True omni-directional antenna

An antenna structure for use in a wireless appliance, comprising:

• a first antenna for providing a gain with respect to electromagnetic (“EM”) radiation polarized in an XY plane of a Cartesian XYZ frame;
• and
• a second antenna for providing a gain with respect to EM radiation polarized along the Z axis of the Cartesian XYZ frame;
• wherein the first and second antennas share a conductive surface extending in the XY plane, wherein the conductive surface is for providing coupling to EM radiation polarized in the XY plane;
• wherein the second antenna comprises a conductive plate spaced from the conductive surface along the Z axis, the conductive plate having a contact portion connected to the conductive surface;
• wherein:
• in a projection onto the XY plane along the Z axis, the conductive plate lies entirely within the conductive surface;
• the second antenna structure comprises a gap between the conductive surface and the conductive plate, the gap having a width along the Z axis to provide a gain with respect to EM radiation polarized along the Z axis in the gap;
• the second antenna is operable to provide coupling to EM radiation polarized along the Z axis in the gap;
• the antenna structure comprises one or more feed-point elements connected to the conductive plate and to the conductive surface.