Low-profile adjustable-band antenna

An antenna, comprising

• a feed element;
• a ground-plane element defining a ground plane;
• an elongated radiator element coupled to the feed element and configured and disposed in relation to the ground plane to define a vertical loop when the ground plane is horizontally disposed, with a substantial broad segment of the radiator element being parallel to the ground plane, with one end of the radiator element being connected to the ground-plane element and with another end of the radiator element being capacitively coupled to the ground-plane element;
• and
• a dielectric spacing element disposed between the other end of the radiator element and the ground-plane element for capacitively coupling the radiator element to the ground-plane element, wherein said capacitive coupling and the dimensions and configuration of the radiator element are such as to enable the radiator element to resonate within a band of frequencies determined by said capacitive coupling within a predetermined range of frequencies primarily determined by said dimensions and configuration;
• and
• a tuning circuit coupled to the radiator element for selectively enabling the antenna to transmit signals at a first frequency within said band or to receive signals at a second frequency within said band.

An antenna, comprising

• a ground-plane element defining a ground plane;
• an elongated radiator element configured and disposed in relation to the ground plane to define a vertical loop when the ground plane is horizontally disposed, with a substantial broad segment of the radiator element being parallel to the ground plane, with one end of the radiator element being connected to the ground-plane element and with another end of the radiator element being capacitively coupled to the ground-plane element;
• and
• a dielectric spacing element disposed between the other end of the radiator element and the ground-plane element for capacitively coupling the radiator element to the ground-plane element;
• wherein the other end of the radiator element is configured to include spaced-apart legs respectively having feet that are coupled to the ground-plane element by portions of the dielectric spacing element;
• wherein said capacitive coupling and the dimensions and configurations of the radiator element are such as to enable the radiator element to resonate within a given band of frequencies.

An antenna, comprising

• a ground-plane element defining a ground plane;
• an elongated radiator element configured and disposed in relation to the ground plane to define a vertical loop when the ground plane is horizontally disposed, with a substantial broad segment of the radiator element being parallel to the ground plane, with one end of the radiator element being connected to the ground-plane element and with another end of the radiator element being capacitively coupled to the ground-plane element;
• and
• a dielectric spacing element disposed between the other end of the radiator element and the ground-plane element for capacitively coupling the radiator element to the ground-plane element;
• wherein the radiator element includes longitudinal folds distending from the sides of the substantial broad segment toward, but not extending to, the ground-plane element.

An antenna, comprising

• a feed element;
• a ground-plane element defining a ground plane;
• an elongated radiator element connected to the feed element configured and disposed in relation to the ground plane to define a vertical loop when the ground plane is horizontally disposed, with a substantial broad segment of the radiator element being parallel to the ground plane, with one end of the radiator element being connected to the ground-plane element and with another end of the radiator element being capacitively coupled to the ground-plane element;
• a dielectric spacing element disposed between the other end of the radiator element and the ground-plane element for capacitively coupling the radiator element to the ground-plane element;
• and
• a braided wire connecting the radiator element to the feed element.