Patent ID: 6509873
Filing Date: 2003-01-21
Classification: H01Q

Abstract:
A method of producing a circularly polarized wideband traveling wave from a compact, lightweight, planar microstrip antenna for a mobile communications platform, comprising the steps of:forming a microstrip with an upper dielectric layer and a lower dielectric layer; shaping a first conductive patch and a second conductive patch to be circularly curved; disposing said first conductive patch and said second conductive patch on said lower dielectric layer; separating said first conductive patch and said second conductive patch by a gap; disposing a conductive ground plane on a planar surface of said lower dielectric layer; covering said gap by placing a circularly curved coupling patch on said upper dielectric layer; electro-magnetically coupling a single coaxial feed probe to said first patch and said lower dielectric layer in a direction perpendicular to a direction of propagation across said lower dielectric layer; exciting said microstrip to produce a leaky wave radiation; circularly polarizing the leaky wave radiation; the circularly polarizing step further comprising the steps of: producing two perpendicular, radiating fields; and shifting the phase of at least one of the fields until the two fields are 90 degrees out of phase; controlling an antenna radiation level and an input impedance of said antenna by said upper dielectric layer and said lower dielectric layer causing said input impedance to match a leaky wave propagation mode of said leaky wave radiation; positioning said first, second and coupling patches on said layers causing an alteration of a field strength at said single coaxial probe resulting in said field strength matching said input impedance at said single coaxial probe; and aligning said first, second and coupling patches to circularly polarize the leaky wave radiation when a traveling wave propagates along said first, second and coupling patches; wherein the step of producing two perpendicular, radiating fields comprisespropagating a traveling wave from one of the radiating fields along one quarter of a circumference of a circle, resulting in a 6 dB bandwidth of at least 11 per cent.