Patch antenna

An antenna for radiating at a plurality of frequencies including a ground plane (1) serving as a reflector against which a patch (2) is electrically driven. A further patch (3) is stacked above the first patch (2) and is intended to resonate at a frequency in the upper frequency band and utilises the first patch (2) as its ground plane. The lower patch (2) is driven from voltage sources (4a, 4b, 5a and 5b) established on the ground plane (1) and connected to the patch (2) by means of probe wires (10a-d) and series capacitors (8a-d) formed within the patch. Similarly, the upper patch (3) is driven by voltage sources (6a, 6b, 7a, 7b) established in the lower frequency patch and connected by respective wire probes (11a-d) and series capacitors (9a-d) within the upper frequency patch. Respective lines joining the pairs of points are orthogonal.