Contrawound helical antenna apparatus and method
Example apparatuses and methods relating to antennas are provided. An example apparatus in the form of an antenna assembly includes a first conductor formed into a first helical structure wound around a central axis and a second conductor formed into a second helical structure wound around the central axis. The first helical structure may have a first coil sense and the second helical structure may have second coil sense that is opposite the first coil sense. The first conductor may have a first conductor proximal end and a first conductor distal end and the second conductor may have a second conductor proximal end and a second conductor distal end. The first conductor distal end may be adjacent the second conductor proximal end. The antenna assembly may further include first, second, and third ground planes with one disposed at each end of the conductors and one disposed between the conductors.
1. An antenna assembly comprising:
a first conductor formed into a first helical structure wound around a central axis, the first helical structure having a first coil sense, the first conductor having a first conductor proximal end and a first conductor distal end;
a second conductor formed into a second helical structure wound around the central axis, the second helical structure having a second coil sense, the second conductor having a second conductor proximal end and a second conductor distal end, wherein the first conductor distal end is adjacent the second conductor proximal end, wherein the first coil sense is opposite the second coil sense;
a first ground plane disposed adjacent to the first conductor proximal end;
a second ground plane disposed adjacent to the first conductor distal end and adjacent to the second conductor proximal end; and
a third ground plane disposed adjacent the second conductor distal end.
2. The antenna assembly of claim 1 , wherein the first helical structure has a first diameter and the second helical structure has a second diameter; and
wherein a length of the first diameter is substantially the same as a length of the second diameter.
3. The antenna assembly of claim 2 , wherein the length of the first diameter is non-constant.
4. The antenna assembly of claim 1 , wherein the first helical structure has a two-dimension cross-sectional area on a plane orthogonal to the central axis and the second helical structure has a two-dimension cross-sectional area on a plane orthogonal to the central axis;
wherein the two-dimension cross-sectional area of the first helical structure is substantially the same as the two-dimension cross-sectional area of the second helical structure.
5. The antenna assembly of claim 4 , wherein an area of the first ground plane is substantially the same or smaller than the two-dimension cross-sectional area of the first helical structure;
wherein an area of the second ground plane is substantially the same or smaller than the two-dimension cross-sectional area of the first helical structure; and
wherein an area of the third ground plane is substantially the same or smaller than the two-dimension cross-sectional area of the first helical structure.
6. The antenna assembly of claim 1 , wherein the first conductor and the second conductor operate in an axial mode in conjunction with the first, second, and third ground planes.
7. The antenna assembly of claim 1 , further comprising a switching network configured to receive control signals to activate or deactivate the first ground plane, second ground plane, or third ground plane; and wherein the switching network is configured to receive a feed signal and provide the feed signal to one or more of the first conductor proximal end, the first conductor distal end, the second conductor proximal end, or the second conductor distal end.
8. The antenna assembly of claim 7 , further comprising a core, the first helical structure and the second helical structure being wound around the core, the core comprising a metallic material; and wherein the switching network is housed in the core.
9. The antenna assembly of claim 7 , wherein the switching network is further configured to control a direction and polarization of an antenna beam of the antenna assembly based upon which of the first, second, or third ground planes are activated and which of the ends of the conductors are provided the feed signal.