An Ethernet over coaxial adapter (Eoc) for coupling an Ethernet transceiver to a coaxial cable, said adapter comprising at least: - a transmitting port adapted to the 10Base-T or to the 100Base-TX standard; - a receiving port adapted to the 10Base-T or to the 100Base-TX standard; - a coaxial port adapted to be connected to a coaxial cable; - a first set of passive components; - a second set of passive components; wherein: - the first set of passive components is connected to the transmitting port, the coaxial port and the second set of passive elements; - the first set of passive components comprises at least a first transformer and an impedance matching network (Cm, Rm) having a load impedance, the first transformer connecting the signal from the transmitting port to both the coaxial port and the impedance matching network (Cm, Rm), the load impedance matching the coaxial cable impedance in order to minimize the coupling between the transmission port and the receiving port and to maximize the coupling between the coaxial port and the transmission port; - the second set of passive components is connected to at least the coaxial port through the first set of passive components and to the receiving port, the second set of passive components comprising at least a second transformer adapted to match the impedance of the receiving port and the impedance of the coaxial cable connected to the coaxial port in order to maximize the coupling between the receiving port and the coaxial port; - the transmitting port is connected to the primary coil of the first transformer, the secondary coil of the first transformer comprises a central tap splitting the secondary coil of the first transformer in an upper and a lower secondary coil, the central tap is connected to the second set of passive elements, the lower secondary coil is connected to the impedance matching network (Cm, Rm) and the upper secondary coil is connected to the coaxial port. - a transmitting port adapted to the 10Base-T or to the 100Base-TX standard; - a receiving port adapted to the 10Base-T or to the 100Base-TX standard; - a coaxial port adapted to be connected to a coaxial cable; - a first set of passive components; - a second set of passive components; - the first set of passive components is connected to the transmitting port, the coaxial port and the second set of passive elements; - the first set of passive components comprises at least a first transformer and an impedance matching network (Cm, Rm) having a load impedance, the first transformer connecting the signal from the transmitting port to both the coaxial port and the impedance matching network (Cm, Rm), the load impedance matching the coaxial cable impedance in order to minimize the coupling between the transmission port and the receiving port and to maximize the coupling between the coaxial port and the transmission port; - the second set of passive components is connected to at least the coaxial port through the first set of passive components and to the receiving port, the second set of passive components comprising at least a second transformer adapted to match the impedance of the receiving port and the impedance of the coaxial cable connected to the coaxial port in order to maximize the coupling between the receiving port and the coaxial port; - the transmitting port is connected to the primary coil of the first transformer, the secondary coil of the first transformer comprises a central tap splitting the secondary coil of the first transformer in an upper and a lower secondary coil, the central tap is connected to the second set of passive elements, the lower secondary coil is connected to the impedance matching network (Cm, Rm) and the upper secondary coil is connected to the coaxial port.