Patent ID: 6597316
Filing Date: 2003-07-22
Classification: H01Q

Abstract:
A spatial null steering microstrip antenna array comprising:an inner microstrip patch antenna for use as an auxiliary element in nulling interference; an outer microstrip patch antenna disposed around the inner microstrip patch antenna, the outer microstrip patch antenna having a geometry symmetrical to the inner microstrip patch antenna and resonance in a higher-order mode; a dielectric substrate layer below the inner microstrip patch antenna and outer microstrip patch antenna; a conducting ground plane below the dielectric substrate layer extending beyond the outermost dimensions of the outer microstrip patch antenna; a first set of four coaxial probes, each probe extending up through the conducting ground plane and the dielectric substrate layer and connected on one end to one of four points on the inner microstrip patch antenna symmetrically spaced at 90Â° intervals; a second set of four coaxial probes, each probe extending up through the conducting ground plane and the dielectric substrate layer and connected on one end to one of four points on the outer microstrip patch antenna symmetrically spaced at 90Â° intervals; wherein each of the first set and second set of probes are driven in equal amplitudes but at relative phase angles of 0Â°, 90Â°, 180Â°, and 270Â° respectively, thereby forcing the outer microstrip patch antenna and inner microstrip patch antenna to each generate a right hand circularly polarized lower order TM11 mode far field radiation pattern and allowing co-modal phase tracking between the inner microstrip patch antenna and outer microstrip patch antennas; and means for shaping a combined radiation pattern of the inner microstrip patch antenna and outer microstrip patch antennas to null out received signals from interference sources at a pre-selected elevation angle.