Patent Publication Number: US-9899721-B2

Title: Dielectric waveguide comprised of a dielectric cladding member having a core member and surrounded by a jacket member

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Chinese Patent Application No. 201510477085.7, filed on 6 Aug. 2015, which is incorporated by reference herein in its entirety. 
     BACKGROUND OF THE INVENTION 
     The subject matter herein relates generally to dielectric waveguides. 
     Dielectric waveguides are used in communications applications to convey electromagnetic waves along a path between two ends. Dielectric waveguides provide communication transmission lines for connecting antennas to radio frequency transmitters and receivers and the like. Although electromagnetic waves in open space propagate in all directions, dielectric waveguides direct the electromagnetic waves along a defined path, which allows the waveguides to transmit high frequency signals over relatively long distances. 
     Dielectric waveguides include at least one dielectric material. A dielectric is an electrical insulating material that can be polarized by an applied electrical field. The polarizability of a dielectric material is expressed by a value called the dielectric constant or relative permittivity. The dielectric constant of a given material is its dielectric permittivity expressed as a ratio relative to the permittivity of a vacuum, which is 1 by definition. A first dielectric material with a greater dielectric constant than a second dielectric material is able to store more electrical charge by means of polarization than the second dielectric material. 
     Some known dielectric waveguides include a core dielectric material and a cladding dielectric material that surrounds the core dielectric material. The dielectric constants, in addition to the dimensions and other parameters, of each of the core dielectric material and the cladding dielectric material affect how an electric field through the waveguide is distributed within the waveguide. In known dielectric waveguides, the electric field is distributed through the core dielectric material, the cladding dielectric material, and even partially outside of the cladding dielectric material (for example, within the air surrounding the waveguide). 
     There are several issues associated with portions of the electric field extending outside of the cladding of the dielectric waveguide into the surrounding environment. First, some electric fields in air may travel faster than fields that propagate within the waveguide, which leads to the undesired electrical effect called dispersion. Dispersion occurs when some frequency components of a signal travel at a different speed than other frequency components of the signal, resulting in inter-symbol interference. Second, the portions of the electric field outside of the waveguide may produce high crosstalk levels when multiple dielectric waveguides are bundled together in a bulk cable. Third, the external portions of the electric field, including portions of the field at the outer edge of the cladding dielectric material, may experience interference and signal degradation due to external physical influences, such as a human hand touching the dielectric waveguide. Finally, portions of the electric field outside of the waveguide may be lost along bends in the waveguide, as uncontained fields tend to radiate away in a straight line instead of following the contours of the waveguide. 
     A need remains for a dielectric waveguide for propagating high frequency electromagnetic signals that concentrates the electric field within the waveguide, reducing the amount of the field outside of the waveguide and along the outer boundary of the waveguide. 
     SUMMARY OF THE INVENTION 
     In an embodiment, a dielectric waveguide for propagating electromagnetic signals is provided that includes a cladding member and a jacket member. The cladding member extends a length between two ends. The cladding member is formed of an intermediate dielectric material. The cladding member defines a core region that extends through the cladding member along the length of the cladding member. The core region is filled with a central dielectric material having a dielectric constant value that is less than a dielectric constant value of the intermediate dielectric material of the cladding member. The jacket member engages and surrounds the cladding member along the length of the cladding member. The jacket member is formed of an outer dielectric material having a dielectric constant value that is less than the dielectric constant value of the intermediate dielectric material of the cladding member. 
     In another embodiment, a dielectric waveguide for propagating electromagnetic signals is provided that includes a core member, a cladding member, and a jacket member. The core member extends a length between two ends. The core member is formed of a central dielectric material. The cladding member engages and surrounds the core member along the length of the core member. The cladding member is formed of an intermediate dielectric material having a dielectric constant value that is greater than a dielectric constant value of the central dielectric material of the core member. The jacket member engages and surrounds the cladding member along the length of the cladding member. The jacket member is formed of an outer dielectric material having a dielectric constant value that is less than the dielectric constant value of the intermediate dielectric material of the cladding member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top perspective view of a dielectric waveguide formed in accordance with an embodiment. 
         FIG. 2  is a cross-sectional view of the dielectric waveguide according to a first embodiment. 
         FIG. 3  is a cross-sectional view of the dielectric waveguide according to a second embodiment. 
         FIG. 4  is a plot illustrating field strength across a distance of the dielectric waveguide according to an embodiment. 
         FIG. 5  is a cross-sectional view of the dielectric waveguide according to an alternative embodiment. 
         FIG. 6  is a cross-sectional view of the dielectric waveguide according to another alternative embodiment. 
         FIG. 7  is a top perspective view of a dielectric waveguide formed in accordance with an alternative embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a top perspective view of a dielectric waveguide  100  formed in accordance with an embodiment. The dielectric waveguide  100  is configured to convey electromagnetic signals along a length of the waveguide  100  for transmission of the electromagnetic signals to or from an antenna, a radio frequency transmitter and/or receiver, or another electrical component. The electromagnetic signals may be in the form of electromagnetic waves. The dielectric waveguide  100  may be used to transmit sub-terahertz radio frequency signals, such as in the range of 120-160 GHz. The signals are millimeter-wave signals since the signals in this frequency range have wavelengths less than five millimeters. The dielectric waveguide  100  may be used to transmit modulated radio frequency (RF) signals. The modulated RF signals may be modulated in various domains to increase data throughput. The dielectric waveguide  100  is oriented with respect to a vertical or elevation axis  191 , a lateral axis  192 , and a longitudinal axis  193 . The axes  191 - 193  are mutually perpendicular. Although the elevation axis  191  appears to extend in a vertical direction generally parallel to gravity, it is understood that the axes  191 - 193  are not required to have any particular orientation with respect to gravity. The dielectric waveguide  100  extends a length along the longitudinal axis  193  between two ends  104 . 
     The dielectric waveguide  100  includes a cladding member  102  that extends the length of the dielectric waveguide  100 . The cladding member  102  defines at least a portion of each of the ends  104  of the waveguide  100 . The cladding member  102  is formed of a dielectric material, referred to herein as an intermediate dielectric material. As used herein, dielectric materials are electrical insulators that may be polarized by an applied electric field. The cladding member  102  defines a core region  114  that extends through the cladding member  102  for the length of the cladding member  102  between the two ends  104 . The core region  114  includes an opening  116  at both ends  104  of the cladding member  102 . The core region  114  is filled with a dielectric material, referred to herein as a central dielectric material. The central dielectric material is different than the intermediate dielectric material of the cladding member  102 . The central dielectric material has a dielectric constant value that is different from a dielectric constant value of the intermediate dielectric material. In an exemplary embodiment, the dielectric constant value (or dielectric constant) of the central dielectric material within the core region  114  is less than the dielectric constant of the intermediate dielectric material of the cladding member  102 . 
     The respective dielectric constants of the central dielectric material and the intermediate dielectric material affect the distribution of an electric field within the waveguide  100  between the core region  114  and the cladding member  102  surrounding the core region  114 . Generally, an electric field through a dielectric waveguide concentrates within the material that has the greater dielectric constant, at least for dielectric materials having dielectric constants in the range of 0-15. As stated above, the dielectric constant of the intermediate dielectric material of the dielectric waveguide  100  is greater than the dielectric constant of the central dielectric material. Therefore, a majority of the electric field is distributed within the cladding member  102  (such that the field strength is greatest within the cladding member  102 ), although minor portions of the electric field may be distributed within the core region  114  and/or outside of the cladding member  102 . 
     The dielectric waveguide  100  also includes a jacket member  126  that engages and surrounds the cladding member  102  along the length of the cladding member  102 . The jacket member  126  may be disposed on an outer surface of the cladding member  102 . The jacket member  126  surrounds the cladding member  102  such that the jacket member  126  extends around the periphery of the cladding member  102 . The jacket member  126  defines the outer surface of the dielectric waveguide  100  between the ends  104 . The jacket member  126  is formed of an outer dielectric material. In an exemplary embodiment, the outer dielectric material has a dielectric constant that is less than the dielectric constant of the intermediate dielectric material of the cladding member  102 . Therefore, the intermediate dielectric material of the cladding member  102  has a greater dielectric constant than both the outer dielectric material of the jacket member  126  and the central dielectric material within the core region  114 . As a result, the electric field through the dielectric waveguide  100  may be concentrated within the cladding member  102  with smaller or residual portions of the field extending within the core region  114  and/or the jacket member  126 . 
     Since the cladding member  102 , in which the electric field is concentrated, is spaced apart from the outer boundary of the dielectric waveguide  100  by the surrounding jacket member  126 , the electric field at the outer boundary of the waveguide  100  and external to the waveguide  100  is weak or non-existent. For example, since most of the electric field is concentrated within the cladding member  102 , the jacket member  126  acts as a buffer layer between the electromagnetic energy within the cladding member  102  and the outer boundary of the waveguide  100 . Due to the jacket member  126 , very little, if any, of the field is present at the outer boundary of the waveguide  100  or external of the waveguide  100 . The dielectric waveguide  100  is therefore relatively protected from issues related to portions of the field being external to the waveguide  100 , including disturbances in the electrical field caused by external objects physically engaging the waveguide  100 , crosstalk caused by proximity of multiple waveguides  100  in a bundle, and energy loss due to radiating fields along bends in the waveguide  100 . 
     The dielectric waveguide  100  in one or more embodiments described herein includes a central dielectric material (within the core region  114 ), an intermediate dielectric material (within the cladding member  102 ) surrounding the central dielectric material, and an outer dielectric material (within the jacket member  126 ) surrounding the intermediate dielectric material. As described above, the intermediate dielectric material defining a middle layer of the waveguide  100  may have a higher dielectric constant than both the central dielectric material and the outer dielectric material on either side thereof. The dielectric waveguide  100  may be referred to as a tightly coupled waveguide  100  because the electric field is concentrated within the cladding member  102  that defines the middle layer and little, if any, of the field is at the external boundary of the waveguide  100  or outside of the waveguide  100 . Since the dielectric constant of the middle dielectric layer is greater than the dielectric constants of the materials on either side thereof, the dielectric waveguide  100  may be referred to as having a low-high-low configuration. Each “low” represents the dielectric constant of the central dielectric material or the outer dielectric material, and the “high” represents the dielectric constant of the intermediate dielectric material relative to the dielectric constants of the central and outer dielectric materials. 
       FIG. 2  is a cross-sectional view of the dielectric waveguide  100  according to a first embodiment. The cross-section is taken along a plane defined by the vertical and lateral axes  191 ,  192  (shown in  FIG. 1 ). In the illustrated embodiment, the core region  114  defined by the cladding member  102  is filled with air, which is the central dielectric material. Thus, the core region  114  is filled with a dielectric material in a gas phase instead of a solid phase. Air has a dielectric constant that is approximately 1. The intermediate dielectric material of the cladding member  102  has a dielectric constant that is greater than the dielectric constant of air. For example, the intermediate dielectric material may have a dielectric constant between 2 and 15. More specifically, the intermediate dielectric material may have a dielectric constant between 3 and 7. As used herein, a range that is “between” two end values is meant to be inclusive of the end values. In an embodiment, the dielectric constant value of the intermediate dielectric material may be between 3 and 5 such that the difference between the dielectric constant of the air within the core region  114  and the dielectric constant of the cladding member  102  is between 2 and 4. Due to a relatively small difference between the dielectric constant values, the field strength of the electric field may be distributed within both the cladding member  102  and the core region  114 , although the majority of the field strength concentrates in the cladding member  102 . 
     The intermediate dielectric material of the cladding member  102  may be a dielectric polymer, such as a plastic or another synthetic polymer. For example, the intermediate dielectric material may be polypropylene, polyethylene, polytetrafluoroethylene (PTFE), polystyrene, a polyimide, a polyamide, or the like. Optionally, the intermediate dielectric material may be a composition or mixture of more than one such polymer. The use of such polymers may reduce loss through the dielectric waveguide  100 , allowing signals to propagate farther than other waveguide materials. In other embodiments, the intermediate dielectric material may be or include paper, mica, rubber, salt, concrete, Neoprene synthetic rubber, Pyrex® borosilicate glass, silicon dioxide, or the like. The cladding member  102  may be flexible or semi-rigid. 
     In an embodiment, at least one of the cladding member  102  or the core region  114  of the cladding member  102  has an oblong cross-sectional shape. As used herein, “oblong” means that the respective component or space is longer in one direction than in another direction, such that the component or space is not circular or square. The oblong shape of the cladding member  102  and/or core region  114  may orient the electromagnetic waves in the dielectric waveguide  100  in a horizontal or vertical polarization. The cladding member  102  and/or core region  114  that has the oblong shape may be rectangular with right angle corners, rectangular with curved corners, trapezoidal, elliptical, oval, or the like. 
     In the illustrated embodiment in  FIG. 2 , the cladding member  102  has an oblong cross-sectional shape, and the core region  114  has a circular cross-sectional shape. The cladding member  102  has a top side  106 , a bottom side  108 , a left side  110 , and a right side  112 . As used herein, relative or spatial terms such as “first,” “second,” “top,” “bottom,” “left,” and “right” are only used to distinguish the referenced elements and do not necessarily require particular positions, orders, or orientations in the dielectric waveguide  100  or in the surrounding environment of the dielectric waveguide  100 . The cross-sectional shape of the cladding member  102  is oblong such that the cladding member  102  is longer in one direction than in another direction. In the illustrated embodiment, the top side  106  and the bottom side  108  of the cladding member  102  are longer than the left side  110  and the right side  112 . As such, the cladding member  102  has a width, extending between the left and right sides  110 ,  112 , that is greater than a height of the cladding member  102 , which extends between the top and bottom sides  106 ,  108 . The polarization of the electromagnetic waves through the waveguide  100 , such as whether the waves are oriented horizontally or vertically, may be based on the width of the cladding member  102  being greater than the height. 
     In the illustrated embodiment, the cladding member  102  is rectangular. For example, the top side  106  is parallel to the bottom side  108 , the left side  110  is parallel to the right side  112 , and the cladding member  102  defines right angles between adjacent sides  106 ,  108 ,  110 ,  112 . The adjacent sides  106 ,  108 ,  110 ,  112  intersect one another at right angle corners. Each of the sides  106 ,  108 ,  110 ,  112  is planar. The cladding member  102  in  FIG. 2  thus includes two pairs of opposing planar sides, where the first pair is the top and bottom sides  106 ,  108  and the second pair is the left and right sides  110 ,  112 . The cladding member  102  may have various dimensions. In an embodiment, the cladding member  102  has a height of approximately 0.8 mm and a width of approximately 1.2 mm. The aspect ratio for the width of the cladding member  102  to the height is less than two in an embodiment, but may be at least two in other embodiments. In an alternative embodiment, the cladding member  102  may have another oblong shape, such as a rectangle with rounded corners, a trapezoid, an ellipse, an oval with two planar sides, or the like. For example, in some alternative embodiments, the cladding member  102  may include only one pair of opposing planar sides which orients the electromagnetic waves within the dielectric waveguide  100 . The core region  114  may have various sizes relative to the cladding member  102 . In an embodiment, the diameter (such as 0.4 mm) of the circular core region  114  is approximately half of the height of the cladding member  102 , and the core region  114  is located centrally relative to the sides  106 ,  108 ,  110 ,  112  of the cladding member  102 . In another alternative embodiment, the core region  114  may have an oblong cross-sectional shape instead of, or in addition to, the cladding member  102  having an oblong cross-sectional shape. 
     The outer dielectric material of the jacket member  126  may be a dielectric polymer, such as a plastic or another synthetic polymer. For example, the outer dielectric material may be polypropylene, polyethylene, polytetrafluoroethylene (PTFE), polystyrene, a polyimide, a polyamide, or the like, including combinations thereof. The jacket member  126  may be flexible or semi-rigid. The outer dielectric material is a different material than the intermediate dielectric material and has a lower dielectric constant than the intermediate dielectric material. For example, the dielectric constant of the outer dielectric material may be less than 5, such as between 1.5 and 3.5 or, more specifically, between 2 and 3. The outer dielectric material of the jacket member  126  has a dielectric constant that is greater than, less than, or equal to the central dielectric material within the core region  114  of the cladding member  102 . The outer dielectric material may be the same as the central dielectric material, or, alternatively, the jacket member  126  may be formed of a different material than the material that fills the core region  114 . 
     In an embodiment, the jacket member  126  includes at least one planar outer surface. The planar surface is configured to be used as a reference surface for aligning the jacket member  126  in an interconnection. For example, the reference surface is used for mechanically aligning the dielectric waveguide  100  with a connecting waveguide (not shown), a connector, an antenna, or another electrical component. When the waveguide  100  is being connected at one of the ends  104  (shown in  FIG. 1 ) to a corresponding end of a connecting waveguide to form a butt joint, each reference surface of the waveguide  100  is able to be aligned with a complementary planar surface of the connecting waveguide to ensure that the cladding member  102  and the core region  114  align with respective cladding and core parts of the connecting waveguide. If cladding member  102  and the core region  114  do not align properly with the cladding and core parts, respectively, of the connecting waveguide (such that the oblong cladding member  102  is oriented horizontally while the cladding of the connecting waveguide is oriented vertically), at least some of the electromagnetic waves will not be transmitted across the interface between the two waveguides. For example, the electromagnetic waves leaving the transmitting waveguide may reflect at the interface or otherwise radiate away instead of being received within the receiving waveguide for further propagation along the signal path. 
     In the illustrated embodiment, the jacket member  126  includes four sides including a top side  128 , a bottom side  130 , a left side  132 , and a right side  134 . Each of the sides  128 ,  130 ,  132 ,  134  has a planar surface in the illustrated embodiment, such that each of the sides  128 ,  130 ,  132 ,  134  may be used as a reference surface used to align the dielectric waveguide  100  in an interconnection. The top and bottom sides  128 ,  130  align with the top and bottom sides  106 ,  108  of the cladding member  102  such that the sides  128 ,  130  are parallel to the sides  106 ,  108 . In addition, the left and right sides  132 ,  134  align with the left and right sides  110 ,  112  of the cladding member  102  such that the sides  132 ,  134  are parallel to the sides  110 ,  112 . Although the jacket member  126  may obstruct the view of the cladding member  102  surrounded by the jacket member  126 , when connecting the dielectric waveguide  100  to an identical connecting waveguide, an operator or a machine may align the two waveguides by aligning the jacket member  126  of the waveguide  100  with the outer jacket of the connecting waveguide. For example, the jackets are aligned by aligning the top side  128  of the jacket member  126  with the corresponding top side of the outer jacket of the connecting waveguide such that the two sides define a continuous plane when in abutment. Aligning the jackets aligns the cladding member  102  within the waveguide  100  with the cladding of the connecting waveguide. As a result, the polarized electromagnetic waves through the dielectric waveguide  100  are readily received across the interface and into the connecting waveguide without being reflected back into the transmitting dielectric waveguide  100 . 
     In the illustrated embodiment, the jacket member  126  has an oblong cross-sectional shape. More specifically, the jacket member  126  is rectangular with right angle corners. The top and bottom sides  128 ,  130  of the jacket member  126  are longer than the left and right sides  132 ,  134 . In an embodiment, the jacket member  126  has a cross-sectional area, defined by an outer perimeter of the jacket member  126 , that is at least three times greater than a cross-sectional area of the cladding member  102  that is defined by the outer perimeter of the cladding member  102 . For example, if the height of the cladding member  102  is 1 mm and the width is 1.5 mm, the cross-sectional area of the cladding member  102  is 1.5 mm 2  and the cross-sectional area of the jacket member  126  surrounding the cladding member  102  is at least 4.5 mm 2 . The dimensions of the jacket member  126  may include a height of 2 mm and a width of 2.5 mm, for example, which yields a cross-sectional area greater than 4.5 mm 2 . In an embodiment, the cladding member  102  within the jacket member  126  is spaced apart from each of the four sides  128 ,  130 ,  132 ,  134  of the jacket member  126  by at least a designated threshold distance such that the outer dielectric material provides a buffer between the cladding member  102  and the outer boundary of the waveguide  100 . For example, the cladding member  102  may be at least 0.5 mm away from each of the four sides  128 ,  130 ,  132 ,  134  of the jacket member  126 . Although the jacket member  126  is shown and described in  FIG. 2  as being rectangular with right angle corners, in an alternative embodiment, the jacket member  126  may be circular, square, or have a different oblong shape, such as a rectangle with curved corners, an ellipse, an oval, a trapezoid, or the like. 
     The dielectric waveguide  100  may be fabricated using standard manufacturing processes and/or techniques, such as by extrusion, drawing, fusing, molding, or the like. In one example, the intermediate dielectric material and the outer dielectric material are co-extruded such that the cladding member  102  and the jacket member  126  are formed simultaneously. Alternatively, the cladding member  102  may be pre-formed and the outer dielectric material may be extruded, molded, drawn, or the like, over the cladding member  102  to form the jacket  126  around the cladding member  102 . 
       FIG. 3  is a cross-sectional view of the dielectric waveguide  100  according to a second embodiment. In the embodiment shown in  FIG. 3 , the dielectric waveguide  100  includes a core member  118  within the core region  114  of the cladding member  102 . The core member  118  extends the length of the dielectric waveguide  100  between the two ends  104  (shown in  FIG. 1 ). The core member  118  fills the core region  114  such that no clearances or gaps exist between an outer surface of the core member  118  and an inner surface of the cladding member  102 . The cladding member  102  engages and surrounds the core member  118  along the length of the core member  118 . The core member  118  has a circular cross-sectional shape, defined by the circular shape of the core region  114 . In an alternative embodiment, the core member  118  may have an oblong cross-sectional shape. For example, at least one of the core member  118  and the cladding member  102  has an oblong shape in one or more embodiments described herein. The dielectric material of the core member  118  is referred to as “central” because the dielectric material is central relative to a longitudinal axis through the core member  118 . The dielectric materials of the cladding member  102  and the jacket member  126  are referred to as being “intermediate” and “outer,” respectively, due to the radial locations of these layers relative to the central dielectric material and the axis through the core member  118 . 
     The core member  118  is formed of at least one dielectric polymer that defines the central dielectric material. The central dielectric material is in the solid phase, as opposed to the air described in  FIG. 2 . For example, the central dielectric material of the core member  118  may be polypropylene, polyethylene, PTFE, polystyrene, a polyimide, a polyamide, or the like, including combinations thereof. The central dielectric material is different than the intermediate dielectric material of the cladding member  102  and has a lower dielectric constant than the intermediate dielectric material. For example, the dielectric constant of the central dielectric material may be less than 5, such as between 1.5 and 3.5 or, more specifically, between 2 and 3. The central dielectric material of the core member  118  may be the same as, or different than, the outer dielectric material of the jacket member  126 . The dielectric constant of the central dielectric material may be greater than, less than, or equal to, the dielectric constant of the outer dielectric material. The dielectric waveguide  100  shown in  FIG. 3  may be fabricated by extrusion, drawing, molding, fusing, or the like. For example, the core member  118 , the cladding member  102 , and the jacket member  126  may be co-extruded simultaneously or may be formed at different times. 
       FIG. 4  is a plot  140  illustrating field strength (i.e. Y axis) across a distance (i.e. X axis) of the dielectric waveguide  100  according to an embodiment. The distance extends radially from a center (i.e. 0) of the core member  118  (or the center of the core region  114 ) shown in  FIG. 3  through the cladding member  102  and then the jacket member  126  and eventually beyond the boundary of the waveguide  100  into the external “outside” environment. The widths of the individual sections of the waveguide  100  represented along the X axis of the plot  140  are not meant to represent the actual widths of the core, cladding, and jacket members  118 ,  102 ,  126 , but only to illustrate the configuration of the members  118 ,  102 ,  126  within the waveguide  100 . 
     In an example embodiment of the waveguide  100 , the central dielectric material of the core member  118  and the outer dielectric material of the jacket member  126  are both dielectric polymers. The central dielectric material and the outer dielectric material each include at least one of polypropylene, polyethylene, PTFE, or polystyrene. The dielectric constants of the central dielectric material and the outer dielectric material are both less than 3. The central and outer dielectric materials may be the same or different materials. The intermediate dielectric material of the cladding member  102  has a dielectric constant that is greater than the dielectric constants of the central and outer dielectric materials, such as in the range of 3-12, or between 3 and 7. For example, the intermediate dielectric material may be nylon, having a dielectric constant of 5. The central dielectric material may be polypropylene, having a dielectric constant around 2.3, and the outer dielectric material may be PTFE, having a dielectric constant of 2.1. As such, the dielectric waveguide  100  in this example is a tightly coupled waveguide having a low-high-low configuration of dielectric layers. 
     In  FIG. 4 , the waveguide represented by plot line  142  has a core dielectric constant of 2.3, a cladding dielectric constant of 5, and a jacket dielectric constant of 2.1. The dielectric constant of the air outside of the waveguide  100  is 1. As shown in the plot  140 , the field strength is greatest (i.e. Max) in the cladding member  102 , which has the largest dielectric constant. Minor portions of the electric field are dispersed within the core member  118  and the jacket member  126 . Since the dielectric constant value of the central dielectric material of the core member  118  is greater than the outer dielectric material of the jacket member  126 , although not significantly greater, more of the field may be within the core member  118  than the jacket member  126 . Although some of the electric field is located within the jacket member  126 , the portion of the field within the jacket member  126  is concentrated along the interface  144  between the cladding member  102  and the jacket member  126 . As shown in the plot  140 , the portion of the electric field within the jacket member  126  does not extend to the outer boundary  146  between the jacket member  126  and the outside environment. Thus, the dielectric waveguide  100  may be relatively protected against inter-signal interference, cross-talk, energy loss around bends, and interference due to external physical influences, which may be caused by portions of the electric field being dispersed at the boundary  146  or even outside of the waveguide  100 . 
       FIG. 5  is a cross-sectional view of the dielectric waveguide  100  according to an alternative embodiment. In the illustrated embodiment, the waveguide  100  includes a first cladding member  102 A and a second cladding member  102 B. The two cladding members  102 A,  102 B may be identical or at least substantially similar to each other. The two cladding members  102 A,  102 B may each be identical or at least substantially similar to the cladding member  102  shown in  FIG. 3 . For example, each cladding member  102  has an oblong cross-sectional shape and surrounds a respective core member  118 . The waveguide  100  includes a jacket member  150  that surrounds and engages each of the cladding members  102 A,  102 B. For example, the jacket member  150  is a single body that collectively surrounds both of the cladding members  102 A,  102 B and extends between the cladding members  102 A,  102 B. The cladding members  102 A,  102 B are spaced apart from one another by an intervening portion  152  of the jacket member  150 . The jacket member  150  in the illustrated embodiment has an oblong cross-sectional shape that is an oval having two parallel planar sides  154 . As described above, the waveguide  100  shown in  FIG. 5  may be a tightly coupled waveguide such that the dielectric constants of the intermediate dielectric material(s) of the cladding members  102 A,  102 B are greater than the dielectric constants of both the outer dielectric material of the jacket member  150  and the central dielectric materials of the respective core members  118 . 
       FIG. 6  is a cross-sectional view of the dielectric waveguide  100  according to another alternative embodiment. The components of the dielectric waveguide  100 , including the core member  118 , the cladding member  102 , and the jacket member  126  have different cross-sectional shapes in the embodiment shown in  FIG. 6  than the embodiment shown in  FIG. 3 . For example, the core member  118  is oblong, having a rectangular shape with right angle corners. The cladding member  102  is circular. The jacket member  126  is oblong, having a rectangular shape with rounded corners. The top and bottom sides  128 ,  130  of the jacket member  126  are longer than the left and right sides  132 ,  134 . Likewise, a top side  160  and a bottom side  162  of the rectangular core member  118  are longer than a left side  164  and a right side  166  of the core member  118 . The top and bottom sides  128 ,  130  of the jacket member  126  align with and are parallel to the top and bottom sides  160 ,  162  of the core member  118 , which allows the sides  128 ,  130 ,  132 ,  134  of the jacket member  126  to be used as reference surfaces for aligning the waveguide  100  in an interconnection. The core member  118 , the cladding member  102 , and the jacket member  126  of the embodiment shown in  FIG. 6  may be formed of the same dielectric materials and in the same low-high-low configuration as described with reference to the embodiments shown in  FIGS. 2 and 3 . 
     Optionally, the dielectric waveguide  100  may include a shield layer  170  that engages and surrounds the jacket member  126 . The shield layer  170  is electrically conductive, and is configured to reduce signal degradation caused by electromagnetic interference. The shield layer  170  may extend the length of the jacket member  126 . Although the shield layer  170  around the perimeter of the jacket member  126  is electrically conductive, since the electric field within the waveguide  100  is concentrated within the cladding member  102 , the conductive shield layer  170  is spaced apart from the field concentration such that the shield layer  170  has a negligible effect, if at all, on the electromagnetic signal propagation properties of the waveguide  100 . The buffer between the field concentration and the shield layer  170  prohibits electrical energy loss, hard cut-off frequencies, and other undesirable effects associated with a conductive material interacting with the electric field. 
     The shield layer  170  may be formed of one or more metals, such as copper, aluminum, silver, or the like. Alternatively, the shield layer  170  may be a conductive polymer that includes metal particles dispersed within a dielectric polymer. The shield layer  170  may be a metal foil, a metallized composite heat shrink tubing, a conductive tape (for example, carbon nanotube tape), a lossy conductive polymer overmold, or the like. For example, the shield layer  170  may be applied around the jacket member  126  through various techniques and/or processes, including electroplating, wrapping, heat shrinking, physical vapor deposition (PVD), molding, or the like. 
       FIG. 7  is a top perspective view of a dielectric waveguide  100  formed in accordance with an alternative embodiment. The dielectric waveguide  100  includes a cladding member  102  that defines a core region  114 , a jacket member  126  surrounding the cladding member  102 , and a shield layer  170  surrounding the jacket member  126 . The core region  114  may be filled with air or a core member  118  (shown in  FIG. 3 ) formed of a dielectric polymer. The core region  114  has a circular cross-sectional shape, the cladding member  102  has an oblong, rectangular cross-sectional shape, and the jacket member  126  has a circular cross-sectional shape. Since the jacket member  126  is circular, in order to align the dielectric waveguide  100  with a connecting waveguide, a segment of the jacket  126  at one of the ends  104  may be stripped or otherwise removed to expose the oblong cladding member  102 . A planar side of the exposed cladding member  102  may be used as a reference surface to align the waveguide  100  with the connecting waveguide. In the illustrated embodiment, the shield layer  170  is a metal foil that is spiral-wrapped along the perimeter of the jacket member  126  along the length of the jacket member  126 , defining a helical seam  172 . The foil may be wrapped using other techniques, such as cigarette-wrapping, in other embodiments. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments, and are by no means limiting and are merely exemplary embodiments. Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. § 112(f), unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.