Antenna with rotatable sensitivity pattern

• US 3,996,592 A
• Filed: 01/17/1974
• Issued: 12/07/1976
• Est. Priority Date: 02/04/1965
• Status: Expired due to Term

• Current Assignee: Orion Industries Incorporated
• Original Assignee: Orion Industries Incorporated
• Inventors: Kline, Larry H., Ukmar, Milosh L.
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US05/434,134
• Time in Patent Office: 1,055 Days
• Field of Search: 343/120, 343/817, 343/818, 343/834, 343/835, 343/836, 343/844, 343/876
• US Class Current: 343/817
• CPC Class Codes: H01Q 3/242 Circumferential scanning
• CPC Class Codes: H01Q 3/44 varying the electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element

Abstract

Antenna having a selectively rotatably extendable sensitivity pattern provided by an array of three or more dipole antenna units, each of substantially equal mechanical length and located at the corners of a substantially regular polygon having the same number of sides as the number of units in the array and switching means having connections to each dipole unit to selectively energize at least one of said units and interpose an electrically-lengthening inductive reactance in at least two other units located, with respect to the direction in which the sensitivity is to be extended, behind and on either side of an energized unit to serve as parasitic reflectors extending the lobe of sensitivity of an energized unit in the selected direction.

Claims

1. An antenna having a rotatable sensitivity pattern and comprising an array of three spaced, substantially vertical, centerfed half wavelength dipole antenna units substantially equidistant from each other by a horizontal distance of substantially 0.15 wavelengths and each having an upper and a lower radiating element separated by a dipole gap, three coaxial cables connected respectively at one end to the antenna units, each of said cables at said one end thereof having an outer conductor connected to one of the radiating elements of the respective antenna unit at one side of the dipole gap and an inner conductor connected to the other radiating element of said antenna unit at the opposite side of the dipole gap, and switching means connected to said coaxial cables at the opposite ends thereof and operable selectively to energize the antenna units one at a time through the respective coaxial cables and to de-energize the two remaining antenna units, each of said coaxial cables having an electrical length such that it constitutes an inductive reactance connected across the dipole gap between the radiating elements of the respective antenna unit when the latter is de-energized by said switching means, whereby the two de-energized antenna units and their respective coaxial cables act as parasitic reflectors for the antenna unit then energized, means to support to said antenna units in their said spaced substantially vertical position, including substantially vertical mast means having a centerline substantially coinciding with the line defined by the centers of the upper and lower substantially equilateral triangles defined by the upper and lower ends of said dipole antenna units.

2. The antenna of claim 1, wherein said switching means open-circuits each of the coaxial cables for the deenergized antenna units at said opposite end thereof, and each coaxial cable has an electrical length within the series consisting of substantially 3/8 wavelength and half wavelength additions thereto.

3. The antenna of claim 1, wherein said switching means short-circuits each of the coaxial cables for the deenergized antenna units at said opposite end thereof, and each coaxial cable has an electrical length within the series consisting of substantially 1/8 wavelength and half wavelength additions thereto.

4. An antenna for producing a rotatable sensitivity pattern comprising three or more antenna units spaced apart from each other and each located at a corner of a substantially regular polygon, said antenna units each comprising a dipole unit having a gap at its center across which said dipole unit is fed, switching means having connections to said antenna units and operable selectively to energize less than half the numbers of said antenna units, and means connected to said switching means and effective in response thereto to add to the effective electrical length of remaining idle antenna units, whereby the latter act as parasitic reflectors for the energized antenna unit, said connecting means comprising coaxial cables, each extending from said switching means to the gap in a dipole unit, the center conductor of said cable being connected to one element of said dipole unit and its outer conductor being connected to the other element of said dipole unit, whereby, when a cable does not energize an antenna unit, said inner and outer conductors provide an inductance electrically lengthening the dipole unit to which it is connected, all said reflectors being located, with respect to the desired directionality of increased sensitivity of one or more energized units, behind any energized unit and with at least one electrically lengthened unit on either side of and perpendicularly farther than any energized unit from the line of desired directionality, and no energized unit being at a distance substantially greater than .244 wavelength from a reflector.

5. An antenna according to claim 4 wherein the spacing between said antenna units is substantially 0.15 wavelength, and the mechanical length of the radiating element of each dipole antenna is approximately a quarter wavelength.