casing essentially consisting of one or more biodegradable materials according to the invention the embedding step comprises forming the antenna by layering conductive material directly on biodegradable material and covering the antenna by biodegradable material by means of the invention environmentally friendly and pulping compatible transponders can be manufactured for example for aiding the logistics of forest industry application_number US 200913141190 A description fig1 shows a wedge shaped transponder 10 according to one embodiment of the invention the transponder 10 is elongated in one direction and comprises a first edge 12 on a longitudinal side thereof the first edge 12 being adapted to penetrate to wood foremost the transponder 10 further comprises an elongated wedge shaped first portion 14 extending from the first edge 12 in order to displace wood while the first edge 12 penetrates into the wood the transponder further comprises a second portion 15 which extends from the wedge shaped first portion 14 away from the first edge 12 and forms the second edge 16 of the transponder according to one embodiment the casing comprises one or more shoulders or recesses extending perpendicular to the insertion direction of the transponder for efficiently preventing disengagement of the transponder from the wood material after insertion this is because after displacement of the wood material during penetration of the wedge shaped part of the transponder the resilient wood material expands as it tries to return to its original shape thus locking the transponder firmly to the wood according to the embodiment shown in fig1 the wedge shaped first portion 14 has a maximum width.