Passive wide-band low-elevation nulling antenna

A portable antenna comprising:

• an antenna housing comprising
• a reflector plate forming the base of the antenna housing, the reflector plate having a first side,
• one or more side walls coupled to the first side, and
• a radiating element housing support structure formed within the interior of at least one of the one or more side walls, the radiating element housing support structure positioned at height h from the reflector plate, wherein height h is about one-fourth the wavelength of the operating frequency of the antenna;
• and
• a radiating element contained within a radiating element housing comprised of a dielectric material, the radiating element housing positioned at least partially within the antenna housing and supported by the radiating element housing support structure, the radiating element housing removable from the antenna housing to allow a user to reorient the radiating element housing with respect to the antenna housing, the radiating element positioned substantially parallel to the reflector plate, the radiating element comprising
• a dielectric planar substrate having a first surface and a second surface,
• at least two conductive spiral arms extending outward from and spiraling about an axis of rotation formed on the first surface, and
• a feed conductor formed on the second surface, the feed conductor substantially aligned with one of the conductive spiral arms
• wherein the portable antenna produces an omni-directional antenna pattern in azimuth and a broad antenna pattern in elevation, the omni-directional antenna pattern and the broad antenna pattern both having a null near the horizon.

A portable antenna comprising:

• an antenna housing comprising
• a base having a first side comprised of a reflective material,
• one or more side walls coupled to the first side, and
• a radiating element housing support structure formed within the interior of at least one of the one or more side walls, the radiating element housing support structure positioned at height h from the base, wherein height h is about one-fourth the wavelength of the operating frequency of the antenna;
• and
• a radiating element contained within a radiating element housing comprised of a dielectric material, the radiating element housing positioned at least partially within the antenna housing and supported by the radiating element housing support structure, the radiating element housing removable from the antenna housing to allow a user to readily reorient the radiating element housing with respect to the antenna housing, the radiating element positioned substantially parallel to the base, the radiating element comprising
• a planar substrate comprised of a dielectric material,
• at least two conductive spiral arms formed within the planar substrate, and
• a feed conductor formed within the planar substrate, the feed conductor having an innermost end and an outermost end, wherein the impedance of the feed conductor is greater at the innermost end than at the outermost end.