Integrated PIFA having an embedded connector on the radome thereof

Information

  • Patent Grant
  • 6433747
  • Patent Number
    6,433,747
  • Date Filed
    Friday, June 8, 2001
    23 years ago
  • Date Issued
    Tuesday, August 13, 2002
    22 years ago
Abstract
A Planar Inverted F Antenna (PIFA) is disclosed comprising a radiator assembly positioned in the interior of a lower Radome member. An upper Radome member is placed over the radiator assembly with the upper Radome member and the lower Radome member fully enclosing the radiator assembly. The radiator assembly is held to the upper and lower Radome members by means of three dielectric blocks on each member. The radiator assembly comprises: (1) two radiating elements placed on the opposite sides of common ground plane; (2) two separate shorting strips extending between one end of each radiating element and one end of common ground plane; (3) a common feed conductor in the form of a single strip connecting one edge of each radiating element and the common feed conductor which has a disc-shaped portion with an opening formed therein. A ground tab is formed as an extension of the common ground plane. A hollow cylindrical structure formed as an outward extension of the lower Radome member constitutes the embedded (built-in) connector for the PIFA. A metal rod is inserted through the opening in the disc-shaped portion and protrudes into the hollow cylindrical structure to serve as the feed (center) pin of the embedded connector. A cylindrical dielectric block on the bottom surface of the upper Radome member holds the feed (center) pin in the designed location of the embedded connector. The ground tab protrudes into the hollow cylindrical structure and maintains a flush contact with the side wall of the hollow cylindrical structure to provide the ground potential of the embedded connector.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to a Planar Inverted F Antenna (PIFA) and, in particular, to an integrated composite design of a PIFA having an embedded or built-in plastic connector on the Radome surface of the PIFA.




2. Description of the Related Art




With the rapid progress in wireless communication technology and the ever-increasing emphasis for its expansion, wireless modems on laptop computers and other handheld radio devices will be a common. feature. The technology employing a short-range radio link to connect devices such as cellular handsets, laptop computers, and other handheld devices has already been demonstrated [Wireless Design On-line Newsletter, Vol. 3, Issue 5, Nov. 22, 1999]. The performance of the antenna placed on devices like handsets and laptop computers is one of the critical parameters for the satisfactory operation of such a radio link. Therefore, the performance characteristics of the antenna utilized on communication devices assume significant importance in the evolving technology of wireless modems.




In the cellular communication industry, there recently has been an increasing emphasis on internal antennas instead of conventional external wire antennas. The concept of an internal antenna stems from the avoidance of a protruding external radiating element by the integration of the antenna into the device itself. Internal antennas have several advantageous features such as being less prone to external damage, a reduction in overall size of the handset with optimization, and ease of portability. The printed circuit board of the communication device serves as the ground plane of the internal antenna. Among the various choices for internal antennas, PIFA appears to have great promise. The PIFA is characterized by many distinguishing properties such as relative light weight, ease of adaptation and integration into the device chassis, moderate range of bandwidth, Omni directional radiation patterns in orthogonal principal planes for vertical polarization, versatility for optimization, and multiple potential approaches for size reduction. The PIFA also finds useful applications in diversity schemes. The sensitivity of the PIFA to both vertical and horizontal polarization is of immense practical importance in mobile cellular/RF data communication applications because of the absence of the fixed antenna orientation as well as the multi-path propagation conditions. The features enumerated above render the PIFA to be a good choice as an internal antenna for mobile cellular/RF data communication applications.




A conventional prior art single band PIFA assembly with an external RF connector is illustrated in

FIGS. 5A and 5B

. The PIFA


100


shown in

FIGS. 5A and 5B

consists of a radiating element


101


, a ground plane


102


, a connector feed pin


104




a


, and a conductive post or pin


107


. A power feed hole


103


is formed in the radiating element


101


which receives the connector feed pin


104




a


. The connector feed pin


104




a


serves as a feed path for radio frequency (RF) power to the radiating element


101


. The connector feed pin


104




a


is inserted through the feed hole


103


from the bottom surface of the ground plane


102


and is electrically insulated from the ground plane


102


where the pin passes through the hole in the ground plane


102


. The connector feed pin


104




a


is electrically connected to the radiating element


101


at


105




a


with solder. The body of the feed connector


104




b


is electrically connected to the ground plane at


105




b


with solder. The connector feed pin


104




a


is electrically insulated from the body of the feed connector


104




b


. A through hole


106


is formed in radiating element


101


and a conductive post or pin


107


is inserted through the hole


106


. The conductive post


107


serves as a short-circuit-between the radiating element


101


and the ground plane


102


. The conductive post


107


is electrically connected to the radiating element


101


at


108




a


with solder. The conductive post


107


is also electrically connected to the ground plane


102


at


108




b


with solder. The resonant frequency of the PIFA


100


is determined by the length (L) and width (W) of the radiating element


101


and is slightly affected by the locations of the feed pin


104




a


and the shorting pin


107


. The impedance match of the PIFA


100


is achieved by adjusting the diameter of the connector feed pin


104




a


, by adjusting the diameter of the conductive shorting post


107


, and by adjusting the separation distance between the connector feed pin


104




a


and the conductive shorting post


107


.




In the prior art techniques of PIFA design (Murch R. D., et al., U.S. Pat. No. 5,764,190; Korisch I. A., U.S. Pat. No. 5,926,139) the center conductor of the coaxial cable from the RF source is directly connected to the radiating element of the PIFA at the feed point. Further, in these designs, the feed point of the PIFA is drawn away from the shorted edge of the radiating element and is located within the central surface of the radiating element. Therefore, the feed cable from the RF source has to pass through the interior region (between the radiating element and the ground plane) of the PIFA. Such a prior art feeding scheme of the PIFA will prove to be tedious and cumbersome in the final integration process. An alternative scheme of a PIFA design that circumvents such a tedious feed assembly is therefore desirable. From the structural and fabrication point of view, an avoidance of a feed cable extending through the interior region of the PIFA is preferred. One recourse to accomplish the above task is to terminate the feed point of the PIFA with an external RF connector as explained in the description of a conventional PIFA. In most of the PIFA designs having an external RF connector, the cost of the commercial RF connector is in excess of the cost of the PIFA itself. An innovative design concept of a PIFA circumventing the requirement of an external RF connector for its operation is therefore a significant important feature to realize an enhanced cost-effectiveness of the PIFA technology. Keeping in pace with the rapid miniaturization in the size of the mobile voice and RF data communication devices, the future design of internal antenna should be accomplished without necessitating any change in the overall size of the communication device. The system considerations often warrant placement of the internal antenna at different locations on the device chassis with a very small volume earmarked for it. At times, the ground plane of the internal antenna might be in isolation with the chassis of the radio device resulting in a very small ground plane for the antenna. Under such design restrictions, the internal antenna has to exhibit satisfactory gain and bandwidth performance despite the non-availability of a large ground plane. Therefore, the design concept of an internal antenna such as a PIFA with a very small ground plane which overcomes the existing shortcomings of the PIFA feed structure is highly desirable for wireless applications to facilitate the ease of antenna integration, compactness, and adaptation.




The principal objective of this invention is to provide an encapsulated PIFA module which circumvents the requirement of attachment of a separate and an external RF connector to the feed point of the PIFA.




A further objective of this invention is to provide a design of a PIFA configuration which is devoid of an external metal RF connector.




A further objective of this invention is to provide a PIFA having a very small ground plane so that final PIFA module is compact and miniaturized in size.




Still another objective of this invention is to provide a design configuration of the composite assembly of a PIFA, its Radome and a RF connector for feeding the PIFA as an integrated module.




Still another objective of this invention is provide a structural configuration of a PIFA which is devoid of a feed assembly which passes through the interior region of the PIFA.




Yet another objective of this invention is to provide a composite assembly of a PIFA, its Radome, and a built-in connector which is cost effective to fabricate.




Still another objective of this invention is to provide a PIFA module which is easy for final system integration.




These and other objects will be apparent to those skilled in the art.




SUMMARY OF THE INVENTION




The instant invention provides a composite structure of a radiator assembly, a Radome, and an RF connector of a PIFA as an integrated single module. The PIFA of this invention overcomes the need of a separate external RF connector for the PIFA. In the preferred embodiment, the connection of the PIFA to the RF source of the system is through a simple, built-in, or embedded plastic connector which is a part of the Radome of the PIFA. A hollow cylindrical structure formed as an outward extension of the Radome serves as the embedded plastic connector of the PIFA. A metal rod attached to the feed conductor of the PIFA which protrudes into the hollow cylindrical structure of the Radome forms the center pin of the embedded plastic connector of the PIFA. A tab attached to the common ground plane which extends into the hollow cylindrical structure of the Radome provides the ground potential of the embedded plastic connector. The concept of dual radiating elements with a common ground plane and a common feed conductor is also disclosed to achieve the satisfactory performance of the PIFA despite a very small ground plane.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a partial exploded perspective view of the antenna of this invention;





FIG. 2A

is a top view of the antenna of this invention having the top Radome cover removed therefrom;





FIG. 2B

is a sectional view along line B—B of

FIG. 2A

;





FIG. 2C

is a sectional view along line B—B of

FIG. 2A

with the top Radome cover;





FIG. 3A

is a top view of the antenna of this invention with the top Radome cover;





FIG. 3B

is a partial sectional view of

FIG. 3A

;





FIG. 4

is a frequency response chart which depicts the characteristics of the VSWR of the single band PIFA of

FIG. 1

;





FIG. 5A

is. a top view of a prior art single band PIFA; and





FIG. 5B

is a sectional view taken along the line


5





5


of FIG.


5


A.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




Preferred embodiments of the present invention are now explained while referring to the drawings.




In the accompanying text describing the single band PIFA module


10


with an embedded (built-in) plastic connector of SMA male type covered under the embodiment of this invention, refer to

FIGS. 1

,


2


, and


3


. Generally speaking, the PIFA


10


comprises a radiator assembly placed inside a Radome. The Radome consists of a top cover and a bottom cover with side walls. A hollow cylindrical plastic structure formed as an extension of the bottom cover of the Radome constitutes the embedded (built-in) connector of this invention. The top cover of the Radome, when placed over the open surface of the bottom cover of the Radome, completely encloses the radiator assembly.




The radiator assembly has two identical radiators


11




a


and


11




b


placed on the opposite sides of a common ground plane


12


. A metallic strip


13




a


serves as a short-circuiting element between the first radiating element


11




a


and the common ground plane


12


. The short-circuiting strip


13




a


is connected to the ground plane


12


at


14




a


. The short-circuiting strip


13




a


is also connected to the radiating element


11




a


at


15




a


. Another metallic strip


13




b


serves as a short-circuiting element between the second radiating element


11




b


and the common ground plane


12


. The short-circuiting strip


13




b


is connected to the ground plane


12


at


14




b


. The short-circuiting strip


13




b


is also connected to the radiating element


11




b


at


15




b


. A metallic strip


16


serves as a common feed conductor to both the radiating elements


11




a


and


11




b


. The feed conductor


16


is formed as an integral part of the radiating element


11




a


. Below the conjecture point


16




a


of the feed conductor


16


and the radiating element


11




a


, there is a small notch


17




a


on the radiating element


11




a


through which the feed conductor


16


is drawn towards the ground plane


12


. The feed conductor


16


passes through a notch


17




c


on the ground plane


12


. The size and the location of the notch


17




c


are such that the feed conductor


16


will not touch the ground plane


12


. The feed conductor


16


is then drawn through a notch


17




b


on the radiating element


11




b


. The feed conductor


16


is then attached to the second radiating element


11




b


at


16




b


by solder. The notches


17




a


,


17




b


, and


17




c


are aligned along a straight line with a common horizontal axis.




A small circular disc


18


is also a part of the feed conductor


16


(FIG.


2


A). The circular disc


18


and the feed conductor


16


have a common overlapping area


19


. There is a small hole


20


at the center of the circular disc


18


. The diameter of the hole


20


is equal to the diameter of the center element of standard RF male SMA connector. The metallic rod


21


, while serving as a PIFA feed contact for the RF source, also forms the center conductor (pin) of the proposed (built-in) embedded plastic connector


23


of this invention. At the upper end


21




a


, the diameter of the feed pin


21


is larger than the diameter of the hole


20


thus allowing only the lower end


21




b


of the feed pin


21


to slide through the hole


20


on the disc


18


of the feed conductor


16


. From the top of the disc


18


of the feed conductor


16


, the feed pin


21


is inserted through the hole


20


(FIG.


2


A). The upper end


21




a


of the feed pin


21


makes a flush contact with the disc


18


. The free end


21




b


of the feed pin


21


which is inserted through the hole


20


on the disc


18


of the feed conductor


16


is allowed to pass through vertically down through the hole


33


on the base


27


of the bottom Radome cover


22


.




A metallic strip


24


of narrow width runs parallel to the feed pin


21


and is connected to the ground plane


12


at


25


. The open end of the metallic strip


24


is free to pass through the designated hole


34


on the base


27


of the bottom Radome cover


22


. The metallic strip


24


, which effectively is an extension of the ground plane, provides a ground potential to the embedded plastic connector


23


. Therefore, the metallic strip


24


performs the role similar to that of a metallic body of a conventional RF connector in providing the ground potential.




The bottom Radome cover


22


serves the multiple functions of holding the radiator assembly (comprising the radiating elements


11




a


and


11




b


, the ground plane


12


, the shorting strips


13




a


and


13




b


, and the feed conductor


16


) in the desired location and also provides the base


32


for embedded (built-in) plastic connector


23


. The bottom Radome cover


22


is nearly a square in shape with the top surface open. The bottom Radome cover


22


has side walls


26


and a base


27


. The bottom Radome cover


22


has three small dielectric blocks


28


,


29


, and


30


. The plastic block


28


has a notch


28




a


along its central axis (FIG.


2


C). Likewise, the notch


29




a


is along the central axis of the block


29


. The notch


30




a


runs along the central axis of the block


30


. The radiating element


11




a


is held to the bottom Radome cover


22


through the notch


28




a


(FIG.


2


C). The radiating element


11




b


and the bottom Radome cover


22


are held in the desired position through the notch


29




a


. The notch


30




a


holds the ground plane


12


and the bottom Radome cover


22


in the intended position (FIG.


3


B).




The embedded (built-in) plastic connector


23


is an outward extension of the bottom Radome cover


22


. The embedded plastic connector


23


is a hollow cylindrical structure with a side wall


31


. The side wall


31


has longitudinal perforations (perforations parallel to the axis of the hollow cylinder). The inner diameter of the hollow cylindrical structure is chosen to allow the easy passage of the mating RF connector into the plastic connector


23


. The height of the side wall


31


is chosen to ensure that the mating RF connector rests on the base


32


of the plastic connector


23


. The hole


33


on the base


27


of the bottom Radome cover


22


is for the insertion of the feed pin


21


into the hollow cylindrical area of the plastic connector


23


. The center of the hole


33


coincides with the center of the hollow cylinder of the plastic connector


23


. Also, the center of the hole


20


on the disc


18


of the feed conductor


16


and the center of the hole


33


lie along a common vertical axis. At the upper end


21




a


, the diameter of the feed pin


21


is larger than the diameter of the hole


20


thus allowing only the lower end


21




b


of the feed pin


21


to slide through the hole


20


on the disc


20


of the feed conductor


16


. From the top of the disc


18


of the feed conductor


16


, the feed pin


21


is inserted through the hole


20


(FIG.


2


B). The upper end


21




a


of the feed pin


21


makes a flush contact with surface of the disc


18


. The free end


21




b


of the feed pin


21


which passes through the hole


20


on the disc


18


of the feed conductor


16


is allowed to pass through vertically down through the hole


33


on the base


27


of bottom Radome cover


22


. The free end


21




b


of the feed pin


21


is positioned always to be well within the height of the side wall


31


of the plastic connector


23


and is designed to establish a consistent electrical contact with the center element of the mating connector. Electrically, the feed pin


21


located within the hollow cylindrical structure of the plastic connector


23


performs an identical role of a center pin (element) of a conventional RF SMA male connector. By establishing a consistent electrical contact with the center conductor of the mating RF female connector, the feed pin


21


connects the feed conductor


16


of the radiating elements


11




a


and


11




b


of the PIFA to the RF source of the radio device.




In a conventional RF SMA male or female connector, the metallic body of the connector offers the ground potential. In the design of embedded plastic connector


23


of this invention, the plastic side wall


31


of the plastic connector


23


replaces the metal body of a conventional RF SMA connector. Therefore, for the functioning of the embedded plastic connector


23


built on the bottom Radome cover


22


of the PIFA


10


, recourse is needed to provide a ground potential. From an RF point of view, the desired ground potential for the embedded plastic connector


23


is offered by the ground tab


24


of the ground plane


12


. The ground tab


24


, which is an attachment to the ground plane


12


of the PIFA at


25


, is inserted vertically down through the hole


34


on the bottom Radome cover


22


(FIG.


2


B). The ground tab


24


is then allowed to maintain a flush contact with the interior surface of the side wall


31


of the plastic connector


23


. The ground tab


24


, after running through the full length of the hollow cylindrical structure of the plastic connector


23


, is bent flush at the protruding edge


35


of the side wall


31


(FIGS.


2


B and


2


C). The ground tab


24


is again bent down retaining the flush contact with the exterior surface of the side wall


31


. When the mating RF female connector is inserted into the hollow cylindrical area of the embedded (built-in) SMA male plastic connector


23


, the ground tab


24


is in firm electrical contact with the body of the RF female connector and hence the ground tab


24


offers the desired ground potential. In essence, the non-feasibility of providing the ground potential in lieu of the non-metallic body of the embedded plastic connector


23


is overcome through an innovative design of the ground tab


24


maintaining a flush contact with the side wall


31


of the plastic connector


23


.




The top Radome cover


36


has a flat outer surface


37




a


and an inner surface


37




b


(FIG.


2


C). Attached to the inner surface


37




b


of the top Radome cover


36


are the three dielectric blocks


38


,


39


, and


40


of rectangular shape. The notch


38




a


is along one of the central axis of the plastic block


38


. Similarly, the notch


39




a


is along one of the central axis of the plastic block


39


. Likewise, the notch


40




a


is along one of the central axis of the plastic block


40


. When the top Radome cover


36


is placed on the open surface of the bottom Radome cover


22


(FIG.


2


C), the radiating element


11




a


is held to the top Radome cover


36


through the notch


38




a


, the radiating element


11




b


and the top Radome cover


36


are held in desired position through the notch


40




a


, and the notch


39




a


holds the ground plane


12


and the top Radome cover


36


in desired position. The dielectric block


41


of cylindrical shape is also attached to the inner surface


37




b


of the top Radome cover


36


(FIG.


2


C). The center of the dielectric cylindrical block


41


and the center of the hole


20


on the disc


18


of the feed conductor


16


lie along a common vertical axis. The length of the cylindrical block


41


is designed such that when the top Radome cover


36


is placed over the open surface of the bottom Radome cover


22


, the free end of the dielectric block


41


pushes the upper end


21




a


of the feed pin


21


to make a flush contact with the surface of the disc


18


attached to the feed conductor


16


(FIG.


2


C). Through such a design, the dielectric cylindrical block


41


holds the feed pin


21


in the desired position, as shown in FIG.


2


C.




The significant steps for assembling the different parts of the composite structure of the PIFA


10


with an embedded plastic connector


23


formed on the bottom Radome cover


22


of the PIFA are as follows. In the first step, the radiator assembly comprising the radiating elements (


11




a


and


11




b


), the ground plane


12


, the shorting strips (


13




a


and


13




b


), the common feed conductor


16


(formed as an extension of the radiating element


11




a


) including the disc


18


, and the ground tab


24


are formed as a single unit by the continuous and sequential bending of a metallic sheet of appropriate size and shape. In the second step, the open end of the feed conductor


16


is soldered to the radiating element


11




b


at


16




b


. In the third step, with the upper end


21




a


of the feed pin


21


making a flush contact with the surface of the disc


18


, the open end


21




b


of the feed pin


21


is drawn vertically down through the hole


20


on the disc


18


(FIG.


2


B). In the fourth step, the complete radiator assembly including the feed pin


21


is placed inside the bottom Radome cover


22


of the PIFA. The surfaces of the radiating elements (


11




a


and


11




b


) and the ground plane


12


are held parallel to the side wall


26


of the bottom Radome cover


22


(FIGS.


2


A and


3


A). The notch


28




a


holds the radiating element


11




a


to the bottom Radome cover


22


. Similarly, the notch


29




a


holds the radiating element


11




b


to the bottom Radome cover


22


. Likewise, the ground plane


12


is held to the bottom Radome cover


22


through the notch


30




a


(FIG.


3


B). The open end


21




b


of the feed pin


21


from the radiator assembly is drawn through the hole


33


on the base


27


of the bottom Radome cover


22


. After passing through the base


27


of the bottom Radome cover


22


, the open end


21




b


of the feed pin


21


is then confined to lie within the hollow cylindrical area of the plastic connector


23


. The open end of the ground tab


24


is then drawn through the hole


34


on the bottom Radome cover


22


. The ground tab


24


is then allowed to maintain a flush contact with the interior surface of the side wall


31


of the plastic connector


23


. The ground tab


24


, after passing through the full length of the side wall


31


of the hollow cylindrical structure of the plastic connector


23


, is bent flush at the protruding edge


35


of the side wall


31


. The ground tab


24


is then again bent down retaining the flush contact with the exterior surface of the side wall


31


(FIGS.


2


B and


2


C). In the final step, the top Radome cover


36


is placed over the open surface of the bottom Radome cover


22


(FIG.


2


C). In this step, the radiating element


11




a


is held to the top cover


36


through the notch


38




a


. Likewise, the radiating element


11




b


is held to the top cover


36


through the notch


40




a


. Similarly, the notch


39




a


holds the ground plane


12


to the top cover


36


. The dielectric block


41


pushes the upper end


21




a


of the feed pin


21


to maintain a firm and consistent flush contact with the disc


18


on the feed conductor


16


(FIG.


2


B). With this step, the assembly of the PIFA module with an embedded (built-in) plastic connector on the Radome is complete.




The above description of the composite assembly of a PIFA With an embedded (built-in) plastic connector


23


applies specifically to SMA male type. Without loss of generality, the concept described above for the embedded plastic connector


23


of SMA male type can be extended to the embedded connector of SMA female type also. The only change involved pertains to the feed pin


21


. For the embedded plastic connector of SMA female type, the feed pin


21


must be a hollow metal tube instead of a solid metal rod. The diameter of the hollow metal tube is chosen appropriately to maintain a firm contact with the center element (pin) of the mating SMA male connector.




The composite assembly of a PIFA


10


with an embedded (built-in) plastic connector described under the embodiment of this invention functions as a single band PIFA. The resonant frequency of the PIFA


10


is determined by the linear dimensions of the radiating elements


11




a


and


11




b


, the height of the PIFA radiating elements


11




a


and


11




b


(the distance between the ground plane


12


and the radiating elements


11




a


and


11




b


), the dimensions of the Radome covers


22


and


36


, and the dielectric constant of the material of the Radome. The bandwidth of the PIFA


10


is determined by the linear dimensions of the radiating elements


11




a


and


11




b


, the height of the radiating elements


11




a


and


11




b


, the width of the short-circuiting strips


13




a


and


13




b


, the position of the common feed conductor


16


, and the dielectric loss property of the material of the Radome. To retain the satisfactory pattern performance despite a very small ground plane


12


, two radiating elements


11




a


and


11




b


have been utilized to design a single band PIFA


10


. It is pertinent to point out that the two radiating elements


11




a


and


11




b


are having a common feed conductor


16


. Without loss of generality, the concept of embedded plastic connector of this invention can easily be extended to a PIFA with a single radiating element also. Further, the suggested design of an embedded plastic connector can be extended to the case of multi band PIFA operation also. In addition, the design concept proposed in this invention can be applied to other types of embedded plastic connectors such as TNC (male or female type).




Based on the description covered under the embodiment of this invention, a single band PIFA with an embedded plastic SMA male connector on the Radome of the PIFA


10


has been designed and fabricated. The semi perimeter (sum of the length and width) of the radiating elements


11




a


and


11




b


of the PIFA is 14.5 mm. The width of the ground plane is 7.5 mm and the length of the ground plane is 13 mm. The result of the test conducted on the PIFA module


10


is illustrated in FIG.


4


.

FIG. 4

depicts the




VSWR characteristics of the PIFA


10


. A good bandwidth performance of the PIFA


10


is apparent from the results shown in FIG.


4


.




As can be seen from the foregoing discussions, a novel scheme to design a single band PIFA with an embedded plastic connector on the Radome of the PIFA has been proposed and demonstrated. The proposed PIFA design overcomes the need of a separate external RF connector for the PIFA operation. The concept of embedded plastic connector reduces the weight and cost of the PIFA. The suggested design of the PIFA in a modular form has the distinct advantage and the desirable feature of easy and much simplified integration to the device chassis. In the PIFA design of this invention, the feed assembly is confined only to the exterior of the module resulting in enhanced fabrication ease. The proposed scheme also overcomes the tedious feed assembly of the prior art techniques of the PIFA design. The radiating elements, the shorting strips, the feed conductor, and the ground plane of the PIFA


10


are so configured to facilitate the formation of the radiator assembly of a PIFA in one process of continuos and sequential bending of a single sheet of metal resulting in improved manufacturability. The concept of dual radiating elements with a common ground plane and feed conductor has also been invoked in this invention to achieve the satisfactory pattern performance of the PIFA


10


despite a very small ground plane. The encapsulated single band PIFA


10


with an embedded plastic connector of this invention is lightweight, compact, cost-effective, and easy to manufacture.




Thus, the novel technique of an integrated composite design of a PIFA and an embedded plastic connector on the Radome surface of the PIFA of this invention has accomplished at least all of its stated objectives.



Claims
  • 1. A Planar Inverted F Antenna (PIFA), comprising:a common ground plane having opposite sides; a first radiating element positioned at one side of said common ground plane; a second radiating element positioned at the other side of said common ground plane; said first and second radiating elements being identical; each of said first and second radiating elements having a short-circuiting strip which is connected to said common ground plane.
  • 2. The PIFA of claim 1 wherein a common feed conductor is attached to said first and second radiating elements.
  • 3. The PIFA of claim 2 wherein said common feed conductor includes a disc-shaped portion having an opening formed therein; a feed pin extending through said opening in said disc-shaped portion of said common feed conductor; said feed pin functioning as an analogous center pin of a SMA male connector.
  • 4. The PIFA of claim 3 wherein said feed pin has an enlarged head portion which is in engagement with said disc-shaped portion around said opening formed therein.
  • 5. The PIFA of claim 4 wherein a ground tab extends from said common ground plane so as to serve as the metal body of a SMA connector.
  • 6. The PIFA of claim 5 wherein said ground tab is disposed parallel to said feed pin.
  • 7. The PIFA of claim 6 wherein said first and second radiating elements, said common ground plane, said short-circuiting strips, said common feed conductor, said disc-shaped portion, and said ground tab are of integral one-piece construction.
  • 8. The PIFA of claim 6 wherein said first and second radiating elements, said common ground plane, said common feed conductor, and said ground tab are enclosed within a radome.
  • 9. The PIFA of claim 8 wherein said radome comprises upper and lower radome members; said lower radome member including a base having upstanding walls which defines a compartment, said upper radome member being positioned on said side walls to close said compartment.
  • 10. The PIFA of claim 9 wherein said upper radome member has dielectric blocks extending therefrom for maintaining said radiating elements and said common ground plane in position.
  • 11. The PIFA of claim 10 wherein a dielectric block extends from said upper radome member for engagement with said feed pin to ensure that said feed pin is maintained in contact with said disc-shaped portion.
  • 12. The PIFA of claim 11 wherein a hollow cylindrical member extends from said lower radome member so as to function as an embedded plastic connector for the PIFA.
  • 13. The PIFA of claim 12 wherein said hollow cylindrical member has longitudinally extending slots formed therein.
  • 14. The PIFA of claim 12 wherein said base of said lower radome member has an opening formed therein for receiving said feed pin.
  • 15. The PIFA of claim 14 wherein the center of said opening on said disc-shaped portion, the center of said opening in said base portion of said lower radome member, and the center of said hollow cylindrical member lie along a common vertical axis.
  • 16. The PIFA of claim 15 wherein said base portion of said lower radome member has an opening formed therein which receives said ground tab.
  • 17. The PIFA of claim 16 wherein said opening which receives said ground tab is positioned so as to communicate with the interior of said hollow cylindrical member; said ground tab being in contact with said cylindrical member.
  • 18. The PIFA of claim 17 wherein a ground tab extends through said hollow cylindrical member and is also in contact with the exterior surface thereof.
US Referenced Citations (7)
Number Name Date Kind
5270722 Delestre Dec 1993 A
5764190 Murch et al. Jun 1998 A
5926139 Korisch Jul 1999 A
6114996 Nghiem Sep 2000 A
6286831 Sanford Sep 2001 B1
6295030 Kozakai et al. Sep 2001 B1
6339402 McKivergan Jan 2002 B1
Non-Patent Literature Citations (1)
Entry
“Wireless Design On-line Newsletter”, vol. 3, Issue 5, Nov. 22, 1999.