A dual polarization phased array with connected spirals

International audienceA spiral antenna is a broadband element exhibiting circular polarization: right-hand circularly polarized (RHCP) or left hand circularly polarized (LHCP) depending on its winding. An array of spirals with dual polarization must therefore have spirals winding both right and left. A simple configuration alternates every other RHCP element with a LHCP element. In that case, the spacing is such that the frequency at which the grating lobes appear (so the maximum frequency of the array) is lower than the minimum frequency of the spiral (and, so, of the array, with a return loss less than −10dB)