings (because elastomers are dielectrics) that reduce air gaps (including the radial air-gap 136) at the end of the pin (i.e., front-portion 126 of the center conductor 102) within the HPMC 100 so as to reduce RF breakdowns such as, for example, multipactor and ionization breakdown. As an example, the HPMC 100 may be significantly resistant to both multipactor and corona from low frequencies up to approximately 6 GHz because as the air gaps are reduced or eliminated; the possibility of resonant electron effects correspondingly decreases or is eliminated. As such, in these examples, the first elastomer 108 and second elastomer 140 minimize the possibility of gaps in high electric field (i.e., high radiated electrical flux) areas in mated (i.e., electrically connected) RF connector pairs (i.e., the HPMC 100 and a HPFC). This approach significantly reduces the RF breakdown thresholds for the HPMC 100 as compared to conventional RF connectors by removing or at least reducing all the air gaps within the HPMC 100 to allow breakdown-free or at least reduced breakdown operation of the HPMC 100 at the frequencies of operation of the HPMC 100.
In addition to filling in air gaps via mechanical compression when attaching the HPMC 100 to a HPFC, the first elastomer 108 and second elastomer 140 self-adjust over temperature to keep the air gaps filled when the insulation layer 106 shrinks with cold temperatures since the insulation layer 106 is typically made of solid rigid materials (as listed earlier) that shrink with decreased temperature. Since the first elastomer 108 and second elastomer 140 are constructed of resilient material, the material closes out or reduces the radial air gaps in a controlled fashion since for a temperature change that goes from room temperature to cold, most rigid dielectric materials contract to form gap opening but elastomers under compression from these dielectric materials release the compression to fill in the gaps formed by the rigid dielectric materials.
In an example of operation, the HPMC 100 is configured to propagate a transverse electric magnetic (“TEM”) mode high-power RF signal either from a coaxial cable electrically connected to the outer conductor 104 and attachment-portion 122 of the center conductor 102 to the HPFC via the outer conductor 104 and center-portion 124 and front-portion 126 of the center conductor 102 or from the HPFC to the coaxial cable through outer conductor 104 and the front-portion 126, center-portion 124, and attachment-portion 122 of the center conductor 102. It is appreciated by those of ordinary skill in the art that in the TEM mode of operation, the electrical flux of an RF signal traveling through the HPMC 100 radiate from the center conductor 102 to the outer conductor 104 (or vice versa) through the insulating layer 106, which is a dielectric layer that allows for alternating charge accumulation and discharge between the center conductor 102 and outer conductor 104 based on the power and frequency of operation of the RF signal passing through the HPMC 100. In this example, similar to the insulating layer 106, the first elastomer 108 passes a first radiated electrical flux from either the center conductor 102 (at the center-portion 124) to the outer conductor 104 or the outer conductor 104 to the center conductor 102 (at the center-portion 124) in response to a RF signal being propagated through the HPMC 100. Furthermore, the second elastomer 140 passes a second radiated electrical flux from either the center conductor 102 (at the front-portion 126) to the outer conductor 104 or the outer conductor 104 to the center conductor 102 (at the front-portion 126) in response to the RF signal being propagated through the HPMC 100. As such, unlike pressure gasket type of rings in some RF connectors, both the first elastomer 108 and second elastomer 140 are directly in the RF path of propagation of the RF signal and as such each directly affects the electrical performance of the HPMC 100 by reducing breakdown and providing better impedance matching by reducing the radial air-gap 136 and any other gaps between the HPMC 100 and the HPFC.
Without losing generality, it is appreciated by those of ordinary skill in the art that while the term “air-gap,” “air gaps,” “radial air gaps” have been utilized in this disclosure to represent radial gaps in the HPMC 100 that do not have material within them (such as, for example, the insulating layer 106, first elastomer 108, and second elastomer 140), these radial gaps will also include “vacuum gaps” in space applications where there is no “air” to file these radial gaps.
In these examples, the HPMC 100 may be a male TNC connector configured to mate with a standard female TNC defined by MIL-STD-348 or with a specialized HPFC. In the examples described in this disclosure the HPMC 100 have be described as mating (i.e., electrically connecting) to a HPFC; however, since the HPMC 100 may mate with standard female TNC or BNC RF connectors, it is appreciated that all of these examples will at times be referred to simply as electrically connecting to an HPFC for the purpose of simplicity without waiving the ability to mate with these different types of female RF connectors. Moreover, the HPMC 100 may be a male SMA connector configured to mate with a standard female SMA connector.
In
In this example, the female connector 200 includes a female center conductor 202, a female outer conductor 204, and a female insulating layer 206. The shape of the female insulating layer 206 is such that when mated to the HPMC 100, the female insulating layer 206 pushes against both the first elastomer 108 and second elastomer 140 and compresses both to eliminate or, at least reduce, any air gaps (including radial air-gap 136) within the combined assembly of the HPMC 100 and female connector 200. Specifically, in this example, the female insulating layer 206 is shaped so that a first portion of the female insulating layer 206 enters the ILC 114 and compresses the first elastomer 108 causing it to reduce in height (i.e., thickness) and flow into the radial air-gap 136 shown in
In this example, the front-portion 126 of the center conductor 102 is shown residing within a conductor cavity 210 within the female center conductor 202. Similar to the HPMC 100, the female connector 200 may also include a female back cavity 212 and corresponding female attachment-portion 214 of the female center conductor 202. Similar to the HPMC 100, the female back cavity 212 and female attachment-portion 214 of the female center conductor 202 are configured to physically and electrically connect to a coaxial cable (not shown).
As discussed earlier, both the insulating layer 106 of the HPMC 100 and female insulating layer 206 of the female connector 200 are typically constructed of rigid dielectric material that has thermal characteristics that cause the rigid dielectric material to expand or contract with temperature variations. Specifically, for extreme weather, high-altitude, or space based applications, the temperature of operation may be significantly below room temperature (i.e., about 21° C.) causing the rigid dielectric material to significantly contract (i.e., shrink) causing air gaps between the interfaces of the insulating layer 106 and female insulating layer 206. The HPMC 100 utilizes the first elastomer 108 and second elastomer 140 to fill in these air gaps since both the first elastomer 108 and second elastomer 140 are of sufficient thickness that when the female connector 200 is mated with the HPMC 100, the amount of compression force applied by the female insulating layer 206 on both the first elastomer 108 and second elastomer 140 is sufficient to ensure that even at the coldest temperature of operation the combined assembly of the HPMC 100 and female connector 200, there will still be enough compression force applied on both the first elastomer 108 and second elastomer 140 to allow the material of the both the first elastomer 108 and second elastomer 140 to flow into and fill in any air gaps that are formed by the contracting rigid dielectric material of both the insulating layer 106 and female insulating layer 206.
Turning to
In
In this example, the FILC 418 forms a ring cylinder (i.e., a cavity opening that is in the shape and form of an empty cylindrical ring) having a depth 426, an outer wall 428, an inner wall 430, a bottom surface 432, and an FILC diameter 434. The outer wall 428 is a female outer conductor portion 436 of the female outer conductor 404 and the inner wall 430 is a female insulating layer portion 438 of the female insulating layer 406. The female first elastomer 408 has a ring shape having an inner diameter 440 approximately equal to the FILC diameter 434 and is located adjacent to the bottom surface 432 and has a ring thickness. The ring thickness of the female first elastomer 408 is less than the depth 426 of the FILC 418. As discussed earlier with regards to the HPMC 100, the female first elastomer 408 is compressible and passes a radiated electrical flux from either the female center conductor 402 to the female outer conductor 404 or the female outer conductor 404 to the female first elastomer 408 in response to a RF signal being propagated through the HPFC 400. Similar to the first elastomer 108 and second elastomer 140, the female first elastomer 408 is composed of a material that selected from a group consisting of nature rubber or polyisoprene, polybutadiene, polyisobutylene, RTV silicone, and polyurethanes.
Similar to the example described in
In this example, the attachment-portion 522 may be a part of the center conductor 102 that is electrically and physically connected to a center conductor (not shown) of a coaxial cable (not shown). In this example, the HPMC 500 may include a back cavity 530 within the housing 516 to properly accommodate the physical attachment of the coaxial cable. The center-portion 524 may be a solid cylindrical portion of the center conductor 502 that extends out from attachment-portion 522 to the front-portion 526. In this example, the diameters of the attachment-portion 522, center-portion 524, and front-portion 526 may be equal to varying in size based on the desired design of the HPMC 500 and corresponding HPFC or standard female SMA connector. Similar to the outer conductor 504, the center conductor 502 may include any conductive material capable of electrically conducting a current such as, for example, a metal material (such as, for example, copper, silver, gold, aluminum, steel, or any similar conductive alloy). The insulating layer 506 may be any dielectric material utilized for RF coaxial cable applications that may include, for example, fluorocarbon materials such as, for example, PTFE. In this example, the first elastomer 508 is located adjacent to a bottom surface 532 and a wall 534 of the second-portion 520 of the housing 516. The first elastomer 508 is also located adjacent to a surface 536 of the center-portion 524 of the center conductor 502; however, the first elastomer 508 is constructed of an elastomer material formed of a ring (i.e., a ring-shaped washer gasket) having an opening that surrounds the center-portion 524 of the center conductor 502. In some situations, the opening of the ring of the first elastomer 508 may have a diameter that does not cause the first elastomer 508 to physically press against both the wall 534 of the second-portion 520 of the housing 516 and the surface 536 of the center-portion 524 of the center conductor 502 creating a small radial air-gap between the inner surface of the opening of the ring of the first elastomer 508 and the surface 536 of the center-portion 524 of the center conductor 502. In other words, the first elastomer 508 may be positioned between the center conductor 502 and the outer conductor 504 within the ILC 514 in a way that creates the radial air-gap between the first elastomer 508 and the center conductor 502. Moreover, the first elastomer 508 may have a height (i.e., a thickness in the direction that is perpendicular to the direction of the diameter of the ring) that extends out from the bottom surface 532 of the ILC 514. In general, if there is a radial air-gap present, once the HPMC 500 is physically connected to the female SMA connector, the HPMC 500 is designed to allow the first elastomer 508 to approximately fill in the radial air-gap with the material of the first elastomer 508 when the first elastomer 508 is compressed in a normal direction towards the bottom surface 532 of the ILC 514. In this example, the compression of the first elastomer 508 is the result of physically connecting the HPMC 500 to the female SMA since the height (i.e., thickness) of the first elastomer 508 will be slightly oversized as compared to the material that would be present in a standard known RF connector. The first elastomer 508 may be natural rubber or a polymer material with viscoelasticity (i.e., having both viscosity and elasticity) that is relatively soft and deformable. Examples of the first elastomer 508 may include nature rubber or polyisoprene, polybutadiene, polyisobutylene, polyurethanes, RTV silicone, and other similar materials. In the case of RTV silicone, the first elastomer 108 may be constructed of CV-2289 material produced by NUSIL™ Technology LLC of Carpinteria, Calif.
In this example, the first elastomer 508 is compressible dielectric ring that reduces the radial air-gap at the end of the pin (i.e., front-portion 526 of the center conductor 502) within the HPMC 500 so as to reduce RF breakdowns such as, for example, multipactor and ionization breakdown. As described earlier, in this example, the HPMC 500 may be significantly resistant to both multipactor and corona from low frequencies because as the radial air-gap is reduced or eliminated; the possibility of resonant electron effects correspondingly decreases or is eliminated. In addition to filling in air gaps via mechanical compression when attaching the HPMC 500 to a HPFC, the first elastomer 508 self-adjusts over temperature to keep the radial air-gap filled when the insulation layer 506 shrinks with cold temperatures since the insulation layer 506 is typically made of solid rigid materials (as listed earlier) that shrink with decreased temperature. Since the first elastomer 508 is constructed of resilient material, the material closes out or reduces the radial air-gap in a controlled fashion since for a temperature change that goes from room temperature to cold, most rigid dielectric materials contract to form gap opening but elastomers under compression from these dielectric materials release the compression to fill in the gaps formed by the rigid dielectric materials.
It will be understood that various aspects or details of the invention may be changed without departing from the scope of the invention. It is not exhaustive and does not limit the claimed inventions to the precise form disclosed. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation. Modifications and variations are possible in light of the above description or may be acquired from practicing the invention. The claims and their equivalents define the scope of the invention.
In some alternative examples of implementations, the function or functions noted in the blocks may occur out of the order noted in the figures. For example, in some cases, two blocks shown in succession may be executed substantially concurrently, or the blocks may sometimes be performed in the reverse order, depending upon the functionality involved. Also, other blocks may be added in addition to the illustrated blocks in a flowchart or block diagram.
The description of the different examples of implementations has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the examples in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. Further, different examples of implementations may provide different features as compared to other desirable examples. The example, or examples, selected are chosen and described in order to best explain the principles of the examples, the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various examples with various modifications as are suited to the particular use contemplated.
The invention described herein was made in the performance of work under NASA Contract No. NNM07AB03C and is subject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958 (72 Stat. 435: 42 U.S.C. 2457).