A low visibility, field-diverse antenna provides cross-polarized fields enhancing signal communications. A generally flat, but helical, antenna is achieved in conjunction with a core substrate about which the antenna is wrapped, wound, or fixed. The core substrate, pitch or angle of the helix, and length...http://www.google.com.au/patents/US5977931?utm_source=gb-gplus-sharePatent US5977931 - Low visibility radio antenna with dual polarization
