Abstract:
There is provided a monopole antenna including a helical radiating element including a first longitudinal portion having a first winding pitch and a second longitudinal portion having a second winding pitch and a cylindrical radiating element generally coaxial with the helical radiating element and extending along at least most of the first longitudinal portion.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is related to U.S. Provisional Patent Application Ser. No. 60/661,795 filed Mar. 14, 2005, and entitled BROADBAND LAND MOBILE ANTENNA, the disclosure of which is hereby incorporated by reference and priority of which is hereby claimed pursuant to 37 CFR 1.78(a) (4) and (5)(i). 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to antennas generally and more particularly to broadband antennas for mobile devices. 
       BACKGROUND OF TE INVENTION 
       [0003]    The following Patent documents are believed to represent the current state of the art: 
         [0004]    U.S. Pat. No. 4,772,895. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention seeks to provide an improved antenna for mobile devices. 
         [0006]    There is thus provided in accordance with a preferred embodiment of the present invention a monopole antenna including a helical radiating element including a first longitudinal portion having a first winding pitch and a second longitudinal portion having a second winding pitch and a cylindrical radiating element generally coaxial with the helical radiating element and extending along at least most of the first longitudinal portion. 
         [0007]    In accordance with a preferred embodiment of the present invention the monopole antenna also includes a dielectric separator located between the helical radiating element and the cylindrical radiating element. Preferably, the monopole antenna also includes a dielectric insert located interior of the helical radiating element and being configured to maintain the first winding pitch of the first longitudinal portion of the helical radiating element. 
         [0008]    In accordance with another preferred embodiment of the present invention the second winding pitch is greater than the first winding pitch. Preferably, the second winding pitch is 40-50% greater than the first winding pitch. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0009]    The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which: 
           [0010]      FIG. 1  is a simplified exploded view illustration of an antenna constructed and operative in accordance with a preferred embodiment of the present invention; 
           [0011]      FIGS. 2A ,  2 B and  2 C are, respectively, a simplified assembled pictorial illustration, a partially cut away pictorial illustration and a sectional illustration of the antenna of  FIG. 1 , the sectional illustration being taken along section lines IIC-IIC in  FIG. 2A ; 
           [0012]      FIGS. 3A and 3B  are a simplified assembled pictorial illustration and a sectional illustration of a coil base internal support and a coil base element, forming part of the antenna assembly of  FIGS. 1-2C , the sectional illustration being taken along section lines IIIB-IIIB in  FIG. 3A ; 
           [0013]      FIGS. 4A and 4B  are a simplified assembled pictorial illustration and a sectional illustration of the engagement of an antenna coil with the coil base internal support and the coil base element, as well as the mutual engagement therewith of a pin socket element, a pin socket collar and a pin, all forming part of the antenna assembly of  FIGS. 1-2C , the sectional illustration being taken along section lines IVB-IVB in  FIG. 4A ; 
           [0014]      FIGS. 5A and 5B  are a simplified assembled pictorial illustration and a sectional illustration of the engagement of an antenna coil with the coil base internal support and the coil base element, as well as the mutual engagement therewith of pin socket element, pin socket collar, pin and a base, all forming part of the antenna assembly of  FIGS. 1-2C , the sectional illustration being taken along section lines VB-VB in  FIG. 5A ; and 
           [0015]      FIGS. 6A and 6B  are a simplified assembled pictorial illustration and a sectional illustration of the engagement of the antenna coil with a dielectric separator and an antenna base element, as well as with the coil base internal support and the coil base element, and the mutual engagement therewith of pin socket element, pin socket collar, pin and base, all forming part of the antenna assembly of  FIGS. 1-2C , the sectional illustration being taken along section lines VIB-VIB in  FIG. 6A . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0016]    Reference is now made to  FIG. 1 , which is a simplified exploded view illustration of an antenna constructed and operative in accordance with a preferred embodiment of the present invention and to  FIGS. 2A ,  2 B and  2 C, which are, respectively, a simplified assembled pictorial illustration, a partially cut away pictorial illustration and a sectional illustration of the antenna of  FIG. 1 . 
         [0017]    As seen in FIGS.  1  and  2 A- 2 C, the antenna comprises a conductive base  100  having a relatively narrow externally threaded portion  102  which is adapted to threadably engage an antenna base socket in a communicator, such as a mobile telephone. Base  100  also includes a relatively wide externally threaded portion  104 . 
         [0018]    An insulative pin socket element  110  and an insulative pin socket collar  112  are disposed interiorly of base  100 . A conductive pin  114  is also disposed within base  100 , interiorly of pin socket element  110  and pin socket collar  112 . A conductive coil base element  116  is seated in pin socket collar  112  and surrounds a head portion of pin  114 . An insulative externally threaded locking element  118  threadably engages internal threading  120  formed on base  100 . 
         [0019]    In accordance with a preferred embodiment of the present invention, a dielectric insert, such as an insulative coil base internal support  122 , is formed with a coil pitch determining template  124  on an outer generally cylindrical surface thereof, which defines a first coil pitch, preferably in the range of 7-8 turns per cm. Engagement of a helical radiating element, such as a conductive antenna coil  126 , with dielectric coil base internal support  122  ensures that a first longitudinal portion, designated by reference numeral  128 , of the antenna coil  126  in engagement with template  124  has the first coil pitch. Preferably, a second longitudinal portion, designated by reference numeral  130 , of antenna coil  126 , which does not engage template  124 , has a second coil pitch, typically 40-50% greater than the first coil pitch, preferably in the range of 4-6 turns per cm. The coil base element  116  and the coil base internal support  122  are shown in detail in  FIGS. 3A and 3B . 
         [0020]      FIGS. 4A and 4B  illustrate the engagement of antenna coil  126  with the coil base internal support  122  and the coil base element  116 , as well as the mutual engagement therewith of pin socket element  110 , pin socket collar  112  and pin  114 , all forming part of the antenna assembly of  FIGS. 1-2C . It is appreciated that a conductive path is defined by tight engagement between the interior of coil  126  at the bottom thereof with an exterior surface  131  of coil base element  116  and by mutual tight engagement between coil base element  116  and pin  114 . 
         [0021]      FIGS. 5A and 5B  are similar to  FIGS. 4A and 4B  and additionally illustrate engagement of the pin socket element  110  and pin socket collar  112  with base  100 . It is appreciated that a conductive path is defined by tight engagement between the interior of coil  126  at the bottom thereof with an exterior surface  131  of coil base element  116  and by mutual tight engagement between coil base element  116  and pin  114 , which are insulated from base  100  by pin socket collar  112  and pin socket element  110 . 
         [0022]      FIGS. 6A and 6B  are similar to  FIGS. 5A  and SB, and additionally illustrate threadable engagement between internal threading  120  of base  100  and externally threaded locking element  118 , thereby locking the coil base element  116  within base  100 . A dielectric separator  132  is disposed in engagement with threaded locking element  118  overlying an outside surface of first longitudinal portion  128  of antenna coil  126  and separating first longitudinal portion  128  from a cylindrical radiating element, such as a conductive outer antenna base element  134 , mounted on dielectric separator  132 , which is shown with particular clarity in  FIG. 2C . The conductive outer antenna base element  134  includes an interior threaded portion  136  which threadably engages external threading  104  of base  100 , as shown with particular clarity in  FIG. 2C . 
         [0023]    As seen with particular clarity in  FIG. 2A , a dielectric flexible antenna cover element  138  is located externally of the assembly that is described hereinabove with reference to  FIGS. 5A and 5B , and has an associated tip  140 . 
         [0024]    It is appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of various features described hereinabove as well as variations and modifications thereto which would occur to a person of skill in the art upon reading the above description and which are not in the prior art.