A Miniature Circularly Polarized Air-Borne Antenna With Wide Angle Coverage

A novel miniature air-borne antenna with circular polarization and wide angle coverage is presented. The antenna is formed with two pairs of modified printed monopoles that are orthogonally placed, and each pair of them coupled with interdigital capacitors and grounding strip lines at the outside. Radiating elements are fed by a power distribution network printed on the bottom. The antenna has a compact size of only 0.17 λ × 0.17 λ × 0.13 (λ is the wavelength corresponding to center frequency in free space) and a shape matching the aircraft nose, which makes it attractive for small-scale air-borne applications. A prototype was fabricated and measured. The measured results agree well with the simulation ones, which reveals that the antenna works on the GPS band (1.575 GHz) and achieves a wide angle coverage (3-dB axial-ratio beamwidth is 112°, from -55° to +57° off the boresight).