A contactless payment card reader has a frusto-conical operating volume. The frusto-conical shaped operating volume has defined magnetic field strengths for powering and communicating with proximity payment cards. The reader can serve as a reference reader, which is representative of product readers...http://www.google.de/patents/US7520435?utm_source=gb-gplus-sharePatent US7520435 - Contactless payment card reader with a frusto-conical operating volume
