fig1 is a diagrammatic sectional view of a reflector according to the invention . as is shown , it is composed essentially of three concentric layers 2 , 3 , 4 of dielectric of suitable index around a spherical core 1 . the number of successive layers used depends upon the performances of the reflector and upon the nature of the dielectric . in accordance with the invention , there is disposed between the two outer layers 3 and 4 grating of parallel wires 5 ( perpendicular to the sectional plane ) and , outside the last layer , a second grating of parallel wires 6 orthogonal to the preceding ones ( one of which is in the sectional plane ). the thickness of the layer 4 is equal to λ / 4 , where λ is the wavelength in the material of which it consists . a radome 7 is usually disposed around the reflector to protect it mechanically . the angles at the center subtended by the gratings 5 and 6 are equal . the reflector operates as follows ( cf . fig2 ): a circularly polarized incident wave consists of two rectilinearly polarized waves whose respective electric fields are parallel to the wires of the grating 5 ( shown at ab ) and those of the grating 6 ( shown at cd ). the component ab is entirely reflected by the wires 5 . the component cd is integrally transmitted by the wires 5 and reflected by the grating 6 . the wave reflected by 6 passes without attenuation through the grating of wires 5 and combines with the wave reflected by the latter . at the front of the reflector the two orthogonal rectilinearly polarized waves reconstitute a circularly polarized reflected wave . owing to the additional path of one of the components of λ / 2 ( forward and return travel through the layer 4 ), the direction of rotation of the circularly polarized wave is reversed and , taking into account the conventions referred to in the foregoing , the reflected wave will be transmitted through the transmitting polarizer and the wave guide of the source of the transmitted waves towards the associated receiver . in the case where the source is a radar transmitter , the reflected wave is therefore given a direction of rotation which permits its reception by the associated receiver . the additional attenuation due to the travel through the layer 4 is negligible and the reflection introduces substantially no ellipticity , as has been confirmed by experiment . in order that the reflection may be effected in the form of a circularly polarized wave with a maximum angular aperture , it is important that the following conditions should be satisfied : ( 3 ) the distance between two conductors 5 remains small as compared with the wavelength ( of the order of 1 to 2 tenths of the latter ). in order that the second reflection may be ensured , the wires 6 must be perpendicular to the wires 5 . in practice , the reflection of the first component may be regarded as total if the conditions relative to the first reflection are satisfied . under these conditions , the wires 6 are advantageously replaced by a continuous metallization on the inside face of the radome 7 which obviously results in a simplification of the production process . the grating 5 as shown in fig5 is produced by weaving metal wires on a warp of textile fibers 8 and applying the woven fabric to the layer 3 in accordance with the dome of desired angle . the woven fabric is adhesively secured to its periphery to the dielectric shell 3 . this solution makes it possible to spare any machining step of the shells once manufactured . the conditions which must be satisfied by the conductors 5 involve proper selection of the weaving operation parameters as follows : the nature of the textile fiber is chosen as a function of the elasticity of the conductor wire so as to avoid any permanent deformation of the latter due to weaving : the cohesion of the woven fabric is ensured by interposing texile filaments between the conductor wires ; the positioning of the piece of woven fabric on the sphere must be such as to ensure parallelism of the conductors and the woven fabric must follow the shape of the sphere 3 . with regard to the nature of the textile fibres , it only has a mechanical function for avoiding deformation of the metal wire . good results have been obtained at 15 . 5 ghz by using an enamelled brass wire of a diameter of 0 . 25 mm woven on a flax warp with a pitch of 2 . 7 millimeters , two flax filaments being disposed between each pair of conductor wires to ensure cohesion of the fabric . the diameters of the textile filaments and the conductor wires are approximately the same . the diagrams of fig3 and 4 corresponds to this embodiment . a fabric comprising a completely metallic weft has too much rigidity to adapt itself to the shape of the sphere on which the fabric must rest when applied by permanent deformation . experiments have shown that cotton is also suitable in the case of enamelled brass . like flax , cotton deforms to constitute the fabric , the conductors remaining rectilinear . on the other hand , tests made with 0 . 15 mm silver - coated copper wire have given poor results , because the conductor wire deforms in the course of the weaving . any deformation of the conductor wire results in a reduction of the gain of the reflector , which cannot be compensated for by an increase in the conductivity of the wire . the above values are not critical . more particularly , a fabric comprising a flax warp and a weft consisting of alternate flax and enamel - coated copper wires of 0 . 25 mm has given good results . the pitch of the conductors in this case is 2mm . the minimum value of the pitch is fixed by the mechanical properties of the woven fabric . with regard to the diameter of the conductors , the minimum value is fixed by the condition of non - deformation of the conductor by weaving . the maximum value of the diameter is fixed by the electrical performances of the reflector . at excessively high values , the gain decreases . the thickness of the layer 4 is not a very critical parameter . it is about one - quarter of the wavelength . the important condition to be met is the electrical distance between the two metallizations . experiments have shown that the grating of wires 5 behaves as an impedance difference from that of the dielectric propagation medium and that the distance between the two layers must be less than one - quarter the wave - length in order to compensate for the impedance discontinuity due to the wires . for example , at 15 . 5 ghz , the optimum distance between the two reflecting surfaces has been found to be 4 . 5 millimeters when the permittivity of the intermediate medium is between 1 . 10 and 1 . 20 . experiments have shown that a distance of 4 millimeters gives equivalent performances , but a reduction to 3 millimeters is sufficient to bring about a reduction of the gain . likewise , an increase in this distance also decreases the gain , but more slowly . a distance of 6 millimeters makes the reflector almost useless . a compromise may be obtained between the distance of the two surfaces and the permittivity of the intermediate medium . the latter does not affect the position of the focus of the reflector . an important factor in the good operation of the reflector is the adhesion of the fabric to the spherical surface 3 . poor adhesion results in the interposition of a wedge of air , which is cause of rapid gain loss . the focus of the lens is slightly displaced by the presence of the grating of wires 5 and a displacement of the focus , moving it away from the center of the sphere is noted . this displacement may be compensated for by an increase of the permittivity of at least a part of the layer 3 supporting the grating 5 in relation to the value expected in the absence of the grating of wires . by way of example , a reflector operating in the ku band has been produced giving the pattern of fig4 using a layer having a permittivity of 1 . 2 ε 4 supporting the grating 5 and the metallisation 6 applied to the internal face of the radome . in the absence of 5 , the layers 3 and 4 are unique and have a permittivity ε 4 this corresponds to 1 . 2 times the value given by luneberg &# 39 ; s law . in the construction corresponding to the diagrams of fig3 and 4 , ε 4 = 1 . 13 . the dome angle in the embodiment corresponding to fig3 is 50 °. it is 120 ° in the embodiment corresponding to fig4 . all the other parameters are identical . it can be seen in the diagrams that the equivalent surface is slightly higher for the smaller aperture reflector ( fig3 ). this characteristic is well known from the man of art . the two above examples are not to be considered as limitative . some designs have been made with an angular aperture of 140 °. in the foregoing , it has been assumed that the reflector is of the monostatic type , that is to say that the focus is on the second reflecting surface . it is to be understood that the invention makes it possible to produce bistatic reflectors by an appropriate choice of the indices of the layers . likewise , the reflecting dome at 5 and 6 may be replaced by a belt , as described in the aforesaid u . s . pat . no . 2 , 989 , 746 when the corresponding pattern is suitable for the user . fig3 illustrates the characteristic of such a reflector in relation to an incident wave rectilinearly polarized in parallel relationship to the wires 5 extending in two orthogonal directions ( curves a and b ) and at 45 ° in relation to the electric field ( curve c ). the ordinates are proportional to the equivalent surface or to the gain of the reflector and the abscissae to the aperture . this reflector has an aperture of about 50 ° and a maximum equivalent surface of 10 . 5 m 2 . fig4 illustrates , in polar coordinates , the equivalent surface of a ( 120 ° aperture ) reflector with an equivalent surface over 7 . 5 m 2 . each radial line in the figure is 30 ° away the adjacent lines . the design of such a reflector has been already described . fig6 merely shows the positioning of the reflector of the present invention so as to receive a circularly polarized incident wave emitted by a transmitter , such as a radar transmitter , and the reflected wave is received by an associated receiver as is well known to those skilled in this art .