Patent Publication Number: US-10320047-B2

Title: Waveguide assembly comprising a molded waveguide interface having a support block for a launch transducer that is coupled to a communication device through a flange attached to the interface

Description:
This application is a continuation of U.S. patent application Ser. No. 14/803,652 filed on Jul. 20, 2015, now U.S. Pat. No. 9,893,406 issued Feb. 13, 2018, which is a continuation-in-part of U.S. patent application Ser. No. 13/383,203 filed on Jan. 9, 2012, now U.S. Pat. No. 9,088,058 issued Jul. 21, 2015, which is a national phase filing under 35 USC 371 of International Application No. PCT/US2010/046028 having an International Filing Date of Aug. 19, 2010, which claims the benefit of priority based on U.S. Provisional Patent Application Ser. No. 61/235,245, filed on Aug. 19, 2009, each of which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The present disclosure relates generally to microwave and millimeter wave radio frequency waveguide assembly technologies. More specifically, the present disclosure relates to microwave and millimeter wave radio frequency waveguide interface technologies, including waveguide interfaces manufactured using injection molding techniques. 
     BACKGROUND 
     As the semiconductor industry continues to increase circuit complexity and density by reduction of process node geometries, operating signal frequencies continue to increase. It is now possible to obtain semiconductors that operate well into the millimeter wave region of radio spectrum (30 GHz to 300 GHz). Traditionally, the types of semiconductors used have been in the category of “III-V” types, indicating that the semiconductor compounds have been derived from periodic table elements in the third and fifth columns, such as gallium arsenide (GaAs) and indium phosphide (InP). In recent years, less expensive semiconductor processes that arise from column IV of the periodic table, such as silicon (Si) and germanium (Ge) have been produced in silicon CMOS (complementary metal oxide semiconductor) and silicon germanium (SiGe) compounds. The result has been to extend the operating frequency of low-cost silicon semiconductors well into the 60 to 80 GHz range of frequencies. The availability of low-cost semiconductor technology has put pressure on millimeter wave manufacturers to bring the overall costs down for the electromechanical support mechanisms that enable these semiconductor devices. 
     Commercial waveguide structures enable low-loss energy transfer at millimeter wave frequencies, with the additional benefit of standardization of size and mechanical coupling flange designs. The standardized sizes and coupling flanges enable interoperability between different devices and different manufactures, providing maximal flexibility for millimeter wave system design. 
     Traditional methods for interfacing semiconductor devices within a mechanical waveguide have been to either provide a split-cavity type of assembly with expensive precision machining requirements or to couple energy from an orthogonal planar printed circuit launch probe with associated lossy energy transfer. With new semiconductor designs providing balanced transmission line outputs, there has been no straightforward electromechanical method for coupling millimeter wave energy from the balanced outputs directly to a waveguide without added circuitry, such as a balun transformer, which also exhibits excessive losses as the frequency range of operation increases. 
     The prior art methods for coupling energy into and out of semiconductor devices, as set forth above, can be divided into two categories. The first category involves the use of split-cavity metallic structures that allow the semiconductor chip to be placed into one of the cavities, with the other half of the cavity then brought together with the first half in a precision fit. The typical precision required for the internal dimensions of a millimeter wave waveguide is on the order of ±0.001″ (0.025 mm). Obtaining this level of precision in the construction of both upper and lower cavity halves of a split cavity metallic structure through machining while maintaining registration alignment for such an assembly is expensive. 
     The second category used for coupling energy in and out of semiconductor devices is to provide a printed circuit board with a stub or paddle energy launch. The stub or paddle launch is orthogonal to the waveguide cavity, also requiring a split-cavity type of assembly method, creating additional expense. 
     In each case, a custom, highly precision machining process is required to maintain the internal waveguide dimensional requirements. Some cost reduction can be afforded through a casting process, but secondary machining operations are still necessary to realize the precision needed. 
     The above prior methods also are designed for single-ended circuit configurations only. It is necessary, however, to provide low-cost and efficient coupling methods for both single-ended and differential circuits. Millimeter wave semiconductor circuit designs often make use of differential amplifier and output stage configurations to enable high gain and power efficiencies. 
     SUMMARY OF THE INVENTION 
     A waveguide interface comprising a support block configured to support a printed circuit board assembly. An interface is coupled to an end portion of the support block and extends from the support block. The interface includes a slot positioned to receive at least a portion of the printed circuit board assembly and one or more holes positioned to receive attachment devices to secure the interface to a waveguide component. The support block and interface are molded as a monolithic device. 
     A method of forming a precision waveguide interface includes providing a mold configured to form a support block configured to support a printed circuit board assembly and an interface integrally formed to an end portion of the support block and that extends from the support block. The interface includes a slot configured to receive at least a portion of the printed circuit board assembly and one or more holes positioned to receive attachment devices to secure the interface to a waveguide component. The provided mold is utilized to form the waveguide interface as a monolithic device. 
     This exemplary technology provides a number of advantages including providing a waveguide assembly, including a waveguide interface that may be utilized at high operating frequencies. The waveguide assembly of the present technology incorporates, in one example, a waveguide interface that is molded as a single piece with nominal impact on the overall performance of the waveguide assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1C  are side, front end, and top views, respectively, of an exemplary waveguide assembly including an exemplary waveguide interface coupled to a waveguide flange; 
         FIG. 2  is a cross sectional side view of the exemplary waveguide assembly shown in  FIGS. 1A-1C ; 
         FIG. 3  is a detailed rear view of the exemplary waveguide assembly shown in  FIGS. 1A-1C ; 
         FIG. 4  is a cross sectional top view of the exemplary waveguide assembly shown in  FIGS. 1A-1C ; 
         FIG. 5A  is a rear view of an exemplary waveguide flange; 
         FIG. 5B  is rear view of the interface plate of the exemplary waveguide interface shown in  FIGS. 1A-1C ; 
         FIG. 5C  is a rear view of the exemplary waveguide flange shown in  FIG. 5A  coupled to the exemplary interface plate shown in  FIG. 5B ; 
         FIGS. 6A-6C  are a front view, side cross-sectional view, and an end view of a support block of the exemplary waveguide interface shown in  FIGS. 1A-1C ; 
         FIG. 7  is a perspective view of another exemplary waveguide interface that is molded as a single, monolithic device; 
         FIG. 8  is a top view of the exemplary waveguide interface shown in  FIG. 7 ; 
         FIG. 9  is a rear view of the exemplary waveguide interface shown in  FIG. 7 ; 
         FIG. 10  is a front view of the exemplary waveguide interface shown in  FIG. 7 ; 
         FIG. 11  is a side cross-sectional view of the exemplary waveguide interface shown in  FIG. 9  along section A-A; 
         FIG. 12  is a top cross-sectional view of the exemplary waveguide interface shown in  FIG. 10  along section C-C; 
         FIG. 13  is a perspective view of the exemplary waveguide interface shown in  FIG. 7  after machining processes to finalize the waveguide interface; 
         FIG. 14  is a rear view of the exemplary waveguide interface illustrated in  FIG. 13 ; 
         FIGS. 15A-15D  are respectively a top, side, end, and bottom view of an exemplary printed circuit board for use with the exemplary waveguide interfaces of the present technology. 
         FIG. 16A  is a top view of an exemplary transmitter printed circuit board and launch transducer substrate assembly for use with the waveguide interfaces of the present technology; 
         FIG. 16B  is a top view of an exemplary receiver printed circuit board and launch transducer substrate assembly for use with the waveguide interfaces of the present technology; 
         FIGS. 17A and 17B  are top and bottom views of an exemplary transmitter launch transducer substrate; 
         FIGS. 18A and 18B  are top and bottom views of an exemplary receiver launch transducer substrate; and 
         FIG. 19  is a top view of another exemplary launch transducer substrate assembly for use with the waveguide interfaces of the present technology. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1A, 1B, 1C, 2, 3, and 4 , an example of a waveguide assembly  10  includes an exemplary waveguide interface  12 ( 1 ) (shown in  FIGS. 1A, 1C, 2, and 4 ), a printed circuit board assembly  14  ( FIGS. 1A, 1C, 2, 3 and 4 ) including a connector  16 , a communication device  18 ( 1 ) (shown in  FIGS. 2, 3, and 4 ), a launch transducer  20 ( 1 ) (shown in  FIGS. 2 and 4 ), and a waveguide flange  22  (shown in  FIGS. 1A, 1C, 2, 3, and 4 , is illustrated, although the waveguide assembly  10  could include other types and numbers of assemblies, devices, components, and/or other elements in other configurations. As described below, the waveguide assembly  10  may be utilized for electromagnetic transmission and electromagnetic reception. Both the transmission context and the reception context equally apply due to the Lorentz electromagnetic reciprocity theorem. This exemplary technology provides a number of advantages including providing a waveguide assembly, including a waveguide interface that may be utilized at high operating frequencies. The waveguide assembly of the present technology incorporates, in one example, a waveguide interface that is molded as a single piece with nominal impact on the overall performance of the waveguide assembly. The molded waveguide interface significantly reduces the overall cost of the waveguide assembly. 
     Referring again to  FIGS. 1A, 1B, 1C, 2, 3, and 4 , the exemplary waveguide interface  12 ( 1 ) includes a support block  24 ( 1 ) (shown in  FIGS. 1A, 1B, 2 , and  3 ) coupled to an interface plate  26 ( 1 ), although the waveguide interface  12 ( 1 ) may include other elements in other configurations. The waveguide interface  12 ( 1 ) operates in the waveguide assembly  10  to provide an interface between the waveguide flange  22  and the communication device  18 ( 1 ). In one example, as described further below, a waveguide interface may be utilized in the waveguide assembly  10  that is constructed as a single, monolithic, metal injection-molded structure, such as the waveguide interface  12 ( 2 ) illustrated in  FIGS. 7, 8, 9, 10, 11, 12, 13, and 14 . The metal injection-molded waveguide interface  12 ( 2 ) advantageously provides a more economically produced waveguide interface that may be utilized at high operating frequencies, with nominal impact on the performance of the waveguide assembly  10 . 
     Referring again to  FIGS. 1A, 1B, 1C, 2, 3, and 4 , the support block  24  ( 1 ) is configured to support the printed circuit board assembly  14  having the connector  16 , the communication device  18 ( 1 ), and the launch transducer  20 ( 1 ) located on a surface thereof. The support block  24 ( 1 ) extends in a plane orthogonal to the interface plate  26 ( 1 ) and provides for precise alignment of the printed circuit board assembly  14  with the interface plate  26 ( 1 ) and the waveguide flange  22 . 
     The support block  24 ( 1 ), in this example, is coupled to the interface plate  26 ( 1 ) and the waveguide flange  22  by machine screws  28 A (shown in  FIGS. 1A, 1B, 1C, 2, and 3 ) and  28 B (shown in  FIGS. 1B, 2, and 3 ), although other types of fasteners may be utilized. Machine screws  28 A and  28 B couple both the support block  24 ( 1 ) and the interface plate  26 ( 1 ) to the waveguide flange  22  such that the interface plate  26 ( 1 ) is positioned between the support block  24 ( 1 ) and the waveguide flange  22 . In another example, as illustrated in  FIGS. 7, 8, 9, 10, 11, 12, 13, and 14 , the support block  24 ( 2 ) as shown in  FIGS. 7, 8, 10, 11, 12 and 13  and the interface  26 ( 2 ) as shown in  FIGS. 7-14  are molded as a single device and do not require any fastening elements to be coupled together as shown in  FIGS. 7, 8, 11, 12, and 13 . 
     Referring now to  FIGS. 6A-6C , in one example, the support block  24 ( 1 ) includes a counter-bored hole  30  that allows a machine screw, such as the machine screw  28 B ( FIGS. 1B, 1C, 2, 3 ) to be inserted therein to couple the support block  24 ( 1 ) to the waveguide flange  22  and the interface plate  26 ( 1 ), as shown in  FIG. 2 , although the support block  24 ( 1 ) may include other fastening elements in other locations to facilitate the coupling of the support block  24 ( 1 ) to the interface plate  26 ( 1 ) and waveguide flange  22 . In one example, as described below, support block  24 ( 2 ) and interface  26 ( 2 ) are formed as a single, monolithic, part, such that no fastening elements are required on support block  24 ( 2 ). As shown in  FIGS. 6B and 6C , the support block  24 ( 1 ) optionally includes one or more support block guide pins  32  (also shown in  FIG. 2 ) that aid in alignment of the support block  24 ( 1 ) with the interface plate  26 ( 1 ) as discussed further below. 
     Referring now more specifically to  FIGS. 1A, 1B, 1C, 2, 3, 4, and 5B , interface plate  26 ( 1 ) is a circular interface plate, although other configurations may be utilized for the interface plate  26 ( 1 ). The interface plate  26 ( 1 ) includes a rectangular slot  34 ( 1 ) (shown in  FIGS. 1B, 2, 3, and 5B ) located therethrough. The length of the rectangular slot  34 ( 1 ) is configured to accept the printed circuit board assembly  14  and the launch transducer  20 ( 1 ) as illustrated in  FIG. 2 . The printed circuit board assembly  14  and the rectangular slot  34 ( 1 ) form a short waveguide segment  36  as shown in  FIG. 2  within the rectangular slot  34 ( 1 ) when coupled. 
     Referring again to  FIG. 5B , the interface plate  26 ( 1 ) includes interface plate holes  38  which are sized and configured to receive machine screws  28 A and  28 B (not shown in  FIG. 5B ), which secure the waveguide interface  12 ( 1 ) to the waveguide flange  22 . The interface plate  26 ( 1 ) may further have interface plate guide pin holes  41 ( 1 ) that may be aligned with support block guide pins  32  of the support block  24 ( 1 ) to provide precise alignment between the interface plate  26 ( 1 ) and the support block  24 ( 1 ). The interface plate  26 ( 1 ) further includes guide pin holes  41  that are configured to aid in alignment with the waveguide flange  22  as described further below. 
     Referring now to  FIGS. 7-14 , another example of a waveguide interface  12 ( 2 ) for use in waveguide assembly  10  is illustrated. Waveguide interface  12 ( 2 ) interacts with waveguide flange  22  and operates in the same manner as waveguide interface  12 ( 1 ) except as illustrated and described herein. 
     Waveguide interface  12 ( 2 ) includes a support block  24 ( 2 ) and an interface  26 ( 2 ) that are molded in an injection molding process as a single, monolithic structure, although other types of molding techniques may be utilized. The waveguide interface  12 ( 2 ), by way of example only, may be constructed of an injection moldable metal alloy such as Xyloy™ M950, although other types of moldable metal alloys may be utilized to form the waveguide interface  12 ( 2 ). The outer shape of the waveguide interface  12 ( 2 ) has been customized to allow for removal from a mold to enable the generation of the single monolithic structure, as discussed below. Specifically, the waveguide interface  12 ( 2 ) includes a plurality of draft angles as discussed below. The draft angles, discussed more specifically below, provide for removal of the waveguide interface  12 ( 2 ) without significant impact to the overall performance on the waveguide interface  12 ( 2 ) in the waveguide assembly  10 . In particular, by way of example only, the propagation of millimeter wave energy into the opening of a waveguide flange connected to the waveguide interface  12 ( 2 ) is altered by less than one percent, which does not impact the overall operating frequency range. Further, the waveguide cutoff frequency is altered by less than one percent. Although various exemplary dimensions are described below, it is to be understood that the dimensions may be varied. 
     Support block  24 ( 2 ) includes a top surface  100  ( FIGS. 8, 10, 11, and 12 ) configured to support a printed circuit board assembly, such as printed circuit board assembly  14 , by way of example. By way of example, the printed circuit board assembly may be attached to the top surface  100  of the support block  24 ( 2 ) using an adhesive. The top surface  100  has side edges  102  (shown in  FIGS. 7, 8 and 12 ) that are tapered with a draft angle of approximately a 4 degree angle as illustrated in  FIGS. 8 and 12 . As used herein throughout, the term “draft angle” refers to the amount of taper perpendicular to the parting line for the molded or casted part described, as measured in degrees. The top surface  100  of the support block  24 ( 2 ) has a width of approximately 0.400 inches at a junction  104  ( FIGS. 7, 8, 10, and 11 ) with the interface  26 ( 2 ) and a width of approximately 0.358 inches at an upper end edge  105  ( FIGS. 7, 8, and 12 ) thereof. The side edges  102  taper from the junction  104  to the upper end edge at the draft angel of approximately 4 degrees. 
     The support block  24 ( 2 ) includes sides  106  and end  108  as shown in  FIGS. 7 and 10  that taper downward from the top surface  100  with a draft angle of approximately 4 degrees, such that the support block  24 ( 2 ) has a width of approximately 0.315 inches at a lower end edge  110  shown in  FIGS. 7 and 10 . The support block  24 ( 2 ) further includes a tapered bottom surface  112  at a draft angle of approximately 4 degrees as shown in  FIG. 11 , such that support block  24 ( 2 ) has a height of approximately 0.177 inches at the junction  104  with the interface  26 ( 2 ) and a width of approximately 0.120 inches from the lower end edge  110  to the top surface  100 , although support block  24 ( 2 ) may have other dimensions. 
     In this example, with the modified design with the draft angles and dimensions noted above, the support block  24 ( 2 ) and the interface  26 ( 2 ) can be molded as a single, monolithic device. The support block  24 ( 2 ) extends from the interface  26 ( 2 ) in a plane orthogonal to the interface  26 ( 2 ). The interface  26 ( 2 ) is a circular interface configured to be coupled to a waveguide flange (not shown), such as waveguide flange  22 , which by way of example may be a standard waveguide flange known in the art. The interface  26 ( 2 ) includes a slot  34 ( 2 ) (shown in  FIGS. 7 and 11 ) configured to receive a portion of a printed circuit board assembly, including a launch transducer. In use, the slot  34 ( 2 ) and an inserted printed circuit board assembly form a short waveguide segment within the waveguide interface  12 ( 2 ) in the same manner as described with respect to the waveguide interface  12 ( 1 ) above. 
     In this example, the slot  34 ( 2 ) has width of approximately 0.400 inches and a height of approximately 0.080 inches at the front opening as illustrated in  FIG. 11 . The slot  34 ( 2 ) includes a tapered top surface  113  with a draft angle of approximately 2.0 degrees from a front end  113 A to a rear end  113 B of the slot  34 ( 2 ). The slot  34 ( 2 ) also includes a rear portion  114  with a tapered side  116  with a draft angle of approximately 4 degrees from a front end  115 A to a rear end  115 B of the rear portion  114 . The rear portion  114  meets with an opening in a standard waveguide flange. 
     The interface  26 ( 2 ) includes outer edges  118  with a draft angle of approximately 2 degrees from a front end  119 A to a rear end  119 B of the outer edge  118  as shown in  FIGS. 8 and 11 . The interface  26 ( 2 ) further includes a number of interface holes  38 ( 2 ) (shown in  FIGS. 7, 9, 10, 11, 12, 13, and 14 ) located therethrough. The interface holes  38 ( 2 ) are configured to receive machine screws to facilitate coupling of the waveguide interface  12 ( 2 ) to a waveguide flange. The interface holes  38 ( 2 ) include tapered side walls  120  with a draft angle of approximately 2 degrees from a front end  121 A to a rear end  121 B of the side walls  120  to facilitate removal from the mold as shown in  FIG. 11 . The interface holes  38 ( 2 ) are drilled or reamed and tapped with 4-40 threads, although other threads may be utilized, to result in a non-tapered hole in the finished part as discussed below. The interface  26 ( 2 ) also includes guide pin holes  41 ( 2 ) (as shown in  FIGS. 7, 9, 13, and 14 ) to provide alignment with the guide pins of a standard waveguide flange. 
     The interface  26 ( 2 ) also includes interface guide pins  122  (shown in  FIGS. 7, 8, 9, 11, 12, 13, and 14 ) located on a rear surface of the interface  26 ( 2 ) that provide alignment between the interface  26 ( 2 ) and a waveguide flange, although the interface  26 ( 2 ) may have other devices in other locations to facilitate alignment between the interface  26 ( 2 ) and a standard waveguide flange. In this example, the interface guide pins  122  have a tapered shape with a draft angle of approximately 2 degrees from a front end  123 A to a rear end  123 B of the interface guide pins  122  as shown in  FIG. 8 . 
     Referring now to  FIGS. 13 and 14 , the interface holes  38 ( 2 ) and guide pin holes  41 ( 2 ) are machined after the molding process to finalize the waveguide interface  12 ( 2 ). Specifically, interface holes  38 ( 2 ) are tapped with an oversized tap so that the interface holes  38 ( 2 ) are configured to accommodate plating therein. The interface holes  38 ( 2 ) are further drilled or reamed, by example with a 4-40 thread, in order for the interface holes  38 ( 2 ) to accommodate screws for connecting the interface  26 ( 2 ). Further, the guide pin holes  41 ( 2 ) are reamed to allow for entry of a slip fit dowel pin when coupled to a standard waveguide flange. The waveguide interface  12 ( 2 ) is further machined to remove all sharp edges resulting from the molding process. 
     Referring now to  FIGS. 15A-15D , top, side, front end, and bottom views of the exemplary printed circuit board assembly  14  shown in  FIG. 4  are illustrated, respectively. Printed circuit board assembly  14  includes a cut out area  42  (shown in  15 A and  15 B) configured to receive the communication device  18 ( 1 ) (not shown herein), such that the communication device  18 ( 1 ) sits within the recessed cut out bottom surface  44  and cut out side surfaces  46 A and  46 B (shown in  FIG. 15B ). Communication device  18 ( 1 ) is coupled to the printed circuit board assembly  14  using a conductive epoxy adhesive. Various conductive epoxy adhesives are known in the art and are not discussed herein. 
     The cut out area  42  as shown in  FIGS. 4, 15A, 15B, 16A, and 16B , which is a recessed portion of the printed circuit board assembly  14  configured to receive the communication device  18 ( 1 ), includes the cut out bottom surface  44  and cut out side surfaces  46 A and  46 B, is metallized using standard printed circuit plating techniques. The cut out area  42  is copper and gold plated to maintain a continuous electrical ground plane, although other conductive materials may be utilized. Printed circuit board assembly  14  further includes a top ground plane area  48  (as shown in  FIGS. 4, 16A, and 16B ), a side ground plane area  50 , a front ground plane area  52 , and a bottom ground plane area  54  that are metallized using standard printed circuit plating techniques, such that the top ground plane area  48 , the side ground plane area  50 , the front ground plane area  52 , and the bottom ground plane area  54  are electrically contiguous. The top ground plane area  48 , the side ground plane area  50 , the front ground plane area  52 , and the bottom ground plane area  54  are copper and gold plated, although other conductive materials may be utilized. The top ground plane area  48  is further electrically contiguous with the cutout side surfaces  46 A and  46 B and the cut out bottom surface  44  of the cut out area  42 . The front ground plane area  52  provides an electrical ground plane in the local interface region of the interface plate  26 ( 1 ) or interface  26 ( 2 ) and waveguide flange  22 . 
     Referring now to  FIG. 16A , a top detailed view of the of the printed circuit board assembly  14  shown in  FIGS. 15A-15D  along with communication device  18 ( 1 ) and launch transducer  20 ( 1 ), which provide a transmitter printed circuit board assembly, is shown. As shown in  FIG. 16A , the communication device  18 ( 1 ), which is a transmitter communication device, is affixed within the cut out area  42  of the printed circuit assembly  14  and is positioned to abut the cut out area side surface  46 B adjacent to the launch transducer  20 ( 1 ). 
     Low-frequency signal and power connections are supplied to the communication device  18 ( 1 ) via a plurality of wire bonds  56  from corresponding wire bond pads  58 , although other interconnection technologies besides wire bond pads  58  may be utilized. High-frequency millimeter wave connections are provided between the communication device  18 ( 1 ) and the adjacently positioned launch transducer  20 ( 1 ) with low-inductance wire or ribbon bonds  60 ( 1 ), although other connection technologies may be utilized. The printed circuit assembly  14  includes a width defined by edges  62 A and  62 B. 
     Referring now to  FIG. 16B , a top detailed view of the of the printed circuit board assembly  14  along with the communication device  18 ( 2 ) and launch transducer  20 ( 2 ), which provide a receiver printed circuit board assembly, is shown. The communication device  18 ( 2 ), which is a receiver communication device, is affixed within printed circuit assembly cut out area  42 , which is a recessed portion of the printed circuit board assembly  14  configured to receive the communication device  18 ( 1 ), and located to abut the cut out area side surface  46  adjacent to the launch transducer  20 ( 2 ). 
     Low-frequency signal and power connections from the printed circuit assembly  14  are provided to the communication device  18 ( 2 ) via a plurality of wire bonds  56  from corresponding wire bond pads  58 , although other interconnection technologies may be utilized. High-frequency millimeter wave connections are communicated between the communication device  18 ( 2 ) and the launch transducer  20 ( 2 ) with low-inductance wire or ribbon bonds  60 ( 2 ), although other connection technologies may be utilized. 
     Referring again to  FIG. 1A , the connector  16  utilized in the waveguide assembly  10  is a multi-pin connector that provides the lower-frequency electrical signals and power connections to the communication device  18 ( 1 ), although other types of connectors suitable to provide the lower-frequency electrical signals and power connections to the communication device  18 ( 1 ) may be utilized. The connector  16  is located on the printed circuit assembly  14  at the rear of the waveguide interface  12 ( 1 ). 
     The communication device  18 ( 1 ) is a highly integrated millimeter wave radio transmitter that is attached to the printed circuit assembly  14 , although the communication device may alternatively be a highly integrated millimeter wave radio receiver, such as communication device  18 ( 2 ) shown in  FIG. 16B . In one example, the communication device  18 ( 1 ),  18 ( 2 ) is a silicon germanium (SiGe) chip, although gallium arsenide (GaAs), complimentary metal oxide semiconductor (CMOS), or other semiconductor chips may be utilized for the communication device  18 ( 1 ),  18 ( 2 ). The communication device  18 ( 1 ),  18 ( 2 ), by way of example only, may be configured to work with a 60 GHz millimeter wave launch transducer  20 ( 1 ),  20 ( 2 ). The communication device  18 ( 1 ) is a balanced output connection at the transmitter output terminal, while communication device  18 ( 2 ) is an unbalanced input connection to the receiver input terminals. In one example, the communication device  18 ( 1 ),  18 ( 2 ) is protected from the environment by a protective cover  64  as shown in  FIGS. 1A and 1C . The protective cover  64  is made of plastic, although the protective cover  64  may be constructed from other non-conductive materials may be utilized. 
     Referring again to  FIG. 16A , in this example the printed circuit board assembly further includes the launch transducer  20 ( 1 ), which acts as a transmitter. In one example, the waveguide assembly  10  utilizes a 60 GHz millimeter wave launch transducer  20 ( 1 ) and enabled communication device  18 ( 1 ), although the present technology is not limited thereto. Additionally, the launch transducer  20 ( 1 ) is implemented with matching balanced transmission line terminals to efficiently accept high-frequency energy from the communication device  18 ( 1 ). Launch transducer  20 ( 1 ) is located precisely at the midpoint between width edges  62 A and  62 B of the printed circuit assembly  14 . Additionally, the launch transducer  20 ( 1 ) has a width dimension Y t  that is precisely matched to the opening of the waveguide flange dimension, as discussed below. 
       FIGS. 17A and 17B  show top and bottom views of the transmitter launch transducer  20 ( 1 ). As shown in  FIGS. 17A and 17B , the launch transducer  20 ( 1 ) is composed of low-loss substrate  66  which has a top metallization pattern and bottom metallization pattern. In this example, the low-loss substrate  66  is composed of fused silica (silicon dioxide) and is 254 micrometers (μm) thick, although other low-loss substrate materials and other material thickness values may be utilized. The metallization pattern is substantially composed of vacuum deposited gold metal from vacuum deposition techniques, although other deposition methods may be utilized. 
     The top metallization pattern of the transmitter launch transducer  20 ( 1 ) is composed of a first pair of transmission line sections  68 A and  68 B as shown in  FIG. 17A . The first pair of transmission line sections  68 A and  68 B are implemented over a ground plane  70  on the bottom side of the low-loss substrate  66 . The first pair of transmission line sections  68 A and  68 B couple energy from the communication device  18 ( 1 ) via bond wires  60 ( 1 ), as shown in  FIG. 16A , or other means to a second pair of transmission line sections  72 A and  72 B as shown in  FIG. 17A . The first pair of transmission line sections  68 A and  68 B are implemented to match the output impedance of the communication device  18 ( 1 ) and the bond wires  60 ( 1 ), as shown in  FIG. 16A , in a balanced configuration. 
     The second pair of transmission line sections  72 A and  72 B are located over a clear substrate section (with no ground plane on the bottom side of the low-loss substrate  66  in this section as shown in  FIG. 17B ) and provide energy from the first pair of transmission lines  68 A and  68 B to a pair of corresponding transducer elements  74 A and  74 B as shown in  FIG. 17A . The second pair of transmission line sections  72 A and  72 B are implemented to match the input impedance of the transducer elements  74 A and  74 B. 
     The transducer elements  74 A and  74 B are configured to provide substantial energy propagation in a direction parallel to the low-loss substrate  66  and away from the second pair of transmission line sections  72 A and  72 B, thereby forming an end-fire propagation pattern into an opening in the waveguide flange opening. The launch transducer  20 ( 1 ) has a width dimension, Y t  (shown in  FIG. 17B ), that is matched to be inserted into the standard waveguide flange opening having the “b” dimension, as shown in  FIG. 5A , described below. In one example, Y t  is 1.80 mm and the value of X t  (shown in  FIG. 17B ) is 2.87 mm, although other values for these dimensions are contemplated. Although an exemplary configuration for the launch transducer  20 ( 1 ) is illustrated and described, alternative configurations may be utilized. By way of example, in another embodiment, launch transducer  20 ( 1 ) may include a variation of a dipole with a parasitic element as illustrated in  FIG. 19 . 
     Referring again  FIG. 16B , in another example the printed circuit board assembly  14  includes the launch transducer  20 ( 2 ), which acts as a receiver. In one example, the waveguide assembly  10  utilizes a 60 GHz millimeter wave launch transducer  20 ( 2 ) and enabled communication device  18 ( 2 ), although the present technology is not limited thereto. The launch transducer  20 ( 2 ) is implemented with matching unbalanced transmission line terminals to efficiently deliver high-frequency energy to the communication device  18 ( 2 ). The launch transducer  20 ( 2 ) is located precisely at the midpoint between printed circuit assembly  14  width edges  62 A and  62 B The launch transducer  20 ( 2 ) has a width that is precisely matched to the to the opening of the waveguide flange dimension, as discussed below. 
       FIGS. 18A and 18B  show top and bottom views of a receiver launch transducer  20 ( 2 ). Receiver launch transducer has dimensions X r  and Y r  as shown in  FIG. 18B  in a similar manner as described with respect to  FIG. 17B  above. The launch transducer  20 ( 2 ) is composed of a low-loss substrate  76  which has a top metallization pattern and bottom metallization pattern. In this example, the substrate  76  is composed of alumina (aluminum oxide) and is 127 micrometers (μm) thick, although other low-loss substrate materials and other material thickness values may be utilized. The metallization pattern is substantially composed of vacuum deposited gold metal using vacuum deposition techniques or other appropriate methods. 
     In this example, the top metallization pattern includes a transmission line center conductor  78  ( FIG. 18A ) that traverses a length over a ground plane  80 , which is located on the bottom side of the low-loss substrate  76 . Beyond the position of ground plane  80 , the transmission line center conductor  78  continues and is positioned over a bottom side transmission line  82  ( FIG. 18B ). The transmission line center conductor  78  and the bottom side transmission line  82  together are coupled to transducer elements  84 A ( FIG. 17A ),  84 B ( FIG. 17A ),  84 C ( FIG. 17B ), and  84 D ( FIG. 17B ). The transducer elements  84 A and  84 B and  84 C and  84 D, respectively, form dual element dipoles and are configured to provide a directional propagation pattern in a direction parallel to the low-loss substrate  76  and away from the transmission line center conductor  78  and the bottom side transmission line  82 , thereby forming an end-fire propagation pattern into a waveguide flange opening, as discussed below. 
     The unbalanced input circuit configuration is composed of a ground connection  86  and the transmission line center conductor  78 . The ground connection  86  ( FIG. 18A ) is electrically connected through the low-loss substrate  76  and facilitated by metalized plating through holes (also known as vias)  88 A and  88 B, thereby forming a low-inductance connection to the ground plane  80  on the bottom side of the low-loss substrate  76 . In one example, the diameter of via holes  88 A and  88 B is 127 micrometers (μm) with gold metallization formed on the inner walls, although other dimensions and material selections are contemplated.  FIG. 19  illustrates another exemplary launch transducer that may be utilized with the examples of the present technology disclosed herein. 
     Referring again to  FIGS. 1A, 1B, 1C, 2, 3, and 4 , the waveguide interface  12 ( 1 ) is coupled to the waveguide flange  22 . The waveguide flange  22  is a standard waveguide flange known in the art. As shown in  FIGS. 2 and 4 , the waveguide flange  22  includes a waveguide flange opening  90  that may be aligned with the rectangular slot  34 ( 1 ) in the interface plate  26 ( 1 ) of the waveguide interface  12 ( 1 ). The waveguide opening  90  is rectangular having an “a” dimension ( FIGS. 2 and 5A ) representing the H-field for a rectangular waveguide. Precise alignment of interface plate  26 ( 1 ) with the standard waveguide flange  22  is facilitated by the standard waveguide flange guide pins  92  (shown in  FIGS. 1A, 1B, and 3 ) inserted into guide pin holes  41 ( 1 ) as shown in  FIG. 3  contained within interface plate  26 ( 1 ).  FIG. 5C  illustrates the waveguide flange  22  coupled to the interface plate  26 ( 1 ), wherein the interface plate  26 ( 1 ) is aligned to the waveguide flange assembly  22  with the rectangular slot  34 ( 1 ) of the interface plate  26 ( 1 ) overlapping with the waveguide flange opening  90  with the standard waveguide flange guide pins  92  inserted into the guide pin holes  41 ( 1 ). 
     As shown in  FIG. 5A , the waveguide flange  22  includes the waveguide opening  90  positioned substantially in the center of the circular waveguide flange  22 . In particular, the waveguide opening  90  is rectangular having an “a” dimension representing the H-field and a “b” dimension representing the E-field for a rectangular waveguide. In this example, the dimensions of the waveguide opening  90  are configured to be utilized for the frequency range of 50 to 75 GHz, whereby the dimensions are defined by what is known categorized in the art as WR-15 or in military standard MIL-DTL-85/3C as M85/3-018. By way of example only, for the 50 to 75 GHz standard waveguide frequency range, also known as V-band, the “a” dimension is approximately 3.76 mm and the “b” dimension is approximately 1.88 mm, although other “a” and “b” dimensions may be utilized depending on the type of application and/or the frequency range desired. Precise alignment of interface plate  26 ( 1 ) with the standard waveguide flange  22  is facilitated by the standard waveguide flange guide pins  92  inserted into guide pin holes  41 ( 1 ) contained within interface plate  26 ( 1 ), as discussed above. 
     An example of the operation of the waveguide assembly  10 , including either waveguide interface  12 ( 1 ) or waveguide interface  12 ( 2 ) will now be described with respect to  FIGS. 1A, 1B, 1C, 2, 3, 4, 5A, 5B, 5C, 6A, 6B, 6C, 7, 8, 9, 10, 11, 12, 13, 14, 15A ,  15 B,  15 C,  15 D,  16 A,  16 B,  17 A,  17 B,  18 A,  18 B, and  19 . It should be noted that the detailed description of the transmitter waveguide interface operation applies equally to the receiver waveguide interface with the direction of the millimeter wave transduction and energy reversed. Those of ordinary skill in the art will realize that both the transmission context and the reception context equally apply due to the Lorentz electromagnetic reciprocity theorem. It is also noted that although the operation is discussed with respect to waveguide interface  12 ( 1 ), the operation of waveguide interface  12 ( 2 ) is substantially the same as waveguide interface  12 ( 1 ). 
     Critical to the high efficiency and operation of the waveguide interfaces  12 ( 1 ) and  12 ( 2 ) is to facilitate propagation of millimeter wave energy into standard waveguide flange opening  90  and also restrict energy losses as the conducted electrical energy moves from the communications device  18 ( 1 ) through the high frequency wire bonds  60 ( 1 ) to the first pair of transmission lines  68 A and  68 B. The short waveguide segment  36  as shown in  FIGS. 2 and 11  is defined between the rectangular slot  34 ( 1 ) of interface plate  26 ( 1 ), or interface  26 ( 2 ), and the upper ground plane surface  48  of the printed circuit board assembly  14 . The printed circuit board assembly  14  also has contiguous copper plating at side ground plane area  50  and front ground plane area  52 , which form the lower portion of the short waveguide segment  36 . 
     The waveguide cutoff frequency is the frequency at which all frequencies below the cutoff frequency are substantially attenuated. Equation [1], derived from the Helmholtz equation for electromagnetic waves, provides the waveguide cutoff frequency for rectangular waveguide with an internal H-field “a” dimension and internal E-field “b” dimension. 
     
       
         
           
             
               
                 
                   
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                                 m 
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     In equation [1], ω c , is radian frequency, c is the speed of light, a is the H-field rectangular waveguide dimension, b is the E-field rectangular waveguide dimension, and n and m represent the waveguide mode numbers. The dominant waveguide mode is used to determine waveguide cutoff and is known in the art as transverse electric mode 1,0 (TE 1,0 ) where n=1 and m=0. With n=1 and m=0, the only variable remaining is the waveguide H-field “a” dimension. 
     In one example, for the standard waveguide flange  22 , the “a” dimension is 3.76 mm which yields a cutoff frequency of 39.9 GHz, well below the intended operating frequency range of standard waveguide flange  22 , which is 50 to 75 GHz. However, it is desired to substantially attenuate the transduction of energy over the operating frequency range of the waveguide interface in the short waveguide segment  36 . 
     The H-field dimension of short waveguide segment  36  is shown as the “a′” dimension in  FIG. 2 . In one example, the “a′” dimension is approximately 0.98 mm (980 μm). Setting a in equation to 0.98 mm with dominant mode (n=1 and m=0) yields a cutoff frequency of 153 GHz, well above the intended operating range of the waveguide interface. There will be slight variations of the cutoff frequency as the dimension “a′” varies as a function of the thickness of the printed circuit board assembly  14  and the effective dimension “a′” varies due to the dielectric loading properties and thickness variation of launch transducer  20 ( 1 ). However, with all variations taken into account, the minimum waveguide cutoff frequency for either the transmitter waveguide interface or the receiver waveguide interface is greater than 120 GHz. By establishing short segment waveguide  36  cutoff frequency well above the operating frequency range of the waveguide interface, maximum energy is provided to the standard waveguide opening  90 . 
     Accordingly, this exemplary technology provides a number of advantages including providing a waveguide assembly including a waveguide interface that may be utilized at high operating frequencies. The waveguide assembly of the present technology incorporates, in one example, a waveguide interface that is molded as a single piece, with nominal impact on the overall performance of the waveguide assembly. 
     Having thus described the basic concept of the disclosed technology, it will be rather apparent to those skilled in the art that the foregoing detailed disclosure is intended to be presented by way of example only, and is not limiting. Various alterations, improvements, and modifications will occur and are intended to those skilled in the art, though not expressly stated herein. These alterations, improvements, and modifications are intended to be suggested hereby, and are within the spirit and scope of the disclosed technology. Additionally, the recited order of processing elements or sequences, or the use of numbers, letters, or other designations therefore, is not intended to limit the claimed processes to any order except as may be specified in the claims. Accordingly, the invention is limited only by the following claims and equivalents thereto.