Abstract: A quadrifilar antenna having helical windings is fed by a phase shift feed network, each winding having an open circuit termination element, the phase shift feeding network having forward directional phase shift paths from a feed input to phase shift feed output ports, and having a first reverse directional transmission path from one or more of the phase shift feed output ports back to a first isolation port, and a second reverse directional transmission path from another one or more of the phase shift feed output ports back to a second isolation port, the first and second isolation ports isolated from the forward directional phase shift paths, and a differential termination impedance, floating from ground, connected the first and second isolation ports. Optionally, the differential termination impedance is frequency selective.

Abstract: A quadrifilar antenna having helical windings is fed by a phase shift feed network, each winding having an open circuit termination element, the phase shift feeding network having forward directional phase shift paths from a feed input to phase shift feed output ports, and having a first reverse directional transmission path from one or more of the phase shift feed output ports back to a first isolation port, and a second reverse directional transmission path from another one or more of the phase shift feed output ports back to a second isolation port, the first and second isolation ports isolated from the forward directional phase shift paths, and a differential termination impedance, floating from ground, connected the first and second isolation ports. Optionally, the differential termination impedance is frequency selective.

Abstract: Wideband antennas with omnidirectional coverage have both military and commercial applications. In one embodiment, the Planar Inverted Cone Antenna (PICA) is composed of a single flat element vertically mounted above a ground plane. A geometry of Planar Inverted Cone Antenna (PICA) is based on the conventional circular-disc antenna with trimmed top part having the shape of a planar-inverted cone. in a second embodiment, the Fourpoint antenna also provides balanced impedance over the operating band and has useful radiation patterns and dual polarization over its operating frequency.

Abstract: Wideband antennas with omnidirectional coverage have both military and commercial applications. In one embodiment, the Planar Inverted Cone Antenna (PICA) is composed of a single flat element vertically mounted above a ground plane. A geometry of Planar Inverted Cone Antenna (PICA) is based on the conventional circular-disc antenna with trimmed top part having the shape of a planar-inverted cone, in a second embodiment, the Fourpoint antenna also provides balanced impedance over the operating band and has useful radiation patterns and dual polarization over its operating frequency.

Abstract: An improved low profile antenna of the PIPA style is formed from a single piece of useful conductive material and includes a first plate spaced apart from an elongated ground plate. The first and ground plates are interconnected by a shorting plate having a width less than that of either the first ground plate. A feed plate is interposed between the two plates and is either completely covered by the first plate or slightly exposed. Such antennas have extremely large bandwidth of up to about 50%.

Abstract: Wideband antennas with omnidirectional coverage have both military and commercial applications. In one embodiment, the Planar Inverted Cone Antenna (PICA) is composed of a single flat element vertically mounted above a ground plane. A geometry of Planar Inverted Cone Antenna (PICA) is based on the conventional circular-disc antenna with trimmed top part having the shape of a planar-inverted cone. in a second embodiment, the Fourpoint antenna also provides balanced impedance over the operating band and has useful radiation patterns and dual polarization over its operating frequency.

Abstract: A self-resonant quadrifilar helix antenna is formed with four helical electrically conductive elements arranged in each of four quadrants about a common central axis. A coaxial feed extends along the common central axis of the four helical electrically conductive elements. Top ends of first and second ones of the four helical electrically conductive elements are connected to a center conductor of the coaxial feed, and top ends of third and fourth ones of the four helical electrically conductive elements are connected to a shield of the coaxial feed. The bottom ends of each of the four helical electrically conductive elements are electrically connected to the shield of the coaxial feed. This provides a very compact structure in which the coaxial feed serves as a support for the antenna.

Abstract: A ‘four-square element’ phased array antenna structure and associated feed network laminate architecture has a linear physical geometry of multiple trimmed four-square antenna elements disposed on a thin dielectric support layer, which facilitates compactly placing multiple linear arrays in a highly spatially densified side-by-side arrangement. This allows for placement of a greater number of antenna elements in a direction orthogonal to the array than in the longitudinal dimension of the array, so that the frequency of operation of an overall array can be increased relative to that of a conventional four-square architecture, thereby improving bandwidth coverage. For a linearly polarized beam, the trimmed four-square array of the invention enjoys a frequency response that is equal to or better than that of a conventional non-trimmed four-square architecture.

Abstract: A foursquare dual polarized moderately wide bandwidth antenna radiating element is provided which, due to its small size and low frequency response, is well suited to array applications. The foursquare element comprises a printed metalization on a low-loss substrate suspended over a ground plane reflector. Dual linear (i.e., horizontal and vertical), as well as circular and elliptical polarizations of any orientation may be produced with the inventive foursquare element. Further, an array of such elements can be modulated to produce a highly directive beam which can be scanned by adjusting the relative phase of the elements. Operation of the array is enhanced because the individual foursquare elements are small as compared to conventional array element having comparable frequency response. The small size allows for closer spacing of the individual elements which facilitates scanning. Additionally, a family of trimmed foursquare antennas is provided which offer improved performance and size considerations.

Abstract: A helical antenna having stubs spaced along the helix curve length and extending toward the central axis of the helix, such that the performance characteristics of the antenna, such as gain and circular polarization, are maintained while the size of the antenna--diameter and length--are reduced.

Abstract: An antenna for a personal communication device designed for reducing RF emissions to a user's head and body comprises a single half-wave dipole antenna element mounted on the top of a telescoping rod such that the antenna element is raised above the user's head when the rod is extended. The rod is completely inactive and serves only to elevate the active antenna element above the user's head and away from the body. A built-in switch is provided which reduces the transmission RF power when the rod is retracted to further protect the user. In a second embodiment, a co-linear array of dipole antenna elements is used. The full array is active for reception. However, a proximity detector senses the proximity of a human body, and lowers the RF transmission power to those antenna elements in the array that are closest to the user's head.

Abstract: A novel method for calculating the surface shapes for subreflectors in a suboptic assembly of a tri-reflector spherical antenna system is introduced, modeled from a generalization of Galindo-Israel's method of solving partial differential equations to correct for spherical aberration and provide uniform feed to aperture mapping. In a first embodiment, the suboptic assembly moves as a single unit to achieve scan while the main reflector remains stationary. A feed horn is tilted during scan to maintain the illuminated area on the main spherical reflector fixed throughout the scan thereby eliminating the need to oversize the main spherical reflector. In an alternate embodiment, both the main spherical reflector and the suboptic assembly are fixed. A flat mirror is used to create a virtual image of the suboptic assembly. Scan is achieved by rotating the mirror about the spherical center of the main reflector.

Abstract: An improved low profile antenna of the PIPA PIFA style is formed from a single piece of useful conductive material and includes a first plate spaced apart from an elongated ground plate. The first and ground plates are interconnected by a shorting plate having a width less than that of either the first or ground plate. A feed plate is interposed between the two plates and is either completely covered by the first plate or slightly exposed. Such antennas have extremely large bandwidth of up to about 50%.