Abstract: A feed structure for a wearable antenna incorporates a microstrip transmission line designed for mounting on opposite sides of a fabric. The transmission line has a perforated ground plane which reduces capacitance and offers an appropriate impedance, even when the fabric is thin, and allows the use of a relatively robust line conductor having a width of 3 mm or 5 mm or more. The ground plane can be extended to provide the ground plane of a balun and the material of that ground plane can in turn be extended to provide the wearable antenna.

Abstract: A wearable antenna assembly incorporates a coplanar waveguide feed in one of the arms of a two-arm spiral antenna. The antenna has relatively high impedance compared with the feed line from a suitable radio but the coplanar waveguide feed is simply modified to provide a quarter-wave transformer adjacent to the feed connection to the antenna and at least one further impedance transformation step on a tangential extension of the feed at the outer edge of the spiral antenna.

Abstract: A body wearable antenna adapted to be worn against the body, comprising: a first antenna part (4); and a second antenna part (6) insulated from the first part (4); wherein the first antenna part (4) is adapted to be worn circumferentially around a body part (100); and the second antenna part (6) is adapted to be worn longitudinally against a body part (100). The body parts that the first antenna part (4) is adapted to be worn around and that the second antenna part (6) is adapted to be worn against maybe the same. The second antenna part (6) may extend circumferentially around the body part (100) to some extent and may extend along substantially the whole length of the body part (100). The second antenna part (6) may comprise a plurality of radial elements (61, 62, 63) that extend away from the first antenna part (4).

Abstract: Apparatus for providing antenna diversity for a radio transmitter/receiver (TR) comprising measuring means for measuring relative received signal strengths in a plurality of antennas in a selectable frequency range, means for selecting the selectable frequency range according to a transmission frequency of the TR, and connecting means for connecting the antenna having the greatest received signal strength to the TR. The apparatus may be combined with a plurality of antennas to form a diversity antenna system, for example for use with a personal radio. The antennas may then be disposed spaced apart on the user's body e.g. by being incorporated into a garment.

Abstract: A wearable antenna assembly incorporates a coplanar waveguide feed in one of the arms of a two-arm spiral antenna. The antenna has relatively high impedance compared with the feed line from a suitable radio but the coplanar waveguide feed is simply modified to provide a quarter-wave transformer adjacent to the feed connection to the antenna and at least one further impedance transformation step on a tangential extension of the feed at the outer edge of the spiral antenna.

Abstract: A feed structure for a wearable antenna incorporates a microstrip transmission line designed for mounting on opposite sides of a fabric. The transmission line has a perforated ground plane which reduces capacitance and offers an appropriate impedance, even when the fabric is thin, and allows the use of a relatively robust line conductor having a width of 3 mm or 5 mm or more. The ground plane can be extended to provide the ground plane of a balun and the material of that ground plane can in turn be extended to provide the wearable antenna.

Abstract: A structure and a method for modifying an existing design of structure are provided, wherein the structure is provided to at least partially enclose an object that has a large radar cross section. The structure comprises a non-metallic portion having a radar-reflective layer applied to an inclined surface of the structure. The inclined surface is arranged with one or more angles of inclination selected so that the radar cross-section for the structure has a value that is lower than that for the object enclosed in one or more frequency ranges. In a preferred variation, an at least partially detached and appropriately shaped radar-reflective structure may be provided as an alternative to or to supplement the modification of an existing enclosure.

Abstract: Apparatus for providing antenna diversity for a radio transmitter/receiver (TR) comprising measuring means for measuring relative received signal strengths in a plurality of antennas in a selectable frequency range, means for selecting the selectable frequency range according to a transmission frequency of the TR, and connecting means for connecting the antenna having the greatest received signal strength to the TR. The apparatus may be combined with a plurality of antennas to form a diversity antenna system, for example for use with a personal radio. The antennas may then be disposed spaced apart on the user's body e.g. by being incorporated into a garment.

Abstract: A body wearable antenna adapted to be worn against the body, comprising: a first antenna part (4); and a second antenna part (6) insulated from the first part (4); wherein the first antenna part (4) is adapted to be worn circumferentially around a body part (100); and the second antenna part (6) is adapted to be worn longitudinally against a body part (100). The body parts that the first antenna part (4) is adapted to be worn around and that the second antenna part (6) is adapted to be worn against maybe the same. The second antenna part (6) may extend circumferentially around the body part (100) to some extent and may extend along substantially the whole length of the body part (100). The second antenna part (6) may comprise a plurality of radial elements (61, 62, 63) that extend away from the first antenna part (4).

Abstract: An antenna including a number of antenna units, each having a lens and an array of beam ports. The antenna units are arranged in a stack, and are configured to transmit or receive signals from the same field-of-view. Each unit is configured to operate in a different frequency band, with the lenses being configured such that an approximately constant beam shape is maintained across the entire operating bandwidth of the antenna.

Abstract: A structure and a method for modifying an existing design of structure are provided, wherein the structure is provided to at least partially enclose an object that has a large radar cross section. The structure comprises a non-metallic portion having a radar-reflective layer applied to an inclined surface of the structure. The inclined surface is arranged with one or more angles of inclination selected so that the radar cross-section for the structure has a value that is lower than that for the object enclosed in one or more frequency ranges. In a preferred variation, an at least partially detached and appropriately shaped radar-reflective structure may be provided as an alternative to or to supplement the modification of an existing enclosure.

Abstract: A structure, and a method for modifying the design of a structure, are provided such that the structure includes features designed to reduce and preferably minimize the radar cross-section of the structure over one or more predetermined frequency ranges. A structure is provided having an inclined surface, wherein the angle of inclination is selected for which the level of radar cross section is below a local maximum in the sidelobes in each of the scattering patterns of incident electromagnetic radiation at frequencies within one or more predetermined frequency ranges. In the particular case of a tower, for example of a wind turbine, the radar cross-section of the tower may be minimized for two or more radar bands by appropriate selection of the angle of inclination of a frusto-conical portion of the tower. Ideally, the tower is constructed entirely in the form of a cone frustum.

Abstract: An antenna (1) comprises a number of antenna units (10, 20, 30), each comprising a lens (11, 12, 13) and any array (21, 22, 23) of beam ports (32). The antenna units (10, 20, 30) are arranged in a stack, and are configured to transmit or receive signals from the same field-of-view. Each unit 10, 20, 30) is configured to operate in a different frequency band, with the lenses (11, 12, 13) being configured such that an approximately constant beam shape is maintained across the entire operating bandwidth of the antenna (1).

Abstract: An antenna is provided comprising a first group of part-spherical dielectric lenses supported on a first portion of a conducting ground place arranged to reflect signals emerging from the lens, each of the lenses having a number of associated switchably selectable antenna feed elements arranged around the periphery of at least one sector of the lens for injecting signals into and/or receiving signals propagated by the lens, wherein each lens and the associated feed elements of the first group has a different orientation and may be operated to provide coverage in respect of a different region. The antenna also comprises a second group of one or more spherical or part-spherical dielectric lenses and associated switchably selectable antenna feed elements, oriented and operable to provide coverage to a region other than that covered by lenses of the first group.