Flat antenna for mobile satellite communication

An antenna for providing circular polarization, comprising:

• two identical antennas with antenna connection points (5) and having substantially linear conductor parts (4a, 4b) disposed in orthogonal planes (0), and having impedances (7) connected in series therewith;
• asymmetrizing networks (9) having their inputs connected to said antenna connection points (5);
• matching circuits (17) connected to the outputs of said asymmetrizing networks (9);
• a 90 degree phase-rotation element (18) having its input coupled to at least one of said antenna matching circuits (17);
• and,
• a summation circuit (19) connected to the output of said antenna matching circuits (17).

An antenna for mobile satellite communication and having circular polarization comprising:

• N identical antennas disposed in orthogonal planes (0) having substantially linear conductor parts (4), with vertical conductor parts (4a) at their ends, and respectively disposed in said planes (0), and wherein said planes (0) are respectively spaced apart from one another by an azimuthal angle of 360°/N, and intersect in a rotationally symmetric arrangement around a common vertical symmetry line (8)
• a plurality of N impedances (7) each disposed in series in each of said N antennas;
• a plurality of phase-rotation elements (18), whose electrical phase angle corresponds identically to the associated azimuthal angular spacing of the associated planes (0), and connected respectively to said end conductor parts (4a) for collecting the output signals of said N antennas;
• and,
• a summation circuit (19) connected to the output of said phase rotation elements (18) for combining the collected antenna signals.

An antenna for mobile satellite communication disposed on a substantially horizontally oriented conductive base surface (1) for providing circular polarization comprising:

• two identical antennas disposed in intersecting planes with antenna connection points (T1a, T1b and T2a, T2b) at each end, and having substantially linear conductor parts (4a) disposed in orthogonal planes (0) with respect to the base surface (1) and having impedances (7) connected in series therewith;
• a vertical antenna conductor (20) coupled to the intersection and symmetry point (12) of said two antennas and having a central antenna connection point (Tu);
• at least one asymmetrizing network (9) having its inputs connected to the antenna connection points (T1a, T1b and T2a, T2b);
• at least one matching circuit (17) coupled to the output of said at least one asymmetrizing network (9) for producing at its output a symmetrical voltage (Us);
• and,
• a matching network (29) coupled to said central connection point (Tu) for producing at its output an asymmetrical voltage (Uu) so that in the event of a frequency difference of the frequencies of the symmetrical and asymmetrical voltages (Us, Uu), the decoupling between the symmetrical voltage outputs which is limited due to the residual asymmetry of the network is improved by frequency selective adjustment of said matching network (29) and said matching circuit (17).