Abstract: A planar spiral antenna is fed from the outer end, and one embodiment includes a capacitive plate adjacent the interior end. Two such planar spiral antennas are arrayed over a ground plane by the use of a phase shifter which provides a 90.degree. phase difference between the two elements of the array. In this array, the rotational positions of the arrays differ by 90.degree.. Two such two-spiral arrays are arrayed together, with elements of like phase delay diametrically opposite to each other in the overall array. This overall array has two feed ports, which are fed in parallel.

Abstract: A wideband lens antenna lens of reduced thickness includes a lens antenna constructed of a flat inhomogeneous dielectric plate. A radiation source is located on one side of the dielectric plate and a reflector is located on another side of the dielectric plate opposite the radiation source. In operation, signals generated by the radiation source of arbitrary polarization pass through the dielectric plate, are reflected by the reflector, and pass back through the dielectric plate a second time before being emitted from the lens antenna. In such a case, the provision of the reflector allows the thickness of the dielectric plate to be cut in half as compared with conventional lens antennas. If the signals supplied by the radiation source are linearly polarized, a polarization transformer is provided on the same surface of the dielectric plate as the radiation source.