Patent Number: 
Section: claims

1. An antenna system, comprising a first end-fire antenna element and a second end-fire antenna element facing each other in a planar arrangement, said antenna elements having a thickness which is larger than a skin depth of a material forming said antenna elements, said antenna elements being positioned to form one or more air gaps therebetween, and being configured to cause destructive interference between individual end-fire radiations of said elements, while maintaining constructive interference generally perpendicular to said planar arrangement. 2. The system of claim 1, wherein said first end-fire antenna element is identical to said second end-fire antenna. 3. The system according to claim 1, wherein each of said antenna elements is a slot antenna element having a tapered profile. 4. The system according to claim 3, wherein said tapered profile is characterized by an opening rate selected such that a ratio between an imaginary part and a real part of an impedance of said antenna system is less than 50%. 5. The system according to claim 4, wherein said opening rate is from about 0.0001 to about 0.01 nm−1. 6. The system according to claim 3, wherein each slot has a stub and an aperture and is symmetric with respect to a meridian line connecting said stub and aperture, perpendicularly to said aperture. 7. The system according to claim 3, wherein each slot has a stub and an aperture and is asymmetric with respect to a meridian line connecting said stub and aperture, perpendicularly to said aperture. 8. The system according to claim 1, wherein each of said antenna elements is a Vivaldi antenna element. 9. The system according to claim 1, wherein a thickness of said antenna elements is at least 2 times said skin depth. 10. The system according to claim 1, wherein a width of said gap is selected so as to allow emission of radiation in a transverse optical mode while suppressing higher optical modes. 11. The system according to claim 1, wherein a width of said gap is at least 10 nm. 12. The system according to claim 1, further comprising a waveguide coupled to said gap. 13. The system according to claim 12, wherein said waveguide is a parallel plate waveguide. 14. The system according to claim 1, wherein at least one of said first and said second end-fire antenna elements has a nanometric size along at least one dimension of said element. 15. The system according to claim 1, wherein at least one of said first and said second end-fire antenna elements has a nanometric size along a largest dimension of said element. 16. An antenna array, comprising a plurality of antenna systems according to claim 1. 17. The array according to claim 16, wherein at least a portion of said antenna systems are connected in series with respect to a characteristic direction of said end-fire radiations. 18. The array according to claim 16, wherein at least a portion of said antenna systems are connected in parallel with respect to a characteristic direction of said end-fire radiations. 19. The array according to claim 16, wherein said antenna systems are connected via DC connection. 20. A method of detecting electromagnetic radiation, comprising generating condition for the radiation to interact with the antenna system or array according to claim 1, and collecting electrical signals generated by said antenna system. 21. The method according to claim 20, wherein said electromagnetic radiation comprises radiation in the infrared range. 22. The method according to claim 20, wherein said electromagnetic radiation comprises radiation in the visible range. 23. A method of emitting electromagnetic radiation, comprising applying voltage to the antenna system or array according to claim 1, thereby generating the electromagnetic radiation. 24. A method of converting electromagnetic radiation into electricity, comprising generating condition for the radiation to interact with the antenna system or array according to claim 1, and collecting electrical signals generated by said antenna system. 25. A system, comprising the antenna system or array according to claim 1, wherein the system is selected from the group consisting of an optical sensor system, optical communication system, an imaging system, a light projector, a high harmonics generating system, a wave mixing system, a frequency conversion system, and a phased array. 26. The method according to claim 1, wherein said antenna elements comprise metal.