Planar microwave antenna for producing circular polarization from a patch radiator
First Claim
1. A low-profile antenna for sending and/or receiving circularly polarized waves and which employs aperture coupling with a series feed line, the combination comprising:
- conductive patch means substantially parallel to and supported above a first surface of a conductive ground plane;
at least first and second orthogonally oriented, coupling apertures formed in the said ground plane, said apertures positioned beneath said conductive patch means;
a pair of coupling means; and
a microstrip transmission line series connected between said coupling means and positioned parallel to and supported below a second surface of said ground plane, said transmission line positioned to pass beneath both said apertures, said coupling means positioned at both ends of said microstrip transmission line for connection to external circuitry.
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Abstract
A planar antenna is described which employs a thin patch of conductive material supported above and substantially parallel to a closely spaced thin conductive ground surface. Two or more narrow slots are positioned in the ground surface beneath the conductive patch. A microstrip transmission line, placed below the ground surface, excites the slots in series. The length of the microstrip line between the slots, the position of the microstrip line across the slots, and the dimensions of the slots are chosen to excite two orthogonal modes in the conductive patch in phase quadrature. This excitation results in a planar antenna which receives and transmits electromagnetic waves of circular polarization. The antenna may also employ a coplanar waveguide transmission line instead of the aformentioned microstrip transmission line. The coupling apertures then form slot discontinuities in series with the coplanar transmission line, which are positioned under the conductive patch. The antenna may also employ several conductive patches stacked over each other in a parallel fashion to enhance antenna performance.
45 Citations
18 Claims
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1. A low-profile antenna for sending and/or receiving circularly polarized waves and which employs aperture coupling with a series feed line, the combination comprising:
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conductive patch means substantially parallel to and supported above a first surface of a conductive ground plane; at least first and second orthogonally oriented, coupling apertures formed in the said ground plane, said apertures positioned beneath said conductive patch means; a pair of coupling means; and a microstrip transmission line series connected between said coupling means and positioned parallel to and supported below a second surface of said ground plane, said transmission line positioned to pass beneath both said apertures, said coupling means positioned at both ends of said microstrip transmission line for connection to external circuitry. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A low-profile antenna for sending and/or receiving circularly polarized waves and which employs aperture coupling with a series feed line, the combination comprising:
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conductive patch means substantially parallel to and supported above a first surface of a conductive ground plane; at least first and second orthogonally oriented, coupling apertures formed in the said ground plane, said apertures positioned beneath said conductive patch means; a pair of coupling means; and a coplanar waveguide comprising a central strip disposed within a channel in said ground plane, said waveguide positioned to intersect both said apertures, - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification