An RF identification system having an interrogator operable to send RF interrogations to a transponder and to receive RF responses from the transponder. The interrogator is in electrical communication with a closed slot antenna. The closed slot antenna is formed by an an outer visual magnetic...http://www.google.com.au/patents/US5691731?utm_source=gb-gplus-sharePatent US5691731 - Closed slot antenna having outer and inner magnetic loops
