Integrated Strip Gratings on Top of Microstrip Antennas and Arrays for Low and Ultra-Low Cross-Polar Radiation

Abstract

Antennas with very low levels of cross-polarization are useful for many applications in communication, radar and remote-sensing. Printed antennas and arrays, although attractive due to their light weight, conformability and low cost [1,2], may not meet the low cross-polarization requirements. The cross-polar radiation may be introduced due to unwanted radiation from feed networks and active circuitry. Orthogonal currents, either inherently excited on the antenna elements, or additionally induced due to mutual coupling with other elements in an array environment, can contribute to cross-polar radiation. The dielectric substrate of the antenna can also introduce cross-polar radiation in off-principal directions. It may be particularly difficult to maintain a uniformly low level of cross-polarization over a broad scan angle or a broad bandwidth.