Abstract: A two-element driven array with improved tuning and matching. First and second elongate conductive elements are provided having respective feed point gaps disposed substantially at their centers, the second elongate element being substantially coplanar and parallel with the first elongate element and spaced a predetermined distance therefrom. A phasing transmission line is connected between the feed point gap of the first elongate element and the feed point gap of the second elongate element so as to reverse the polarity there between. A variable transmission line having a movable shorting member is connected at one end thereof to the second end of the phasing transmission line. The first end of the phasing transmission line is the feed point for the antenna. A combined balun and impedance matching network is providing for coupling the antenna to an unbalanced, coaxial feed line. The combined network includes a shorting stub to adjust the impedance match between the antenna and the feed line.

Abstract: An antenna comprises a dielectric sheet, a pair of conductive feed stems facing one another on opposite sides of the sheet, and a plurality of conductive antenna elements extending away from each feed stem. Each antenna element on one feed stem forms a pair with an antenna element on the other feed stem. In an embodiment, the antenna comprises four pairs of metal feed stems, radiating from a common center. The antenna elements extend alternately to the two sides of each feed stem. Each antenna element forms a dipole with a matching antenna element directly opposite it on the other feed stem of the same pair. Each pair of feed stems and its antenna elements occupies a quadrant of the antenna. The antenna elements do not overlap with other quadrants. Each antenna element zig-zags so that its electrical length is greater than the distance between its ends. Antenna elements on the same side of a pair of stems form zig-zags that are aligned to minimize variations in the spacing between elements.

Abstract: A broadband antenna having closely spaced dipole antenna elements to form a log-periodic array, arranged normal to a signal feed network having a separate feed line for each of the dipole elements. The length of each feed line is selected to compensate for phase delays such that all frequency components of the radiated signal are in phase at a predetermined phase reference point of the antenna.

Abstract: An optical antenna collects, modifies and emits energy at light wavelengths. Linear conductors sized to correspond to the light wavelengths are used. Nonlinear junctions of small dimension are used to rectify an alternating waveform induced upon the conductors by the lightwave electromagnetic energy. The optical antenna and junctions are effective to produce harmonic energy at light wavelengths. The linear conductors may be comprised of carbon nanotubes that are attached to a substrate material, which may then be connected to an electrical port.

Abstract: A broadband antenna incorporating both electric and magnetic dipole radiators includes a tapered feed, such as a bow-tie feed, having a central feedpoint and first and second outer regions displaced from the central feedpoint. One or more conducting loop elements are connected between the outer regions of the tapered feed. Top loading capacitive elements extending from each of the outer regions may also be provided.

Abstract: An antenna system that includes a plurality of mounting plates arranged in a generally circular configuration. Each mounting plate has an inside surface and an outside surface. Each antenna element has a high frequency end and a low frequency end. The low frequency end of each antenna element is mounted to the inside surface of one of the mounting plates such that the high frequency ends of opposed antenna elements face each other. The high frequency ends of opposed antennas are separated by one wavelength of the signal frequency received at the high frequency end. The antenna system also includes a beamforming network having a plurality of input ports equal to the number of antenna elements. Each antenna element is coupled to the beamforming network through a respective input port.

Abstract: A bent-segment helical antenna utilizes one or more radiators wrapped in a helical fashion. The radiators are comprised of a plurality of segments. A first segment extends from a feed network at a first end of a radiator portion of the antenna toward a second end of the radiator portion. A second segment is adjacent to and offset from the first segment. A third segment connects the first and second segments at the second end of the radiator portion.

Abstract: An improved log periodic dipole antenna, adapted for use in a cellular telephone system, has a plurality of radiating elements with differing lengths. The sequence of lengths selected results in a horizontal beam width of about 65 degrees and a front-to-back signal strength ratio exceeding 45 dB. This combination of characteristics reduces interference among adjacent cellular telephone transmitter sites, and reduces waste of transmission energy from the back of the antenna. A preferred sequence of radiating element lengths is long-short-long-short-long, which may be described as a “double stacked hourglass” configuration.

Abstract: An antenna includes at least two planar conductors cooperatingly arranged in a planar configuration having a bifilar spiral winding structure, a log-periodic structure or a sinuous configuration and a frequency-independent reflective backing situated on one axial side of the planar configuration. The backing includes a solid, disk-shaped dielectric substrate having a relatively high dielectric constant, and three mutually perpendicular arrays of elongated dielectric elements at least partially embedded in the solid dielectric substrate. The elongated dielectric elements have a relatively low dielectric constant. The elongated dielectric elements of the three mutually perpendicular arrays are formed as rods, cones and rings.

Abstract: A polarized planar log periodic antenna is described that is simple in structure and compact in form and which in the dual circularly polarized form may serve as a direct replacement for less capable antennas in RF systems, such as countermeasures systems. An embodiment is characterized by a pair of relatively flat planar linear polarized log periodic antennas of the kind including a plurality of metal radiating elements, each of said radiating elements having the geometry of a circular arc; and the pair of antennas are attached in common to a planar dielectric base; one of said antennas being angularly oriented by ninety degrees relative to the other of said antennas with the radiating elements of one antenna interleaved with the corresponding radiating elements of the other antenna without direct electrical contact between the two antennas. Variations of the structure and novel RF feed line assembly are also described.

Abstract: A low phase error antenna. The antenna is adapted for use with the Global Positioning System and includes a spiral antenna for receiving electromagnetic energy at a first standard frequency (L1) and a second standard frequency (L2). The spiral antenna has a spiral element with a circumference greater than approximately one and a half times the wavelength of electromagnetic energy at the lowest frequency (L2). The cavity of the antenna is unloaded and includes a balun adjusted for zero squint. The antenna element is either a logarithmic spiral or an archimedian spiral. In the illustrative embodiment, the spiral antenna includes a cavity having a depth which varies in accordance with the received electromagnetic energy. The cavity is approximately ¼ of a wavelength deep at the positions along spiral that receive electromagnetic energy.

Abstract: A reconfigurable photoconducting antenna is created on a semiconductor substrate. At equilibrium, the semiconductor is semi-insulating, and therefore appears as a dielectric. Illuminating a region of the substrate results in the generation of free carriers in the substrate and allows the creation of a conductive region (semi-metallic) in the substrate. This conductive region functions as the radiating element of the antenna. Controlling the pattern of the illuminated region directly controls the pattern of the radiating antenna. By using a digital micromirror device (DMD™) to control the pattern of the light, a desired antenna design may be placed on the semiconductor substrate. The pattern can be dynamically adjusted simply by changing the position of the individual mirrors in the DMD™ array. The device operates through a standardized digital interface and can be switched between patterns in a period of approximately 20 microseconds.

Abstract: A sectored antenna system has one or more dielectric lenses, each having a surface and two or more low profile antenna feed devices. At least one of the feed devices radiate signals into said lens that emerge as separate directional beams, and/or the lenses receive incoming signals from different directions and focus them onto different antenna feed devices. The feed devices of the sectored antenna system are low-profile broadband feed devices, such as log periodic dipole arrays or tapered notch antennas. Special design guidelines are given for their use with a lens. In addition, a method to reduce the cut off frequency of the tapered notch antenna is shown.