Reivindicaciones
1. A planar reflector in printed circuit technology characterized by reflecting the electromagnetic energy coming from a feed located at a focal point forming a collimated beam in a given direction at a given frequency, or reflecting a collimated beam coming from a given direction at a given frequency by concentrating it at the focal point where the feed is located, and characterised by having at least two layers of conductive patch arrays, that consists of: a conductive plane, a sheet of dielectric material called separator, a thin film of dielectric material that supports a planar array of rectangular conductive patches, a new separator layer and a new layer of conductive patches on a dielectric support; in which the dimensions of the conductive patches in each layer are adjusted individually to achieve a phase shift in the reflected field to collimate the electromagnetic field coming from the feed or to concentrate the collimated beam incident onto the reflector at the feed. 2. Planar reflector according to claim 1, wherein the conductive patches are deposited directly onto the dielectric separator. 3. Planar reflector according to claim 1, characterised by having more than two layers of dielectric material between the conductor plane and the conductive patches, or between the planar arrays of patches. 4. Planar reflector according to claim 1 and claims 2 to 3 or anyone of them, built in materials qualified for space applications. 5. Planar reflector according to claim 1 and claims 2 to 4 or anyone of them, characterised by having more than two layers of conductive patch arrays and stacked dielectric sheets. 6. Planar reflector as in claims 1 and claims 2 to 5 or anyone of them, wherein the conductive patches in any layer are square or in the shape of a cross, instead of rectangular. 7. Planar reflector according to claim 1 and claims 2 to 6 or anyone of them, wherein the patch array in each layer is manufactured by means of selective elimination of conductive material from a dielectric sheet covered by a conductive film, by means of photo-etching and chemical etching techniques, or by selective elimination of the conductive material by laser, or cutting the conductive patches by using a cutting plotter and removing the conductive material between the patches. 8. Planar reflector according to claim 1 and claims 2 to 7 or anyone of them, characterised by being built in several pieces to be folded and deployed. 9. Planar reflector according to claim 1 and claims 2 to 7 or anyone of them, characterised by being built in flexible materials to be fitted to curved surfaces. 10. Method for design characterized by obtaining the photo-etching masks for the construction of a planar reflector made up of several layers of planar arrays of conductive patches separated by dielectric sheets on a conductor plane, and that consists of the following steps: 1) defining the phase of the reflection coefficient for each element so that the electromagnetic energy of a certain frequency coming from a feed located at a focal point is reflected forming a collimated beam in a certain direction, where each element is made up of two or more stacked conductive patches above a conductor plane separated from each other and from the conductor plane by dielectric sheets; 2) determination of the patch dimensions so that the phase of the reflection coefficient in each element defined in the previous stage is achieved, by using an iterative routine for zero searching that adjusts the patch dimensions and computes the reflection coefficient by an analysis method of multilayer periodic structures, based on the Moments Method, until required phase is achieved; 3) fine adjustment of the conductive patch dimensions in each element of the multilayer reflector, by means of an optimisation routine, to achieve the phase defined in stage 1) for an incident field with any polarisation type for one or several frequencies within the working band of the reflector. 11. Method for design according to claim 10, wherein the adjustment of the dimensions of the conductive patches in each element in stages 2) and 3) is carried out simultaneously for two independent orthogonal polarisations of the incident field. 12. Method for design according to claims 10 and 11, wherein the phase of the reflection coefficient is defined in stage 1) for two independent feeds, one for each of the two orthogonal polarisations, located at different focal points. 13. Method for design according to claim 10 and claims 11 to 12 or anyone of them, wherein the phase of the reflection coefficient is defined in stage 1) so that the field coming from the feed or feeds is reflected forming two collimated beams, one for each polarisation of the incident field, in different directions. 14. Method for design according to claim 10, wherein the phase of the reflection coefficient is defined in stage 1) so that the field coming from the feed is reflected forming a collimated beam with a different polarisation than that of the incident field. 15. Method for design according to claim 10 and claims 11, 12 and 14 or anyone of them, wherein the phase of the reflection coefficient is defined in stage 1) so that the field coming from the feed or feeds is reflected forming a conformal beam, instead of a collimated beam. 16. Method for design according to claim 10 or claims 10 and 11, wherein the phase of the reflection coefficient is defined in stage 1) so that the field coming from the feed is reflected forming several collimated beams in different directions. 17. Planar reflector according to claims 1 to 6 and 10 to 11 or anyone of them, wherein the phase of the reflection coefficient is defined, and the dimensions of the patches are adjusted in each element to collimate the beam coming from the feed, or to concentrate the collimated beam incident on the reflector at the focal point where the feed is located, with the same characteristics as those of a parabolic reflector. 18. Planar reflector according to claims 1 to 6 and 10 to 11 or anyone of them, wherein the dimensions of the conductive patches in each layer are adjusted to collimate the beam coming from the feed, or to concentrate the collimated beam incident on the reflector at the focal point where the feed is located, for two polarisations of the electromagnetic field simultaneously. 19. Planar reflector according to claims 1 to 6 or anyone of them, characterised as having two feeds located at two different focal points that works in orthogonal polarisations, which is designed according to claims 10 to 12 so that, the beams coming from the two feeds are reflected forming collimated beams in the same predetermined direction. 20. Planar reflector according to claims 1 to 6 and 10 to 13 or anyone of them with one or two feeds working in two orthogonal polarisations, characterised by generating or receiving two collimated beams, one for each polarisation of the incident field, in different directions. 21. Planar reflector according to claims 1 to 6 or anyone of them, and claims 10 and 14, wherein the dimensions of the conductive patches are adjusted in each layer to get a collimated reflected beam with circular polarisation when a linear polarised field coming from the feed is incident, or to concentrate at the focal point of the feed a linear polarised field when a collimated field with circular polarisation impinges on the reflector. 22. Planar reflector according to claims 1 to 6, 18, 19 and 21 or anyone of them, wherein the dimensions of the conductive patches in each element are adjusted to achieve the electric characteristics of a conformal beam reflector. 23. Multilayer Reflector according to claims 1 to 6, 18, 19, 21 and 22 or anyone of them, characterised by being parabolic in shape, instead of planar, with the feed or feeds near the focus of the paraboloid, wherein the dimensions of the conductive patches in each element are adjusted to achieve the electric characteristics of a conformal beam reflector, for single or dual polarisation. 24. Planar reflector according to claims 1 to 6 or anyone of them and claims 10 and 16, with a feed working in simple or dual polarisation, characterised by generating several collimated beams in different directions, or receiving electromagnetic signals from different directions and concentrating them at the focal point where the feed is located. 25. Planar reflector according to claims 1 to 23 or anyone of them wherein the dimensions of the patches are adjusted in each element to achieve a collimation, redirection, shaped or change of polarisation of the beam at several frequencies within the working band of the reflector. Amended claims under Art. 19.1 PCT 26. A planar reflector in printed circuit technology that reflects the electromagnetic energy coming from a feed (110) located at a focal point, forming a collimated beam in a given direction at a given frequency, or that receives a collimated beam from a given direction at a given frequency and reflects it by concentrating it at the focal point where the feed is located, characterised by having at least two layers of conductive patch arrays with which a smaller sensibility to the manufacturing tolerances and a larger bandwidth are obtained, that consists of: a conductive plane (440), a sheet of dielectric material called a separator (430), a thin film of dielectric material (460) that supports a planar array of rectangular conductive patches (410), a new separator layer (420) and a new layer of conductive patches (400) on a dielectric support (450); in which the dimensions of the conductive patches in each layer are adjusted individually to achieve a phase shift in the reflected field to collimate the electromagnetic field coming from the feed or to concentrate the collimated beam incident onto the reflector at the feed. 27. Planar reflector according to claim 1, wherein the conductive patches are deposited directly onto the dielectric separator. 28. Planar reflector according to claim 1, characterised by having more than two layers of dielectric material between the conductor plane (440) and the conductive patches (410), or between the planar arrays of patches (400 and 410). 29. Planar reflector according to claims 1, 2 or 3, built in materials qualified for space applications. 30. Planar reflector according to claims 1, 2, 3 or 4, characterised by having more than two layers of conductive patch arrays and stacked dielectric sheets. 31. Planar reflector as in claims 1, 2, 3, 4 or 5, wherein the conductive patches in any layer are square, rectangular or in the shape of a cross. 32. Planar reflector according to claim 6, wherein the patch array in each layer is manufactured by means of selective elimination of conductive material from a dielectric sheet covered by a conductive film, by means of photo-etching and chemical etching techniques, or by selective elimination of the conductive material by laser, or cutting the conductive patches by using a cutting plotter and removing the conductive material between the patches. 33. Planar reflector according to claim 6 or 7, characterised by being built in several pieces to be folded and deployed. 34. Planar reflector according to claim 6 or 7, characterised by being built in flexible materials to be fitted to curved surfaces. 35. Method for design to obtain the photo-etching masks for the construction of a planar reflector made up of several layers of planar arrays of conductive patches separated by dielectric sheets above a
