Flat lens antenna
Various examples are provided for flat lens antennas and their operation. In one example, among others, an antenna includes electrically thin (W<<λhigh), highly conducting, TEM mode antenna arms fed at a first end by a balun. The TEM mode antenna arms can be embedded in a spatially varied anisotropic dielectric material. A separation between the TEM mode antenna arms can increase from the first end to a second end where the TEM mode antenna arms transition to resistive card (Rcard) terminations when the TEM mode antenna arms are separated by a distance Hr, where a ratio of Hr to a height (H) of the antenna is in a range from about 0.2 to about 0.8.
1. An antenna, comprising:
electrically thin (W<<λ high ), highly conducting, TEM mode antenna arms fed at a first end by a balun, where the TEM mode antenna arms are embedded in a spatially varied anisotropic dielectric material, and a separation between the TEM mode antenna arms increases from the first end to a second end where the TEM mode antenna arms transition to resistive card (Rcard) terminations when the TEM mode antenna arms are separated by a distance Hr, where a ratio of Hr to a height (H) of the antenna is in a range from about 0.2 to about 0.8.
2. The antenna of claim 1 , wherein the balun is a chip balun.
3. The antenna of claim 1 , wherein the balun is a geometric balun.
4. The antenna of claim 1 , wherein the balun is an infinite balun.
5. The antenna of claim 1 , wherein the spatially varied anisotropic dielectric material comprises an antenna throat region, an antenna transition region, an antenna lens region, an antenna back region and a balun region.
6. The antenna of claim 5 , wherein the balun region comprises a printed circuit board.
7. The antenna of claim 5 , wherein the antenna throat region comprises a machined unfilled polymer.
8. The antenna of claim 1 , wherein the spatially varied anisotropic dielectric material inside the TEM mode antenna arms forms an elliptical lens profile.
9. The antenna of claim 1 , wherein the spatially varied anisotropic dielectric material inside the TEM mode antenna arms forms a parabolic lens profile.
10. The antenna of claim 1 , wherein the spatially varied anisotropic dielectric material inside the TEM mode antenna arms forms a hyperbolic lens profile.
11. The antenna of claim 1 , wherein the spatially varied anisotropic dielectric material inside the TEM mode antenna arms forms a graded dielectric lens.
12. The antenna of claim 1 , wherein the TEM mode antenna arms are terminated in a resistive card.
13. The antenna of claim 1 , wherein a loss of the antenna back region is realized with a single resistive card.
14. The antenna of claim 1 , wherein the spatially varied anisotropic dielectric material is formed using a lattice of conducting sticks in a low-density foam host.
15. The antenna of claim 14 , wherein the lattice of conducting sticks in the low-density foam host is manufactured by milling one side of foam crackers and 3D printing a carbon fiber filament on the other side, the foam crackers coupled together by a snap fit connection.
16. The antenna of claim 1 , wherein the ratio of Hr/H is in a range from about 0.4 to about 0.6.
17. The antenna of claim 1 , wherein the spatially varied anisotropic dielectric material inside the TEM mode antenna arms is concentrated near an axis of the antenna and a remaining width is formed of low dielectric material.
18. The antenna of claim 1 , wherein a separation between the TEM mode antenna arms follows an exponential function.
19. The antenna of claim 1 , wherein an impedance of the TEM mode antenna arms follows an exponential function.
20. The antenna of claim 1 , wherein the TEM mode antenna arms comprise a transition at an end, wherein the transition exponentially varies to flat at the end.
21. The antenna of claim 1 , wherein the TEM mode antenna arms terminate into a resistive sheet at an end of the TEM mode antenna arms.
22. The antenna of claim 21 , wherein the resistive sheet is curved to reduce end reflection.
23. The antenna of claim 1 , wherein the spatially varied anisotropic dielectric material outside the TEM mode antenna arms comprises a lattice of lossy dielectric sticks.
24. The antenna of claim 1 , wherein the spatially varied anisotropic dielectric material outside the TEM mode antenna arms comprises an on-axis resistive card.
25. The antenna of claim 1 , wherein an end of the TEM mode antenna arms is tangent matched to a balun at the end of the TEM mode antenna arms.
26. The antenna of claim 1 , wherein the spatially varied anisotropic dielectric material inside the TEM mode antenna comprises a lattice of conductive sticks of different sizes and shapes etched on thin printed circuit boards separated with foam sheets.