A hand-held antenna specifically for GPS applications is provided which includes a microstrip patch antenna having a ground board, a single radiating patch spaced from the ground board and a resonant cavity defined between the ground board and the single radiating patch. Feed points are provided, one...http://www.google.com.hk/patents/US6252553?utm_source=gb-gplus-share專利 US6252553 - Multi-mode patch antenna system and method of forming and steering a spatial null
