The invention relates to a method for the continuous production of ethylene homo- and ethylene co-polymers in the presence of radical polymerisation initiators and, optionally, molecular weight regulators in a tubular reactor with a hot water jacket and one or several reaction zones at pressures of 1000 to 4000 bar and temperatures of 120 C. The method includes opening a credit account for a customer. The hard mask and the low-k material layer therebelow are etched to form cavities. The transceiver further includes at least one downlink transmitter, which is adapted to receive an echo signal from the respective transducer, and is configured to extract envelope information from the echo signal and to transmit a modulated echo signal over a respective downlink wireless channel.