Abstract: A transponder comprises a retro-reflective antenna array in which the length of the transmission lines is given by I=±A n&lgr; where: A is an arbitrary length; n is zero, or an integer, &lgr; is the wavelength of the retro-reflected signal. The array is fabricated on a board (71) of insulating material, using microstrip techniques. Rectangular patches (not shown) form the individual antennae and these are interconnected by transmission lines (75 to 82), each of which pass through a respective modulation device (43) whereby the retro-reflected signal is modulated. A positioning/tracking system incorporating one or more modulated transponders is also disclosed.

Abstract: Method/apparatus for extracting substance from carrier liquid in first container into an immiscible extraction liquid of different density in second container receiving and locating the first. Substance transfers to extraction liquid at liquids admixture in second container aided by flow control and fine division of carrier liquid force supplied into extraction liquid. Separated liquids receive separator member cooperating with second container as physical barrier with only separated extraction and acquired substance at one side. Centrifuging produces three-stage dividing flow of carrier liquid on the second container wall. Moulded parts suit single use in centrifuge.

Abstract: Apparatus for dispensing items desired by the user in response to the introduction of a valid security card and additional predetermined information. The apparatus includes means for reading data from the security card, keyboard means for introducing additional information and electronic logic for determining the validity of the card and the validity of the predetermined information. A security card is provided including a first area to record the number of uses of said card and a second area to record the date of the last use. The apparatus includes logic to prevent dispensing and to retain the card if the card has been used more than a predetermined number of times or more than once within a predetermined time interval.