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Integrated antenna system

  • US 6,011,524 A
  • Filed: 05/24/1994
  • Issued: 01/04/2000
  • Est. Priority Date: 05/24/1994
  • Status: Expired due to Fees
First Claim
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1. An integrated quadrifilar helix antenna system for receiving and transmitting electromagnetic waves of wave length λ

  • , comprising;

    four spaced apart helical conductors wound in a common direction, the helical conductors defining a common central axis and helix antenna, the helical conductors each having a top end and a bottom end;

    a first ground plane perpendicular to the central axis, the ground plane having a top surface and a bottom surface and a thickness therebetween, the first ground plane extending radially outward at least a preselected distance from the central axis beyond the bottom ends of the helical conductors;

    conductive connections connecting the respective bottom ends of the helical conductors to the top surface of the first ground plane;

    a dome enclosure having a proximal opening to receive the helical conductors and the conductive connections, the opening configured for mounting to the top surface of the ground plane;

    a second ground plane having a second top surface and a second bottom surface and a thickness therebetween, the second ground plane mounted below the first ground plane, the first and second ground planes configured to define a first planar cavity between a recessed portion of the bottom surface of the first ground plane and a second planar cavity between a corresponding recessed portion of the top surface of the second ground plane, the periphery of the first and second ground planes configured to provide an electrically conductive connection surrounding the first and second cavities, the second ground plane providing an input port for transmitting RF signals in and out of the second cavity;

    a signal feed having;

    a) a signal transmission network having a first connection end and a second connection end, the first connection end for coupling RF signals to the top ends of the corresponding helical conductors, the second connection end passing through the first ground plane feedthrough opening;

    b) a signal conditioning circuit including means for impedance matching and power splitting the RF signals to and from the transmission network, the signal conditioning circuit electrically connected to the second connection end of the signal transmission network, the signal conditioning circuit mounted parallel to the ground planes and inside the cavity;

    a transmit/receive board having an upper and a lower surface and a thickness therebetween, the transmit/receive board including a low noise preamplifier means for amplifying RF signals from the signal conditioning circuit, the amplifier means having a predetermined gain and noise figure;

    a conducting planar cover plate having an upper and a lower surface, the lower surface defining a base plane distal to the helix antenna, the upper surface of the cover plate defining a third cavity recessed from the upper surface of the cover plate, the third cavity configured to receive the transmit/receive circuit board, the circuit board mounted parallel to and spaced apart between the upper surface of the cover plate and the lower surface of the second ground plane, the cover plate mounted perpendicular to the central axis, the cover plate mounted below the second ground plane, the cover plate providing an axial bore therethrough;

    a coaxial cable connector for connecting the amplified RF signals from the preamplifier means to a proximal end of a coaxial cable, the cable connector mounted below the lower surface of the transmit/receive board, the connector projecting axially through the cover plate axial bore;

    in combination, the elevation and azimuthal gain profile of the helix antenna and the dome enclosure, the signal splitting and impedance matching of the signal conditioning circuit, the gain and noise figure of the preamplifier means each having predetermined characteristics, the antenna system defining an overall height between the top end of the enclosure and the cover plate base plane of about 127 mm;

    the antenna system having a G/T profile as measured at the distal end of the coaxial cable, including up to 10 dB of cable loss between the cable distal end and the cable proximal end, which meets the SDM specification;

    wherein the first and second ground planes provide a conducting shield between the helical conductors above the ground planes and other conducting elements located below the ground planes such that the cavity between the first and second ground planes providing a suitable containment structure for the signal conditioning circuit effectively isolating the circuit from the antenna helical conductors.

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