RF connector element and RF connector system

Abstract

To provide an RF connector system capable of improving the signal transmission performance thereof.SOLUTION: A first coaxial connector element 100 includes a first inner conductor 104, a first outer conductor, and a first electrical insulator element 102. A first electrical insulator element 102 includes: a first contact support part 114 which is integrally formed of a first dielectric material that has a first relative dielectric constant; and a first compensation part 116 which is integrally formed, together with the first contact support part 114, of a second dielectric material that has a second relative dielectric constant larger than the first relative dielectric constant. The first compensation part 116 is arranged in a front end region of the electrical insulator element 102, and improves the signal transmission performance by at least partly surrounding a first contact region 110 of the first inner conductor 104.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a matable radio frequency (RF) connector element, and to an RF connector system comprising a first RF connector element and a second RF connector element. [Background technology]

[0002] RF connectors, such as coaxial connectors, twin-axial connectors, or universal serial bus (USB) connectors, and RF connector systems are used to connect the transmission lines of RF cables that transmit radio frequency RF signals with an operating bandwidth of several GHz. For example, a conventional coaxial connector includes an inner conductor that serves to connect the transmission lines of the coaxial cable, and the inner conductor is provided in the center of the coaxial connector. An outer conductor that serves as a grounding conductor is provided around the inner conductor, and the outer conductor shields the inner conductor. An insulating element is provided in the gap between the outer conductor and the inner conductor to electrically insulate the inner conductor and the outer conductor and stabilize the coaxial connector.

[0003] Conventional twinaxial and USB connectors include multiple inner conductors, each of which serves to connect a respective transmission line of a corresponding twinaxial or USB cable, and an insulating element provided in the twinaxial or USB cable therefore electrically insulates the multiple inner conductors from the shielding outer conductor as well as from each other.

[0004] Today, the main goal is to provide a communication link with higher data transfer rates by transmission lines, especially for applications in the automotive and information and communication technology (ICT) industries. For this purpose, it is necessary to maintain a homogeneous impedance throughout the entire transmission system, including the RF connector and the RF cable, because impedance discontinuities lead to reflections of radio frequency signals and thus cause loss of signal transmission performance. Therefore, in order to avoid impedance inhomogeneities within the transmission system, it is necessary to match the impedance of the RF connector to the impedance of the connected RF cable and provide a homogeneous impedance throughout the RF connector.

[0005] On the other hand, it is also a goal to miniaturize the RF connector and enable the use of simple fastening mechanisms, which only require linear movements such as snap-fit ​​connections, levers, or slides, making it possible to provide a cheap, lightweight, space-saving RF connector. Although such fastening mechanisms further enable easy mating of the RF connector, for example, in a vehicle, they inevitably result in mating tolerances, which reduces the signal transmission performance of the RF connector. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, the underlying objective of the present invention is to improve the signal transmission performance of an RF connector system, and to provide an RF connector system that can be miniaturized, easily mated, and easily installed. Furthermore, the objective of the present invention is to provide a simple and economical solution. [Means for solving the problem]

[0007] At least one of these objects is solved by the subject matter of the independent claims. Advantageous embodiments of the invention are the subject matter of the dependent claims.

[0008] The present invention provides a first RF connector element for mating with a second RF connector element, the first RF connector element comprising a first terminal having a first contact area for electrically connecting to a first mating terminal of the second RF connector element, a second terminal having a second contact area for electrically connecting to a second mating terminal of the second RF connector element, and a first insulating element for electrically insulating the first terminal and the second terminal.

[0009] The invention is based on the idea that a first insulating element comprises a first contact support integrally formed from a first dielectric material having a first relative dielectric constant and a first compensation portion integrally formed with the first contact support from a second dielectric material having a second relative dielectric constant greater than the first relative dielectric constant, the first compensation portion being arranged in a front end region of the first insulating element and at least partially surrounding a first contact region of the first terminal.

[0010] In other words, the inventors have found that a first insulating element integrally formed from at least two materials having different relative dielectric constants can improve the signal transmission performance of an RF connector element. By providing a first compensation part having a higher relative dielectric constant, the capacitance between the first terminal and the second terminal is increased in the connection area where these terminals are electrically connected to the corresponding mating terminal. Thus, when the RF connector element is mated with the corresponding RF connector element, the reduction in capacitance caused by the air gap induced by the contact gap variation is compensated. Thus, the effect of the contact gap variation on the signal transmission performance of the RF connector element is reduced, and the mating tolerance of the RF connector element is increased.

[0011] Thus, the present invention enables the use of a linear fastening mechanism for fastening a first RF connector element without degrading the data transmission performance of the RF connector system that includes the first RF connector element, which is particularly important for arrays of multiple RF connector elements that must be plugged together simultaneously.

[0012] According to an advantageous embodiment of the invention, the first terminal is a first inner conductor and the second terminal element is a first outer conductor, the first outer conductor surrounding the first inner conductor. Alternatively, the first terminal is a first inner conductor and the second terminal is a second inner conductor, and may optionally further comprise a first outer conductor, the first outer conductor surrounding the first terminal and the second terminal.

[0013] The invention is therefore applicable to coaxial connector elements with a single inner conductor and a single outer conductor for shielding the inner conductor. However, the invention is also applicable to twin-axial connector elements with two insulated inner conductors and an outer conductor for shielding the two inner conductors, and to multi-conductor connector elements such as USB connector elements with multiple inner conductors, optionally shielded by outer conductors. Of course, other RF connector elements are also possible.

[0014] In order to optimize the operating bandwidth and signal transmission performance of the first RF connector element, the ratio between the first relative dielectric constant and the second relative dielectric constant is preferably in the range of 1 / 35 to 5 / 8.

[0015] According to an advantageous embodiment of the invention, the first insulating element is formed by injection molding the first contact support from a first dielectric material and then overmolding the first compensation part from a second dielectric material, thus realizing a highly reproducible, simple and cost-saving manufacturing process for the first insulating element, even when the first insulating element comprises a first compensation part with a small area.

[0016] In order to realize an efficient increase in capacitance in the connection area of ​​the first RF connector element, the first compensating portion has a thickness in the range of 0.2 mm to 0.8 mm in the longitudinal direction of the first RF connector element, whereby the thickness of the first compensating portion can be varied based on the ratio between the first and second dielectric constants in order to optimize the compensation of the capacitance reduction caused by the air gap.

[0017] Alternatively, the thickness of the first compensation section can be varied based on a maximum compensation length, where the maximum compensation length means the maximum length possible for the longitudinal air gap between the front surface of the first insulating element and the front surface of the second insulating element that compensates for the capacitance reduction caused by the air gap without significantly reducing the data transmission performance. For example, the thickness of the first compensation section can be 0.5 to 1.5 times the maximum compensation length.

[0018] According to an advantageous embodiment, the first inner conductor is a receptacle, but of course a pin is also possible.

[0019] The present invention further relates to a second RF connector element for mating with the first RF connector element, the second RF connector element comprising a first mating terminal having a first mating terminal contact area for electrically connecting to a first terminal of the first RF connector element and a first mating terminal end area for electrically connecting to a first conductor of an RF cable element, a second mating terminal having a second mating terminal contact area for electrically connecting to a second terminal of the first RF connector element and a second mating terminal end area for electrically connecting to a second conductor of the RF cable element, and a second insulating element for electrically insulating the first mating terminal and the second mating terminal.

[0020] According to the present invention, the second insulating element comprises a second contact support integrally formed from a third dielectric material having a third relative dielectric constant, and a second compensation portion integrally formed with the second contact support from a fourth dielectric material having a fourth relative dielectric constant greater than the third relative dielectric constant, and the second compensation portion is arranged at least partially between the first mating terminal end region and the second mating terminal end region in a rear end region of the second insulating element.

[0021] In other words, the inventors have found that the signal transmission performance of the RF connector system can be further improved by providing the second RF connector element with a second insulating element integrally formed from at least two materials with different dielectric constants. For this purpose, the second insulating element comprises a second compensation section in the area where at least one transmission line of the RF cable enters the second RF connector element. In this way, the capacitance between the first and second mating terminals can be increased in this area, thus compensating for the impedance mismatch resulting from the geometric discontinuity between the RF cable and the second RF connector element.

[0022] To optimize the operating bandwidth and signal transmission performance of the second RF connector element, the ratio between the third relative dielectric constant and the fourth relative dielectric constant is in the range of 1 / 35 to 5 / 8.

[0023] According to an advantageous embodiment of the invention, the second insulating element is manufactured by injection molding the second contact support from a third dielectric material and then overmolding the second compensation part from a fourth dielectric material, thus realizing a highly reproducible, simple and inexpensive manufacturing process for the second insulating element, even when the second compensation part has a small area.

[0024] According to an exemplary embodiment, the first mating terminal is a pin, but of course a receptacle is also possible.

[0025] The invention further relates to an RF connector system comprising a first RF connector element according to the invention and a second RF connector element according to the invention, whereby, when the first RF connector element and the second RF connector element are mated, the first compensation part preferably at least partially surrounds the second contact area. In this way, when the RF connector system is mated, it is possible to improve the compensation of the capacitance reduction caused by the air gap induced by the variation of the contact gap between the first insulating element and the second insulating element. Thus, the RF connector system according to the invention can reduce the influence of the variation of the contact gap on the signal transmission performance of the RF connector system when the RF connector system is mated, and can provide an improved signal transmission performance.

[0026] To simplify production and reduce manufacturing costs, it is preferred that the second and fourth dielectric constants are equal. It is further preferred that the first and third dielectric constants are equal. In this way, it is possible to fabricate the first and second RF connector elements from the same material and to establish a common fabrication method for both.

[0027] At this point, it should be mentioned that the term "radio frequency signal" refers to an alternating electric signal having an oscillation frequency of about 20 kHz to 20 GHz, but the present invention can also be applied to frequency ranges above 20 GHz. The term "signal" refers to analog signals as well as digital signals.

[0028] Furthermore, in this disclosure, the term "dielectric constant" refers to the relative dielectric constant of a material. Generally, the dielectric constant of a material is understood to be its absolute dielectric constant expressed as a ratio to the vacuum dielectric constant.

[0029] The accompanying drawings are incorporated into and form a part of this specification to illustrate some embodiments of the present invention. These drawings, together with the description, serve to explain the principles of the present invention. These drawings are only intended to illustrate preferred alternative examples of how the present invention can be made and used, and should not be construed as limiting the present invention to only the embodiments shown and described. Furthermore, some aspects of the embodiments can form solutions according to the present invention individually or in various combinations. Thus, the embodiments described below can be considered alone or in any combination. Further features and advantages will become apparent from the following more detailed description of various embodiments of the present invention as illustrated in the accompanying drawings. In the accompanying drawings, like reference numerals refer to like elements. [Brief description of the drawings]

[0030] [Figure 1] 1 is a schematic cross-sectional view of an RF connector system according to a first embodiment of the present invention comprising a first RF connector element and a second RF connector element; [Diagram 2] FIG. 2 is a detailed view of FIG. [Diagram 3] FIG. 2 is a schematic cross-sectional view of a first RF connector element according to a first embodiment. [Figure 4] FIG. 4 is a schematic top view of a first RF connector element according to a second embodiment of the present invention. [Diagram 5] FIG. 11 is a schematic top view of a first RF connector element according to a third embodiment of the present invention. [Figure 6] 4 is a graph illustrating simulation results of return loss of an RF connector system according to a first embodiment of the present invention for various contact gap variations. [Figure 7] 4 is a graph illustrating simulated time domain reflectometry (TDR) results for an RF connector system according to a first embodiment of the present invention for various contact gap variations. [Figure 8]4 is a graph showing measured return loss of an RF connector system according to a first embodiment of the present invention for various contact gap variations. [Figure 9] 4 is a graph showing TDR measurements of an RF connector system according to a first embodiment of the present invention for various contact gap variations. [Figure 10] 4 is a schematic cross-sectional view of a second RF connector element according to a first embodiment of the present invention. FIG. [Figure 11] 13 is a graph showing measurement results illustrating the effect of the second compensation section on the return loss of the RF connector system. [Figure 12] 13 is a graph showing measurement results illustrating the effect of the second compensation section on the TDR of the RF connector system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The present invention will now be described in more detail with reference to the figures. First, reference is made to Figs. 1 and 2, which show schematic cross-sectional views of an RF connector system according to a first embodiment of the present invention. In the example of the first embodiment, the RF connector system is a coaxial connector system 1000, comprising a first coaxial connector element 100 and a second coaxial connector element 200. More specifically, Figs. 1 and 2 show an example of a coaxial connector system 1000, in which the air gap 300 between the front face 103 of the first insulating element 102 and the front face 203 of the second insulating element 202 in the longitudinal direction 302 shown by the arrow in Figs. 1 and 2 is 0 mm. However, the length of the air gap 300 between the front face 103 of the first insulating element 102 and the front face 203 of the second insulating element 202 can vary, for example, within a range of 0 to 2 mm.

[0032] 1 and 2, the first coaxial connector element 100 includes a first insulating element 102, a first inner conductor 104 which is an example of a first terminal, and a first outer conductor 106 which is an example of a second terminal, whereby the first insulating element 102 is disposed between the first inner conductor 104 and the first outer conductor 106 so as to electrically insulate the first inner conductor 104 and the first outer conductor 106.

[0033] The second coaxial connector element 200 includes a second insulating element 202, a first mating inner conductor 204, which is an example of a first mating terminal, and a first mating outer conductor 206, which is an example of a second mating terminal. The second insulating element 202 is disposed between the first mating inner conductor 204 and the first mating outer conductor 206 so as to electrically insulate the first mating inner conductor 204 and the first mating outer conductor 206. In the example of FIGS. 1 and 2, the first coaxial connector element 100 is a receptacle and the second connector element is a pin.

[0034] The first coaxial connector element 100 will now be described with reference to FIGS.

[0035] The first inner conductor 104 comprises a first contact area 110 for electrically connecting the first inner conductor to a first mating terminal contact area 210 of the second coaxial connector element 200. For that purpose, the first contact area 110 is formed as a hollow member and comprises a contact opening 108, such that the first contact area 110 can receive the first mating terminal contact area 210. For electrically connecting the transmission line 304 of the coaxial cable element 305 to the first inner conductor 104, the first inner conductor 104 comprises a first terminal end area.

[0036] Additionally, the first inner conductor 104 may include a first barb protruding radially from a center of the first inner conductor 104. After manufacture of the first coaxial connector element 100, the first barb may engage a first recess included in the first insulating element 102. In this manner, the first barb may prevent the first inner conductor 104 from moving in the longitudinal direction 302 relative to the first insulating element 102 after the first coaxial connector element 100 is manufactured.

[0037] The first outer conductor 106 surrounds the first inner conductor 104 so as to shield the first inner conductor 104. To ensure that the first outer conductor 106 is electrically connected to the first mating outer conductor 206 when the coaxial connector system is mated, the first outer conductor may include a first spring 113 adapted to press the first outer conductor 106 against the first mating outer conductor 206. To electrically connect the ground wire 306 of the coaxial cable element 305 to the first outer conductor 106, the first outer conductor 106 includes a second terminal end region.

[0038] Additionally, the first outer conductor 106 may be provided with an outer conductor inspection opening (not shown in these figures) to enable camera inspection of the alignment of the first inner conductor 104 relative to the first insulating element 102 after manufacture of the first connector element 100.

[0039] According to the present invention, the first insulating element 102 comprises a first contact support 114 and a first compensation portion 116, which is integrally formed with the first contact support 114 to form a single part. The first contact support 114 is integrally formed from a first dielectric material having a first relative dielectric constant. To provide isotropic electrical insulation and isotropic capacitance between the first inner conductor 104 and the first outer conductor 106, the first contact support 114 may be substantially ring-shaped.

[0040] According to the present invention, the first compensation portion 116 is integrally formed from a second dielectric material having a second relative dielectric constant greater than the first relative dielectric constant. As shown in FIGS. 1-3, the first compensation portion 116 is disposed near the front end portion 118 of the first contact region 110, and thus the first compensation portion 116 at least partially surrounds the first contact region 110 of the first inner conductor 104. Furthermore, the first compensation portion 116 can protrude above the front end portion 118 toward the opening 119 of the first coaxial connector element. In this manner, the first compensation portion 116 can increase the capacitance between the inner conductor 104 and the outer conductor 106 near the front end portion 118, and thus compensate for the capacitance reduction caused by the air gap 300 when the coaxial connector system 1000 is mated.

[0041] Preferably, the first compensation portion 116 is substantially ring-shaped, thus providing isotropic capacitance compensation in the vicinity of the front end portion 118. Moreover, this geometry allows the first inner conductor 104 to be easily inserted into the first insulating element 102 during manufacturing of the first coaxial connector element 100. As is evident from FIG. 3, the first compensation portion 116 may also include a compensation opening 126. The compensation opening 126 may receive the first mating terminal contact area 210 of the second coaxial connector element 200, such that the first compensation portion 116 may at least partially surround the first mating terminal contact area 210 when the coaxial connector system 1000 is mated.

[0042] To enable camera inspection to control the alignment of the first inner conductor 104 relative to the first insulating element 102, the first insulating element 102 may optionally be provided with an inspection opening extending radially to the center of the first insulating element 102. In this way, after manufacture of the first coaxial connector element 100, it becomes possible to control via camera inspection whether the front end portion 118 of the first inner conductor 104 is aligned with the inspection opening.

[0043] It should be noted here that the first compensation portion 116 is disposed at least near the inspection aperture, and therefore the first compensation portion 116 also compensates for the reduction in capacitance between the first inner conductor 104 and the first outer conductor 106 induced by the inspection aperture formed from air having a relative dielectric constant of 1.

[0044] Preferably, the first contact support 114 is formed from a polymer, resin, or rubber. For example, the first contact support 114 is formed from an injection moldable dielectric material such as polyethylene (PE) or polypropylene (PP). Alternatively, the first contact support 114 can be formed from a material processed by ram extrusion such as polytetrafluoroethylene (PTFE), or from a 3D printable ceramic dielectric material. Typically, such materials have a relative dielectric constant in the range of 1 to 5, and therefore the first compensation portion 116 is preferably formed from a material having a relative dielectric constant in the range of at least 8 to 35.

[0045] To achieve the second dielectric constant within such a range, the second dielectric material can be fabricated by ceramic powder filling of a plastic-based material. For example, the first compensation portion 116 can be formed from an injection moldable polymer mixed with a mineral such as barium titanate (BaTiO3). By optimizing the volume fraction of the mineral, a range of 8 to 23 can be achieved for the second dielectric constant at a transmission signal frequency of 1 GHz.

[0046] Alternatively, the second dielectric material can be any 3D printable ceramic having a dielectric constant greater than the first dielectric constant of the first dielectric material. Additionally, the second dielectric material can be a dispenseable semi-liquid mixed with a mineral. For example, semi-liquids mixed with minerals such as BaTiO3 are known to have a dielectric constant of 35 at a transmission signal frequency of 1 GHz.

[0047] Preferably, the first insulating element 102 is manufactured by a fabrication process known in the art as overmolding or multi-material injection molding, whereby the first contact support 114 is first manufactured by injection molding of a first dielectric material, and then the first compensating portion 116 is overmolded on the first contact support 114 by injection molding of a second dielectric material. In this way, the first insulating element 102 can be manufactured as a single piece, and thus the first coaxial connector element 100 can be assembled in a conventional manner from the first insulating element 102, the first inner conductor 104, and the first outer conductor 106.

[0048] Moreover, injection molding and overmolding are well-known methods that provide reliable and inexpensive manufacturing even for miniature coaxial connector elements. For example, these techniques make it possible to manufacture a first insulating element having a first outer diameter 128 of 2 mm and to fabricate a first compensating portion 116 having a longitudinal 302 thickness of 0.6 mm and a compensating opening 126 having a diameter of 0.6 mm. However, these dimensions are given only as examples to illustrate the length scale of the miniature first coaxial connector element 100 and are not meant to be limiting, since aspects of the invention can also be applied to coaxial connector systems having larger or smaller dimensions.

[0049] Alternatively, the first compensation portion 116 can be fabricated by dispensing a dispenseable semi-fluid in a dispensed volume after the first contact support portion 114 is manufactured. As another alternative, the first insulating element 102 can be manufactured as a single part comprising the first contact support portion 114 and the first compensation portion 116 using 3D printing in combination with a suitable dielectric material.

[0050] Furthermore, it may be useful to vary the thickness of the first compensation portion 116 in the longitudinal direction 302, for example, within a range of 0.2 mm to 0.8 mm, based on the ratio of the first relative dielectric constant and the second relative dielectric constant. For example, the thickness of the first compensation portion 116 in the longitudinal direction 302 can be increased when the ratio of the first relative dielectric constant and the second relative dielectric constant decreases, and can be decreased when the ratio of the first relative dielectric constant and the second relative dielectric constant increases. In this way, it is possible to optimize the compensation of the capacitance reduction caused by the air gap 300 and further improve the signal transmission performance of the first coaxial connector element 100.

[0051] Alternatively, the thickness of the first compensation portion 116 can be varied based on a maximum compensation length, which is the maximum length of the air gap 300 in the longitudinal direction 302 that compensates for the capacitance reduction caused by the air gap 300 without significantly degrading the data transmission performance. For example, the thickness of the first compensation portion 116 can be 0.5 to 1.5 times the maximum compensation length. For example, to achieve a tolerance for the air gap 300 of up to 1 mm, the thickness of the first compensation portion 116 can be varied within a range of 0.5 mm to 1.5 mm.

[0052] With reference to the above figures, an embodiment has been described in detail in which the RF connector system is a coaxial connector system 1000 and thus includes a single inner conductor for transmitting RF signals and an outer conductor for shielding the inner conductor. However, the present invention is not limited to such connector systems and can also be applied to RF connector systems such as twin-axial or USB connector systems that include multiple inner conductors, whether shielded or not.

[0053] FIG. 4 shows a schematic top view of a first RF connector element according to a second embodiment of the present invention. In the example of the second embodiment, the RF connector system is a biaxial connector system, and the first RF connector element is a first biaxial connector element 400. The first biaxial connector element 400 comprises a first inner conductor, which is an example of a first terminal, and a second inner conductor, which is an example of a second terminal. The first inner conductor has a first contact area for electrically connecting to a first mating inner conductor, which is an example of a first mating terminal, and the second inner conductor has a second contact area for electrically connecting to a second mating inner conductor, which is an example of a second mating terminal. Here, the first inner conductor and the second inner conductor are exemplified by receptacles and can be substantially equivalent to the first inner conductor 104 of the first embodiment. However, it is to be understood that the first inner conductor and the second inner conductor can also be pins.

[0054] The first biaxial connector element 400 further includes a first insulating element 402 that electrically insulates the first inner conductor from the second inner conductor. Optionally, a first outer conductor 406 may be provided surrounding the first inner conductor and the second inner conductor to shield the first inner conductor and the second inner conductor. In this case, the first insulating element 402 is arranged to electrically insulate the first inner conductor and the second inner conductor from the first outer conductor 406.

[0055] As can be seen from Fig. 4, the first insulating element 402 comprises a first contact support 414 integrally formed from a first dielectric material having a first relative dielectric constant and a first compensation portion 416 integrally formed from a second dielectric material having a second relative dielectric constant greater than the first relative dielectric constant. According to the present invention, the first compensation portion 416 is integrally formed with the first contact support 414. Furthermore, the first compensation portion 416 is arranged in a front end region of the first insulating element 402, so that the first compensation portion 416 at least partially surrounds the first contact region and the second contact region.

[0056] Preferably, the first compensation portion 416 is substantially ring-shaped and includes a first compensation opening 426 and a second compensation opening 428. The first compensation opening 426 is capable of receiving a first mating contact area of ​​a first mating inner conductor, and the second compensation opening 428 is capable of receiving a second mating contact area of ​​a second mating inner conductor. In this way, the first compensation portion 416 is capable of at least partially surrounding the first mating contact area and the second mating contact area when the twin-axial connector element 400 is mated to a mating twin-axial connector element.

[0057] In this way, the first compensation portion 416 increases the capacitance between the first inner conductor and the second inner conductor, and between each of the first and second inner conductors and the first outer conductor 406 near the first and second contact areas, thereby compensating for the capacitance reduction induced by the air gap at the front surface 403 of the first insulating element 402 when the twin-axial connector element 400 is mated with a mating twin-axial connector element.

[0058] Furthermore, it is apparent to those skilled in the art that the first insulating element 402 can be manufactured by any of the fabrication processes described with respect to the first embodiment of the present invention. Similarly, the first contact support 414 can be formed from any of the materials mentioned with respect to the first contact support 114 of the first embodiment, and the first compensation portion 416 can be formed from any of the materials mentioned with respect to the first compensation portion 116 of the first embodiment.

[0059] 5 shows a schematic top view of a first RF connector element according to a third embodiment of the present invention. In the third exemplary embodiment, the RF connector system is a USB connector system and the first RF connector element is a first USB connector element 500. The first USB connector element 500 includes a plurality of inner conductors 504, which are an example of a plurality of terminals of an RF connector element. Each of the first inner conductors 504 includes a first contact area 510 for electrically connecting to a corresponding mating terminal of a second USB connector element.

[0060] Optionally, the first USB connector element 500 may include a first outer conductor 506 surrounding the multiple inner conductors 504 to shield the multiple inner conductors 504 .

[0061] A first insulating element 502 is further provided, which can also be represented as a first tongue. The first insulating element 502 comprises a first contact support 514 made of a first dielectric material having a first relative permittivity and a first compensation part 516 made of a second dielectric material having a second relative permittivity greater than the first relative permittivity. According to the present invention, the first compensation part 516 is integrally formed with the first contact support 514. Furthermore, the first compensation part 516 is arranged in a front end region of the first insulating element 502, and thus at least partially surrounds the plurality of contact regions 510 in the first compensation part 516. As shown by FIG. 5, this can be realized by sandwiching the first contact support 514 between the first compensation parts 516, so that the plurality of inner conductors 504 are in direct contact with the first contact support.

[0062] As can be seen in FIG. 5, the first compensation portion 516 is substantially rectangular in shape and includes a plurality of compensation recesses 528 for receiving the plurality of first contact regions 510 .

[0063] In this manner, the first compensation portion 516 increases the capacitance between the inner conductors 504 near the first contact regions 510. Thus, the capacitance reduction induced by the air gap near the first contact regions 510 can be compensated for when the first USB connector element 500 is mated to a second USB connector element.

[0064] It is apparent to those skilled in the art that the first insulating element 502 can be manufactured by any of the fabrication processes described with respect to the first embodiment of the present invention. Similarly, the first contact support 514 can be formed from any of the materials mentioned with respect to the first contact support 114 of the first embodiment, and the first compensation portion 516 can be formed from any of the materials mentioned with respect to the first compensation portion 116 of the first embodiment.

[0065] The influence of the first insulating element 102 with the first compensation portion 116 on the signal transmission performance of the coaxial connector system 1000 according to the first embodiment of the present invention will be described below with reference to Figs. 6 to 9. Figs. 6 and 7 show a graph (Fig. 6) showing a simulation result of the return loss as a function of the frequency of the transmission signal and a graph (Fig. 7) showing the time domain reflectance (TDR) as a function of time for the coaxial connector system 1000 with the first coaxial connector element 100 shown in Figs. 1 to 3. Thus, simulations were performed for various examples of the air gap 300 and various examples of the second relative dielectric constant of the first compensation portion 116. Here, the TDR was simulated for a pulse rise time of 60 ps.

[0066] Dashed lines 1402 and 1410 respectively show simulation results for an air gap 300 of 0.8 mm (shown in FIGS. 3 and 4) and for a first compensating portion 116 formed from a second dielectric material having a second dielectric constant equal to the first dielectric constant, i.e., between 1 and 5. Solid lines 1404 and 1412 respectively show simulation results for an air gap 300 of 0.8 mm and for a first compensating portion 116 formed from a second dielectric material having a second dielectric constant equal to 13, i.e., greater than the first dielectric constant.

[0067] Dashed lines 1406 and 1414 respectively show simulation results for an air gap 300 of 0 mm (shown in FIGS. 1 and 2) and for a first compensating portion 116 formed from a second dielectric material having a second dielectric constant equal to the first dielectric constant, i.e., between 1 and 5. Solid lines 1408 and 1416 respectively show simulation results for an air gap 300 of 0 mm and for a first compensating portion 116 formed from a second dielectric material having a second dielectric constant equal to 13, i.e., greater than the first dielectric constant.

[0068] As is evident from these graphs, especially the graph of FIG. 7, the use of a second dielectric material having a higher dielectric constant reduces the maximum deviation of the TDR from the nominal impedance value, here for example 50 ohms. The reduction in maximum deviation is indicated by arrow 1418, which in this example is about 3 ohms for an air gap 300 of 0.8 mm. At the same time, the maximum deviation of the TDR from the nominal impedance value, indicated by arrow 1420, remains approximately constant for an air gap 300 of 0 mm.

[0069] Thus, it has been shown that the first compensating portion 116 formed from the second dielectric material having a second dielectric constant higher than the first dielectric constant can suppress the effect of the air gap 300 on the impedance of the coaxial connector system 1000. In particular, the first compensating portion 116 reduces the maximum deviation from the nominal impedance value to within a tolerance of 10 percent around the nominal impedance value for both the 0 mm and 0.8 mm air gaps 300. Thus, the present invention can increase the tolerance of the signal transmission performance for the air gap 300.

[0070] Figures 8 and 9 show a graph of measured return loss S11 as a function of transmitted signal frequency (Figure 8) and a graph of TDR as a function of time (Figure 9) for a coaxial connector system 1000 including the first coaxial connector element 100 shown in Figures 1-3, where the TDR was measured for a pulse rise time of 20 ps.

[0071] Solid lines 1422 and 1432 respectively show measurement results for an air gap 300 of 0 mm (shown in FIGS. 1 and 2) and for a first compensating portion 116 formed from a second dielectric material having a second dielectric constant equal to 13, i.e., greater than the first dielectric constant. Dashed lines 1424 and 1434 respectively show measurement results for an air gap 300 of 0 mm and for a first compensating portion 116 formed from a second dielectric material having a second dielectric constant equal to the first dielectric constant, i.e., between 1 and 5.

[0072] Solid lines 1426 and 1436 respectively show measurement results for an air gap 300 of 1.0 mm and for a first compensating portion 116 formed from a second dielectric material having a second dielectric constant equal to the first dielectric constant, i.e., greater than the first dielectric constant, i.e., 13. Dashed lines 1428 and 1438 respectively show measurement results for an air gap 300 of 1.0 mm and for a first compensating portion 116 formed from a second dielectric material having a second dielectric constant equal to the first dielectric constant, i.e., between 1 and 5.

[0073] The measurement results of FIG. 8 and FIG. 9 support the simulation results of FIG. 6 and FIG. 7. In particular, FIG. 8 shows that the high frequency bandwidth for a return loss of −10 dB is improved by adding the first compensation portion 116 having a higher dielectric constant. In particular, for an air gap 300 of 1 mm, when the first compensation portion 116 has a dielectric constant equal to that of the first contact support portion 114, the return loss is below −10 dB only at frequencies below 10 GHz, but when the first compensation portion 116 has a higher dielectric constant, the return loss is below −10 dB even at frequencies up to about 11 GHz. For an air gap 300 of 0 mm, when the first compensation portion has a dielectric constant equal to that of the first contact support portion, the return loss is below −10 dB only at frequencies below about 11.5 GHz, but when the first compensation portion has a higher dielectric constant, the return loss is below −10 dB even at frequencies up to about 12 GHz.

[0074] 9 also shows that the use of the first compensation section 116 with a high dielectric material can significantly reduce the maximum deviation of the TDR from the nominal value for an air gap 300 of 1 mm. Thus, for both 0 mm and 1 mm air gaps 300, the deviation of the TDR remains within the 10 percent tolerance range in the full frequency range. Thus, the use of the first compensation section 116 can significantly reduce the impact of the air gap 300 on the signal transmission performance of the first connector element 100 for air gaps up to 1 mm, thus making it possible to use linear fastening mechanisms that may induce such air gaps.

[0075] FIG. 10 shows a schematic cross-sectional view of a second coaxial connector element 200 according to a first embodiment of the invention, which will be described in detail below.

[0076] As discussed above, the second coaxial connector element 200 includes a second insulating element 202, a first mating inner conductor 204, and a first mating outer conductor 206 arranged in a conventional manner.

[0077] The first mating inner conductor 204 comprises a first mating terminal contact area 210 for electrically connecting to the first contact area 110 of the first connector element 100, and the first mating terminal contact area 210 may be a pin-like member. For electrically connecting to the transmission line 304 of the coaxial cable element 305, the first mating inner conductor 204 comprises a first mating terminal end area 208. Furthermore, the first mating inner conductor 204 may comprise a second barb that may engage with a second recess comprised in the second insulating element 202. In this way, the second barb may prevent the first mating inner conductor 204 from moving in the longitudinal direction 302 relative to the second insulating element 202 after manufacturing of the second coaxial connector element 200.

[0078] The first mating outer conductor 206 surrounds the first mating inner conductor 204 so as to shield the first mating inner conductor 204. Furthermore, the first mating outer conductor 206 may include a recess that prevents the first mating outer conductor 206 from moving in the longitudinal direction 302 relative to the second insulating element 202 after manufacturing of the second coaxial connector element 200.

[0079] The first mating outer conductor 206 includes a second mating terminal end region 214 for electrically connecting the first mating outer conductor 206 to the ground conductor 306 of the coaxial cable element 305. For example, the first mating outer conductor 206 and the ground conductor 306 can be electrically connected by a conventional method such as crimping or soldering. However, it will be understood by those skilled in the art that the first mating outer conductor 206 can also be electrically connected to the ground conductor 306 using any other conventional method.

[0080] In accordance with the present invention, the second insulating element 202 comprises a second contact support 216 and a second compensating portion 218, the second compensating portion 218 being integrally formed with the second contact support 216 to form a single piece. The second contact support 216 is integrally formed from a third dielectric material having a third dielectric constant. The second compensating portion 218 is integrally formed from a fourth dielectric material having a fourth dielectric constant greater than the third dielectric constant.

[0081] 10 , the second compensating portion 218 is disposed at a rear end portion of the second insulating element 202 and at least partially surrounds the first mating terminal end region 208 of the first mating inner conductor 204. Optionally, the second compensating portion 218 may include a second contact opening 220 that may protrude above the first mating terminal end region 208 of the first mating inner conductor 204 and may at least partially receive the coaxial cable insulating element 308 that electrically insulates the transmission line 304 and the ground line 306.

[0082] With this arrangement, the compensation section 218 can increase the capacitance between the first mating inner conductor 204 and the first mating outer conductor 206 in the vicinity of the first mating terminal end region 208. Thus, it is possible to compensate for the capacitance reduction caused by the pigtail of the transmission line 304 of the coaxial cable 305 required to electrically connect the transmission line 304 to the first mating terminal end region 208 of the first mating inner conductor 204. Such capacitance compensation can further improve the signal transmission performance of the coaxial connector system 1000.

[0083] In order to provide isotropic electrical insulation and isotropic capacitance between the first mating inner conductor 204 and the first mating outer conductor 206, the second contact support portion 216 and the second compensation portion 218 may be substantially ring-shaped.

[0084] Preferably, the second contact support 216 is formed from a polymer, resin, or rubber. For example, the second contact support 216 is formed from an injection moldable dielectric material such as polyethylene (PE) or polypropylene (PP). However, the second contact support 216 can also be formed from a material processed by ram extrusion such as polytetrafluoroethylene (PTFE) or from a 3D printable ceramic dielectric material. Typically, such materials have a relative dielectric constant in the range of 1-5.

[0085] In order to provide a homogenous capacitance within the coaxial connector system 1000, the first contact support 114 and the second contact support 216 are preferably formed from the same material and therefore have the same dielectric constant. In this manner, the manufacture of the first contact support 114 and the second contact support 216 can also be integrated and therefore simplified.

[0086] To achieve a high fourth dielectric constant, the fourth dielectric material can be fabricated by ceramic powder filling of a plastic-based material. Preferably, the fourth dielectric material can be an injection moldable polymer mixed with a mineral such as barium titanate (BaTiO3). By optimizing the volume fraction of the mineral, a range of 8 to 23 can be achieved for the fourth dielectric constant at a transmission signal frequency of 1 GHz.

[0087] Alternatively, the fourth dielectric material can be any 3D printable ceramic having a dielectric constant greater than the third dielectric constant of the third dielectric material. Alternatively, the fourth dielectric material can be a dispenseable semi-liquid mixed with a mineral. For example, semi-liquids mixed with minerals such as BaTiO3 are known to have a dielectric constant of 35 at a frequency of 1 GHz.

[0088] Preferably, the second insulating element 202 is manufactured by a fabrication process known in the art as overmolding or multi-material injection molding, whereby the second contact support 216 is first manufactured by injection molding of a third dielectric material, and then the second compensation portion 218 is overmolded onto the second contact support 216 by injection molding of a fourth dielectric material.

[0089] In this way, the second insulating element 202 can be manufactured as a single piece, and therefore the second coaxial connector element 200 can be assembled in a well-established manner from the second insulating element 202, the first mating inner conductor 204, and the first mating outer conductor 206. Furthermore, injection molding and overmolding provide a reliable and inexpensive manufacturing technique for miniature coaxial connector elements. For example, by these techniques, it is possible to manufacture the second insulating element 202 shown in Figures 1 and 2 and 10 having a first outer diameter 128 of 2 mm and to produce the first compensation portion 116 having a thickness in the longitudinal direction 302 of 2 mm.

[0090] However, these dimensions are given only as examples to illustrate the approximate dimensions of the miniature second coaxial connector element 200 and are not meant to be limiting, as aspects of the present invention may be applied to coaxial connector systems 1000 having larger or even smaller dimensions.

[0091] Furthermore, it may be useful to vary the thickness of the second compensation portion 218 in the longitudinal direction 302 based on the ratio of the third relative dielectric constant and the fourth relative dielectric constant. For example, the thickness of the second compensation portion 218 in the longitudinal direction 302 may be increased when the ratio of the third relative dielectric constant and the fourth relative dielectric constant decreases, and may be decreased when the ratio of the third relative dielectric constant and the fourth relative dielectric constant increases. In this way, it is possible to optimize the compensation of the capacitance reduction caused by the pigtail of the transmission line 304 and improve the signal transmission performance of the second coaxial connector element 200.

[0092] Alternatively, the second compensation portion 218 can be fabricated by dispensing a dispenseable semi-fluid in a dispensed volume after the second contact support portion 216 is manufactured. As another alternative, the second insulating element 202 can be manufactured as a single part comprising the second contact support portion 216 and the second compensation portion 218 using 3D printing in combination with a suitable dielectric material.

[0093] In order to integrate and simplify the manufacturing process of the coaxial connector system 1000, it is preferable to use the same material as the second dielectric material and the fourth dielectric material. Therefore, it is preferable that the second relative dielectric constant and the fourth relative dielectric constant are equal.

[0094] An embodiment has been described in detail with reference to Figures 1, 2 and 10 in which the second RF connector element is a second coaxial connector element 200 and thus comprises an inner conductor for transmitting an RF signal and an outer conductor for shielding the inner conductor. However, the invention is not limited to coaxial connector systems and may also be applied to RF connector systems such as twin-axial or USB connector systems that comprise multiple inner conductors, whether shielded or not.

[0095] In a twin-axis or USB connector system, the second compensation portion 218 can be formed to be disposed between each of the mating terminal end regions of the multiple inner conductors, thereby optimizing the compensation of the capacitance reduction caused by the pigtail of an RF cable element having multiple transmission lines each electrically connected to one of the multiple inner conductors.

[0096] The effect of the second compensator 218 on the performance of the RF connector system is illustrated below with reference to FIGS.

[0097] 11 and 12 show a graph of measured return loss S11 as a function of transmitted signal frequency (FIG. 11) and TDR as a function of time (FIG. 12) for an exemplary RF connector system, where the TDR was measured for a pulse rise time of 50 ps.

[0098] Solid lines 1442 and 1446 respectively show measurement results for an RF connector system with a second compensating portion 218 formed from a fourth dielectric material having a fourth dielectric constant equal to the third dielectric constant, i.e., between 1 and 5. Solid lines 1444 and 1448 respectively show measurement results for an RF connector system with a second compensating portion 218 formed from a fourth dielectric material having a fourth dielectric constant equal to 11, i.e., greater than the third dielectric constant.

[0099] 11 shows that the high frequency bandwidth for a return loss of -15 dB is improved by adding the second compensation section 116 having a higher dielectric constant. In particular, it is shown that the operating bandwidth of -15 dB is increased from 2.5 GHz to 4 GHz when the second compensation section 116 has a fourth dielectric constant higher than the third dielectric constant. In other words, the coverage of the operating bandwidth is increased by 60%, which means that the channel capacity of the transmission channel can be increased from less than 5 Gbps to 7.5 Gbps.

[0100] 12 shows that by using a second compensating section 218 having a fourth dielectric constant higher than the third dielectric constant, the maximum deviation of the TDR from the nominal value, which in this example is 100 ohms, can be significantly reduced. This is indicated by arrow 1450. Thus, by using a second compensating section 218 having a higher dielectric constant, the maximum deviation of the TDR from the nominal value is further reduced to remain within the allowable tolerance of 10 percent over the entire frequency range (indicated by dashed lines 1452 and 1454). Thus, by using a second compensating section 218 having a higher dielectric constant, the signal transmission performance of the RF connector system can be further improved.

[0101] It should be mentioned here that up to this point, the first RF connector element according to the present invention has been exemplified by a receptacle and the second RF connector element by a pin. However, it will be clear to those skilled in the art that the aspects of the present invention described in the example of the first RF connector element can also be applied to the second RF connector element. Similarly, the aspects of the present invention described in the example of the second RF connector element can also be applied to the first RF connector element.

[0102] In particular, the first insulating element may comprise a second compensating portion in addition to the first compensating portion, the second compensating portion being integrally formed with the first contact support and at least partially surrounding the first terminal end region of the first inner conductor, and similarly, the second insulating element may comprise a first compensating portion in addition to the second compensating portion, the first compensating portion being integrally formed with the second contact support and located in the front end region of the second insulating element. [Explanation of symbols]

[0103] 100 First coaxial connector element 102, 402, 502 First insulating element 103, 403 Front surface of first insulating element 104 first inner conductor 106 first outer conductor 108 Contact opening 110 first contact region 113 First Spring 114, 414, 514 First contact support 116, 416, 516 First compensation section 118 Front end part 119 Aperture 126 Compensation aperture 200 second coaxial connector element 202 Second insulating element 203 Front of second insulating element 204 First mating inner conductor 206 First mating outer conductor 208 first mating terminal end area 210 first mating terminal contact area 214 Second mating terminal end area 216 Second contact support 218 Second Compensation Section 220 Second contact opening 300 Air gap 302 Longitudinal 304 Transmission Line 305 Coaxial Cable 306 Ground wire 308 Coaxial Cable Insulation Elements 400 first biaxial connector element 406 First outer conductor 426 First Compensation Opening 428 Second Compensation Opening 500 First USB Connector Element 504 Inner conductor 506 First outer conductor 510 first contact region 528 Compensation recess 1402, 1406, 1410, 1414 dashed line 1404, 1408, 1412, 1416 Solid line 1418, 1420 Arrow 1422, 1426, 1432, 1436 Solid line 1424, 1428, 1434, 1438 dashed line 1442, 1444 solid line 1446, 1448 Solid line 1450 Arrow 1452, 1454 dashed line

Claims

1. A first RF connector element (100, 400, 500) for mating with a second RF connector element, a first terminal (104, 404, 504) having a first contact area (110, 410, 510) for electrically connecting to a first mating terminal of the second RF connector element; a second terminal (106, 406, 506) having a second contact area for electrically connecting to a second mating terminal of the second RF connector element; a first insulating element (102, 402, 502) for electrically insulating the first terminal (104, 404, 504) and the second terminal (106, 406, 506); the first insulating element (102, 402, 502) is configured to support the first terminal (104, 404, 504) and comprises a first contact support portion (114, 414, 514) integrally formed from a first dielectric material having a first relative dielectric constant, and a first compensation portion (116, 416, 516) integrally formed with the first contact support portion (114, 414, 514) from a second dielectric material having a second relative dielectric constant greater than the first relative dielectric constant; the first compensation portion (116, 416, 516) is disposed in a front end region of the first insulating element (102, 402, 502) and at least partially surrounds the first contact region (110, 510) of the first terminal (104, 404, 504); A first RF connector element (100, 400, 500), wherein the second terminal (106, 406, 506) comprises a first spring (113) adapted to press the second terminal (106, 406, 506) against the second mating terminal of the second RF connector element.

2. 2. The first RF connector element (100) of claim 1, wherein the first terminal (104) is a first inner conductor and the second terminal (106) is a first outer conductor, the first outer conductor surrounding the first inner conductor.

3. The first RF connector element (100, 400, 500) of claim 1, wherein a ratio between said first relative dielectric constant and said second relative dielectric constant is in the range of 1 / 35 to 5 / 8.

4. 2. The first RF connector element (100, 400, 500) of claim 1, wherein the first insulating element (102, 402, 502) is formed by injection molding the first contact support portion (114, 414, 514) from the first dielectric material and then overmolding the first compensation portion (116, 416, 516) from the second dielectric material.

5. The first RF connector element (100, 400, 500) of claim 1, wherein the first terminal (104, 404, 504) is a receptacle.

6. The first RF connector element (100, 400, 500) of claim 1, wherein the second terminal has a different outer diameter at a portion that covers the first insulating element.

7. A second RF connector element (200) for mating with the first RF connector element (100), comprising: a first mating terminal (204) having a first mating terminal contact area (210) for electrically connecting to a first terminal (104) of said first RF connector element (100) and a first mating terminal end area (208) for electrically connecting to a first conductor (304) of an RF cable element (305); a second mating terminal (206) having a second mating terminal contact area for electrically connecting to a second terminal (106) of said first RF connector element (100) and a second mating terminal end area (214) for electrically connecting to a second conductor (306) of said RF cable element (305); a second insulating element (202) for electrically insulating the first mating terminal (204) and the second mating terminal (206); the second insulating element (202) comprises a second contact support (216) integrally formed from a third dielectric material having a third dielectric constant, and a second compensation portion (218) integrally formed with the second contact support (216) from a fourth dielectric material having a fourth dielectric constant greater than the third dielectric constant; A second RF connector element (200), wherein the second compensation portion (218) is arranged at least partially between the first mating terminal end region (208) and the second mating terminal end region (204) at a rear end region of the second insulating element (202) so that the second compensation portion (218) at least partially covers the first mating terminal end region (208) of the first mating terminal (204) from a direction intersecting the longitudinal direction (302) of the second RF connector element (200).

8. The second RF connector element (200) of claim 7, wherein a ratio of said third relative dielectric constant to said fourth relative dielectric constant is in a range of 1 / 35 to 5 / 8.

9. 8. The second RF connector element (200) of claim 7, wherein the second insulating element (202) is fabricated by injection molding the second contact support portion (216) from the third dielectric material and then overmolding the second compensation portion (218) from the fourth dielectric material.

10. 8. The second RF connector element (200) of claim 7, wherein the second compensation portion (218) comprises a second contact opening (220) capable of at least partially receiving an insulating element (308) of the RF cable element (305) that electrically insulates the first conductor (304) and the second conductor (306).

11. A first RF connector element (100, 400, 500) for mating with a second RF connector element, a first terminal (104, 404, 504) having a first contact area (110, 410, 510) for electrically connecting to a first mating terminal of the second RF connector element; a second terminal (106, 406, 506) having a second contact area for electrically connecting to a second mating terminal of the second RF connector element; a first insulating element (102, 402, 502) for electrically insulating the first terminal (104, 404, 504) and the second terminal (106, 406, 506); the first insulating element (102, 402, 502) is configured to support the first terminal (104, 404, 504) and comprises a first contact support portion (114, 414, 514) integrally formed from a first dielectric material having a first relative dielectric constant, and a first compensation portion (116, 416, 516) integrally formed with the first contact support portion (114, 414, 514) from a second dielectric material having a second relative dielectric constant greater than the first relative dielectric constant; the first compensation portion (116, 416, 516) is disposed in a front end region of the first insulating element (102, 402, 502) and at least partially surrounds the first contact region (110, 510) of the first terminal (104, 404, 504); A first RF connector element (100, 400, 500), wherein the first insulating element (102, 402, 502) comprises a first portion between the first contact support (114, 414, 514) and the first compensation portion (116, 416, 516), the first portion having a first inner diameter greater than an inner diameter of the first contact support (114, 414, 514), and the first compensation portion (116, 416, 516) and the first portion at least partially surrounding the first contact area (110, 510) of the first terminal (104, 404, 504) at a distance from the first contact area (110, 510).

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