Patent Publication Number: US-2022239017-A1

Title: Dipole Antenna

Description:
TECHNOLOGICAL FIELD 
     Embodiments of the present disclosure relate to a new dipole antenna. Some relate to a dual polarized antenna comprising the new dipole antenna. Some relate to an array of dual polarized antenna some of which comprises the new dipole antenna. 
     BACKGROUND 
     Electrical interference can occur between neighboring electrical conductors. This can cause problems when antennas are placed near to conductors within an apparatus. 
     A dipole antenna is a common form of antenna. It is designed to have a resonant frequency determined by a length dimension. The dipole normally has two opposing elongate arms. The arm of a dipole antenna often has a length that is just less than a quarter of a resonant wavelength of the dipole antenna. 
     BRIEF SUMMARY 
     According to various, but not necessarily all, embodiments there is provided an apparatus comprising: 
     a dipole antenna, configured for operation with a first polarization, the dipole antenna comprising:
         a feed; and   a pair of conductive elements fed by the feed,       

     wherein the pair of conductive elements are grounded, and extend in parallel on opposing sides of the feed and then diverge. 
     In some but not necessarily all examples, the dipole antenna comprises a pair of dipole arms configured for the first polarization wherein one of the dipole arms comprises the pair of conductive elements. 
     In some but not necessarily all examples, the pair of conductive elements, where parallel, are parallel to a virtual line aligned with the first polarization and then diverge from that virtual line. 
     In some but not necessarily all examples, the pair of conductive elements diverge symmetrically from a virtual line aligned with the first polarization. 
     In some but not necessarily all examples, the pair of conductive elements, at least where they diverge, have reflection symmetry in a virtual line aligned with the first polarization. 
     In some but not necessarily all examples, the pair of conductive elements diverge via one or more pairs of correspondingly opposite bends. 
     In some but not necessarily all examples, each bend in a conductive element before an extremity of the conductive element defines a bearing, and a sum of said one or more bearings for one of the pair of conductive elements and a sum of said one or more bearings for the other one of the pair of conductive elements are different by substantially 90 degrees. 
     In some but not necessarily all examples, one of the pair of conductive elements extends substantially in a first direction to an extremity and the other of the pair of conductive elements extends substantially in a second direction towards an extremity, wherein the second direction is orthogonal to the first direction. 
     In some but not necessarily all examples, the conductive elements comprise an L-shaped portion wherein one limb of the L extends from a ground plane to a vertex of the L and the other limb of the L extends from the vertex parallel to the feed. 
     In some but not necessarily all examples, at least one of the pair of conductive elements bends towards or away from a ground plane. 
     In some but not necessarily all examples, the pair of conductive elements are asymmetric and bend towards or away from a ground plane by different amounts. 
     In some but not necessarily all examples, the pair of conductive elements are asymmetric and have different lengths. 
     In some but not necessarily all examples, the dipole antenna comprises:
         another pair of conductive elements fed by the feed       

     wherein the other pair of conductive elements are grounded, and extend in parallel on opposing sides of the feed and then diverge,
         wherein the pair of conductive elements extend in parallel on opposing sides of the feed in a first direction and the other pair of conductive elements extend in parallel on opposing sides of the feed in a direction opposite the first direction.       

     In some but not necessarily all examples, the apparatus comprises: 
     a second dipole antenna, configured for operation with a second polarization comprising:
         a second feed; and   a pair of conductive elements fed by the feed       

     wherein the pair of conductive elements are grounded, and extend in parallel on opposing sides of the second feed and then diverge, 
     wherein the dipole antenna and the second dipole antenna are co-located to form a dual-polarized antenna. 
     In some but not necessarily all examples, one of the pair of conductive elements of the dipole antenna, at an extremity, is interconnected to an extremity of one of the pair of conductive elements of the second dipole antenna. 
     In some but not necessarily all examples, the apparatus comprises a ground plane, wherein the feed is provided by a first planar printed wiring board that is orthogonal to the ground plane and the second feed is provided by a second planar printed wiring board that is orthogonal to the ground plane and orthogonal to the first planar printed wiring board, wherein the first planar printed wiring board and the second planar printed wiring board intersect to form a cross in a cross-section parallel to the ground plane. 
     In some but not necessarily all examples, the second dipole antenna comprises
         another pair of conductive elements fed by the second feed       

     wherein the other pair of conductive elements are grounded, and extend in parallel on opposing sides of the second feed and then diverge,
         wherein the pair of conductive elements of the second dipole antenna extend in parallel on opposing sides of the feed in a second direction and the another pair of conductive elements of the second dipole antenna extend in parallel on opposing sides of the second feed in a direction opposite the second direction.       

     In some but not necessarily all examples, a first array of the dual polarized antennas are configured to operate at the same first operational frequency band. 
     In some but not necessarily all examples, the apparatus comprises a second array of second dual polarized antennas configured to operate at the same second operational frequency band that is different to the first operational frequency band, wherein the first dual polarized antennas of the first array and the second dual polarized antennas of the second array are interleaved. 
     According to various, but not necessarily all, embodiments there is provided a network node comprising the apparatus of any preceding claim. 
     According to various, but not necessarily all, embodiments there is provided examples as claimed in the appended claims. 
    
    
     
       BRIEF DESCRIPTION 
       Some examples will now be described with reference to the accompanying drawings in which: 
         FIG. 1  shows an example of the subject matter described herein; 
         FIG. 2  shows another example of the subject matter described herein; 
         FIG. 3  shows another example of the subject matter described herein; 
         FIG. 4  shows another example of the subject matter described herein; 
         FIGS. 5A &amp; 5B  show another example of the subject matter described herein; 
         FIGS. 6A &amp; 6B  show another example of the subject matter described herein; 
         FIGS. 7A &amp; 7B  show another example of the subject matter described herein; 
         FIGS. 8A &amp; 8B  show results for an example of the subject matter described herein; 
         FIGS. 9A to 9D  show another example of the subject matter described herein; 
         FIGS. 10A &amp; 10B  show results for an example of the subject matter described herein; 
         FIGS. 11A to 11D  show another example of the subject matter described herein; 
         FIGS. 12A &amp; 12B  show results for an example of the subject matter described herein; 
         FIGS. 13A to 13D  show another example of the subject matter described herein; 
         FIGS. 14A &amp; 14B  show results for an example of the subject matter described herein; 
         FIG. 15  shows another example of the subject matter described herein; 
         FIGS. 16A to 16C  show another example of the subject matter described herein; 
         FIGS. 17A &amp; 17B  show another example of the subject matter described herein; 
         FIG. 18  shows another example of the subject matter described herein; 
         FIG. 19A  shows another example of the subject matter described herein; 
         FIG. 19B  shows another example of the subject matter described herein; 
         FIGS. 20A &amp; 20B  show another example of the subject matter described herein; 
         FIGS. 21A &amp; 21B  show results for an example of the subject matter described herein; 
         FIG. 22  shows another example of the subject matter described herein. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure including the description and drawings describes examples of an apparatus  10  comprising: 
     a dipole antenna  20 , configured for operation with a first polarization P 1 , the dipole antenna comprising:
         a feed  30 ; and   a pair of conductive elements  42  fed by the feed  30 ,       

     wherein the pair of conductive elements  42  are grounded  50 , and extend in parallel on opposing sides of the feed  30  and then diverge. 
     The arrangement of the pair of grounded conductive elements  42  at the feed  30  improves performance. The use of a pair of conductive elements  42  increases the conducting surface area improving radiation performance. The position of the feed  30  between the grounded conductive elements  42  provides shielding at the feed  30 . 
     The dipole antenna  20  is less susceptible to interference from electromagnetic fields at the feed  30 . 
     The dipole antenna  20  provides a cheaper and easier to manufacture alternative to coaxial feedlines. 
     In at least some examples, a feed is an arrangement for transferring electro-magnetic energy between an antenna and radio frequency (RF) circuitry. In at least some examples a feed is a port or point of connection between an antenna and radio frequency (RF) circuitry. RF signals can be received by the antenna and provided to the RF circuitry and/or RF signals can be generated by the RF circuitry and provided to the antenna for transmission. RF circuitry can for example comprise transmitter and/or receiver circuitry. It can also include circuitry required for controlling or optimising the antenna performance. 
     The dipole antenna  20  provides good radiating performance as illustrated in the results shown in  FIGS. 8A, 8B ;  10 A,  10 B;  12 A,  12 B;  14 A,  14 B;  21 A,  21 B. 
     The results include plots of the gain of a co-polar component of electric field and the gain of a cross-polar component of electric field against azimuthal angle, at boresight ( FIG. 8A, 10A, 12A, 14A, 21A ). The Cross Polar Discrimination can be measured as the co-polar gain (dB) minus the cross-polar gain (dB).  FIG. 8A  provides results for the dual-polarized antenna  100  illustrated in  FIGS. 7A &amp; 7B . There are similar results for the dual-polarized antenna  100  illustrated in  FIGS. 6A &amp; 6B .  FIG. 10A  provides results for the dual-polarized antenna  100  illustrated in  FIG. 9A to 9D .  FIG. 12A  provides results for the dual-polarized antenna  100  illustrated in  FIG. 11A to 11D .  FIG. 14A  provides results for the dual-polarized antenna  100  illustrated in  FIG. 13A to 13D .  FIG. 21A  provides results for the dual-polarized antenna  100  illustrated in  FIG. 20A to 20B . 
     The results include plots of the scattering (S) parameters for the dual-polarized antenna  100  ( FIG. 8B, 10B, 12B, 14B, 21B ). The scattering parameters describe the input-out relationship between ports. S 11  measures input port reflection. S 22  is for output port reflection. S 12  is for transmission gain and S 21  is for reception gain. A requirement for an antenna is that it is frequency selective. S 11 , S 22  have a low value in the operational frequency range of the antenna.  FIG. 8B  provides results for the dual-polarized antenna  100  illustrated in  FIGS. 7A &amp; 7B . There are similar results for the dual-polarized antenna  100  illustrated in  FIGS. 6A &amp; 6B .  FIG. 10B  provides results for the dual-polarized antenna  100  illustrated in  FIG. 9A to 9D .  FIG. 12B  provides results for the dual-polarized antenna  100  illustrated in  FIG. 11A to 11D .  FIG. 14B  provides results for the dual-polarized antenna  100  illustrated in  FIG. 13A to 13D .  FIG. 21B  provides results for the dual-polarized antenna  100  illustrated in  FIG. 20A to 20B . 
     This disclosure including the description and drawings describes examples of a new dipole antenna. The new dipole antenna is referenced using references  20 ,  120 . The new dipole antenna  20  has a feed  30  and the new dipole antenna  130  has a feed  130 . 
     The new dipole antenna is configured for operation with a particular polarization. The new dipole antenna comprises a feed; and a pair of conductive elements fed by the feed, wherein the pair of conductive elements are grounded, and extend in parallel on opposing sides of the feed and then diverge. 
     In the description a dipole antenna has a pair of notional poles or arms  40  used to provide a particular orientation of polarization. The pair of poles or arms can be referenced individually or collectively using a reference  40 ,  140  and poles or arms in a pair can be distinguished by the reference with a subscript. The dipole antenna  20  has poles or arms  40   1 ,  40   2 . The dipole antenna  120  has poles or arms  140   1 ,  140   2 . 
     The new dipole antenna has at least one notional pole or arm comprising a pair of conductive elements fed by the feed, wherein the pair of conductive elements are grounded, and extend in parallel on opposing sides of the feed and then diverge. A pair of conductive elements can be referenced individually or collectively using a reference  42 ,  42 ′,  142 ,  142 ′ and conductive elements in a pair can be distinguished by the reference with a subscript. The dipole antenna  20  can have conductive elements  42   1 ,  42   2  providing the notional pole or arm  40   1 . The dipole antenna  20  can have conductive elements  42   1 ′,  42   2 ′ providing the notional pole or arm  40   2 . The dipole antenna  120  can have conductive elements  142   1 ,  142   2  providing the notional pole or arm  140   1 . The dipole antenna  120  can have conductive elements  142   1 ′,  142   2 ′ providing the notional pole or arm  140   2 . 
     The conductive elements  42   1 ,  42   2  have extremities  44   1 ,  44   2 . The conductive elements  42   1 ′,  42   2 ′ have extremities  44   1 ′,  44   2 ′. The conductive elements  142   1 ,  142   2  have extremities  144   1 ,  144   2 . The conductive elements  142   1 ′,  142   2 ′ have extremities  144   1 ′,  144   2 ′. 
     Each of the conductive elements  42 ,  142  is grounded at a ground  50 . The ground  50  is indicated by a black dot in  FIGS. 1 to 4  but every ground point is not labelled in all FIGs for clarity. In  FIGS. 3 &amp; 4 , black dots are associated with label  50  via a key (an inset that explains the symbols). 
     The  FIGS. 1 to 4  are fully labelled. Other FIGs are not fully labelled for purposes of clarity. The features labelled in  FIGS. 1 to 4  can be present in the other FIGs even if not labelled. 
     In some examples, the apparatus  10  comprises: a dipole antenna  20 , configured for operation with a first polarization P 1 , the dipole antenna  20  comprising: a feed  30 ; and a pair of conductive elements  42  fed by the feed  30 , wherein the pair of conductive elements  42  are grounded  50 , and extend in parallel on opposing sides of the feed  30  and then diverge. 
     In some examples, the apparatus  10  comprises: a dipole antenna  20 , configured for operation with a first polarization P 1 , the dipole antenna  20  comprising: a feed  30 ; and a pair of conductive elements  42 ′ fed by the feed  30 , wherein the pair of conductive elements  42 ′ are grounded  50 , and extend in parallel on opposing sides of the feed  30  and then diverge. 
     In some examples, the apparatus  10  comprises: a dipole antenna  120 , configured for operation with a second polarization P 2 , the dipole antenna  120  comprising: a feed  130 ; and a pair of conductive elements  142  fed by the feed  130 , wherein the pair of conductive elements  142  are grounded  50 , and extend in parallel on opposing sides of the feed  130  and then diverge. 
     In some examples, the apparatus  10  comprises: a dipole antenna  120 , configured for operation with a second polarization P 2 , the dipole antenna  120  comprising: a feed  130 ; and a pair of conductive elements  142 ′ fed by the feed  130 , wherein the pair of conductive elements  142 ′ are grounded  50 , and extend in parallel on opposing sides of the feed  130  and then diverge. 
     In at least some examples, the polarizations P 1  and P 2  are orthogonal. 
     In some FIGs a director  2  (also called a patch) is present. It is a conductor that can be optionally used for impedance matching. 
     In some examples, the pair of conductive elements  42 ,  42 ′ where fed, sandwich the feed  30  and then diverge to provide separated respective radiator elements  42   1 ,  42   2 ;  42   1 ′,  42   2 ′. In some examples, the pair of conductive elements  142 ,  142 ′ where fed, sandwich the feed  130  and then diverge to provide separated respective radiator elements  142   1 ,  142   2 ;  142   1 ′,  142   2 ′. 
     The pair of conductive elements  42 ,  42 ′;  142 ,  142 ′, at the feed  30 ,  130 , are separated from the feed  30 ,  130  by dielectric or a dielectric. The dielectric could be any suitable non-conductive material including air , or a combination of different non-conductive material, including air. 
     In at least some examples, the pair of conductive elements  42 ,  42 ′,  142 ,  142 ′, at the feed  30 ,  130 , are wider than the feed  30 ,  130  and form a stripline arrangement. The pair of conductive elements  42 ,  42 ′,  142 ,  142 ′, at the feed  30 ,  130 , form a transmission line. The transmission line can, in some examples, have a uniform cross-section along its length. The feed  30 ,  130  can be centrally located in the cross-section along its length. 
     The pair of conductive elements  42 ,  42 ′,  142 ,  142 ′, at the feed  30 ,  130 , increase the conducting surface and provide good radiating performance. The pair of conductive elements  42 ,  42 ′,  142 ,  142 ′, at the feed  30 ,  130 , shield the central feed  30 ,  130  from external electric fields. 
     In some but not necessarily all examples a first printed wiring board provides the first dipole feed  30 . The first printed wiring board can, in some examples be planar and stiff and extend substantially perpendicularly from a planar ground plane. 
     In some but not necessarily all examples a second printed wiring board provides the second dipole feed  130 . The second printed wiring board can, in some examples be planar and stiff and extend substantially perpendicularly from the planar ground plane. 
     In some but not necessarily all examples the first printed wiring board and the second printed wiring board intersect to form a cross in a cross-section parallel to the ground plane. In some but not necessarily all examples the first printed wiring board and the second printed wiring board are orthogonal and form a regular cross shape in a cross-section parallel to the ground plane. 
     In the examples illustrated, conductive elements  42 ,  42 ′,  142 ,  142 ′ are in order: grounded  50 ; parallel adjacent a feed  30 ,  130 ; diverging; then reaching respective extremities  44 ,  44 ′,  144 ,  144 ′. 
       FIG. 1  shows an example of a dipole antenna  20  comprising a pair of grounded conductive elements  42  that extend in parallel on opposing sides of the feed  30  and then diverge. 
     The apparatus  10  comprises: a dipole antenna  20 , configured for operation with a first polarization P 1 , the dipole antenna  20  comprising: a feed  30 ; and a pair of conductive elements  42  fed by the feed  30 , wherein the pair of conductive elements  42  are grounded  50 , and extend in parallel on opposing sides of the feed  30  and then diverge. 
     The dipole antenna  20  comprises a pair of dipole poles or arms  40  configured for the first polarization P 1 . One of the dipole arms  40   1  comprises the pair of conductive elements  42 . 
     The pair of conductive elements  42 , where parallel, are parallel to a virtual line L 1  aligned with the first polarization P 1  and then diverge from that virtual line L 1 . 
     In this example but not necessarily all examples, the pair of conductive elements  42  diverge symmetrically from a virtual line L 1  aligned with the first polarization P 1 . 
     In this example but not necessarily all examples, the pair of conductive elements  42 , at least where they diverge, have reflection symmetry in a virtual line L 1  aligned with the first polarization P 1 . 
     In this example but not necessarily all examples one of the pair of conductive elements  42   1  extends substantially in a first direction to an extremity  44   1  and the other of the pair of conductive elements  42   2  extends substantially in a second direction towards an extremity  44   2 , wherein the second direction is orthogonal to the first direction. 
       FIG. 2  shows another example of a dipole antenna  20 . 
     The apparatus  10  comprises: a dipole antenna  20 , configured for operation with a first polarization P 1 . 
     The dipole antenna  20  comprises: a feed  30 ; a pair of conductive elements  42  fed by the feed  30 , wherein the pair of conductive elements  42  are grounded  50 , and extend in parallel on opposing sides of the feed  30  and then diverge; and a pair of conductive elements  42 ′ fed by the feed  30 , wherein the pair of conductive elements  42  are grounded  50 , and extend in parallel on opposing sides of the feed  30  and then diverge. 
     The dipole antenna  20  comprises a pair of dipole poles or arms  40  configured for the first polarization P 1 . One of the dipole arms  40   1  comprises the pair of conductive elements  42  and the other dipole arm  40   2  comprises the pair of conductive elements  42 ′. 
     In this example, the pair of conductive elements  42 , where parallel, are parallel to a virtual line L 1  aligned with the first polarization P 1  and then diverge from that virtual line L 1 . In this example but not necessarily all examples, the pair of conductive elements  42  diverge symmetrically from the virtual line L 1  aligned with the first polarization P 1 . In this example but not necessarily all examples, the pair of conductive elements  42 , at least where they diverge, have reflection symmetry in a virtual line L 1  aligned with the first polarization P 1 . In this example but not necessarily all examples one of the pair of conductive elements  42   1  extends substantially in a first direction to an extremity  44   1  and the other of the pair of conductive elements  42   2  extends substantially in a second direction towards an extremity  44   2 , wherein the second direction is orthogonal to the first direction. 
     The pair of conductive elements  42 ′, where parallel, are parallel to the virtual line L 1  aligned with the first polarization P 1  and then diverge from that virtual line L 1 . In this example but not necessarily all examples, the pair of conductive elements  42 ′ diverge symmetrically from the virtual line L 1  aligned with the first polarization P 1 . In this example but not necessarily all examples, the pair of conductive elements  42 ′, at least where they diverge, have reflection symmetry in a virtual line L 1  aligned with the first polarization P 1 . In this example but not necessarily all examples one of the pair of conductive elements  42   2 ′ extends substantially in a direction to an extremity  44   1 ′ and the other of the pair of conductive elements  42   2 ′ extends substantially in an orthogonal direction towards an extremity  44   2 ′. 
     In this example but not necessarily all examples, the pair of conductive elements  42  and the pair of conductive elements  42 ′ diverge symmetrically by the same amount. In this example but not necessarily all examples one of the pair of conductive elements  42   2 ′ extends substantially in a direction opposite the first direction to the extremity  44   2 ′ and the other of the pair of conductive elements  42   1 ′ extends substantially in a direction opposite the second direction towards the extremity  44   1 ′. 
       FIG. 3  shows an example of a dual-polarized antenna  100  comprising the dipole antenna  20  illustrated in  FIG. 3  and another dipole antenna  120 . 
     The description of the dipole antenna  20  provided for  FIG. 2  is also relevant for  FIG. 3 . It is not repeated for brevity but is incorporated by reference. 
     The apparatus  10  comprises: a dipole antenna  120 , configured for operation with a second polarization P 2 . 
     In this example, the second polarization is orthogonal (substantially orthogonal) to the first polarization P 1 . 
     The dipole antenna  120  comprises: a feed  130 ; a pair of conductive elements  142  fed by the feed  130 , wherein the pair of conductive elements  142  are grounded  50 , and extend in parallel on opposing sides of the feed  130  and then diverge; and a pair of conductive elements  142 ′ fed by the feed  130 , wherein the pair of conductive elements  142  are grounded  50 , and extend in parallel on opposing sides of the feed  130  and then diverge. 
     The dipole antenna  120  comprises a pair of poles or arms  140  configured for the second polarization P 2 . One of the dipole arms  140   1  comprises the pair of conductive elements  142  and the other dipole arm  140   2  comprises the pair of conductive elements  142 ′. 
     In this example, the pair of conductive elements  142 , where parallel, are parallel to a virtual line L 2  aligned with the second polarization P 2  and then diverge from that virtual line L 2 . In this example but not necessarily all examples, the pair of conductive elements  142  diverge symmetrically from the virtual line L 2  aligned with the second polarization P 2 . In this example but not necessarily all examples, the pair of conductive elements  142 , at least where they diverge, have reflection symmetry in the virtual line L 2  aligned with the second polarization P 2 . In this example but not necessarily all examples one of the pair of conductive elements  142   1  extends substantially in a direction to an extremity  144   1  and the other of the pair of conductive elements  142   2  extends substantially in an orthogonal direction towards an extremity  144   2 . 
     In this example, the pair of conductive elements  142 ′, where parallel, are parallel to the virtual line L 2  and then diverge from that virtual line L 2 . In this example but not necessarily all examples, the pair of conductive elements  142 ′ diverge symmetrically from the virtual line L 2 . In this example but not necessarily all examples, the pair of conductive elements  142 ′, at least where they diverge, have reflection symmetry in the virtual line L 2 . In this example but not necessarily all examples one of the pair of conductive elements  142   2 ′ extends substantially in a direction to an extremity  144   1 ′ and the other of the pair of conductive elements  142   2 ′ extends substantially in an orthogonal direction towards an extremity  144   2 ′. 
     In this example but not necessarily all examples, the pair of conductive elements  142  and the pair of conductive elements  142 ′ diverge symmetrically by the same amount. 
     In this example but not necessarily all examples one of the pair of conductive elements  142   1  extends substantially in a direction opposite the first direction (parallel to conductive element  42   2 ′) to the extremity  144   1  and the other of the pair of conductive elements  142   2  extends substantially in the second direction (parallel to conductive elements  42   2 ) towards the extremity  144   2 . 
     In this example but not necessarily all examples one of the pair of conductive elements  142   2 ′ extends substantially in the first direction (parallel to conductive element  42   1 ) to the extremity  144   2 ′ and the other of the pair of conductive elements  142   1 ′ extends substantially in a direction opposite the second direction (parallel to conductive elements  42   1 ′) towards the extremity  144   1 ′. 
       FIG. 4  shows another example of a dual-polarized antenna  100  comprising a dipole antenna  20  and a dipole antenna  120 . 
     The description of the dipole antenna  20  provided for  FIG. 2  is in part relevant for  FIG. 4 . It is not repeated for brevity but is incorporated by reference. The description of the dipole antenna  120  provided for  FIG. 3  is in part relevant for  FIG. 4 . It is not repeated for brevity but is incorporated by reference. The dipole antenna  20  illustrated in  FIG. 4  differs from the dipole antenna  20  illustrated in  FIG. 3  in that the conductive element  42   2 ′ of the dipole antenna  20  does not diverge symmetrically from virtual line L 1  when compared to conductive element  42   1 ′ of the dipole antenna  20 . The dipole antenna  120  illustrated in  FIG. 4  differs from the dipole antenna  120  illustrated in  FIG. 3  in that the conductive element  142   1  of the dipole antenna  120  does not diverge symmetrically from virtual line L 2  when compared to conductive element  142   2  of the dipole antenna  120 . 
     Whereas, in  FIG. 3 , the conductive element  42   2 ′ of the dipole antenna  20  and the conductive element  142   1  of the dipole antenna  120  are parallel, in  FIG. 4 , they are not parallel and are splayed. 
       FIG. 5A  shows another example of a dual-polarized antenna  100  comprising a dipole antenna  20  and a dipole antenna  120 . The dual-polarized antenna  100  is similar to the dual polarized antenna  100  illustrated in  FIG. 3 .  FIG. 5B  shows a notionally exploded view of the dual-polarized antenna  100  illustrated in  FIG. 5A . 
     In this example, a first printed wiring board  110  provides the first dipole feed  30 . The first printed wiring board  110  is planar and stiff and extends substantially perpendicularly from a planar ground plane  50 . Conductive traces on or within the first printed wiring board  110  provide the feed  30 . 
     In this example, a second printed wiring board  112  provides the second dipole feed  130 . The second printed wiring board  112  is planar and stiff and extends substantially perpendicularly from a planar ground plane  50 . Conductive traces on or within the second printed wiring board  120  provide the feed  130 . 
     In this example, the first printed wiring board  110  and the second printed wiring board  112  intersect at right-angles to form a cross. 
     Each of the conductive elements  42   1 ,  42   2 ,  42   1 ′,  42   2 ′,  142   1 ,  142   2 ,  142   1 ′,  142   2 ′ comprises an L-shaped portion. One limb of the L extends from the ground plane  50  where it is grounded, past the feed  30 ,  130  to a vertex of the L. The other limb of the L extends from the vertex to a respective extremity  44   1 ,  44   2 ,  44   1 ′,  44   2 ′,  144   1 ,  144   2 ,  144   1 ′,  144   2 ′. 
     The pairs of vertical limbs (the limbs which extend from the ground plane  50 ) of the L-shaped conductive elements of the same pole or arm of the same dipole antenna form a transmission line. The conductive elements  42   1 ,  42   2  are one pair that shield the feed  30 . The conductive elements  42   1 ′,  42   2 ′ are another pair that shield the feed  30 . The conductive elements  142   1 ,  142   2  are a pair that shield the feed  130 . The conductive elements  142   1 ′,  142   2 ′ are another pair that shield the feed  130 . 
       FIGS. 6A &amp; 6B  show an example of the dual polarized antenna  100 .  FIG. 6A  is a top plan view and  FIG. 6B  is a perspective view. The pairs of conductive elements diverge, then bend outwardly to diverge more than bend inwardly to diverge less and extend at right angles to each other. 
       FIGS. 7A &amp; 7B  show an example of the dual polarized antenna  100 .  FIG. 7A  is a top plan view and  FIG. 7B  is a perspective view. The pairs of conductive elements diverge then bend inwardly to diverge less and extend at right angles to each other. 
     The bends in  FIGS. 6A, 6B, 7A, 7B  are in-plane bends. The bends are in a plane that is parallel to the ground plane (orthogonal to boresight). 
     Each of the pairs of conductive elements  42 ,  42 ′, diverge via one or more pairs of correspondingly opposite bends measured relative to the virtual line L 1 /first polarization direction P 1  (not illustrated). Each of the pairs of conductive elements  142 ,  142 ′, diverge via one or more pairs of correspondingly opposite bends measured relative to the virtual line L 2 /second polarization direction P 2  (not illustrated). 
     Each bend in a conductive element before an extremity of the conductive element defines a bearing, and a sum of said one or more bearings for one of the pair of conductive elements and a sum of said one or more bearings for the other one of the pair of conductive elements are different by substantially 90 degrees. 
       FIG. 9A, 9B, 9C, 9D  show an example of the dual polarized antenna  100 .  FIG. 9A  is a perspective view with a director  2  attached.  FIG. 9B  is a top plan view without the director.  FIGS. 9C and 9D  are different perspective views without the director. In this example, the conductive elements  42 ,  42 ′,  142 ,  142 ′ have out-of-plane bends. The bends are out of a plane that is parallel to the ground plane (orthogonal to boresight). The conductive elements  42 ,  42 ′,  142 ,  142 ′ have bends towards the ground plane. In other examples some but not all of the conductive elements  42  have such bends. In some examples, some or all of conductive elements  42 ,  42 ′,  142 ,  142 ′ have bends away from a ground plane. 
       FIG. 11A, 11B, 11C, 11D  show an example of the dual polarized antenna  100 .  FIG. 11A  is a perspective view with a director  2  attached.  FIG. 11B  is a top plan view without the director.  FIGS. 11C and 11D  are different perspective views without the director. In this example, conductive elements  42 ,  42 ′,  142 ,  142 ′ that belong to adjacent pairs are interconnected. 
     The extremity  44 , of the conductive element  421  is interconnected to the extremity  144   2 ′ of the conductive element  142   2 ′. 
     The extremity  144   1 ′ of the conductive element  142   1 ′ is interconnected to the extremity  44   1 ′ of the conductive element  42   1 ′. 
     The extremity  44   2 ′ of the conductive element  42   2 ′ is interconnected to the extremity  144   1  of the conductive element  142   1 . 
     The extremity  144   2  of the conductive element  142   2  is interconnected to the extremity  44   2  of the conductive element  42   2 . 
       FIG. 13A, 13B, 13C, 13D  show an example of the dual polarized antenna  100 .  FIG. 13A  is a perspective view with a director  2  attached.  FIG. 13B  is a top plan view without the director.  FIG. 13C  perspective view without the director.  FIG. 13D  is an enlargement of part of  FIG. 13C . In this example, conductive elements  42 ,  42 ′,  142 ,  142 ′ that belong to adjacent pairs are interconnected. 
     This example illustrates that dimensions of the conductive elements  42 ,  42 ′,  142 ,  142 ′ can be varied. In this example, a depth of the conductive elements  42 ,  42 ′,  142 ,  142 ′ in the boresight direction is significantly less than a depth of the conductive elements  42 ,  42 ′,  142 ,  142 ′ in the example illustrated in  FIGS. 11A to 11D , for example. 
       FIG. 15  shows another example in which the apparatus  10  comprises a first array  200  of the dual polarized antennas  100 . In this example, the dual polarized antennas  100  of the array  200  are configured to operate at the same first operational frequency band. 
     The apparatus  10  can, for example, be a dual polarized antenna panel. 
       FIG. 16A, 16B, 16C  show an example of the dual polarized antenna  100 .  FIG. 16A  is a perspective view with a director  2  attached.  FIG. 16B  is a front view.  FIG. 16C  is a side view. 
     In this example, the dual polarized antenna  100  is asymmetric. The arrangement of conductive elements  42 ,  42 ′,  142 ,  142 ′ when viewed from the side is different than the arrangement of conductive elements  42 ,  42 ′,  142 ,  142 ′ when viewed from the front. 
     In this example, the conductive elements  42   2 , and  142   2  have a different configuration than the conductive elements  42   1 ,  142   1 ,  42   1 ′,  42   2 ′,  142   1 ′,  142   2 ′. 
     In this example, the conductive elements  42   2 ,  142   1 ,  142   2 ,  42   1 ′,  42   2 ′,  142   1 ′ are asymmetric and bend towards or away from the ground plane by different amounts. 
     In this example, the conductive elements  42   2 , and  142   2  are bent towards the ground plane (away from the director  2 ) and the conductive elements  42   1 ,  142   1 ,  42   1 ′,  42   2 ′,  142   1 ′,  142   2 ′ are bent away from the ground plane (towards the director  2 ). 
     Different arrangements and configurations of the conductive elements  42   1 ,  42   2 ,  142   1 ,  142   2 ,  42   1 ′,  42   2 ′,  142   1 ′,  142   2 ′ can be used to provide asymmetry. For example, some of the conductive elements  42   1 ,  142   1 ,  42   1 ′,  42   2 ′,  142   1 ′,  142   2 ′ can have different lengths. 
       FIG. 17A, 17B  show an example of the dual polarized antenna  100 .  FIG. 17A  is a perspective view with a director  2  attached.  FIG. 17B  is a side view. 
     In this example, the dual polarized antenna  100  is asymmetric. The arrangement of conductive elements  42 ,  42 ′,  142 ,  142 ′ when viewed from the side is different than the arrangement of conductive elements  42 ,  42 ′,  142 ,  142 ′ when viewed from the front. 
     In this example, the conductive elements  42   1  and  142   2 ′ have a different configuration than the conductive elements  42   2 , 142   1 ,  142   2 ,  42   1 ′,  42   2 ′,  142   1 ′. 
     In this example, the conductive elements  42   2 , 142   1 ,  142   2 ,  42   1 ′,  42   2 ′,  142   1 ′ are asymmetric and bend towards or away from the ground plane by different amounts. 
     In this example, the conductive elements  42   1  and  142   2 ′ are bent away from the ground plane (towards the director  2 ) and the conductive elements  42   2 ,  142   1 ,  142   2 ,  42   1 ′,  42   2 ′,  142   1 ′ are bent towards the ground plane (away from the director  2 ). 
     Different arrangements and configurations of the conductive elements  42   1 ,  42   2 ,  142   1 ,  142   2 ,  42   1 ′,  42   2 ′,  142   1 ′,  142   2 ′ can be used to provide asymmetry. For example, some of the conductive elements  42   1 ,  142   1 ,  42   1 ′,  42   2 ′,  142   1 ′,  142   2 ′ have different lengths. 
     An asymmetric topology of conductive elements  42   1 ,  142   1 ,  42   1 ′,  42   2 ′,  142   1 ′,  142   2 ′ can, for example be used to maintain antenna properties over the full base station vertical tilt (generally in a 2-12° tilt range). The asymmetry created in the vertical plane generates a natural tilt and avoids pattern discrepancies. Vertical and horizontal asymmetries can be combined depending on the antenna configuration. 
       FIG. 18  illustrates an example of an apparatus  10  comprising an array  200  of dual polarized antennas some or all of which are the new dual polarized antenna  100  which comprises one or more new dipole antennas  20 ,  120 . The dual polarized antennas of the first array  200  are configured to operate at the same first operational frequency band. 
     The apparatus  10  also comprises an array  202  of dual polarized antennas  102 . The dual polarized antennas  102  of the second array  202  are configured to operate at a shared second operational frequency band. 
     The first operational frequency band and the second operational frequency band are different. In at least some examples, the first operational frequency band and the second operational frequency band do not overlap. 
     Although in the example illustrated the first operational frequency band is a lower frequency than the second operational frequency band (first array  200  has a greater pitch between dual polarized antennas than the second array  202 ) in other examples the first operational frequency band can be higher than the second operational frequency band (second array  202  has a greater pitch between dual polarized antennas than the first array  200 ). 
     The apparatus  10  can, for example be a multi-band dual-polarized antenna panel, also called MBPA (Multi Band Panel Antenna). 
     In this example, the first dual polarized antennas  100  of the first array  200  and the second dual polarized antennas  102  of the second array  202  are interleaved. 
     The first array  200  and the second array  202  overlap. The first array  200  occupies a first area in a first plane, and the second array  202  occupies a second area in a second plane, a projection of the first area in a direction orthogonal to the first plane intersect the second area. The first plane and the second plane can be parallel. The first plane and the second plane can, in some but not necessarily all examples, be co-planar. 
     For some particular cases—for example, when the ratio of pitch between dual polarized antennas in the respective arrays  200 ,  202  cannot be reduced by an even factor, it may be desirable to use a combination of regular-cross dual polarized antennas ( FIG. 3 ) and splayed-cross dual polarized antennas ( FIG. 4 ).  FIGS. 19A and 19B  illustrate some examples. 
       FIG. 20A, 20B  show an example of the splayed-cross dual polarized antenna  100 .  FIG. 20A  is a perspective view with a director  2  attached.  FIG. 20B  is a top view. The splayed-cross dual polarized antenna  100  has previously been described with reference to  FIG. 3 . 
     The arrays  200 ,  202  can for example be phased arrays. 
     The arrays  200 ,  202  can for example be configured for multiple-input multiple-output (MIMO) operation. 
     The illustrated arrays  200 ,  202  can for example be configured to operate with the same orthogonal dual polarizations P 1 , P 2 . 
       FIG. 22  illustrates an example of a network access node  300  such as a base station or base station system that comprises the apparatus  10 . 
     Where a structural feature has been described, it may be replaced by means for performing one or more of the functions of the structural feature whether that function or those functions are explicitly or implicitly described. 
     An operational frequency (operational bandwidth) is a frequency range over which an antenna can efficiently operate. An operational resonant frequency (operational bandwidth) may be defined as where the return loss S 11  of the dipole antenna  20  is greater than an operational threshold T and where the radiated efficiency is greater than an operational threshold. 
     The above described examples find application as enabling components of: automotive systems; telecommunication systems; electronic systems including consumer electronic products; distributed computing systems; media systems for generating or rendering media content including audio, visual and audio visual content and mixed, mediated, virtual and/or augmented reality; personal systems including personal health systems or personal fitness systems; navigation systems; user interfaces also known as human machine interfaces; networks including cellular, non-cellular, and optical networks; ad-hoc networks; the internet; the internet of things; virtualized networks; and related software and services. 
     The term ‘comprise’ is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising Y indicates that X may comprise only one Y or may comprise more than one Y. If it is intended to use ‘comprise’ with an exclusive meaning then it will be made clear in the context by referring to “comprising only one . . . ” or by using “consisting”. 
     In this description, reference has been made to various examples. The description of features or functions in relation to an example indicates that those features or functions are present in that example. The use of the term ‘example’ or ‘for example’ or ‘can’ or ‘may’ in the text denotes, whether explicitly stated or not, that such features or functions are present in at least the described example, whether described as an example or not, and that they can be, but are not necessarily, present in some of or all other examples. Thus ‘example’, ‘for example’, ‘can’ or ‘may’ refers to a particular instance in a class of examples. A property of the instance can be a property of only that instance or a property of the class or a property of a sub-class of the class that includes some but not all of the instances in the class. It is therefore implicitly disclosed that a feature described with reference to one example but not with reference to another example, can where possible be used in that other example as part of a working combination but does not necessarily have to be used in that other example. 
     Although examples have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the claims. 
     Features described in the preceding description may be used in combinations other than the combinations explicitly described above. 
     Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not. 
     Although features have been described with reference to certain examples, those features may also be present in other examples whether described or not. 
     The term ‘a’ or ‘the’ is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising a/the Y indicates that X may comprise only one Y or may comprise more than one Y unless the context clearly indicates the contrary. If it is intended to use ‘a’ or ‘the’ with an exclusive meaning then it will be made clear in the context. In some circumstances the use of ‘at least one’ or ‘one or more’ may be used to emphasis an inclusive meaning but the absence of these terms should not be taken to infer any exclusive meaning. 
     The presence of a feature (or combination of features) in a claim is a reference to that feature or (combination of features) itself and also to features that achieve substantially the same technical effect (equivalent features). The equivalent features include, for example, features that are variants and achieve substantially the same result in substantially the same way. The equivalent features include, for example, features that perform substantially the same function, in substantially the same way to achieve substantially the same result. 
     In this description, reference has been made to various examples using adjectives or adjectival phrases to describe characteristics of the examples. Such a description of a characteristic in relation to an example indicates that the characteristic is present in some examples exactly as described and is present in other examples substantially as described. 
     Whilst endeavoring in the foregoing specification to draw attention to those features believed to be of importance it should be understood that the Applicant may seek protection via the claims in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not emphasis has been placed thereon.